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Sample records for biocontrol harlequin ladybird

  1. Bridgehead effect in the worldwide invasion of the biocontrol harlequin ladybird.

    PubMed

    Lombaert, Eric; Guillemaud, Thomas; Cornuet, Jean-Marie; Malausa, Thibaut; Facon, Benoît; Estoup, Arnaud

    2010-03-17

    Recent studies of the routes of worldwide introductions of alien organisms suggest that many widespread invasions could have stemmed not from the native range, but from a particularly successful invasive population, which serves as the source of colonists for remote new territories. We call here this phenomenon the invasive bridgehead effect. Evaluating the likelihood of such a scenario is heuristically challenging. We solved this problem by using approximate Bayesian computation methods to quantitatively compare complex invasion scenarios based on the analysis of population genetics (microsatellite variation) and historical (first observation dates) data. We applied this approach to the Harlequin ladybird Harmonia axyridis (HA), a coccinellid native to Asia that was repeatedly introduced as a biocontrol agent without becoming established for decades. We show that the recent burst of worldwide invasions of HA followed a bridgehead scenario, in which an invasive population in eastern North America acted as the source of the colonists that invaded the European, South American and African continents, with some admixture with a biocontrol strain in Europe. This demonstration of a mechanism of invasion via a bridgehead has important implications both for invasion theory (i.e., a single evolutionary shift in the bridgehead population versus multiple changes in case of introduced populations becoming invasive independently) and for ongoing efforts to manage invasions by alien organisms (i.e., heightened vigilance against invasive bridgeheads).

  2. Harmonine, a defence compound from the harlequin ladybird, inhibits mycobacterial growth and demonstrates multi-stage antimalarial activity

    PubMed Central

    Röhrich, Christian Rene; Ngwa, Che Julius; Wiesner, Jochen; Schmidtberg, Henrike; Degenkolb, Thomas; Kollewe, Christian; Fischer, Rainer; Pradel, Gabriele; Vilcinskas, Andreas

    2012-01-01

    The harlequin ladybird beetle Harmonia axyridis has been introduced in many countries as a biological control agent, but has become an invasive species threatening the biodiversity of native ladybirds. Its invasive success has been attributed to its vigorous resistance against diverse pathogens. This study demonstrates that harmonine ((17R,9Z)-1,17-diaminooctadec-9-ene), which is present in H. axyridis haemolymph, displays broad-spectrum antimicrobial activity that includes human pathogens. Antibacterial activity is most pronounced against fast-growing mycobacteria and Mycobacterium tuberculosis, and the growth of both chloroquine-sensitive and -resistant Plasmodium falciparum strains is inhibited. Harmonine displays gametocytocidal activity, and inhibits the exflagellation of microgametocytes and zygote formation. In an Anopheles stephensi mosquito feeding model, harmonine displays transmission-blocking activity. PMID:21937493

  3. Increase in male reproductive success and female reproductive investment in invasive populations of the harlequin ladybird Harmonia axyridis.

    PubMed

    Laugier, Guillaume J M; Le Moguédec, Gilles; Tayeh, Ashraf; Loiseau, Anne; Osawa, Naoya; Estoup, Arnaud; Facon, Benoît

    2013-01-01

    Reproductive strategy affects population dynamics and genetic parameters that can, in turn, affect evolutionary processes during the course of biological invasion. Life-history traits associated with reproductive strategy are therefore potentially good candidates for rapid evolutionary shifts during invasions. In a series of mating trials, we examined mixed groups of four males from invasive and native populations of the harlequin ladybird Harmonia axyridis mating freely during 48 hours with one female of either type. We recorded the identity of the first male to copulate and after the 48 h-period, we examined female fecundity and share of paternity, using molecular markers. We found that invasive populations have a different profile of male and female reproductive output. Males from invasive populations are more likely to mate first and gain a higher proportion of offspring with both invasive and native females. Females from invasive populations reproduce sooner, lay more eggs, and have offspring sired by a larger number of fathers than females from native populations. We found no evidence of direct inbreeding avoidance behaviour in both invasive and native females. This study highlights the importance of investigating evolutionary changes in reproductive strategy and associated traits during biological invasions.

  4. The invasion history, distribution and colour pattern forms of the harlequin ladybird beetle Harmonia axyridis (Pall.) (Coleoptera, Coccinellidae) in Slovakia, Central Europe

    PubMed Central

    Panigaj, Ľubomír; Zach, Peter; Honěk, Alois; Nedvěd, Oldřich; Kulfan, Ján; Martinková, Zdenka; Selyemová, Diana; Viglášová, Sandra; Roy, Helen E.

    2014-01-01

    Abstract The harlequin ladybird beetle Harmonia axyridis (Coleoptera, Coccinellidae) has invaded and established in Slovakia. Following unintentional introduction in 2008, the spread of the alien coccinellid was very fast. By the end of 2009, it was recorded across the whole country, and by the end of 2012 it was widely distributed and common in various habitats, particularly gardens, orchards and urban areas, where it was most frequent on trees. The rate of eastward spread was approximately 200 km year-1, similar to the overall rate of spread in Europe. Between 2008 and 2012, the coccinellid was recorded in a total of 153 localities, in altitudes ranging from 98 to 1,250 m. Most records of this species were made in lowlands, hilly areas and valleys separating mountain ridges. However, it was only rarely documented in areas above 700 m a.s.l. The non-melanic colour form (f. succinea) was dominant along a longitudinal transect including eight urban areas across Slovakia, with the frequency of melanic forms (f. spectabilis and f. conspicua together) between 6.3 and 19.2% and a median equal to 10.5%. The invasion history and distribution of H. axyridis in Slovakia are discussed with regard to the time sequence of records, rate of spread, altitudinal distribution, anthropogenic dispersal, effective recording, proportion of melanic forms and other relevant aspects associated with the spread of this successful invader. PMID:24899863

  5. Can things get worse when an invasive species hybridizes? The harlequin ladybird Harmonia axyridis in France as a case study

    PubMed Central

    Facon, Benoît; Crespin, Laurent; Loiseau, Anne; Lombaert, Eric; Magro, Alexandra; Estoup, Arnaud

    2011-01-01

    So far, only a few studies have explicitly investigated the consequences of admixture for the adaptative potential of invasive populations. We addressed this question in the invasive ladybird Harmonia axyridis. After decades of use as a biological control agent against aphids in Europe and North America, H. axyridis recently became invasive in four continents and has now spread widely in Europe. Despite this invasion, a flightless strain is still sold as a biological control agent in Europe. However, crosses between flightless and invasive individuals yield individuals able to fly, as the flightless phenotype is caused by a single recessive mutation. We investigated the potential consequences of admixture between invasive and flightless biological control individuals on the invasion in France. We used three complementary approaches: (i) population genetics, (ii) a mate-choice experiment, and (iii) a quantitative genetics experiment. The invasive French population and the biological control strain showed substantial genetic differentiation, but there are no reproductive barriers between the two. Hybrids displayed a shorter development time, a larger size and a higher genetic variance for survival in starvation conditions than invasive individuals. We discuss the potential consequences of our results with respect to the invasion of H. axyridis in Europe. PMID:25567954

  6. Investigating the genetic load of an emblematic invasive species: the case of the invasive harlequin ladybird Harmonia axyridis

    PubMed Central

    Tayeh, A; Estoup, A; Hufbauer, R A; Ravigne, V; Goryacheva, I; Zakharov, I A; Lombaert, E; Facon, B

    2013-01-01

    Introduction events can lead to admixture between genetically differentiated populations and bottlenecks in population size. These processes can alter the adaptive potential of invasive species by shaping genetic variation, but more importantly, they can also directly affect mean population fitness either increasing it or decreasing it. Which outcome is observed depends on the structure of the genetic load of the species. The ladybird Harmonia axyridis is a good example of invasive species where introduced populations have gone through admixture and bottleneck events. We used laboratory experiments to manipulate the relatedness among H. axyridis parental individuals to assess the possibility for heterosis or outbreeding depression in F1 generation offspring for two traits related to fitness (lifetime performance and generation time). We found that inter-populations crosses had no major impact on the lifetime performance of the offspring produced by individuals from either native or invasive populations. Significant outbreeding depression was observed only for crosses between native populations for generation time. The absence of observed heterosis is indicative of a low occurrence of fixed deleterious mutations within both the native and invasive populations of H. axyridis. The observed deterioration of fitness in native inter-population crosses most likely results from genetic incompatibilities between native genomic backgrounds. We discuss the implications of these results for the structure of genetic load in H. axyridis in the light of the available information regarding the introduction history of this species. PMID:23610631

  7. Can things get worse when an invasive species hybridizes? The harlequin ladybird Harmonia axyridis in France as a case study.

    PubMed

    Facon, Benoît; Crespin, Laurent; Loiseau, Anne; Lombaert, Eric; Magro, Alexandra; Estoup, Arnaud

    2011-01-01

    So far, only a few studies have explicitly investigated the consequences of admixture for the adaptative potential of invasive populations. We addressed this question in the invasive ladybird Harmonia axyridis. After decades of use as a biological control agent against aphids in Europe and North America, H. axyridis recently became invasive in four continents and has now spread widely in Europe. Despite this invasion, a flightless strain is still sold as a biological control agent in Europe. However, crosses between flightless and invasive individuals yield individuals able to fly, as the flightless phenotype is caused by a single recessive mutation. We investigated the potential consequences of admixture between invasive and flightless biological control individuals on the invasion in France. We used three complementary approaches: (i) population genetics, (ii) a mate-choice experiment, and (iii) a quantitative genetics experiment. The invasive French population and the biological control strain showed substantial genetic differentiation, but there are no reproductive barriers between the two. Hybrids displayed a shorter development time, a larger size and a higher genetic variance for survival in starvation conditions than invasive individuals. We discuss the potential consequences of our results with respect to the invasion of H. axyridis in Europe.

  8. First finding of the parasitic fungus Hesperomyces virescens (Laboulbeniales) on native and invasive ladybirds (Coleoptera, Coccinellidae) in South Africa

    PubMed Central

    Haelewaters, Danny; Minnaar, Ingrid A.; Clusella-Trullas, Susana

    2016-01-01

    Hesperomyces virescens is a fungal ectoparasite (Laboulbeniales) that infects adult ladybirds. Research has recently focused on this parasite due to the discovery of its prevalence on the globally invasive harlequin ladybird Harmonia axyridis and for its potential use in studies of co-evolution and pathogen spread. We collected adults from ten species of ladybirds in the Western Cape Province, South Africa, and screened for the presence of H. virescens. Infections with H. virescens were found in the samples of two species, H. axyridis and the native Cheilomenes propinqua. This marks the first record of H. virescens on H. axyridis from the African continent and the first record on Cheilomenes worldwide. PMID:26861616

  9. Persecutors, Victims and Rescuers in Harlequin Romances.

    ERIC Educational Resources Information Center

    Hassencahl, Fran

    Based on a pattern of interaction, in which the interactants fulfill the roles of victim, persecutor, or rescuer, a study of ten Harlequin romantic novels was undertaken to determine what factors provided for the readers' identification with the Harlequin characters. It was found that Harlequin heroines manifested their status as victims by…

  10. A pediatric case of idiopathic Harlequin syndrome

    PubMed Central

    Kim, Ju Young; Lee, Moon Souk; Kim, Seung Yeon; Kim, Hyun Jung; Lee, Soo Jin; You, Chur Woo; Kim, Jon Soo

    2016-01-01

    Harlequin syndrome, which is a rare disorder caused by dysfunction of the autonomic system, manifests as asymmetric facial flushing and sweating in response to heat, exercise, or emotional factors. The syndrome may be primary (idiopathic) with a benign course, or can occur secondary to structural abnormalities or iatrogenic factors. The precise mechanism underlying idiopathic harlequin syndrome remains unclear. Here, we describe a case of a 6-year-old boy who reported left hemifacial flushing and sweating after exercise. He had an unremarkable birth history and no significant medical history. Complete ophthalmological and neurological examinations were performed, and no other abnormalities were identified. Magnetic resonance imaging was performed to exclude lesions of the cerebrum and cervicothoracic spinal cord, and no abnormalities were noted. His final diagnosis was classic idiopathic harlequin syndrome. Herein, we report the first pediatric case of idiopathic harlequin syndrome in Korea. PMID:28018464

  11. Intraguild predation and successful invasion by introduced ladybird beetles.

    PubMed

    Snyder, William E; Clevenger, Garrett M; Eigenbrode, Sanford D

    2004-08-01

    Introductions of two ladybird beetle (Coleoptera: Coccinellidae) species, Coccinella septempunctata and Harmonia axyridis, into North America for aphid biocontrol have been followed by declines in native species. We examined intraguild predation (IGP) between larvae of these two exotic species and larvae of the two most abundant native coccinellids in eastern Washington State, C. transversoguttata and Hippodamia convergens. In pairings between the two native species in laboratory microcosms containing pea ( Pisum sativum) plants, neither native had a clear advantage over the other in IGP. When the natives were paired with either Harmonia axyridis or C. septempunctata, the natives were more frequently the victims than perpetrators of IGP. In contrast, in pairings between the exotic species, neither had an IGP advantage, although overall rates of IGP between these two species were very high. Adding alternative prey (aphids) to microcosms did not alter the frequency and patterns of relative IGP among the coccinellid species. In observations of encounters between larvae, the introduced H. axyridis frequently survived multiple encounters with the native C. transversoguttata, whereas the native rarely survived a single encounter with H. axyridis. Our results suggest that larvae of the native species face increased IGP following invasion by C. septempunctata and H. axyridis, which may be contributing to the speed with which these exotic ladybird beetles displace the natives following invasion.

  12. Harlequin Syndrome Following Resection of Mediastinal Ganglioneuroma

    PubMed Central

    Jeon, Yeong Jeong; Son, Jongbae; Cho, Jong Ho

    2017-01-01

    Harlequin syndrome is a rare disorder of the sympathetic nervous system characterized by unilateral facial flushing and sweating. Although its etiology is unknown, this syndrome appears to be a dysfunction of the autonomic nervous system. To the best of our knowledge, thus far, very few reports on perioperative Harlequin syndrome after thoracic surgery have been published in the thoracic surgical literature. Here, we present the case of a 6-year-old patient who developed this unusual syndrome following the resection of a posterior mediastinal mass. PMID:28382275

  13. Reproduction in Risky Environments: The Role of Invasive Egg Predators in Ladybird Laying Strategies

    PubMed Central

    Paul, Sarah C.; Pell, Judith K.; Blount, Jonathan D.

    2015-01-01

    Reproductive environments are variable and the resources available for reproduction are finite. If reliable cues about the environment exist, mothers can alter offspring phenotype in a way that increases both offspring and maternal fitness (‘anticipatory maternal effects’—AMEs). Strategic use of AMEs is likely to be important in chemically defended species, where the risk of offspring predation may be modulated by maternal investment in offspring toxin level, albeit at some cost to mothers. Whether mothers adjust offspring toxin levels in response to variation in predation risk is, however, unknown, but is likely to be important when assessing the response of chemically defended species to the recent and pervasive changes in the global predator landscape, driven by the spread of invasive species. Using the chemically defended two-spot ladybird, Adalia bipunctata, we investigated reproductive investment, including egg toxin level, under conditions that varied in the degree of simulated offspring predation risk from larval harlequin ladybirds, Harmonia axyridis. H. axyridis is a highly voracious alien invasive species in the UK and a significant intraguild predator of A. bipunctata. Females laid fewer, larger egg clusters, under conditions of simulated predation risk (P+) than when predator cues were absent (P-), but there was no difference in toxin level between the two treatments. Among P- females, when mean cluster size increased there were concomitant increases in both the mass and toxin concentration of eggs, however when P+ females increased cluster size there was no corresponding increase in egg toxin level. We conclude that, in the face of offspring predation risk, females either withheld toxins or were physiologically constrained, leading to a trade-off between cluster size and egg toxin level. Our results provide the first demonstration that the risk of offspring predation by a novel invasive predator can influence maternal investment in toxins within

  14. Reproduction in Risky Environments: The Role of Invasive Egg Predators in Ladybird Laying Strategies.

    PubMed

    Paul, Sarah C; Pell, Judith K; Blount, Jonathan D

    2015-01-01

    Reproductive environments are variable and the resources available for reproduction are finite. If reliable cues about the environment exist, mothers can alter offspring phenotype in a way that increases both offspring and maternal fitness ('anticipatory maternal effects'-AMEs). Strategic use of AMEs is likely to be important in chemically defended species, where the risk of offspring predation may be modulated by maternal investment in offspring toxin level, albeit at some cost to mothers. Whether mothers adjust offspring toxin levels in response to variation in predation risk is, however, unknown, but is likely to be important when assessing the response of chemically defended species to the recent and pervasive changes in the global predator landscape, driven by the spread of invasive species. Using the chemically defended two-spot ladybird, Adalia bipunctata, we investigated reproductive investment, including egg toxin level, under conditions that varied in the degree of simulated offspring predation risk from larval harlequin ladybirds, Harmonia axyridis. H. axyridis is a highly voracious alien invasive species in the UK and a significant intraguild predator of A. bipunctata. Females laid fewer, larger egg clusters, under conditions of simulated predation risk (P+) than when predator cues were absent (P-), but there was no difference in toxin level between the two treatments. Among P- females, when mean cluster size increased there were concomitant increases in both the mass and toxin concentration of eggs, however when P+ females increased cluster size there was no corresponding increase in egg toxin level. We conclude that, in the face of offspring predation risk, females either withheld toxins or were physiologically constrained, leading to a trade-off between cluster size and egg toxin level. Our results provide the first demonstration that the risk of offspring predation by a novel invasive predator can influence maternal investment in toxins within their

  15. Eating chemically defended prey: alkaloid metabolism in an invasive ladybird predator of other ladybirds (Coleoptera: Coccinellidae).

    PubMed

    Sloggett, J J; Davis, A J

    2010-01-15

    By comparison with studies of herbivore physiological adaptation to plant allelochemicals, work on predator physiological adaptation to potentially toxic prey has been very limited. Such studies are important in understanding how evolution could shape predator diets. An interesting question is the specificity of predator adaptation to prey allelochemicals, given that many predators consume diverse prey with different chemical defences. The ladybird Harmonia axyridis, an invasive species in America, Europe and Africa, is considered a significant predatory threat to native invertebrates, particularly other aphid-eating ladybirds of which it is a strong intraguild predator. Although ladybirds possess species-specific alkaloid defences, H. axyridis exhibits high tolerance for allospecific ladybird prey alkaloids. Nonetheless, it performs poorly on species with novel alkaloids not commonly occurring within its natural range. We examined alkaloid fate in H. axyridis larvae after consumption of two other ladybird species, one containing an alkaloid historically occurring within the predator's native range (isopropyleine) and one containing a novel alkaloid that does not (adaline). Our results indicate that H. axyridis rapidly chemically modifies the alkaloid to which it has been historically exposed to render it less harmful: this probably occurs outside of the gut. The novel, more toxic alkaloid persists in the body unchanged for longer. Our results suggest metabolic alkaloid specialisation, in spite of the diversity of chemically defended prey that the predator consumes. Physiological adaptations appear to have made H. axyridis a successful predator of other ladybirds; however, limitations are imposed by its physiology when it eats prey with novel alkaloids.

  16. Harlequin syndrome in childhood - Case report*

    PubMed Central

    Breunig, Juliano de Avelar; Hartmann, Mariana; Freire, Cristiano Firpo; de Almeida Jr, Hiram Larangeira

    2012-01-01

    Harlequin syndrome happens in only one side of the face. In the affected half, the face does not sweat or flush even with simulation. Arms and trunk could also be affected. This condition is induced by heat, exercise and emotional factors. The article reports a case of a nine-year-old female with a 3-year history of unilateral flushing and sweating after exercise; a brief literature review is included. Despite the rarity of this syndrome, dermatologists should recognize this condition and refer these patients to ophthalmological and neurological examination. PMID:23197213

  17. Do wintering Harlequin Ducks forage nocturnally at high latitudes?

    USGS Publications Warehouse

    Rizzolo, D.J.; Esler, Daniel; Roby, D.D.; Jarvis, R.L.

    2005-01-01

    We monitored radio-tagged Harlequin Ducks (Histrionicus histrionicus) to determine whether nocturnal feeding was part of their foraging strategy during winter in south-central Alaska. Despite attributes of our study site (low ambient temperatures, harsh weather, short day length) and study species (small body size, high daytime foraging rates) that would be expected to favor nocturnal foraging, we found no evidence of nocturnal dive-feeding. Signals from eight radio-tagged Harlequin Ducks never exhibited signal loss due to diving during a total of 780 minutes of nocturnal monitoring. In contrast, the same eight birds exhibited signal loss during 62 ± 7% (SE) of 5-minute diurnal monitoring periods (total of 365 minutes of monitoring). Our results suggest that Harlequin Ducks in south-central Alaska face a stringent time constraint on daytime foraging during midwinter. Harlequin Ducks wintering at high latitudes, therefore, may be particularly sensitive to factors that increase foraging requirements or decrease foraging efficiency.

  18. Predation of Ladybird Beetles (Coleoptera: Coccinellidae) by Amphibians

    PubMed Central

    Sloggett, John J.

    2012-01-01

    Studies of predation of ladybird beetles (Coccinellidae) have focused on a limited number of predator taxa, such as birds and ants, while other potential predators have received limited attention. I here consider amphibians as predators of ladybirds. Published amphibian gut analyses show that ladybirds are quite often eaten by frogs and toads (Anura), with recorded frequencies reaching up to 15% of dietary items. Salamanders (Caudata) eat ladybirds less frequently, probably as their habits less often bring them into contact with the beetles. Amphibians do not appear to be deleteriously affected by the potentially toxic alkaloids that ladybirds possess. Amphibians, especially frogs and toads, use primarily prey movement as a release cue to attack their food; it is thus likely that their ability to discriminate against ladybirds and other chemically defended prey is limited. Because of this poor discriminatory power, amphibians have apparently evolved non-specific resistance to prey defensive chemicals, including ladybird alkaloids. Although amphibian-related ladybird mortality is limited, in certain habitats it could outweigh mortality from more frequently studied predators, notably birds. The gut analyses from the herpetological literature used in this study, suggest that in studying predation of insects, entomologists should consider specialized literature on other animal groups. PMID:26466621

  19. Predation of Ladybird Beetles (Coleoptera: Coccinellidae) by Amphibians.

    PubMed

    Sloggett, John J

    2012-07-18

    Studies of predation of ladybird beetles (Coccinellidae) have focused on a limited number of predator taxa, such as birds and ants, while other potential predators have received limited attention. I here consider amphibians as predators of ladybirds. Published amphibian gut analyses show that ladybirds are quite often eaten by frogs and toads (Anura), with recorded frequencies reaching up to 15% of dietary items. Salamanders (Caudata) eat ladybirds less frequently, probably as their habits less often bring them into contact with the beetles. Amphibians do not appear to be deleteriously affected by the potentially toxic alkaloids that ladybirds possess. Amphibians, especially frogs and toads, use primarily prey movement as a release cue to attack their food; it is thus likely that their ability to discriminate against ladybirds and other chemically defended prey is limited. Because of this poor discriminatory power, amphibians have apparently evolved non-specific resistance to prey defensive chemicals, including ladybird alkaloids. Although amphibian-related ladybird mortality is limited, in certain habitats it could outweigh mortality from more frequently studied predators, notably birds. The gut analyses from the herpetological literature used in this study, suggest that in studying predation of insects, entomologists should consider specialized literature on other animal groups.

  20. Ladybirds as Teaching Aids: 1 Collecting and Culturing.

    ERIC Educational Resources Information Center

    Majerus, M. E. N.; And Others

    1989-01-01

    Described are methods for locating, collecting and culturing ladybird beetles. Included are necessary equipment for feeding and breeding the insects and modifications for various species found in Great Britain. Overwintering spots of various species are also listed. (CW)

  1. Idiopathic Harlequin Syndrome Manifesting during Exercise: A Case Report and Review of the Literature

    PubMed Central

    Algahtani, Raghad; Alkahtani, Abdulah

    2017-01-01

    Harlequin syndrome is a rare autonomic disorder characterized by unilateral facial flushing and sweating with contralateral anhidrosis induced by exercise, heat, and emotion. It is usually idiopathic but could be the first manifestation of several serious underlying medical conditions. Medical or surgical treatments are not required for idiopathic Harlequin syndrome, but social and psychological factors may indicate sympathectomy or botulinum toxin injection. In this article, we report a case of idiopathic Harlequin syndrome and review the literature. PMID:28316628

  2. Mixed release of two parasitoids and a polyphagous ladybird as a potential strategy to control the tobacco whitefly Bemisia tabaci

    PubMed Central

    Tan, Xiaoling; Hu, Nana; Zhang, Fan; Ramirez-Romero, Ricardo; Desneux, Nicolas; Wang, Su; Ge, Feng

    2016-01-01

    A mixed species release of parasitoids is used to suppress outbreaks of tobacco whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae); however, this biocontrol may be inhibited by interspecific interactions. We investigated the effects of mixed releases of natural enemies of B. tabaci on predation rates, parasite performance and adult parasitoid emergence under greenhouse conditions. We tested the polyphagous predatory ladybird Harmonia axyridis (Coleoptera: Coccinellidae) and two whitefly-specific parasitoids, namely Encarsia formosa and Encarsia sophia (both, Hymenoptera: Aphelinidae). Harmonia axyridis exhibited the lowest rates of predation when released with each parasitoid than with both parasitoid species together and showed a significant preference for non-parasitized nymphs as prey. Both E. formosa and E. sophia parasitized more B. tabaci when released with the ladybird than when the wasps were released either alone or mixed with the other parasitoid. We also found that the presence of H. axyridis significantly reduced adult parasitoid emergence; the highest rate of adult emergence was obtained with parasitoids released alone. Our results indicate that different combinations of natural enemies can influence observed rates of predation, parasitism, and parasitoid emergence. Therefore, the combination of natural enemies to be used for a particular biological control program should depend on the specific objectives. PMID:27312174

  3. Identification of conditions for successful aphid control by ladybirds in greenhouses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As part of my research on the mass production and augmentative release of ladybirds, I reviewed the primary research literature to test the prediction that ladybirds are effective aphid predators in greenhouses. Aphid population reduction exceeded 50% in most studies and ladybird release rates usual...

  4. A Case of Undiagnosed Harlequin Syndrome Presenting in General Dental Practice.

    PubMed

    Edwards, Kathryn; Schaefer, Andrew; Greenwood, Mark; Staines, Konrad

    2016-01-01

    Harlequin syndrome is a rare, clinically striking syndrome characterized by distinctly demarcated asymmetric facial flushing and sweating. It may be of idiopathic aetiology or caused by demonstrable ipsilateral damage to the sympathetic nervous system. A case is described where a patient presented to her general dental practitioner complaining of distinctly demarcated unilateral facial flushing and sweating. Onward referral resulted in a diagnosis of Harlequin syndrome. CPD/CLINICAL RELEVANCE: This article highlights the neurological signs and symptoms of Harlequin syndrome, making it easier to recognize if it presents in general dental practice.

  5. Shaping leg muscles in Drosophila: role of ladybird, a conserved regulator of appendicular myogenesis.

    PubMed

    Maqbool, Tariq; Soler, Cedric; Jagla, Teresa; Daczewska, Malgorzata; Lodha, Neha; Palliyil, Sudhir; VijayRaghavan, K; Jagla, Krzysztof

    2006-12-27

    Legs are locomotor appendages used by a variety of evolutionarily distant vertebrates and invertebrates. The primary biological leg function, locomotion, requires the formation of a specialised appendicular musculature. Here we report evidence that ladybird, an orthologue of the Lbx1 gene recognised as a hallmark of appendicular myogenesis in vertebrates, is expressed in leg myoblasts, and regulates the shape, ultrastructure and functional properties of leg muscles in Drosophila. Ladybird expression is progressively activated in myoblasts associated with the imaginal leg disc and precedes that of the founder cell marker dumbfounded. The RNAi-mediated attenuation of ladybird expression alters properties of developing myotubes, impairing their ability to grow and interact with the internal tendons and epithelial attachment sites. It also affects sarcomeric ultrastructure, resulting in reduced leg muscle performance and impaired mobility in surviving flies. The over-expression of ladybird also results in an abnormal pattern of dorsally located leg muscles, indicating different requirements for ladybird in dorsal versus ventral muscles. This differential effect is consistent with the higher level of Ladybird in ventrally located myoblasts and with positive ladybird regulation by extrinsic Wingless signalling from the ventral epithelium. In addition, ladybird expression correlates with that of FGF receptor Heartless and the read-out of FGF signalling downstream of FGF. FGF signals regulate the number of leg disc associated myoblasts and are able to accelerate myogenic differentiation by activating ladybird, leading to ectopic muscle fibre formation. A key role for ladybird in leg myogenesis is further supported by its capacity to repress vestigial and to down-regulate the vestigial-governed flight muscle developmental programme. Thus in Drosophila like in vertebrates, appendicular muscles develop from a specialised pool of myoblasts expressing ladybird/Lbx1. The

  6. Effect of photoperiod on slow and fast developing individuals in aphidophagous ladybirds, Menochilus sexmaculatus and Propylea dissecta (Coleoptera: Coccinellidae).

    PubMed

    Singh, Neha; Mishra, Geetanjali; Omkar

    2016-02-01

    The effects of environmental parameters on insect development have been studied extensively. But the reasons for 2 differential developmental rates within same cohort under varying environmental factors have not been explored. For the purpose, in this study the existence and stability of slow and fast development under 5 photoperiods (i.e., 8L: 16D, 10L : 14D, 12L : 12D, 14L : 10D and 16L : 8D; light and dark hours per day) and its effect on body mass and reproductive attributes in 2 aphidophagous ladybirds, Menochilus sexmaculatus (Fabricius) and Propylea dissecta (Mulsant) was examined on Aphis craccivora Koch at 27 ± 1 °C temperature. A clear bimodal (2 peaks, where the first peak represented the fast developing and the 2nd peak slow developing individuals) pattern of distribution at each photoperiod was found. The proportion of slow and fast developing individuals in a cohort differed with photoperiods. The slow developing individuals were more in numbers at 8L : 16D, in equal numbers at 14L : 10D and in less numbers at 16L: 8D, indicating that the variation in emergence was owing to exogenous cues influenced differential rates of mortality. Slow developing individuals had female biased sex ratio, higher longevity and lower body mass than fast developing individuals. Fast developing females laid higher numbers of eggs with higher egg viability than slow developing females. Study of such variations in development at different photoperiods is helpful to understand its role in the development of insects particularly ladybirds and permits the selection of fast developing bioagents for their use in biocontrol of pest species.

  7. Effects of ACTH, capture, and short term confinement on glucocorticoid concentrations in harlequin ducks (Histrionicus histrionicus)

    USGS Publications Warehouse

    Nilsson, P.B.; Hollmén, Tuula E.; Atkinson, S.; Mashburn, K.L.; Tuomi, P.A.; Esler, Daniel; Mulcahy, D.M.; Rizzolo, D.J.

    2008-01-01

    Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks. Harlequin ducks responded to the ACTH challenge with an average three-fold increase in serum corticosterone concentration approximately 90??min post injection, and a four- to five-fold increase in fecal glucocorticoid concentration 2 to 4??h post injection. Serum corticosterone concentrations in wild harlequin ducks increased within min of capture and elevated levels were found for several hours post capture, indicating that surgery and confinement maintain elevated corticosterone concentrations in this species. Mean corticosterone concentrations in wild harlequin ducks held in temporary captivity were similar to the maximum response levels during the ACTH challenge in captive birds. However, large variation among individuals was observed in responses of wild birds, and we found additional evidence suggesting that corticosterone responses varied between hatch year and after hatch year birds. ?? 2008.

  8. Fetal inhibition of inflammation improves disease phenotypes in harlequin ichthyosis.

    PubMed

    Cottle, Denny L; Ursino, Gloria M A; Ip, Sally Chi Ieng; Jones, Lynelle K; Ditommaso, Tia; Hacking, Douglas F; Mangan, Niamh E; Mellett, Natalie A; Henley, Katya J; Sviridov, Dmitri; Nold-Petry, Claudia A; Nold, Marcel F; Meikle, Peter J; Kile, Benjamin T; Smyth, Ian M

    2015-01-15

    Harlequin ichthyosis (HI) is a severe skin disease which leads to neonatal death in ∼50% of cases. It is the result of mutations in ABCA12, a protein that transports lipids required to establish the protective skin barrier needed after birth. To better understand the life-threatening newborn HI phenotype, we analysed the developing epidermis for consequences of lipid dysregulation in mouse models. We observed a pro-inflammatory signature which was characterized by chemokine upregulation in embryonic skin which is distinct from that seen in other types of ichthyosis. Inflammation also persisted in grafted HI skin. To examine the contribution of inflammation to disease development, we overexpressed interleukin-37b to globally suppress fetal inflammation, observing considerable improvements in keratinocyte differentiation. These studies highlight inflammation as an unexpected contributor to HI disease development in utero, and suggest that inhibiting inflammation may reduce disease severity.

  9. Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services.

    PubMed

    Lu, Yanhui; Wu, Kongming; Jiang, Yuying; Guo, Yuyuan; Desneux, Nicolas

    2012-07-19

    Over the past 16 years, vast plantings of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have helped to control several major insect pests and reduce the need for insecticide sprays. Because broad-spectrum insecticides kill arthropod natural enemies that provide biological control of pests, the decrease in use of insecticide sprays associated with Bt crops could enhance biocontrol services. However, this hypothesis has not been tested in terms of long-term landscape-level impacts. On the basis of data from 1990 to 2010 at 36 sites in six provinces of northern China, we show here a marked increase in abundance of three types of generalist arthropod predators (ladybirds, lacewings and spiders) and a decreased abundance of aphid pests associated with widespread adoption of Bt cotton and reduced insecticide sprays in this crop. We also found evidence that the predators might provide additional biocontrol services spilling over from Bt cotton fields onto neighbouring crops (maize, peanut and soybean). Our work extends results from general studies evaluating ecological effects of Bt crops by demonstrating that such crops can promote biocontrol services in agricultural landscapes.

  10. Marking and retention of harlequin bug, Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae), on pheromone baited and unbaited plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Harlequin bug (HB) is an important pest of cole crops in the USA. The sap-sucking adults and nymphs feed on aboveground plant tissues, and can seriously damage the host. Current control measures on cole crops target mainly lepidopteran pests, and the products generally used do not control harlequin ...

  11. Attraction of harlequin bug (Hemiptera: Pentatomidae) to male-produced pheromone and host plants in the field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The harlequin bug is a serious stink bug pest of cruciferous vegetables. New tools are needed for vegetable growers to manage this pest with reduced or no pesticide inputs. We investigated attractants for harlequin bugs as part of a larger project to develop new traps or trap crops to manage this ...

  12. Harlequin Ichthyosis: Prenatal Diagnosis of a Rare Yet Severe Genetic Dermatosis

    PubMed Central

    David, Liji Sarah; Beck, Manisha Madhai; Bindra, Mandeep Singh; Arunachal, Gautham

    2015-01-01

    Harlequin Ichthyosis (HI) is an extremely rare genetic skin disorder. It is the most severe type of ichthyosis. It is characterized by thickened, dry, rough and armor like plates of skin with deep cracks in between. Alternative names for HI include- keratosis diffusafetalis, ichthyosis congenital, icthyosis fetalis, harlequin fetus and icthyosis congenital gravior. It is an autosomal recessive disorder with the majority of affected individuals being homozygous for mutation in the ABCA 12 gene. This condition presents with a wide range of severity and symptoms. Affected neonates usually do not survive beyond first few days of life. We are presenting prenatal diagnosis of a case of this rare condition. PMID:26675324

  13. Nutrition-dependent phenotypes affect sexual selection in a ladybird

    PubMed Central

    Xie, Jiaqin; De Clercq, Patrick; Zhang, Yuhong; Wu, Hongsheng; Pan, Chang; Pang, Hong

    2015-01-01

    Environmental factors play a crucial role in influencing sexual selection in insects and the evolution of their mating systems. Although it has been reported that sexual selection in insects may change in response to varying environments, the reason for these changes remains poorly understood. Here, we focus on the mate selection process of a ladybird, Cryptolaemus montrouzieri, when experiencing low- and high-nutrition diet regimes both in its larval and adult stages. We found that female ladybirds preferred to mate with males reared under high-nutrition diet regimes, regardless of the nutritional conditions they experienced during their own larval stages, indicating that mate choice of female C. montrouzieri is non-random and phenotype-dependent. Such mate choice may depend on visual cues (body or genitalia size) and/or chemical cues (pheromones). Further, females from high-nutrition larval diet regimes produced more eggs than those from low-nutrition larval diet regimes. In addition, diet regimes during adulthood also exerted strong effects on egg production. In summary, our study provides new insight into the mate choice of C. montrouzieri as affected by seasonal changes in resources, and suggests that food availability may be a driving force in mate choice. PMID:26269214

  14. Functional morphology and structural characteristics of wings of the ladybird beetle, Coccinella septempunctata (L.).

    PubMed

    Xiang, Jinwu; Du, Jianxun; Li, Daochun; Zhen, Chong

    2016-06-01

    In recent years, the surface morphology and microstructure of ladybird (Coccinella septempunctata) wings have been used to help design the flapping-wing micro air vehicle (FWMAV). In this study, scanning electron microscopy (SEM) was used to verify the functional roles of the ladybird forewing and hindwing. Surface morphology and the cross-sectional microstructure of the wings are presented. Detailed morphology of ladybird forewings was observed using atomic force microscopy (AFM) and the composition of the wings was characterized using Fourier transformed infrared spectroscopy (FTIR). The ladybird forewing may possess different performance characteristics than the beetle, Allomyrina dichotoma. Additionally, the circular holes in the forewing might be important for decreasing the weight of the forewing and to satisfy requirements of mechanical behavior. Microsc. Res. Tech. 79:550-556, 2016. © 2016 Wiley Periodicals, Inc.

  15. Ladybirds as Teaching Aids: 2. Potential for Practical and Project Work.

    ERIC Educational Resources Information Center

    Majerus, M. E. N.; And Others

    1989-01-01

    Presented are several ideas for projects involving ladybird beetles. Discussed is background information about the insects; and projects involving life histories, intra-specific variation, taxonomy, genetics, behavior, ecology, habitat surveys, population biology, and overwintering biology. Lists 12 references. (CW)

  16. Harlequin ichthyosis in an infant born to a father with eczema.

    PubMed

    Fatima, Saba; Rafiq, Ali; Majid, Zain

    2015-04-01

    Harlequin ichthyosis is characterized by thickening of the layer of the skin which contains keratin. Eczema is a chronic relapsing skin disorder which is also associated with disrupted epidermal barrier. We report the case of a 6-hour-old male patient who was brought to the neonatal intensive care unit of our hospital with crusting skin lesions all over the body, presence of a severe ectropion and deranged electrolytes. A diagnosis of harlequin ichthyosis was made, and the neonate was managed accordingly. However, the infant eventually expired on the seventh day of life. The infant's father was a patient of eczema with a chronic relapsing course and was on oral steroid therapy. As per our knowledge, this is the first reported case of an infant with harlequin ichthyosis born to a father suffering from eczema. The similarities in the pathogenesis of the two diseases and the genetic mutation of filaggrin might suggest an association between the two conditions. Harlequin ichthyosis can hence be looked out for in infants born of parents with eczema.

  17. PCB exposure in sea otters and harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill

    USGS Publications Warehouse

    Ricca, Mark A.; Miles, A. Keith; Ballachey, Brenda E.; Bodkin, James L.; Esler, Daniel; Trust, Kimberly A.

    2010-01-01

    Exposure to contaminants other than petroleum hydrocarbons could confound interpretation of Exxon Valdez oil spill effects on biota at Prince William Sound, Alaska. Hence, we investigated polychlorinated biphenyls (PCBs) in blood of sea otters and harlequin ducks sampled during 1998. PCB concentrations characterized by lower chlorinated congeners were highest in sea otters from the unoiled area, whereas concentrations were similar among harlequin ducks from the oiled and unoiled area. Blood enzymes often elevated by xenobiotics were not related to PCB concentrations in sea otters. Only sea otters from the unoiled area had estimated risk from PCBs, and PCB composition or concentrations did not correspond to reported lower measures of population performance in sea otters or harlequin ducks from the oiled area. PCBs probably did not influence limited sea otter or harlequin duck recovery in the oiled area a decade after the spill.

  18. PCB exposure in sea otters and harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill.

    PubMed

    Ricca, Mark A; Keith Miles, A; Ballachey, Brenda E; Bodkin, James L; Esler, Daniel; Trust, Kimberly A

    2010-06-01

    Exposure to contaminants other than petroleum hydrocarbons could confound interpretation of Exxon Valdez oil spill effects on biota at Prince William Sound, Alaska. Hence, we investigated polychlorinated biphenyls (PCBs) in blood of sea otters and harlequin ducks sampled during 1998. PCB concentrations characterized by lower chlorinated congeners were highest in sea otters from the unoiled area, whereas concentrations were similar among harlequin ducks from the oiled and unoiled area. Blood enzymes often elevated by xenobiotics were not related to PCB concentrations in sea otters. Only sea otters from the unoiled area had estimated risk from PCBs, and PCB composition or concentrations did not correspond to reported lower measures of population performance in sea otters or harlequin ducks from the oiled area. PCBs probably did not influence limited sea otter or harlequin duck recovery in the oiled area a decade after the spill.

  19. Harlequin duck population recovery following the 'Exxon Valdez' oil spill: Progress, process and constraints

    USGS Publications Warehouse

    Esler, Daniel; Bowman, Timothy D.; Trust, Kimberly A.; Ballachey, Brenda E.; Dean, Thomas A.; Jewett, Stephen C.; O'Clair, Charles E.

    2002-01-01

    Following the 1989 'Exxon Valdez' oil spill in Prince William Sound, Alaska, we studied the status of recovery of harlequin duck Histrionicus histrionicus populations during 1995 to 1998. We evaluated potential constraints on full recovery, including (1) exposure to residual oil; (2) food limitation; and (3) intrinsic demographic limitations on population growth rates. In this paper, we synthesize the findings from our work and incorporate information from other harlequin duck research and monitoring programs to provide a comprehensive evaluation of the response of this species to the 'Exxon Valdez' spill. We conclude that harlequin duck populations had not fully recovered by 1998. Furthermore, adverse effects continued as many as 9 yr after the oil spill, in contrast to the conventional paradigm that oil spill effects on bird populations are short-lived. These conclusions are based on the findings that (1) elevated cytochrome P450 (CYP1A) induction on oiled areas indicated continued exposure to oil in 1998; (2) adult female winter survival was lower on oiled than unoiled areas during 1995 to 1998; (3) fall population surveys by the Alaska Department of Fish and Game indicated numerical declines in oiled areas during 1995 to 1997; and (4) densities on oiled areas in 1996 and 1997 were lower than expected using models that accounted for effects of habitat attributes. Based on hypothesized links between oil contamination and demography, we suggest that harlequin duck population recovery was constrained primarily by continued oil exposure. Full population recovery will also be delayed by the time necessary for intrinsic population growth to allow return to pre-spill numbers following cessation of residual oil spill effects. Although not all wildlife species were affected by the 'Exxon Valdez' oil spill, and some others may have recovered quickly from any effects, harlequin duck life history characteristics and benthic, nearshore feeding habits make them susceptible to

  20. Asymmetric reproductive interference between specialist and generalist predatory ladybirds.

    PubMed

    Noriyuki, Suzuki; Osawa, Naoya; Nishida, Takayoshi

    2012-09-01

    1. Closely related species often differ greatly in the quality and breadth of resources exploited, but the actual mechanisms causing these differences are poorly understood. Because in the laboratory specialized species often survive and perform as well or better on host species that are never utilized in nature, negative ecological interactions restricting host range must exist. Here, we focused on reproductive interference, which has been theoretically predicted to drive niche separation between closely related species with overlapping mating signals. 2. We examined the interspecific sexual interactions in relation to ecological specialization and generalization in two sibling ladybird species, Harmonia yedoensis and Harmonia axyridis. Harmonia yedoensis is a specialist predator that preys only on pine aphids, which are highly elusive prey for ladybird hatchlings, whereas H. axyridis is a generalist predator with a broad prey and habitat range. 3. We experimentally showed that conspecific sperm fertilized the vast majority of eggs regardless of mating order (i.e. conspecific sperm precedence) when a female of H. yedoensis or H. axyridis mated with both a conspecific and a heterospecific male. Moreover, we demonstrated that mating opportunities of H. yedoensis females strongly decreased as heterospecific density increased relative to conspecific density. In contrast, in H. axyridis, female mating success was high regardless of conspecific or heterospecific density. 4. Our results suggest that the generalist H. axyridis should be dominant to the specialist H. yedoensis in terms of reproductive interference. Our results support the hypothesis that asymmetric reproductive interference from the dominant species may force the non-dominant species to become a specialist predator that exclusively utilizes less preferred prey in nature.

  1. Movements and foraging effort of Steller's Eiders and Harlequin Ducks wintering near Dutch Harbor, Alaska

    USGS Publications Warehouse

    Reed, J.A.; Flint, P.L.

    2007-01-01

    We studied the movements and foraging effort of radio-marked Steller's Eiders (Polysticta stelleri) and Harlequin Ducks (Histrionicus histrionicus) to evaluate habitat quality in an area impacted by industrial activity near Dutch Harbor, Alaska. Foraging effort was relatively low, with Steller's Eiders foraging only 2.7 ± 0.6 (SE) hours per day and Harlequin Ducks 4.1 ± 0.5 hours per day. Low-foraging effort during periods of high-energetic demand generally suggests high food availability, and high food availability frequently corresponds with reductions in home range size. However, the winter ranges of Harlequin Ducks did not appear to be smaller than usual, with the mean range size in our study (5.5 ± 1.1 km2) similar to that reported by previous investigators. The mean size of the winter ranges of Steller's Eiders was similar (5.1 ± 1.3 km2), but no comparable estimates are available. Eutrophication of the waters near Dutch Harbor caused by seafood processing and municipal sewage effluent may have increased populations of the invertebrate prey of these sea ducks and contributed to their low-foraging effort. The threat of predation by Bald Eagles (Haliaeetus leucocephalus) that winter near Dutch Harbor may cause Steller's Eiders and Harlequin Ducks to move further offshore when not foraging, contributing to an increase in range sizes. Thus, the movement patterns and foraging behavior of these ducks likely represent a balance between the cost and benefits of wintering in a human-influenced environment.

  2. Characteristics and Drivers of High-Altitude Ladybird Flight: Insights from Vertical-Looking Entomological Radar

    PubMed Central

    Jeffries, Daniel L.; Chapman, Jason; Roy, Helen E.; Humphries, Stuart; Harrington, Richard; Brown, Peter M. J.; Handley, Lori-J. Lawson

    2013-01-01

    Understanding the characteristics and drivers of dispersal is crucial for predicting population dynamics, particularly in range-shifting species. Studying long-distance dispersal in insects is challenging, but recent advances in entomological radar offer unique insights. We analysed 10 years of radar data collected at Rothamsted Research, U.K., to investigate characteristics (altitude, speed, seasonal and annual trends) and drivers (aphid abundance, air temperature, wind speed and rainfall) of high-altitude flight of the two most abundant U.K. ladybird species (native Coccinella septempunctata and invasive Harmonia axyridis). These species cannot be distinguished in the radar data since their reflectivity signals overlap, and they were therefore analysed together. However, their signals do not overlap with other, abundant insects so we are confident they constitute the overwhelming majority of the analysed data. The target species were detected up to ∼1100 m above ground level, where displacement speeds of up to ∼60 km/h were recorded, however most ladybirds were found between ∼150 and 500 m, and had a mean displacement of 30 km/h. Average flight time was estimated, using tethered flight experiments, to be 36.5 minutes, but flights of up to two hours were observed. Ladybirds are therefore potentially able to travel 18 km in a “typical” high-altitude flight, but up to 120 km if flying at higher altitudes, indicating a high capacity for long-distance dispersal. There were strong seasonal trends in ladybird abundance, with peaks corresponding to the highest temperatures of mid-summer, and warm air temperature was the key driver of ladybird flight. Climatic warming may therefore increase the potential for long-distance dispersal in these species. Low aphid abundance was a second significant factor, highlighting the important role of aphid population dynamics in ladybird dispersal. This research illustrates the utility of radar for studying high

  3. Geographic and temporal patterns of variation in total mercury concentrations in blood of harlequin ducks and blue mussels from Alaska.

    PubMed

    Savoy, Lucas; Flint, Paul; Zwiefelhofer, Denny; Brant, Heather; Perkins, Christopher; Taylor, Robert; Lane, Oksana; Hall, Jeff; Evers, David; Schamber, Jason

    2017-04-15

    We compared total mercury (Hg) concentrations in whole blood of harlequin ducks (Histrionicus histrionicus) sampled within and among two geographically distinct locations and across three years in southwest Alaska. Blue mussels were collected to assess correlation between Hg concentrations in locally available forage and birds. Mercury concentrations in harlequin duck blood were significantly higher at Unalaska Island (0.31±0.19 mean±SD, μg/g blood) than Kodiak Island (0.04±0.02 mean±SD, μg/g blood). We found no evidence for annual variation in blood Hg concentration between years at Unalaska Island. However, blood Hg concentration did vary among specific sampling locations (i.e., bays) at Unalaska Island. Findings from this study demonstrate harlequin ducks are exposed to environmental sources of Hg, and whole blood Hg concentrations are associated with their local food source.

  4. Geographic and temporal patterns of variation in total mercury concentrations in blood of harlequin ducks and blue mussels from Alaska

    USGS Publications Warehouse

    Savoy, Lucas; Flint, Paul L.; Zwiefelhofer, Denny; Brant, Heather; Perkins, Christopher R.; Taylor, Robert J.; Lane, Oksana P.; Hall, Jefferson S.; Evers, David C.; Schamber, Jason

    2017-01-01

    We compared total mercury (Hg) concentrations in whole blood of harlequin ducks (Histrionicus histrionicus) sampled within and among two geographically distinct locations and across three years in southwest Alaska. Blue mussels were collected to assess correlation between Hg concentrations in locally available forage and birds. Mercury concentrations in harlequin duck blood were significantly higher at Unalaska Island (0.31 ± 0.19 mean ± SD, μg/g blood) than Kodiak Island (0.04 ± 0.02 mean ± SD, μg/g blood). We found no evidence for annual variation in blood Hg concentration between years at Unalaska Island. However, blood Hg concentration did vary among specific sampling locations (i.e., bays) at Unalaska Island. Findings from this study demonstrate harlequin ducks are exposed to environmental sources of Hg, and whole blood Hg concentrations are associated with their local food source.

  5. Cessation of oil exposure in harlequin ducks after the Exxon Valdez oil spill: Cytochrome P4501A biomarker evidence.

    PubMed

    Esler, Daniel; Ballachey, Brenda E; Bowen, Lizabeth; Miles, A Keith; Dickson, Rian D; Henderson, John D

    2016-10-20

    The authors quantified hepatic hydrocarbon-inducible cytochrome P4501A (CYP1A) expression, as ethoxyresorufin-O-deethylase (EROD) activity, in wintering harlequin ducks (Histrionicus histrionicus) captured in Prince William Sound, Alaska (USA), during 2011, 2013, and 2014 (22-25 yr following the 1989 Exxon Valdez oil spill). Average EROD activity was compared between birds from areas oiled by the spill and those from nearby unoiled areas. The present study replicated studies conducted from 1998 to 2009 demonstrating that harlequin ducks using areas oiled in 1989 had elevated EROD activity, indicative of oil exposure, up to 2 decades post spill. In the present study, it was found that average EROD activity during March 2011 was significantly higher in wintering harlequin ducks captured in oiled areas relative to unoiled areas, which the authors interpret to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 22 yr after the original spill. However, the 2011 results also indicated reductions in exposure relative to previous years. Average EROD activity in birds from oiled areas was approximately 2 times that in birds from unoiled areas in 2011, compared with observations from 2005 to 2009, in which EROD activity was 3 to 5 times higher in oiled areas. It was also found that average EROD activity during March 2013 and March 2014 was not elevated in wintering harlequin ducks from oiled areas. The authors interpret these findings to indicate that exposure of harlequin ducks to residual Exxon Valdez oil abated within 24 yr after the original spill. The present study finalizes a timeline of exposure, extending over 2 decades, for a bird species thought to be particularly vulnerable to oil contamination in marine environments. Environ Toxicol Chem 2016;9999:1-7. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  6. Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Schamber, J.L.; Trust, K.A.; Miles, A.K.; Henderson, J.D.; Wilson, B.W.

    2012-01-01

    We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons. These results indicated that harlequin ducks were exposed to lingering hydrocarbons more than three years after the spill.

  7. Chronic hydrocarbon exposure of harlequin ducks in areas affected by the Selendang Ayu oil spill at Unalaska Island, Alaska.

    PubMed

    Flint, Paul L; Schamber, Jason L; Trust, Kimberly A; Miles, A Keith; Henderson, John D; Wilson, Barry W

    2012-12-01

    We evaluated chronic exposure of harlequin ducks (Histrionicus histrionicus) to hydrocarbons associated with the 2004 M/V Selendang Ayu oil spill at Unalaska Island, Alaska. We measured levels of hepatic 7-ethoxyresorufin-O-deethylase activity (EROD) in liver biopsy samples as an indicator of hydrocarbon exposure in three oiled bays and one reference bay in 2005, 2006, and 2008. Median EROD activity in ducks from oiled bays was significantly higher than in the reference bay in seven of nine pairwise comparisons. These results indicated that harlequin ducks were exposed to lingering hydrocarbons more than three years after the spill.

  8. Effects of rearing density of survival, growth, and development of the ladybird Coleomegilla maculata in Culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our research focuses on developing cost- and space-efficient techniques to rear ladybird beetles (Coleoptera: Coccinellidae). We evaluated the effects of rearing density on survival, growth and development of Coleomegilla maculata. The hypothesis that survival decreases as rearing density increases ...

  9. Aphid and ladybird beetle abundance depend on the interaction of spatial effects and genotypic diversity.

    PubMed

    Genung, Mark A; Crutsinger, Gregory M; Bailey, Joseph K; Schweitzer, Jennifer A; Sanders, Nathan J

    2012-01-01

    Intraspecific variation and genotypic diversity of host-plants can affect the structure of associated arthropod communities and the dynamics of populations. Similarly, neighboring plants can also affect interactions between host-plants and their associated arthropods. However, most studies on the effects of host-plant genotypes have largely ignored the potential effects of neighboring host-plants on arthropod communities. In this study, we used a common garden experiment to ask how spatial effects of neighboring patches, along with genotype identity and genotypic diversity in tall goldenrod (Solidago altissima), affect the abundances of a common goldenrod herbivore (Uroleucon nigrotuberculatum) and their dominant predator (Harmonia axyridis, a ladybird beetle). Aphid abundance varied 80-fold among genotypes, while ladybird beetle abundance was not affected by genotype identity. Additionally, there were strong effects of neighboring plots: aphid abundance in a focal plot was positively correlated to aphid abundance in nearby plots, suggesting strong spatial patterning in the abundance of aphids. Neither aphid nor ladybird beetle abundance was affected by genotypic diversity. However, focal plot genotypic diversity mediated the strength of the neighborhood effect (i.e., strong effects for genotype polyculture focal plots and weak effects for genotype monoculture focal plots). Our results show that aphids were directly influenced by host-plant genotype identity while ladybird beetles responded mainly to prey abundance, and suggest that genotypic diversity can influence the effects of spatial processes on the plant-herbivore interactions.

  10. Complete mitochondrial genome sequence of a phytophagous ladybird beetle, Henosepilachna pusillanima (Mulsant) (Coleoptera: Coccinellidae).

    PubMed

    Behere, G T; Firake, D M; Tay, W T; Azad Thakur, N S; Ngachan, S V

    2016-01-01

    Ladybird beetles are generally considered as agriculturally beneficial insects, but the ladybird beetles in the coleopteran subfamily Epilachninae are phytophagous and major plant feeding pest species which causes severe economic losses to cucurbitaceous and solanaceous crops. Henosepilachna pusillanima (Mulsant) is one of the important pest species of ladybird beetle. In this report, we sequenced and characterized the complete mitochondrial genome of H. pusillanima. For sequencing of the complete mitochondrial genome, we used the Ion Torrent sequencing platform. The complete circular mitochondrial genome of the H. pusillanima was determined to be 16,216 bp long. There were totally 13 protein coding genes, 22 transfer RNA, 2 ribosomal RNA and a control (A + T-rich) region estimated to be 1690 bp. The gene arrangement and orientations of assembled mitogenome were identical to the reported predatory ladybird beetle Coccinella septempunctata L. This is the first completely sequenced coleopteran mitochondrial genome from the beetle subfamily Epilachninae from India. Data generated in this study will benefit future comparative genomics studies for understanding the evolutionary relationships between predatory and phytophagous coccinellid beetles.

  11. Spotlight on the positive effects of the ladybird Harmonia axyridis on agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the midst of considerable negativity surrounding the ladybird Harmonia axyridis (Pallas), this paper sheds some light on the positive effects that this predator has had on agriculture. Using resources available at the USDA, National Agricultural Library (DigiTop literature database, Navigator pla...

  12. Powder from cedar heartwood affects oviposition behavior in Coleomegilla maculata: a ladybird native to the Americas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Coleomegilla maculata is a predatory ladybird inhabiting ecosystems in North, Central, and South America. The aim of our research is to discover efficient, low-cost materials that boost oviposition in mass-reared C. maculata fed non-natural foods. We tested the hypothesis that eastern ...

  13. Postharvest Biocontrol: Introspection and Paradigm Shifts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of postharvest biocontrol agents as an alternative to the synthetic, chemical fungicides on a widespread basis has many constraints. During the last twenty years, the field of postharvest biocontrol research has significantly grown and developed and seen the creation of several products. Des...

  14. 75 FR 21568 - Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition to List the Harlequin...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-26

    ... on a Petition to List the Harlequin Butterfly as Endangered AGENCY: Fish and Wildlife Service... butterfly (Atlantea tulita), a butterfly endemic to Puerto Rico, as endangered under the Endangered Species... butterfly may be warranted. Therefore, with the publication of this notice, we are initiating a review...

  15. HABITAT CHARACTERISTICS ASSOCIATED WITH THE DISTRIBUTION AND ABUNDAANCE OF HISTRIONICUS HISTRIONICUS (HARLEQUIN DUCKS)WINTERING IN SOUTHERN NEW ENGLAND

    EPA Science Inventory

    Harlequin ducks that winter along the east coast of North America are listed as an endangered population in Canada, and they use several coastal wintering sites in southern New England, USA that are subject to varying degrees of urbanization. We studied patterns of habitat use b...

  16. Attractiveness of harlequin bug, Murgantia histrionica (Hemiptera: Pentatomidae), aggregation pheromone: field response to isomers, ratios and dose

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-component sesquiterpene pheromone, (3S,6S,7R,10S)- and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol (murgantiol), present in emissions from adult male harlequin bugs Murgantia histrionica, is most attractive in field bioassays to adults and nymphs in the naturally-occurring approximately 1.4:1...

  17. Loss from harlequin ducks of abdominally implanted radio transmitters equipped with percutaneous antennas

    USGS Publications Warehouse

    Mulcahy, D.M.; Esler, Daniel; Stoskopf, M.K.

    1999-01-01

    We documented extrusion and loss of abdominally implanted radio transmitters with percutaneous antennas from adult female Harlequin Ducks (Histrionicus histrionicus). Birds were captured during wing molt (late August to mid-September) in 1995-1997. Of 44 Harlequin Ducks implanted with radios and recaptured, 7 (16%) had lost their transmitters and 5 (11%) had radios in the process of extruding. Most (11 of 12) extrusions and losses occurred in birds implanted with radios in 1996 and recaptured in 1997. We suggest that transmitter extrusions and losses were due largely to changes in transmitter design made between 1095 and 1996. Transmitters implanted in 1996 were cylindrical rather than spherical, had a flat end with an abrupt edge, and the lower portion of the antenna was reinforced. Radio losses occurred after the 7-mo monitoring period and caused no apparent harm to the birds. Investigators using implanted radios with percutaneous antennas for long-term projects should be aware of the potential for radio extrusion and should minimize the problem by using transmitters that have no sharp edges and that are wide, rather than narrow.

  18. Correlates of Harlequin Duck densities during winter in Prince William Sound, Alaska

    USGS Publications Warehouse

    Esler, Daniel; Bowman, Timothy D.; Dean, T.A.; O'Clair, Charles E.; Jewett, S.C.; McDonald, L.L.

    2000-01-01

    We evaluated relationships of Harlequin Duck (Histrionicus histrionicus) densities to habitat attributes, history of habitat contamination by the 1989 Exxon Valdez oil spill, and prey biomass density and abundance during winters 1995-1997 in Prince William Sound, Alaska. Habitat features that explained variation in duck densities included distance to streams and reefs, degree of exposure to wind and wave action, and dominant substrate type. After accounting for these effects, densities were lower in oiled than unoiled areas, suggesting that population recovery from the oil spill was not complete, due either to lack of recovery from initial oil spill effects or continuing deleterious effects. Prey biomass density and abundance were not strongly related to duck densities after accounting for habitat and area effects. Traits of Harlequin Ducks that reflect their affiliation with naturally predictable winter habitats, such as strong site fidelity and intolerance of increased energy costs, may make their populations particularly vulnerable to chronic oil spill effects and slow to recover from population reductions, which may explain lower densities than expected on oiled areas nearly a decade following the oil spill.

  19. Survival of captive and free-ranging Harlequin Ducks (Histrionicus histrionicus) following surgical liver biopsy

    USGS Publications Warehouse

    Mulcahy, D.M.; Esler, Daniel

    2010-01-01

    We measured intra- and postoperative mortality rates of captive and free-ranging Harlequin Ducks (Histrionicus histrionicus) undergoing surgical liver biopsy sampling for determination of the induction of cytochrome P4501A, a biomarker of oil exposure. Liver biopsies were taken from and radio transmitters were implanted into 157 free-ranging Harlequin Ducks over three winters (55 in 2000, 55 in 2001, and 47 in 2002). No birds died during surgery, but seven (4.5%) died during recovery from anesthesia (three in 2001 and four in 2002). None of the deaths could be attributed directly to the liver biopsy. Four of the 150 (2.7%) birds that were released died in the 2 wk period after surgery. All post-release deaths occurred in 2001; no birds died after release in 2000 or 2002. No mortalities of 36 captive birds occurred during surgery or recovery or in the 2 wk period following surgery. Hemorrhage was a minor problem with one captive bird. Surgical liver biopsies appear to be a safe procedure, but anesthetic complications may occur with overwintering ducks. ?? Wildlife Disease Association 2010.

  20. Survival of captive and free-ranging Harlequin Ducks (Histrionicus histrionicus) following surgical liver biopsy

    USGS Publications Warehouse

    Mulcahy, Daniel M.; Esler, Daniel N.

    2010-01-01

    We measured intra- and postoperative mortality rates of captive and free-ranging Harlequin Ducks (Histrionicus histrionicus) undergoing surgical liver biopsy sampling for determination of the induction of cytochrome P4501A, a biomarker of oil exposure. Liver biopsies were taken from and radio transmitters were implanted into 157 free-ranging Harlequin Ducks over three winters (55 in 2000, 55 in 2001, and 47 in 2002). No birds died during surgery, but seven (4.5%) died during recovery from anesthesia (three in 2001 and four in 2002). None of the deaths could be attributed directly to the liver biopsy. Four of the 150 (2.7%) birds that were released died in the 2 wk period after surgery. All post-release deaths occurred in 2001; no birds died after release in 2000 or 2002. No mortalities of 36 captive birds occurred during surgery or recovery or in the 2 wk period following surgery. Hemorrhage was a minor problem with one captive bird. Surgical liver biopsies appear to be a safe procedure, but anesthetic complications may occur with overwintering ducks.

  1. Two Strains of Male-Killing Wolbachia in a Ladybird, Coccinella undecimpunctata, from a Hot Climate

    PubMed Central

    Elnagdy, Sherif; Messing, Susan

    2013-01-01

    Ladybirds are a hot-spot for the invasion of male-killing bacteria. These maternally inherited endosymbionts cause the death of male host embryos, to the benefit of female sibling hosts and the bacteria that they contain. Previous studies have shown that high temperatures can eradicate male-killers from ladybirds, leaving the host free from infection. Here we report the discovery of two maternally inherited sex ratio distorters in populations of a coccinellid, Coccinella undecimpunctata, from a hot lowland region of the Middle East. DNA sequence analysis indicates that the male killing is the result of infection by Wolbachia, that the trait is tetracycline sensitive, and that two distinct strains of Wolbachia co-occur within one beetle population. We discuss the implications of these findings for theories of male-killing and suggest avenues for future field-work on this system. PMID:23349831

  2. Influence of ambient humidity on the attachment ability of ladybird beetles (Coccinella septempunctata)

    PubMed Central

    2016-01-01

    Summary Many insects possess adhesive foot pads, which enable them to scale smooth vertical surfaces. The function of these organs may be highly affected by environmental conditions. Ladybird beetles (Coccinellidae) possess dense tarsal soles of tenent setae, supplemented with an adhesive fluid. We studied the attachment ability of the seven-spotted ladybird beetle (Coccinella septempunctata) at different humidities by horizontal traction experiments. We found that both low (15%) and high (99%) relative humidities lead to a decrease of attachment ability. The significantly highest attachment forces were revealed at 60% humidity. This relationship was found both in female and male beetles, despite of a deviating structure of adhesive setae and a significant difference in forces between sexes. These findings demonstrate that not only dry adhesive setae are affected by ambient humidity, but also setae that stick due to the capillarity of an oily secretion. PMID:27826506

  3. Influence of ambient humidity on the attachment ability of ladybird beetles (Coccinella septempunctata).

    PubMed

    Heepe, Lars; Wolff, Jonas O; Gorb, Stanislav N

    2016-01-01

    Many insects possess adhesive foot pads, which enable them to scale smooth vertical surfaces. The function of these organs may be highly affected by environmental conditions. Ladybird beetles (Coccinellidae) possess dense tarsal soles of tenent setae, supplemented with an adhesive fluid. We studied the attachment ability of the seven-spotted ladybird beetle (Coccinella septempunctata) at different humidities by horizontal traction experiments. We found that both low (15%) and high (99%) relative humidities lead to a decrease of attachment ability. The significantly highest attachment forces were revealed at 60% humidity. This relationship was found both in female and male beetles, despite of a deviating structure of adhesive setae and a significant difference in forces between sexes. These findings demonstrate that not only dry adhesive setae are affected by ambient humidity, but also setae that stick due to the capillarity of an oily secretion.

  4. Two strains of male-killing Wolbachia in a ladybird, Coccinella undecimpunctata, from a hot climate.

    PubMed

    Elnagdy, Sherif; Messing, Susan; Majerus, Michael E N

    2013-01-01

    Ladybirds are a hot-spot for the invasion of male-killing bacteria. These maternally inherited endosymbionts cause the death of male host embryos, to the benefit of female sibling hosts and the bacteria that they contain. Previous studies have shown that high temperatures can eradicate male-killers from ladybirds, leaving the host free from infection. Here we report the discovery of two maternally inherited sex ratio distorters in populations of a coccinellid, Coccinella undecimpunctata, from a hot lowland region of the Middle East. DNA sequence analysis indicates that the male killing is the result of infection by Wolbachia, that the trait is tetracycline sensitive, and that two distinct strains of Wolbachia co-occur within one beetle population. We discuss the implications of these findings for theories of male-killing and suggest avenues for future field-work on this system.

  5. Inferring the origin of populations introduced from a genetically structured native range by approximate Bayesian computation: case study of the invasive ladybird Harmonia axyridis.

    PubMed

    Lombaert, E; Guillemaud, T; Thomas, C E; Lawson Handley, L J; Li, J; Wang, S; Pang, H; Goryacheva, I; Zakharov, I A; Jousselin, E; Poland, R L; Migeon, A; Van Lenteren, J; DE Clercq, P; Berkvens, N; Jones, W; Estoup, A

    2011-11-01

    Correct identification of the source population of an invasive species is a prerequisite for testing hypotheses concerning the factors responsible for biological invasions. The native area of invasive species may be large, poorly known and/or genetically structured. Because the actual source population may not have been sampled, studies based on molecular markers may generate incorrect conclusions about the origin of introduced populations. In this study, we characterized the genetic structure of the invasive ladybird Harmonia axyridis in its native area using various population genetic statistics and methods. We found that native area of H. axyridis most probably consisted of two geographically distinct genetic clusters located in eastern and western Asia. We then performed approximate Bayesian computation (ABC) analyses on controlled simulated microsatellite data sets to evaluate (i) the risk of selecting incorrect introduction scenarios, including admixture between sources, when the populations of the native area are genetically structured and sampling is incomplete and (ii) the ability of ABC analysis to minimize such risks by explicitly including unsampled populations in the scenarios compared. Finally, we performed additional ABC analyses on real microsatellite data sets to retrace the origin of biocontrol and invasive populations of H. axyridis, taking into account the possibility that the structured native area may have been incompletely sampled. We found that the invasive population in eastern North America, which has served as the bridgehead for worldwide invasion by H. axyridis, was probably formed by an admixture between the eastern and western native clusters. This admixture may have facilitated adaptation of the bridgehead population.

  6. Rickettsial relative associated with male killing in the ladybird beetle (Adalia bipunctata).

    PubMed

    Werren, J H; Hurst, G D; Zhang, W; Breeuwer, J A; Stouthamer, R; Majerus, M E

    1994-01-01

    A cytoplasmically inherited microorganism associated with male killing in the two-spot ladybird beetle, Adalia bipunctata, is shown to be closely related to bacteria in the genus Rickettsia. Sequencing of a PCR-amplified product of the 16S genes coding for rRNA (16S rDNA) shows the organism associated with male killing in ladybirds to share a common ancestry with the Rickettsias relative to other genera (e.g., Anaplasma, Ehrlichia, and Cowdria). The rickettsial 16S rDNA product is found in four strains of ladybird beetle showing male embryo lethality and is absent from two uninfected strains and an antibiotic-cured strain. In addition, a revertant strain that had naturally lost the male-killing trait failed to amplify the rickettsial 16S rDNA product. Use of PCR primers for a 17-kDa protein antigen which is found only in rickettsias also resulted in an amplified product from infected strains. Uninfected, cured, and revertant strains and insect species infected with related bacteria (cytoplasmic-incompatibility bacteria from Nasonia wasps) failed to amplify the product. Discovery of a close relative of rickettsias associated with sex ratio distortion in insects has implications for the evolution and population dynamics of this bacterial genus.

  7. Winter survival of adult female harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill

    USGS Publications Warehouse

    Esler, Daniel; Schmutz, J.A.; Jarvis, R.L.; Mulcahy, D.M.

    2000-01-01

    Harlequin duck (Histrionicus histrionicus) life-history characteristics make their populations particularly vulnerable to perturbations during nonbreeding periods. The 1989 Exxon Valdez oil spill was a major perturbation to nonbreeding habitats of harlequin ducks in Prince William Sound, Alaska, which resulted in population injury. To assess the status of population recovery from the oil spill and to evaluate factors potentially constraining full recovery, we used radiotelemetry to examine survival of adult female harlequin ducks during winters of 1995-96, 1996-97, and 1997-98. We implanted 294 harlequin ducks (154 and 140 in oiled and unoiled areas, respectively) with transmitters and tracked their signals from aircraft during October through March. We examined variation in survival rates relative to area and season (early, mid, and late winter) through comparisons of models using Akaike's information criterion (AIC(c)) values. The 3 models best supported by the data indicated that survival of birds in oiled areas was lower than in unoiled areas. Inclusion of standardized body mass during wing molt in the 3 best models did not improve their fit, indicating that body mass during wing molt did not affect subsequent winter survival. In the model that best fit our data, survival was high in early winter for both areas, lower during mid and late winter seasons, and lowest in oiled areas during mid winter. Cumulative winter survival estimated from this model was 78.0% (SE = 3.3%) in oiled areas and 83.7% (SE = 2.9%) in unoiled areas. We determined that area differences in survival were more likely related to oiling history than intrinsic geographic differences. Based on a demographic model, area differences in survival offer a likely mechanism for observed declines in populations on oiled areas. Concurrent studies indicated that harlequin ducks continued to be exposed to residual Exxon Valdez oil as much as 9 years after the spill. We suggest that oil exposure

  8. When a repellent becomes an attractant: harmful saponins are kairomones attracting the symbiotic Harlequin crab.

    PubMed

    Caulier, Guillaume; Flammang, Patrick; Gerbaux, Pascal; Eeckhaut, Igor

    2013-01-01

    Marine organisms have developed a high diversity of chemical defences in order to avoid predators and parasites. In sea cucumbers, saponins function as repellents and many species produce these cytotoxic secondary metabolites. Nonetheless, they are colonized by numerous symbiotic organisms amongst which the Harlequin crab, Lissocarcinus orbicularis, is one of the most familiar in the Indo-Pacific Ocean. We here identify for the first time the nature of the molecules secreted by sea cucumbers and attracting the symbionts: saponins are the kairomones recognized by the crabs and insuring the symbiosis. The success of this symbiosis would be due to the ability that crabs showed during evolution to bypass the sea cucumber chemical defences, their repellents becoming powerful attractants. This study therefore highlights the complexity of chemical communication in the marine environment.

  9. Harlequin syndrome with crossed sympathetic deficit of the face and arm.

    PubMed

    Moon, So Young; Shin, Dong-In; Park, Seong-Ho; Kim, Ji Soo

    2005-04-01

    Harlequin syndrome is characterized by unilateral hyperhidrosis and flushing, which are predominantly induced by heat or exercise. Usually, the sympathetic deficits confine to the face. Rarely, the autonomic deficits involve the arm or the parasympathetic neurons in the ciliary ganglia. We report a 43-yr-old woman who presented with facial flushing and sweating in the right side, which were mainly induced by exercise. The facial flushing accompanied relative coldness in the right arm. Valsalva maneuver, cold pressure and 0.125% pilocarpine test, and computed tomography of the chest were normal. The crossed sympathetic deficit in the left face and right arm suggested that the lesions were multifocal. The sympathetic impairment in our patient may lie on a spectrum of pre- and postganglionic autonomic dysfunction, which was observed in Holmes-Adie, Ross, and Guillain-Barre syndromé.

  10. Testing assumptions for unbiased estimation of survival of radiomarked harlequin ducks

    USGS Publications Warehouse

    Esler, Daniel; Mulcahy, Daniel M.; Jarvis, Robert L.

    2000-01-01

    Unbiased estimates of survival based on individuals outfitted with radiotransmitters require meeting the assumptions that radios do not affect survival, and animals for which the radio signal is lost have the same survival probability as those for which fate is known. In most survival studies, researchers have made these assumptions without testing their validity. We tested these assumptions by comparing interannual recapture rates (and, by inference, survival) between radioed and unradioed adult female harlequin ducks (Histrionicus histrionicus), and for radioed females, between right-censored birds (i.e., those for which the radio signal was lost during the telemetry monitoring period) and birds with known fates. We found that recapture rates of birds equipped with implanted radiotransmitters (21.6 ± 3.0%; x̄ ± SE) were similar to unradioed birds (21.7 ± 8.6%), suggesting that radios did not affect survival. Recapture rates also were similar between right-censored (20.6 ± 5.1%) and known-fate individuals (22.1 ± 3.8%), suggesting that missing birds were not subject to differential mortality. We also determined that capture and handling resulted in short-term loss of body mass for both radioed and unradioed females and that this effect was more pronounced for radioed birds (the difference between groups was 15.4 ± 7.1 g). However, no difference existed in body mass after recapture 1 year later. Our study suggests that implanted radios are an unbiased method for estimating survival of harlequin ducks and likely other species under similar circumstances.

  11. Harlequin Duck population injury and recovery dynamics following the 1989 Exxon Valdez oil spill.

    PubMed

    Iverson, Samuel A; Esler, Daniel

    2010-10-01

    The 1989 Exxon Valdez oil spill caused significant injury to wildlife populations in Prince William Sound, Alaska, USA. Harlequin Ducks (Histrionicus histrionicus) were particularly vulnerable to the spill and have been studied extensively since, leading to one of the most thorough considerations of the consequences of a major oil spill ever undertaken. We compiled demographic and survey data collected since the spill to evaluate the timing and extent of mortality using a population model. During the immediate aftermath of the spill, we estimated a 25% decrease in Harlequin Duck numbers in oiled areas. Survival rates remained depressed in oiled areas 6-9 years after the spill and did not equal those from unoiled areas until at least 11-14 years later. Despite a high degree of site fidelity to wintering sites, immigration was important for recovery dynamics, as the relatively large number of birds from habitats outside the spill zone provided a pool of individuals to facilitate numerical increases. On the basis of these model inputs and assumptions about fecundity rates for the species, we projected a timeline to recovery of 24 years under the most-likely combination of variables, with a range of 16 to 32 years for the best-case and worst-case scenarios, respectively. Our results corroborate assertions from other studies that the effects of spilled oil on wildlife can be expressed over much longer time frames than previously assumed and that the cumulative mortality associated with chronic exposure to residual oil may actually exceed acute mortality, which has been the primary concern following most oil spills.

  12. Harlequin Duck recovery from the Exxon Valdez oil spill: A population genetics perspective

    USGS Publications Warehouse

    Lanctot, R.; Goatcher, B.; Scribner, K.; Talbot, S.; Pierson, B.; Esler, Daniel; Zwiefelhofer, D.

    1999-01-01

    Concerns about Harlequin Duck (Histrionicus histrionicus) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds located in different molting and wintering areas belong to genetically distinct and, thus, demographically independent populations. Owing to the lack of direct observations of movements among marine areas, three classes of genetic markers that differed in mode of inheritance were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound (PWS) and the Alaska Peninsula and Kodiak Archipelago (APKA). We could not reject the null hypothesis that the wintering aggregations within each region are composed of a single genetically panmictic population. Differences in genotype frequencies among wintering locations within PWS and APKA were low and nonsignificant for all three classes of markers. Furthermore, we saw no evidence for deviations in Hardy-Weinberg equilibrium or gametic disequilibrium between loci within a winter collection site as would be expected if these locales were composed of individuals from reproductively isolated (and genetically distinct) breeding locales. Finally, no evidence for significant structuring was noted between PWS and APKA. Lack of spatial genetic structuring could be due to the cumulative effects of low levels of gene flow over long time periods, low levels of gene flow by immature birds moving between marine habitats, or to episodic dispersal caused by habitat alteration (e.g. volcanic eruptions). Harlequin Ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from non-affected areas. Demographic studies suggest, however, that levels of movements are low, and that population recovery by emigration is a long-term process.

  13. Feather and faecal corticosterone concentrations predict future reproductive decisions in harlequin ducks (Histrionicus histrionicus)

    PubMed Central

    Hansen, Warren K.; Bate, Lisa J.; Landry, Devin W.; Chastel, Olivier; Parenteau, Charline; Breuner, Creagh W.

    2016-01-01

    Understanding sources of reproductive variation can inform management and conservation decisions, population ecology and life-history theory. Annual reproductive variation can drive population growth rate and can be influenced by factors from across the annual cycle (known as carry-over effects). The majority of studies, however, focus solely on the role of current environmental events. Past events often influence future reproductive decisions and success but can be logistically difficult to collect and quantify, especially in migratory species. Recent work indicates that glucocorticoids may prove good indicators to evaluate carry-over effects across life-history transitions. Here, we evaluated three different measures of glucocorticoid physiology (feathers, faeces and plasma) to evaluate the predictability of future breeding decision in the harlequin duck (Histrionicus histrionicus). We collected tail and back feathers, plasma and faeces for glucocorticoid analysis, and fitted female harlequin ducks with very high-frequency transmitters to track their breeding decisions. Both back feathers (moulted immediately before the current season) and faecal glucocorticoid metabolites were identified as important predictive factors of reproductive decisions; high concentrations of glucocorticoid metabolites in back feathers and faeces predicted a higher likelihood of reproductive deferral for the year. Although back and tail feather corticosterone concentrations were correlated, tail feathers (moulted at the end of the previous breeding season) did not predict breeding decisions. Plasma corticosterone concentrations were collected over too broad a time range after capture to be useful in this study. This study demonstrates the utility of non-invasive corticosterone metrics in predicting breeding decisions and supports the use of feathers to measure carry-over effects in migratory birds. With this technique, we identified the prenuptial moult as an important life

  14. Vestigial and scalloped in the ladybird beetle: a conserved function in wing development and a novel function in pupal ecdysis.

    PubMed

    Ohde, T; Masumoto, M; Morita-Miwa, M; Matsuura, H; Yoshioka, H; Yaginuma, T; Niimi, T

    2009-10-01

    In Drosophila melanogaster, Vestigial (Vg) and Scalloped (Sd) form a transcription factor complex and play a crucial role in wing development. To extend our knowledge of insect wing formation, we isolated vg and sd homologues from two ladybird beetle species, Henosepilachna vigintioctopunctata and Harmonia axyridis. Although the ladybird beetle vg homologues had only low homology with D. melanogaster vg, ectopic expression of H. vigintioctopunctata vg induced wing-like tissues in antennae and legs of D. melanogaster. Subsequent larval RNA interference (RNAi) analysis in H. vigintioctopunctata demonstrated conserved functions of vg and sd in wing development, and an unexpected novel function of sd in pupal ecdysis. Furthermore, our results can be applied to the production of a flightless ladybird beetle for biological control purposes using larval RNAi.

  15. Biotransfer of Cd along a soil-plant- mealybug-ladybird food chain: A comparison with host plants.

    PubMed

    Wang, Xingmin; Zhang, Can; Qiu, Baoli; Ashraf, Umair; Azad, Rashid; Wu, Jianhui; Ali, Shaukat

    2017-02-01

    Agro-ecosystem contamination by the heavy metals present in different agricultural products is a serious challenge faced by the living organisms. This study explains the cadmium (Cd) transfer from soils contaminated with different cadmium concentrations through a plant (eggplant and tomato) - mealybug (Dysmicoccus neobrevipes) - predator (Cryptolaemus-montrouzieri) food chain. The soils were amended with Cd at the rates of 0, 12.5, 25 and 50 mg/kg (w/w). Our findings showed that considerably higher Cd transfer through tomato plant. Cadmium was biomagnified during soil-root transfer while bio-minimization of Cd was observed for shoot-mealybug - ladybird transfer. Our results further showed sequestration of Cd during the metamorphosis of ladybird beetle whilst transfer of Cd through soil-plant-mealybug-ladybird multi-trophic food chain increased in a dose dependent manner. Our results emphasize the need of further studies to elaborate possible mechanisms of Cd bio-minimization by plants, mealybugs and ladybirds observed during this study.

  16. Effects of bioflavonoids on oviposition behavior in the pink-spotted ladybird beetle Coleomegilla maculata (Coleoptera: Coccinellidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One goal of our current research is to mass produce ladybird beetles for biological control of plant pests in greenhouses and other protective structures. Cost-effective mass production involves the use of alternative prey/foods or artificial diets (rather than natural prey, e.g., aphids). One chall...

  17. Does a change from whole to powdered food (Artemia franciscana eggs) increase oviposition in the ladybird Coleomegilla maculata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The limited availability of alternative foods to replace natural prey hinders cost-effective mass production of ladybird beetles for augmentative biological control. We compared the effects of powdered versus whole Artemia franciscana (brine shrimp) eggs with or without a dietary supplement on devel...

  18. Mutations in ABCA12 Underlie the Severe Congenital Skin Disease Harlequin Ichthyosis

    PubMed Central

    Kelsell, David P.; Norgett, Elizabeth E.; Unsworth, Harriet; Teh, Muy-Teck; Cullup, Thomas; Mein, Charles A.; Dopping-Hepenstal, Patricia J.; Dale, Beverly A.; Tadini, Gianluca; Fleckman, Philip; Stephens, Karen G.; Sybert, Virginia P.; Mallory, Susan B.; North, Bernard V.; Witt, David R.; Sprecher, Eli; E. M. Taylor, Aileen; Ilchyshyn, Andrew; Kennedy, Cameron T.; Goodyear, Helen; Moss, Celia; Paige, David; Harper, John I.; Young, Bryan D.; Leigh, Irene M.; Eady, Robin A. J.; O’Toole, Edel A.

    2005-01-01

    Harlequin ichthyosis (HI) is the most severe and frequently lethal form of recessive congenital ichthyosis. Although defects in lipid transport, protein phosphatase activity, and differentiation have been described, the genetic basis underlying the clinical and cellular phenotypes of HI has yet to be determined. By use of single-nucleotide–polymorphism chip technology and homozygosity mapping, a common region of homozygosity was observed in five patients with HI in the chromosomal region 2q35. Sequencing of the ABCA12 gene, which maps within the minimal region defined by homozygosity mapping, revealed disease-associated mutations, including large intragenic deletions and frameshift deletions in 11 of the 12 screened individuals with HI. Since HI epidermis displays abnormal lamellar granule formation, ABCA12 may play a critical role in the formation of lamellar granules and the discharge of lipids into the intercellular spaces, which would explain the epidermal barrier defect seen in this disorder. This finding paves the way for early prenatal diagnosis. In addition, functional studies of ABCA12 will lead to a better understanding of epidermal differentiation and barrier formation. PMID:15756637

  19. Evaluation of a Portable Automated Serum Chemistry Analyzer for Field Assessment of Harlequin Ducks, Histrionicus histrionicus.

    PubMed

    Stoskopf, Michael K; Mulcahy, Daniel M; Esler, Daniel

    2010-01-01

    A portable analytical chemistry analyzer was used to make field assessments of wild harlequin ducks (Histrionicus histrionicus) in association with telemetry studies of winter survival in Prince William Sound, Alaska. We compared serum chemistry results obtained on-site with results from a traditional laboratory. Particular attention was paid to serum glucose and potassium concentrations as potential indicators of high-risk surgical candidates based on evaluation of the field data. The median differential for glucose values (N = 82) between methods was 0.6 mmol/L (quartiles 0.3 and 0.9 mmol/L) with the median value higher when assayed on site. Analysis of potassium on site returned a median of 2.7 mmol/L (N = 88; quartiles 2.4 and 3.0 mmol/L). Serum potassium values were too low for quantitation by the traditional laboratory. Changes in several serum chemistry values following a three-day storm during the study support the value of on site evaluation of serum potassium to identify presurgical patients with increased anesthetic risk.

  20. Phylogeography and demography of Guianan harlequin toads (Atelopus): diversification within a refuge.

    PubMed

    Noonan, Brice P; Gaucher, Philippe

    2005-09-01

    We investigated the genetic structure of populations of Guianan harlequin toads (genus Atelopus) and their evolutionary affinities to extra-Guianan congeners. Phylogenetic analysis of mitochondrial cytochrome b (cyt b) and NADH dehydrogenase subunit 2 (ND2) gene sequences produced well-supported clades largely corresponding to the four recognized taxa in the Guianas (Atelopus spumarius hoogmoedi, Atelopus spumarius barbotini, Atelopus franciscus, and Atelopus flavescens). Our findings suggest that the Guianan A. spumarius represent distinct evolutionary lineages that merit distinction from Amazonian conspecifics, and that the status of A. flavescens and A. franciscus is somewhat less clear. Approximately 69% of the observed genetic variation is accounted for by differences between these four recognized taxa. Coalescent-based estimates of gene flow between taxa suggest that these lineages are largely isolated from one another. Negligible rates of migration between populations and significant divergence within such close proximity suggests that although the region inhabited by these taxa is almost entirely undisturbed, significant habitat heterogeneity exists as to have produced a remarkable diversification of Atelopus within the eastern Guiana Shield. These results contradict the commonly held view of the Guiana Shield as a 'refuge' whose stability during late Tertiary and Quaternary climatic fluctuations served as a biotic reservoir. Instead, we provide evidence that climatic fluctuations during this time had a diversifying effect within the Guianan region.

  1. Evaluation of a Portable Automated Serum Chemistry Analyzer for Field Assessment of Harlequin Ducks, Histrionicus histrionicus

    PubMed Central

    Stoskopf, Michael K.; Mulcahy, Daniel M.; Esler, Daniel

    2010-01-01

    A portable analytical chemistry analyzer was used to make field assessments of wild harlequin ducks (Histrionicus histrionicus) in association with telemetry studies of winter survival in Prince William Sound, Alaska. We compared serum chemistry results obtained on-site with results from a traditional laboratory. Particular attention was paid to serum glucose and potassium concentrations as potential indicators of high-risk surgical candidates based on evaluation of the field data. The median differential for glucose values (N = 82) between methods was 0.6 mmol/L (quartiles 0.3 and 0.9 mmol/L) with the median value higher when assayed on site. Analysis of potassium on site returned a median of 2.7 mmol/L (N = 88; quartiles 2.4 and 3.0 mmol/L). Serum potassium values were too low for quantitation by the traditional laboratory. Changes in several serum chemistry values following a three-day storm during the study support the value of on site evaluation of serum potassium to identify presurgical patients with increased anesthetic risk. PMID:20445783

  2. Neuroglobin Gene Therapy Prevents Optic Atrophy and Preserves Durably Visual Function in Harlequin Mice

    PubMed Central

    Lechauve, Christophe; Augustin, Sébastien; Cwerman-Thibault, Hélène; Reboussin, Élodie; Roussel, Delphine; Lai-Kuen, René; Saubamea, Bruno; Sahel, José-Alain; Debeir, Thomas; Corral-Debrinski, Marisol

    2014-01-01

    Neuroglobin (NGB) is considered as an endogenous neuroprotective molecule against stroke, since the protein alleviates the adverse effects of hypoxic and ischemic insults. We previously demonstrated the functional link between NGB and mitochondria since it is required for respiratory chain function. Thus, here, we evaluated the relevance of this effect in the Harlequin (Hq) mouse strain, which exhibits retinal ganglion cell (RGC) loss and optic atrophy due to a respiratory chain complex I (CI) defect. A twofold decrease of NGB amounts was observed in Hq retinas. We constructed a recombinant adeno-associated virus which combines to the mouse NGB open reading frame, its 5′ and 3′UTR, for guarantying mRNA stability and translation capacity. The vector was administrated intravitreally to Hq mice and NGB expression was stable for up to 7 months without negative effect on retinal architecture or function. On the contrary, RGCs and their axons were substantially preserved from degeneration; consequently, CI activity in optic nerves was protected conferring improvements in vision. Hence, we established that NGB prevents respiratory chain impairment, therefore, protecting visual function otherwise compromised by mitochondrial energetic failure. PMID:24622090

  3. Species sorting and patch dynamics in harlequin metacommunities affect the relative importance of environment and space.

    PubMed

    Leibold, Mathew A; Loeuille, Nicolas

    2015-12-01

    Metacommunity theory indicates that variation in local community structure can be partitioned into components including those related to local environmental conditions vs. spatial effects and that these can be quantified using statistical methods based on variation partitioning. It has been hypothesized that joint associations of community composition with environment and space could be due to patch dynamics involving colonization-extinction processes in environmentally heterogeneous landscapes but this has yet to be theoretically shown. We develop a two-patch, type-two, species competition model in such a "harlequin" landscape (where different patches have different environments) to evaluate how composition is related to environmental and spatial effects as a function of background extinction rate. Using spatially implicit analytical models, we find that the environmental association of community composition declines with extinction rate as expected. Using spatially explicit simulation models, we further find that there is an increase in the spatial structure with extinction due to spatial patterning into clusters that are not related to environmental conditions but that this increase is limited. Natural metacommunities often show both environment and spatial determination even under conditions of relatively high isolation and these could be more easily explained by our model than alternative metacommunity models.

  4. Harlequin ichthyosis model mouse reveals alveolar collapse and severe fetal skin barrier defects.

    PubMed

    Yanagi, Teruki; Akiyama, Masashi; Nishihara, Hiroshi; Sakai, Kaori; Nishie, Wataru; Tanaka, Shinya; Shimizu, Hiroshi

    2008-10-01

    Harlequin ichthyosis (HI), which is the most severe genodermatosis, is caused by loss-of-function mutations in ABCA12, a member of the ATP-binding cassette transporter family. To investigate the pathomechanism of HI and the function of the ABCA12 protein, we generated ABCA12-deficient mice (Abca12(-/-)) by targeting Abca12. Abca12(-/-) mice closely reproduce the human HI phenotype, showing marked hyperkeratosis with eclabium and skin fissure. Lamellar granule abnormalities and defective ceramide distribution were remarkable in the epidermis. Skin permeability assay of Abca12(-/-) fetuses revealed severe skin barrier dysfunction after the initiation of keratinization. Surprisingly, the Abca12(-/-) mice also demonstrated lung alveolar collapse immediately after birth. Lamellar bodies in alveolar type II cells of the Abca12(-/-) mice lacked normal lamellar structures. The level of surfactant protein B, an essential component of alveolar surfactant, was reduced in the Abca12(-/-) mice. Fetal therapeutic trials with systemic administration of retinoid or dexamethasone, which are effective for HI and respiratory distress, respectively, to the pregnant mother mice neither improved the skin phenotype nor extended the survival period. Our HI model mice reproduce the human HI skin phenotype soon after the initiation of fetal skin keratinization and provide evidence that ABCA12 plays pivotal roles in lung and skin barrier functions.

  5. Inflammatory reaction to fabric collars from percutaneous antennas attached to intracoelomic radio transmitters implanted in harlequin ducks (Histrionicus histrionicus)

    USGS Publications Warehouse

    Mulcahy, Daniel M.; Burek, K.A.; Esler, Daniel

    2007-01-01

    In wild birds implanted intracoelomically with radio transmitters, a synthetic fabric collar placed around the base of a percutaneous antenna is believed to function as a barrier to contamination of the coelom. We examined 13 fabric collars recovered from percutaneous antennas of radio transmitters implanted intracoelomically in harlequin ducks (Histrionicus histrionicus) 12 months earlier. Both the transmitters and antenna collars were encapsulated in fibrous connective tissue, with adhesions to internal organs. Histologically, bacteria were evident at the fabric-plastic interface in 8 of 10 collars examined in cross section and along the length of the collar in 3 collars examined longitudinally. Bacteria were confined within the fibrotic sheath surrounding the transmitter and the antenna collar in all birds. No evidence of chronic systemic effects secondary to implantation was present on hematologic or serum biochemical testing. These findings indicate that antenna collars do not prevent the entry of bacteria along the percutaneous antenna but may help stabilize the antenna and minimize coelomic contamination. We conclude that radio transmitters implanted into the coelom of harlequin ducks do not appear to cause significant health problems for at least 1 year after implantation.

  6. Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM223

    PubMed Central

    Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J.; Novinscak, Amy

    2015-01-01

    Pseudomonas fluorescens LBUM223 is a plant growth-promoting rhizobacterium (PGPR) with biocontrol activity against various plant pathogens. It produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of Streptomyces scabies, the causal agent of common scab of potato. Here, we report the complete genome sequence of P. fluorescens LBUM223. PMID:25953163

  7. A blood survey of elements, viral antibodies, and hemoparasites in wintering Harlequin Ducks (Histrionicus histrionicus) and Barrow's Goldeneyes (Bucephala islandica)

    USGS Publications Warehouse

    Heard, D.J.; Mulcahy, D.M.; Iverson, S.A.; Rizzolo, D.J.; Greiner, E.C.; Hall, J.; Ip, H.; Esler, Daniel

    2008-01-01

    Twenty-eight Harlequin Ducks (Histrionicus histrionicus) and 26 Barrow's Goldeneyes (Bucephala islandica) were captured in Prince William Sound, Alaska, between 1 and 15 March 2005. Blood was collected for quantification of element concentrations, prevalence of antibodies to several viruses, and hemoparasite prevalence and identification. Although we found selenium concentrations that have been associated with selenosis in some birds (???.0 ppm ww), our findings contribute to a growing literature describing relatively high selenium in apparently healthy birds in marine environments. Avian influenza virus antibodies were detected in the plasma of 28% of the ducks. No antibodies against adenovirus, reovirus, or paramyxovirus 1 were detected. Several hemoparasite species were identified in 7% of ducks. Our findings are similar to those in other free-living marine waterfowl and do not indicate unusual concerns for the health of these species in this area in late winter. ?? Wildlife Disease Association 2008.

  8. Molecular Characterization and Identification of Biocontrol Isolates of Trichoderma spp.

    PubMed Central

    Hermosa, M. R.; Grondona, I.; Iturriaga, E. A.; Diaz-Minguez, J. M.; Castro, C.; Monte, E.; Garcia-Acha, I.

    2000-01-01

    The most common biological control agents (BCAs) of the genus Trichoderma have been reported to be strains of Trichoderma virens, T. harzianum, and T. viride. Since Trichoderma BCAs use different mechanisms of biocontrol, it is very important to explore the synergistic effects expressed by different genotypes for their practical use in agriculture. Characterization of 16 biocontrol strains, previously identified as “Trichoderma harzianum” Rifai and one biocontrol strain recognized as T. viride, was carried out using several molecular techniques. A certain degree of polymorphism was detected in hybridizations using a probe of mitochondrial DNA. Sequencing of internal transcribed spacers 1 and 2 (ITS1 and ITS2) revealed three different ITS lengths and four different sequence types. Phylogenetic analysis based on ITS1 sequences, including type strains of different species, clustered the 17 biocontrol strains into four groups: T. harzianum-T. inhamatum complex, T. longibrachiatum, T. asperellum, and T. atroviride-T. koningii complex. ITS2 sequences were also useful for locating the biocontrol strains in T. atroviride within the complex T. atroviride-T. koningii. None of the biocontrol strains studied corresponded to biotypes Th2 or Th4 of T. harzianum, which cause mushroom green mold. Correlation between different genotypes and potential biocontrol activity was studied under dual culturing of 17 BCAs in the presence of the phytopathogenic fungi Phoma betae, Rosellinia necatrix, Botrytis cinerea, and Fusarium oxysporum f. sp. dianthi in three different media. PMID:10788356

  9. Molecular cytogenetic studies in the ladybird beetle Henosepilachna argus Geoffroy, 1762 (Coleoptera, Coccinellidae, Epilachninae)

    PubMed Central

    Mora, Pablo; Vela, Jesús; Sanllorente, Olivia; Palomeque, Teresa; Lorite, Pedro

    2015-01-01

    Abstract The ladybird Henosepilachna argus Geoffroy, 1762 has been cytogenetically studied. In addition we have conducted a review of chromosome numbers and the chromosomal system of sex determination available in the literature in species belonging to the genus Henosepilachna and in its closely related genus Epilachna. Chromosome number of Henosepilachna argus was 2n=18, including the sex chromosome pair, a common diploid chromosome number within the tribe Epilachnini. The study of prophase I meiotic chromosomes showed the typical Xyp “parachute” bivalent as in the majority of species of Coccinellidae. C-banding and fluorescent staining with AT-specific DAPI fluorochrome dye have been carried out for the first time in H. argus. C-banding technique revealed that heterochromatic blocks are pericentromerically located and DAPI staining showed that this heterochromatin is AT rich. Fluorescence in situ hybridizations using rDNA and the telomeric TTAGG sequence as probes have been carried out. FISH using rDNA showed that the nucleolar organizing region is located on the short arm of the X chromosome. FISH with the telomeric sequence revealed that in this species telomeres of chromosomes are composed of the pentanucleotide TTAGG repeats. This is the first study on the telomeric sequences in Coccinellidae. PMID:26312131

  10. Sublethal effects of imidacloprid on the predatory seven-spot ladybird beetle Coccinella septempunctata.

    PubMed

    Xiao, Da; Zhao, Jing; Guo, Xiaojun; Chen, Hongying; Qu, Mengmeng; Zhai, Weigang; Desneux, Nicolas; Biondi, Antonio; Zhang, Fan; Wang, Su

    2016-12-01

    The seven-spot ladybird beetle, Coccinella septempunctata, is a major natural enemy of aphids in the field and in greenhouses in China and is part of integrated pest management (IPM). Imidacloprid, a highly efficient insecticide that not only kills aphids at lethal concentrations, but also can cause various sublethal effects in nontarget organisms. To strengthen IPM and its sustainability, it is important assessing possible side effects on natural enemies. When the effects of sublethal concentrations (LC5 and 10%LC5) of imidacloprid on C. septempunctata were evaluated, the adult longevity was shortened by 23.97 and 28.68 %, and the fecundity reduced by 52.81 and 56.09 % compared to control population. In the F1 generation (i.e., the progeny of the exposed individuals), the juvenile development was slower by 1.44 days and 0.66 days, and the oviposition period was shortened by 10 and 13 days, respectively. The fecundity of the F1 generation decreased by 17.88, 44.03 and 51.69 % when exposed to 1%LC5, 10%LC5, and LC5, respectively. The results of demographical growth estimates showed that the intrinsic rate of increase (r m ) and net reproductive rate (R 0 ) were lower in C. septempunctata populations that had been exposed to sublethal concentrations of imidacloprid. The results emphasize the importance of assessing side effects of low imidacloprid concentrations on such predator species, even at the transgenerational level.

  11. Effects of Rearing Density on Survival, Growth, and Development of the Ladybird Coleomegilla maculata in Culture.

    PubMed

    Riddick, Eric W; Wu, Zhixin

    2015-10-09

    Our research focuses on developing techniques to rear ladybird beetles (Coleoptera: Coccinellidae). We evaluated the effects of rearing density on survival, growth, and development of Coleomegilla maculata. The hypothesis that a low to moderate rearing density has limited or no effects on survival and development was tested. C. maculata first instars were reared to pupae at a density of 1, 5, 10, 15, or 20 individuals per arena (2.5 cm high, 9.0 cm diameter, and 159 cm3 volume) and fed powdered brine shrimp (Artemia franciscana) eggs. More larvae survived at the 1 and 5 densities, but no differences were detected between the 10, 15, or 20 densities. Median survival rate was at least 90% for larvae and 100% for pupae at the 10, 15, and 20 densities. Development time, body weight, and sex ratio were unaffected by rearing density. Overall, this study suggests that C. maculata larvae can be reared successfully at a density of 20 larvae/159 cm3 (≈ 0.126 larvae/cm3) in containers provisioned with powdered A. franciscana eggs. Scaling-up the size of containers, and C. maculata density in these containers, should be possible.

  12. The direct effects of male killer infection on fitness of ladybird hosts (Coleoptera: Coccinellidae).

    PubMed

    Elnagdy, S; Majerus, M E N; Gardener, M; Lawson Handley, L-J

    2013-08-01

    Male killing bacteria are common in insects and are thought to persist in host populations primarily by indirect fitness benefits to infected females, whereas direct fitness effects are generally assumed to be neutral or deleterious. Here, we estimated the effect of male killer infection on direct fitness (number of eggs laid, as a measure of fecundity, together with survival) and other life-history traits (development time and body size) in seven ladybird host/male killer combinations. Effects of male killers on fecundity ranged, as expected, from costly to neutral; however, we found evidence of reduced development time and increased survival and body size in infected strains. Greater body size in Spiroplasma-infected Harmonia axyridis corresponded to greater ovariole number and therefore higher potential fecundity. To our knowledge, this is the first report of direct benefits of male killer infection after explicitly controlling for indirect fitness effects. Neutral or deleterious fitness effects of male killer infection should not therefore be automatically assumed.

  13. Defensive allomones function as aggregation pheromones in diapausing Ladybird Beetles, Hippodamia convergens.

    PubMed

    Wheeler, Christopher A; Cardé, Ring T

    2013-06-01

    Identification of the stimuli responsible for the formation of an aggregation can be used to distinguish between social and non-social aggregations and help in the process of identifying the adaptive benefits of the gregarious behavior. The convergent ladybird beetle, Hippodamia convergens, forms dense aggregations during winter diapause. The mechanisms of conspecific attraction and hibernacula site selection of H. convergens are not well understood. In laboratory and field bioassays, we evaluated the role of three defensive compounds in the formation of H. convergens aggregations. Diapausing H. convergens aggregated within the section of an arena exposed to alkylmethoxypyrazines. 2-Isobutyl-3-methoxypyrazine (IBMP) caused the strongest aggregative effect. Beetles also aggregated to some doses of 2-sec-butyl-3-methoxypyrazine, but appeared to be repelled at higher doses. A third constituent, 2-isopropyl-3-methoxypyrazine, generally had little effect on the distribution of beetles, although the highest dose tested was repellent. Beetles also aggregated to a blend of these alkylmethoxypyrazines at their natural ratio. During fall migration to overwintering sites, more beetles aggregated in artificial hibernacula baited with IBMP, confirming its function as an aggregation pheromone. These three pyrazines also function as warning odors that, in conjunction with other aposematic displays (contrasting red and black coloration, gregarious behavior, reflex bleeding), contribute to the multi-modal, anti-predatory defense of coccinellid beetles and some other arthropods. Confirmation of the role of some alkylmethoxypyrazines in coccinellid aggregations suggests that these defensive allomones have been co-opted for intraspecific communication.

  14. Contribution of multiple isolating barriers to reproductive isolation between a pair of phytophagous ladybird beetles.

    PubMed

    Matsubayashi, Kei W; Katakura, Haruo

    2009-10-01

    Reproductive isolation between species may often be attained by multiple isolating barriers, but the components are rarely studied in animal taxa. To elucidate the nature of multiple isolating barriers, we quantified the strength of three premating barriers, including ecologically based ones (seasonal, habitat, and sexual), two postmating-prehatching barriers (reduced egg hatchability and conspecific sperm precedence [CSP]), and one posthatching barrier, including four components of F(1) hybrid reduced fitness, between two phytophagous ladybird beetles, Henosepilachna vigintioctomaculata and H. pustulosa. We detected five positive barriers (habitat isolation, sexual isolation, reduced egg hatchability, CSP, and reduced egg hatchability in backcrosses of F(1) hybrids). None of these barriers entirely prevents gene exchange when it acts alone, but jointly they generate nearly complete reproductive isolation even between sympatric populations. Host fidelity contributed most strongly to reproductive isolation by reducing interspecific hybridization through several important types of ecological isolation, including microspatial, habitat, and seasonal isolation. The existence of multiple isolating barriers likely helps keep reproductive isolation stable and robust, by complementing changes in the strength of leaky barriers. This complementarity of multiple isolating barriers yields the concept of robustness of reproductive isolation, which is important when considering the long-term maintenance of species boundaries in coexisting species pairs.

  15. Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill.

    PubMed

    Esler, Daniel; Trust, Kimberly A; Ballachey, Brenda E; Iverson, Samuel A; Lewis, Tyler L; Rizzolo, Daniel J; Mulcahy, Daniel M; Miles, A Keith; Woodin, Bruce R; Stegeman, John J; Henderson, John D; Wilson, Barry W

    2010-05-01

    Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009. This result was consistent across four sampling periods; furthermore, results generated from two independent laboratories using paired liver samples from one of the sampling periods were similar. The EROD activity did not vary in relation to age, sex, or body mass of individuals, nor did it vary strongly by season in birds collected early and late in the winter of 2006 to 2007, indicating that these factors did not confound inferences about observed differences between oiled and unoiled areas. We interpret these results to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 20 years after the original spill. This adds to a growing body of literature suggesting that oil spills have the potential to affect wildlife for much longer time frames than previously assumed.

  16. Biocontrol: Bacillus penetrans and Related Parasites of Nematodes

    PubMed Central

    Sayre, R. M.

    1980-01-01

    Bacillus penetrans Mankau, 1975, previously described as Duboscqia penetrans Thorne 1940, is a candidate agent for biocontrol of nematodes. This review considers the life stages of this bacterium: vegetative growth phase, colony fragmentation, sporogenesis, soil phase, spore attachment, and penetration into larvae of root-knot nematodes. The morphology of the microthallus colonies and the unusual external features of the spore are discussed. Taxonomic affinities with the actinomycetes, particularly with the genus Pasteuria, are considered. Also discussed are other soil bacterial species that are potential biocontrol agents. Products of their bacterial fermentation in soil are toxic to nematodes, making them effective biocontrol agents. PMID:19300701

  17. Predacious bacteria, Bdellovibrio with potential for biocontrol.

    PubMed

    Markelova, Natalia Y

    2010-11-01

    Bacteria of the genus of Bdellovibrio are highly motile Gram-negative predators of other Gram-negative bacteria causing lysis of their prey. Here we report results of studies on the interactions of Bdellovibrio with species of Alcaligenes, Campylobacter, Erwinia, Escherichia, Helicobacter, Pseudomonas, Legionella, and Shigella in agar lower, liquid media and cells attached to a surface. Helicobacter pylori was studied employing both actively growing and viable but nonculturable (VBNC) cells. The majority of the bacterial strains tested were found to be susceptible to Bdellovibrio. A significant observation was that Bdellovibrio attacked both actively growing and VBNC H. pylori, that phenomenon has never been reported. The results indicate that bdellovibrios have potential as biocontrol agents.

  18. Bacteriophages as biocontrol agents in food.

    PubMed

    Hudson, J A; Billington, C; Carey-Smith, G; Greening, G

    2005-02-01

    Bacteriophages possess attributes that appear to be attractive to those searching for novel ways to control foodborne pathogens and spoilage organisms. These phages have a history of safe use, can be highly host specific, and replicate in the presence of a host. Campylobacter, Salmonella, and Listeria monocytogenes and various spoilage organisms have responded to phage control on some foods. However, the use of phages as biocontrol agents is complicated by factors such as an apparent requirement for a threshold level of host before replication can proceed and by suboptimal performance, at best, at temperatures beneath the optimum for the host. This review is a summary of the information on these issues and includes brief descriptions of alternative phage-based strategies for control of foodborne pathogens.

  19. Spatial and taxonomical overlap of fungi on phylloplanes and invasive alien ladybirds with fungal infections in tree crowns of urban green spaces.

    PubMed

    Howe, Andy G; Ravn, Hans Peter; Jensen, Annette B; Meyling, Nicolai V

    2016-09-01

    Occurrence of entomopathogenic fungi on phylloplanes in Tilia × europaea crowns between 1 and 13 m was assessed in urban parks. Prevalence of fungal infections in ladybirds (Coleoptera: Coccinellidae) collected from Tilia × europaea was assessed to determine whether fungi found on phylloplanes also occurred as infections in ladybirds. Isaria spp. was most abundant on phylloplanes (mean colony forming units (CFU) per leaf ± SE, 0.33 ± 0.03) followed by Beauveria spp. (0.22 ± 0.02 CFU per leaf) and Lecanicillium spp. (0.19 ± 0.02 CFU per leaf). Densities of inoculum were higher in inner crowns and decreased with height, although Lecanicillium spp. peaked at 5-7 m. Upper phylloplane surfaces harboured higher densities of Isaria spp. and Beauveria spp. than lower surfaces, whereas Lecanicillium spp. was equally distributed. Most prevalent on ladybirds were Isaria spp. (20.6% Harmonia axyridis; 4.8% natives), Lecanicillium spp. (13.6% H. axyridis; 4.8% natives), with fewer Beauveria spp. infections (2.6% H. axyridis). Molecular identification revealed Beauveria bassiana, B. pseudobassiana, Isaria farinosa and Lecanicillium muscarium among isolates of both tree and ladybird origin. Tilia × europaea phylloplanes support a diverse assemblage of entomopathogenic fungal species with a different prevalence in coccinellids compared to their relative abundance in this habitat.

  20. Sexual dimorphism in the attachment ability of the ladybird beetle Coccinella septempunctata on soft substrates

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Petersen, Dennis S.; Tölle, Lisa; Wolff, Jonas O.; Gorb, Stanislav N.

    2017-01-01

    Many insects possess adhesive foot pads, which enable reliable attachment to diverse and unpredictable substrates. The function of these adhesive organs was shown to be affected by environmental conditions such as substrate roughness, chemistry, and ambient humidity. So far, the attachment ability of insects and also that of spiders and geckos has been tested on rigid substrates only. However, the natural habitats of climbing animals may provide a variety of substrate stiffness ranging from rigid rock surfaces to soft, biofilm covered substrates. In order to test the effect of different substrate stiffness on the attachment ability of insects, we have performed friction experiments with female and male ladybird beetles Coccinella septempunctata on smooth silicone elastomer substrates of different stiffness, using a centrifugal force tester. Whereas in females, the attachment ability was not affected by the substrate stiffness within the range of tested stiffness, males showed decreasing attachment ability with decreasing substrate stiffness. This sexual dimorphism in attachment ability is explained by the presence of a specialized, discoidal seta type in males, which is not present in females. It is argued that discoidal setae, when softer if compared to the substrate, may show an advantageous peak-free interfacial stress distribution when being pulled off the substrate. For such setae being stiffer if compared the substrate, they potentially show increased edge stress concentration. In this case, lower pull-off forces are expected, in agreement with the experimentally obtained results. With the present study, we demonstrate for the first time that the substrate stiffness may have an effect on the attachment ability of climbing animals, which may also be of relevance for technical and medical applications involving adhesion to soft substrates.

  1. The Japanese ladybirds, Coccinula crotchi and Coccinula sinensis, are infected with very closely related strains of male-killing Flavobacterium.

    PubMed

    Elnagdy, Sherif; Messing, Susan; Majerus, Michael E N

    2014-12-01

    Male-killing is 1 of 4 known strategies that inherited parasitic endosymbionts have evolved to manipulate their host's reproduction. In early male-killing, infected male offspring are killed early in embryogenesis. Within the Insecta, male-killing bacteria have been found in a wide range of hosts. The Coccinellidae families of beetles, better known as ladybirds, are particularly prone to male-killer invasion. In samples of the coccinellid, Coccinula crotchi, from Japan, a new male-killing bacterium was revealed by phenotypic assay. Molecular genetic analysis revealed the identity to be a tetracycline-sensitive Flavobacterium that causes female-biased offspring sex ratio. Furthermore, that Flavobacterium strain was found to be closely related to the Flavobacterium causing male-killing in the congeneric Japanese coccinellid, Coccinula sinensis, which was collected from the same region. However, we found slightly different Flavobacterium strains infecting C. sinensis from regions with different environmental conditions. This may be an indication of horizontal transmission of male-killing Flavobacterium between these 2 ladybird spices. Finally, environmental conditions may affect the spread of male-killing bacteria among their hosts.

  2. The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

    PubMed

    Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

    2015-04-01

    Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties.

  3. Quantitative Assessment of Current Risks to Harlequin Ducks in Prince William Sound, Alaska, from the Exxon Valdez Oil Spill

    PubMed Central

    Harwell, Mark A.; Gentile, John H.; Parker, Keith R.; Murphy, Stephen M.; Day, Robert H.; Bence, A. Edward; Neff, Jerry M.; Wiens, John A.

    2012-01-01

    Harlequin Ducks (Histrionicus histrionicus) were adversely affected by the Exxon Valdez oil spill (EVOS) in Prince William Sound (PWS), Alaska, and some have suggested effects continue two decades later. We present an ecological risk assessment evaluating quantitatively whether PWS seaducks continue to be at-risk from polycyclic aromatic hydrocarbons (PAHs) in residual Exxon Valdez oil. Potential pathways for PAH exposures are identified for initially oiled and never-oiled reference sites. Some potential pathways are implausible (e.g., a seaduck excavating subsurface oil residues), whereas other pathways warrant quantification. We used data on PAH concentrations in PWS prey species, sediments, and seawater collected during 2001–2008 to develop a stochastic individual-based model projecting assimilated doses to seaducks. We simulated exposures to 500,000 individuals in each of eight age/gender classes, capturing the variability within a population of seaducks living in PWS. Doses to the maximum-exposed individuals are ∼400–4,000 times lower than chronic toxicity reference values established using USEPA protocols for seaducks. These exposures are so low that no individual-level effects are plausible, even within a simulated population that is orders-of-magnitude larger than exists in PWS. We conclude that toxicological risks to PWS seaducks from residual Exxon Valdez oil two decades later are essentially non-existent. PMID:23723680

  4. Surgical and immediate postrelease mortality of harlequin ducks (Histrionicus histrionicus) implanted with abdominal radio transmitters with percutaneous antennae

    USGS Publications Warehouse

    Mulcahy, Daniel M.; Esler, Daniel

    1999-01-01

    Radiotelemetry is an essential tool in the study of free-ranging bird populations, and a variety of transmitter-attachment methods have been developed. A promising new method is abdominal implantation of a transmitter with a percutaneous antenna. Researchers using this technique should be concerned about and aware of mortality during surgery and during the immediate postrelease period (the 14-day period following surgery). Of 307 radio-implant surgeries performed between 1995 and 1997 in harlequin ducks (Histrionicus histrionicus), 7 (2.3%) deaths were documented during surgery or anesthetic recovery. Of 295 birds released with implanted radios, 10 (3.4%) died during the immediate postrelease period. Modifications to anesthetic procedures used in the 204 surgeries performed in 1996 and 1997 reduced mortality to 1.5% during surgery and 1.5% during the immediate postrelease period. Anesthetic modifications included intubation of all birds, placement of birds on an elevated platform that allowed the head to rest at a level lower than the body during surgery, placement of a heated water blanket under the birds during surgery, monitoring of body temperature, and use of electrocardiogram and Doppler ultrasound to monitor heart rates and arrhythmias. Low levels of mortality associated with abdominal implantation of radio transmitters may be unavoidable, but mortality can be minimized with adjustments to anesthetic technique.

  5. Quantitative Assessment of Current Risks to Harlequin Ducks in Prince William Sound, Alaska, from the Exxon Valdez Oil Spill.

    PubMed

    Harwell, Mark A; Gentile, John H; Parker, Keith R; Murphy, Stephen M; Day, Robert H; Bence, A Edward; Neff, Jerry M; Wiens, John A

    2012-03-01

    Harlequin Ducks (Histrionicus histrionicus) were adversely affected by the Exxon Valdez oil spill (EVOS) in Prince William Sound (PWS), Alaska, and some have suggested effects continue two decades later. We present an ecological risk assessment evaluating quantitatively whether PWS seaducks continue to be at-risk from polycyclic aromatic hydrocarbons (PAHs) in residual Exxon Valdez oil. Potential pathways for PAH exposures are identified for initially oiled and never-oiled reference sites. Some potential pathways are implausible (e.g., a seaduck excavating subsurface oil residues), whereas other pathways warrant quantification. We used data on PAH concentrations in PWS prey species, sediments, and seawater collected during 2001-2008 to develop a stochastic individual-based model projecting assimilated doses to seaducks. We simulated exposures to 500,000 individuals in each of eight age/gender classes, capturing the variability within a population of seaducks living in PWS. Doses to the maximum-exposed individuals are ∼400-4,000 times lower than chronic toxicity reference values established using USEPA protocols for seaducks. These exposures are so low that no individual-level effects are plausible, even within a simulated population that is orders-of-magnitude larger than exists in PWS. We conclude that toxicological risks to PWS seaducks from residual Exxon Valdez oil two decades later are essentially non-existent.

  6. Harlequin ichthyosis: ABCA12 mutations underlie defective lipid transport, reduced protease regulation and skin-barrier dysfunction.

    PubMed

    Scott, Claire A; Rajpopat, Shefali; Di, Wei-Li

    2013-02-01

    Harlequin ichthyosis (HI) is a devastating autosomal recessive congenital skin disease. It has been vital to elucidate the biological importance of the protein ABCA12 in skin-barrier permeability, following the discovery that ABCA12 gene mutations can result in this rare disease. ATP-binding cassette transporter A12 (ABCA12) is a member of the subfamily of ATP-binding cassette transporters and functions to transport lipid glucosylceramides (GlcCer) to the extracellular space through lamellar granules (LGs). GlcCer are hydrolysed into hydroxyceramides extracellularly and constitute a portion of the extracellular lamellar membrane, lipid envelope and lamellar granules. In HI skin, loss of function of ABCA12 due to null mutations results in impaired lipid lamellar membrane formation in the cornified layer, leading to defective permeability of the skin barrier. In addition, abnormal lamellar granule formation (distorted shape, reduced in number or absent) could further cause aberrant production of LG-associated desquamation enzymes, which are likely to contribute to the impaired skin barrier in HI. This article reviews current opinions on the patho-mechanisms of ABCA12 action in HI and potential therapeutic interventions based on targeted molecular therapy and gene therapy strategies.

  7. Vorticella sp: Prospective Mosquito Biocontrol Agent

    PubMed Central

    Patil, Chandrashekhar Devidas; Narkhede, Chandrakant Prakash; Suryawanshi, Rahul Khushal; Patil, Satish Vitthal

    2016-01-01

    Background: Considering the disadvantages of chemical insecticides, we aimed to evaluate Vorticella parasites for control of mosquito larvae of Anopheles stephensi and Aedes aegypti at different larval stages. Methods: Vorticella sp infected mosquito larvae were crushed in the 0.85% saline and homogenized well to get Vorticella in suspension. The effects of Vorticella sp infections on larval development were investigated by inoculating protozoan on different larval instars of An. stephensi and Ae. aegypti and observed under light microscope. Lethal time of the Vorticella infected larvae at different stages was calculated. Results: First and 2nd larval instars of both An. stephensi and Ae. aegypti did not show signs of infection by Vorticella sp., whereas 3rd instars of An. stephensi showed more Vorticella infection than those of Ae. aegypti. However, 4th larval instars of both mosquitoes were heavily infected with Vorticella parasite which was responsible for sluggish movements of larvae and eventually death. Moreover, parasites (Vorticella spp) were responsible for more than 90% reduction in adult emergence for both infected An. stephensi and Ae. aegypti. Conclusion: This study provides insights for mosquito larvicidal action of surface parasite Vorticella on different larval stages of An. stephensi and Ae. Aegypti. It could be suggested as a potential candidate in mosquito biocontrol programs. PMID:28032113

  8. Exposure of sea otters and harlequin ducks in Prince William Sound, Alaska, USA, to shoreline oil residues 20 years after the Exxon Valdez oil spill.

    PubMed

    Neff, Jerry M; Page, David S; Boehm, Paul D

    2011-03-01

    We assessed whether sea otters and harlequin ducks in an area of western Prince William Sound, Alaska, USA (PWS), oiled by the 1989 Exxon Valdez oil spill (EVOS), are exposed to polycyclic aromatic hydrocarbons (PAH) from oil residues 20 years after the spill. Spilled oil has persisted in PWS for two decades as surface oil residues (SOR) and subsurface oil residues (SSOR) on the shore. The rare SOR are located primarily on the upper shore as inert, nonhazardous asphaltic deposits, and SSOR are confined to widely scattered locations as small patches under a boulder/cobble veneer, primarily on the middle and upper shore, in forms and locations that preclude physical contact by wildlife and diminish bioavailability. Sea otters and harlequin ducks consume benthic invertebrates that they collect by diving to the bottom in the intertidal and subtidal zones. Sea otters also dig intertidal and subtidal pits in search of clams. The three plausible exposure pathways are through the water, in oil-contaminated prey, or by direct contact with SSOR during foraging. Concentrations of PAH in near-shore water off oiled shores in 2002 to 2005 were at background levels (<0.05 ng/L). Median concentrations of PAH in five intertidal prey species on oiled shores in 2002 to 2008 range from 4.0 to 34 ng/g dry weight, indistinguishable from background concentrations. Subsurface oil residues are restricted to locations on the shore and substrate types, where large clams do not occur and where sea otters do not dig foraging pits. Therefore, that sea otters and harlequin ducks continue to be exposed to environmentally significant amounts of PAH from EVOS 20 years after the spill is not plausible.

  9. Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill

    USGS Publications Warehouse

    Esler, Daniel; Trust, Kimberly A.; Ballachey, Brenda E.; Iverson, Samuel A.; Lewis, Tyler L.; Rizzolo, Daniel; Mulcahy, Daniel M.; Miles, A. Keith; Woodin, Bruce R.; Stegeman, John J.; Henderson, John D.; Wilson, Barry W.

    2010-01-01

    Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009. This result was consistent across four sampling periods; furthermore, results generated from two independent laboratories using paired liver samples from one of the sampling periods were similar. The EROD activity did not vary in relation to age, sex, or body mass of individuals, nor did it vary strongly by season in birds collected early and late in the winter of 2006 to 2007, indicating that these factors did not confound inferences about observed differences between oiled and unoiled areas. We interpret these results to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 20 years after the original spill. This adds to a growing body of literature suggesting that oil spills have the potential to affect wildlife for much longer time frames than previously assumed.

  10. Optimization and evaluation of microencapsulated artificial diet for mass rearing the predatory ladybird Propylea japonica (Coleoptera: Coccinellidae).

    PubMed

    Tan, Xiao-Ling; Zhao, Jing; Wang, Su; Zhang, Fan

    2015-02-01

    Artificial diet optimization is a key aspect in mass rearing of natural enemies since it influences the quality and feeding effectiveness, and thus the success of the biological control program. Here, we introduced the microencapsulation method to package liquid artificial diet for feeding of the ladybird Propylea japonica. An orthogonal test of the quality of microencapsulated artificial diets (ADMs) was performed on key variables in production; Ca-alginate concentration, chitosan concentration and weight ratio of wall material to inner diet. We compared the development and reproduction of P. japonica fed on the ADMs under different cold-stored periods with those fed on fresh aphids and liquid artificial diets, in addition to a comparison of respiration, locomotion and predation. Our results indicated that chitosan concentration and ratio of shell to core significantly influence the quality of ADMs. The optimal recipe is 1.0% Ca-alginate, 1.6% chitosan and shell : core = 1 : 2. Insects reared on fresh optimized ADMs were similar to those fed on fresh prey in all developmental and reproductive characteristics except for survival ratio and female fertility. ADMs appeared more beneficial than using a liquid artificial diet, although this may decrease with the prolonging of the cold-storage period. P. japonica fed either on fresh ADMs or fresh prey showed improved respiration and predation abilities compared to where liquid artificial diet was used. Our study indicates advantages of microencapsulation in the production of artificial diet for predatory ladybird rearing. A microencapsulated diet can directly increase the efficiency and stability of mass rearing.

  11. Use of a pollen-based diet to expose the ladybird beetle Propylea japonica to insecticidal proteins.

    PubMed

    Zhang, Xiaojie; Li, Yunhe; Romeis, Jörg; Yin, Xinming; Wu, Kongming; Peng, Yufa

    2014-01-01

    A rape seed pollen-based diet was developed and found to be suitable for use in a dietary exposure assay for Propylea japonica. Using the diet, we established and validated a dietary exposure assay by using the protease inhibitor E-64 as positive control. Dose-dependent responses were documented for all observed life-table parameters of P. japonica including survival, pupation and eclosion rates, development time and adult weight. Results suggested that the dietary assay can detect the effects of insecticidal compounds on the survival and development of P. japonica. Using the established dietary assay, we subsequently tested the toxicity of Cry1Ab, Cry1Ac and Cry1F proteins that are expressed by transgenic maize, cotton or rice plants to P. japonica larvae. The diet containing E-64 was included as a positive control. Survival and development of P. japonica larvae were not adversely affected when the diet contained purified Cry1Ab, Cry1Ac, or Cry1F at 500 µg/g diet representing a worst-case exposure scenario. In contrast, P. japonica larvae were adversely affected when the diet contained E-64. The bioactivity and stability of the Cry proteins in the diet and Cry protein uptake by the ladybird larvae were confirmed by bioassay with a Cry-sensitive insect species and by ELISA. The current study describes a suitable experimental system for assessing the potential effects of gut-active insecticidal compounds on ladybird beetle larvae. The experiments with the Cry proteins demonstrate that P. japonica larvae are not sensitive to Cry1Ab, Cry1Ac and Cry1F.

  12. From biocontrol to cancer, probiotics and beyond.

    PubMed

    Dunne, Colum

    2013-01-01

    This invited commentary covers the period 1997-2012 and has seen changes in terminology that progressed from "basic" and "applied" to "translational" research. In the context of Bioengineered, these changes map readily onto the processes of identifying microbial characteristics appropriate for specific applications, isolation of suitable cultures, strain or genome manipulation and exploitation of these or their metabolomes across a range of settings.   To a great degree, this commentary and my career reflect an engagement with molecular microbiology and the trialling of bacteria and derived constructs in applications ranging from intensive-scale crop protection to amelioration of gastrointestinal disease. This engagement began with laboratory and field evaluations of biocontrol, specifically use of pseudomonads effective against nematode and fungal plant pathogens, characterization of mechanisms mediating beneficial effects of probiotic lactobacilli and bifidobacteria and assessment of functional foods in multinational clinical trials relating to inflammatory bowel disease. Subsequent work focused on (1) intellectual property (IP)-based medical devices for localized delivery of systemically toxic and gene cancer therapies; (2) growth of the science base supporting expansion of a multinational business including company acquisitions; (3) complementing existing inter-institutional research capabilities through development of a national industry-led collaboration; and, most recently, (4) strategic research programs at Ireland's newest medical school. My activities as outlined above parallel two distinct aspects of translational research: (1) involvement in knowledge-driven (commercial and research) organizations that brought together necessary resources and infrastructure and (2) availability of scale research funding from European Framework and Irish national programs.

  13. Defects in Stratum Corneum Desquamation Are the Predominant Effect of Impaired ABCA12 Function in a Novel Mouse Model of Harlequin Ichthyosis

    PubMed Central

    Feng, Weiguo; Hupe, Melanie; Crumrine, Debra A.; Chen, Jiang; Elias, Peter M.; Holleran, Walter M.; Niswander, Lee; Hohl, Daniel; Williams, Trevor; Torchia, Enrique C.; Roop, Dennis R.

    2016-01-01

    Harlequin Ichthyosis is a severe skin disease caused by mutations in the human gene encoding ABCA12. Here, we characterize a novel mutation in intron 29 of the mouse Abca12 gene that leads to the loss of a 5’ splice donor site and truncation of the Abca12 RNA transcript. Homozygous mutants of this smooth skin or smsk allele die perinatally with shiny translucent skin, typical of animal models of Harlequin Ichthyosis. Characterization of smsk mutant skin showed that the delivery of glucosylceramides and CORNEODESMOSIN was defective, while ultrastructural analysis revealed abnormal lamellar bodies and the absence of lipid lamellae in smsk epidermis. Unexpectedly, mutant stratum corneum remained intact when subjected to harsh chemical dissociation procedures. Moreover, both KALLIKREIN 5 and -7 were drastically decreased, with retention of desmoplakin in mutant SC. In cultured wild type keratinocytes, both KALLIKREIN 5 and -7 colocalized with ceramide metabolites following calcium-induced differentiation. Reducing the intracellular levels of glucosylceramide with a glucosylceramide synthase inhibitor resulted in decreased secretion of KALLIKREIN proteases by wild type keratinocytes, but not by smsk mutant keratinocytes. Together, these findings suggest an essential role for ABCA12 in transferring not only lipids, which are required for the formation of multilamellar structures in the stratum corneum, but also proteolytic enzymes that are required for normal desquamation. Smsk mutant mice recapitulate many of the pathological features of HI and can be used to explore novel topical therapies against a potentially lethal and debilitating neonatal disease. PMID:27551807

  14. Self-Improvement of Keratinocyte Differentiation Defects During Skin Maturation in ABCA12-Deficient Harlequin Ichthyosis Model Mice

    PubMed Central

    Yanagi, Teruki; Akiyama, Masashi; Nishihara, Hiroshi; Ishikawa, Junko; Sakai, Kaori; Miyamura, Yuki; Naoe, Ayano; Kitahara, Takashi; Tanaka, Shinya; Shimizu, Hiroshi

    2010-01-01

    Harlequin ichthyosis (HI) is caused by loss-of-function mutations in the keratinocyte lipid transporter ABCA12. The patients often die in the first 1 or 2 weeks of life, although HI survivors’ phenotypes improve within several weeks after birth. In order to clarify the mechanisms of phenotypic recovery, we studied grafted skin and keratinocytes from Abca12-disrupted (Abca12−/−) mice showing abnormal lipid transport. Abca12−/− neonatal epidermis showed significantly reduced total ceramide amounts and aberrant ceramide composition. Immunofluorescence and immunoblotting of Abca12−/− neonatal epidermis revealed defective profilaggrin/filaggrin conversion and reduced protein expression of the differentiation-specific molecules, loricrin, kallikrein 5, and transglutaminase 1, although their mRNA expression was up-regulated. In contrast, Abca12−/− skin grafts kept in a dry environment exhibited dramatic improvements in all these abnormalities. Increased transepidermal water loss, a parameter representing barrier defect, was remarkably decreased in grafted Abca12−/− skin. Ten-passage sub-cultured Abca12−/− keratinocytes showed restoration of intact ceramide distribution, differentiation-specific protein expression and profilaggrin/filaggrin conversion, which were defective in primary-cultures. Using cDNA microarray analysis, lipid transporters including four ATP-binding cassette transporters were up-regulated after sub-culture of Abca12−/− keratinocytes compared with primary-culture. These results indicate that disrupted keratinocyte differentiation during the fetal development is involved in the pathomechanism of HI and, during maturation, Abca12−/− epidermal keratinocytes regain normal differentiation processes. This restoration may account for the skin phenotype improvement observed in HI survivors. PMID:20489143

  15. Pathology smorgasboard: Biocontrol, pathogen movement, and recent fumigation results.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research on soilborne pathogens, disease control, and new forest diseases of interest were presented at the Western Forest and Conservation Nursery Association meeting in 2016. Research topics included reduced-rate soil fumigation, Pythium diversity and biocontrol, pathogen movement among nurseries,...

  16. Grouper as a natural biocontrol of invasive lionfish.

    PubMed

    Mumby, Peter J; Harborne, Alastair R; Brumbaugh, Daniel R

    2011-01-01

    Lionfish (Pterois volitans/miles) have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean.

  17. Grouper as a Natural Biocontrol of Invasive Lionfish

    PubMed Central

    Mumby, Peter J.; Harborne, Alastair R.; Brumbaugh, Daniel R.

    2011-01-01

    Lionfish (Pterois volitans/miles) have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean. PMID:21731769

  18. Metacridamides A and B from the biocontrol fungus metarhizium acridum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metarhizium acridum, an entomopathogenic fungus, has been commercialized and used successfully for biocontrol of grasshopper pests in Africa and Australia. As part of an effort to catalog the secondary metabolites of this fungus we discovered that its conidia produce two novel 17-membered macrocycl...

  19. Biology of the harlequin fish Othos dentex (Serranidae), with particular emphasis on sexual pattern and other reproductive characteristics.

    PubMed

    French, B; Potter, I C; Hesp, S A; Coulson, P G; Hall, N G

    2014-01-01

    Key biological characteristics of the harlequin fish Othos dentex, a representative of a monospecific genus of the Anthiinae (Serranidae), were determined from samples collected around reefs on the south coast of Western Australia. The females of this relatively long-lived species (maximum recorded age in this study = 37 years) attained only a slightly greater maximum total length and age than males and neither the length nor the age-frequency distributions showed a conspicuous sex-based bimodality. Furthermore, gonads from a wide size and age range of O. dentex were shown by histology, at several locations along their length, to always comprise exclusively either ovarian or testicular tissues. Thus, O. dentex is a gonochorist, a sexual pattern only previously recorded definitively for one other anthiine serranid, i.e. Epinephelides armatus, which also occurs in south-western Australia. Similar to E. armatus, O. dentex possesses 'solid' testes with a central sperm duct, thereby differing in structure from those typically found in serranids, in which there is a central membrane-bound 'ovarian' lumen and peripherally located sperm sinuses. The gonadal characteristics and sexual pattern of these two gonochoristic anthiines are not consistent with a recent proposal for the trends exhibited by the evolution of gonochorism and protogyny within the Serranidae. Othos dentex has indeterminate fecundity and a protracted spawning period (7 months) and, on the basis of underwater observations and a low gonado-somatic index (I(G)) for males, is a pair spawner, which is unusual for a gonochorist of a serranid or member of a related family. While the large spots on the lower half of the body of O. dentex are shown quantitatively to be similarly yellow in juveniles and adult females, they then become blue in males at maturity and this intensifies during the spawning period, when they presumably play an important role in agonistic interactions among males and courtship with

  20. Viral biocontrol: grand experiments in disease emergence and evolution

    PubMed Central

    Di Giallonardo, Francesca; Holmes, Edward C.

    2014-01-01

    Although viral emergence is commonly associated with cross-species transmission, the processes and determinants of viral evolution in a novel host environment are poorly understood. We address key questions in virus emergence and evolution using data generated from two unique natural experiments: the deliberate release of myxoma virus (MYXV) and rabbit hemorrhagic disease virus (RHDV) as biological control (biocontrol) agents against the European rabbit in Australia, and which have been of enormous benefit to Australia’s ecosystem and agricultural industries. Notably, although virulence evolution in MYXV and RHDV followed different trajectories, a strongly parallel evolutionary process was observed in Australia and Europe. These biocontrol agents were also characterised by a lack of transmission to non-target host species, suggesting that there are major barriers to successful emergence. PMID:25455418

  1. Viral biocontrol: grand experiments in disease emergence and evolution.

    PubMed

    Di Giallonardo, Francesca; Holmes, Edward C

    2015-02-01

    Although viral emergence is commonly associated with cross-species transmission, the processes and determinants of viral evolution in a novel host environment are poorly understood. We address key questions in virus emergence and evolution using data generated from two unique natural experiments: the deliberate release of myxoma virus (MYXV) and rabbit hemorrhagic disease virus (RHDV) as biological control (biocontrol) agents against the European rabbit in Australia, and which have been of enormous benefit to Australia's ecosystem and agricultural industries. Notably, although virulence evolution in MYXV and RHDV followed different trajectories, a strongly parallel evolutionary process was observed in Australia and Europe. These biocontrol agents were also characterized by a lack of transmission to nontarget host species, suggesting that there are major barriers to successful emergence.

  2. Physiological characteristics of the biocontrol yeast Pichia anomala J121.

    PubMed

    Fredlund, Elisabeth; Druvefors, Ulrika; Boysen, Marianne E; Lingsten, Karl-Johan; Schnürer, Johan

    2002-08-01

    The yeast Pichia anomala J121 prevents mold spoilage and enhances preservation of moist grain in malfunctioning storage systems. Development of P. anomala J121 as a biocontrol agent requires in-depth knowledge about its physiology. P. anomala J121 grew under strictly anaerobic conditions, at temperatures between 3 degrees C and 37 degrees C, at pH values between 2.0 and 12.4, and at a water activity of 0.92 (NaCl) and 0.85 (glycerol). It could assimilate a wide range of C- and N-sources and produce killer toxin. A selective medium containing starch, nitrate, acetic acid, and chloramphenicol was developed for P. anomala. P. anomala was equally sensitive as Candida albicans to common antifungal compounds. Growth ability at a range of environmental conditions contributes to the competitive ability of the biocontrol yeast P. anomala J121.

  3. Responses of Yeast Biocontrol Agents to Environmental Stress

    PubMed Central

    Sui, Yuan; Wisniewski, Michael; Droby, Samir

    2015-01-01

    Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeast species, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management of postharvest decay of fruits, vegetables, and grains. A yeast-based biocontrol system is composed of a tritrophic interaction between a host (commodity), a pathogen, and a yeast species, all of which are affected by environmental factors such as temperature, pH, and UV light as well as osmotic and oxidative stresses. Additionally, during the production process, biocontrol agents encounter various severe abiotic stresses that also impact their viability. Therefore, understanding the ecological fitness of the potential yeast biocontrol agents and developing strategies to enhance their stress tolerance are essential to their efficacy and commercial application. The current review provides an overview of the responses of antagonistic yeast species to various environmental stresses, the methods that can be used to improve stress tolerance and efficacy, and the related mechanisms associated with improved stress tolerance. PMID:25710368

  4. Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and harlequin ducks (Histronicus histronicus) in the Eastern Aleutian Islands, Alaska, USA

    USGS Publications Warehouse

    Miles, A.K.; Flint, P.L.; Trust, K.A.; Ricca, M.A.; Spring, S.E.; Arrieta, D.E.; Hollmen, T.; Wilson, B.W.

    2007-01-01

    Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([Mytilus trossilus] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (∼1,180–5,980 ng/g) approached those found at highly contaminated sites (∼4,100–7,500 ng/g).

  5. Effect of temperature and photoperiod on the development, reproduction, and predation of the predatory ladybird Cheilomenes sexmaculata (Coleoptera: Coccinellidae).

    PubMed

    Wang, Su; Tan, Xiao-Ling; Guo, Xiao-Jun; Zhang, Fan

    2013-12-01

    The polyphagous predatory ladybird Cheilomenes. sexmaculata (F.) (Coleoptera: Coccinellidae) is distributed throughout southern China and has been investigated as a potential biological control agent against herbivorous insects in various agroecosystems. In the current study, we evaluated the preimaginal development, eclosion rate, reproduction, fertility, adult longevity, and prey consumption of C. sexmaculata under five temperature and five photoperiod regimens. The results showed that preadult developmental duration decreased significantly with increasing temperature and amount of daylight. Adult eclosion rate was highest at 35 degrees C and under conditions of complete darkness. Higher temperatures shortened the duration of copulation and preoviposition, prolonged the duration of oviposition, and increased the level of fecundity. Hatchability was highest at 30 degrees C. By contrast, the shortest copulation and oviposition duration and lowest level of fecundity and hatchability occurred with a completely dark photoperiod. Temperature and the gender of C. sexmaculata influenced adult longevity. In addition, there was a significant interaction effect of photoperiod and gender on adult longevity. Furthermore, prey consumption by fourth instar larvae and adult females both increased with increasing temperature and photoperiod. Our results reveal the high thermal and light sensitivities of C. sexmaculata, which highlight the importance of environment regulation in the mass rearing of this natural enemy for application as a biological control in agroecosystems in China.

  6. Does a Change from Whole to Powdered Food (Artemia franciscana eggs) Increase Oviposition in the Ladybird Coleomegilla maculata?

    PubMed Central

    Riddick, Eric W.; Wu, Zhixin

    2015-01-01

    The limited availability of alternative foods to replace natural prey hinders cost-effective mass production of ladybird beetles for augmentative biological control. We compared the effects of powdered vs. whole Artemia franciscana (A. franciscana) (brine shrimp) eggs with or without a dietary supplement on development and reproduction of Coleomegilla maculata (C. maculata) (Coleoptera: Coccinellidae). We tested the hypotheses that (1) powdered A. franciscana eggs are more suitable than whole eggs; and (2) palmitic acid, a common fatty acid in natural prey, i.e., aphids, is an effective dietary supplement. Development time, pre-imaginal survival, sex ratio, and body weight of adults did not differ significantly amongst individuals fed powdered vs. whole eggs, with or without 5% palmitic acid. Significantly more oviposition occurred when females were fed powdered eggs than whole eggs and powdered eggs with 5% palmitic acid than whole eggs with or without 5% palmitic acid. A weak functional relationship was found between pre-oviposition time and total oviposition by females fed powdered eggs with 5% palmitic acid; pre-oviposition time decreased as oviposition increased. Food treatments had no significant differential effect on progeny (egg) hatch rate. In conclusion, a simple change in A. franciscana egg texture and particle size (i.e., blending whole eggs into a dust-like powder) increases oviposition in C. maculata. Supplementing powdered eggs with 5% palmitic acid might accelerate oogenesis (egg maturation) in some females. PMID:26466902

  7. Yeast microflora of nectarines and their potential for biocontrol of brown rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resident fruit microflora has been the source of biocontrol agents for the control of postharvest decays of fruits and the active ingredient in commercialized biocontrol products. With the exception of grapes and apples, information on the resident microflora of other fruits is only fragmentary; ho...

  8. Characterization of Two ABC Transporters from Biocontrol and Phytopathogenic Fusarium oxysporus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ABC transporter genes from four strains of Fusarium oxysporum [two biocontrol and two phytopathogenic (f. sp. lycopersici Race 1) isolates] indicated that this gene is well conserved. However, sequences of promoter regions of FoABC1 differed between 8 phytopathogenic and 11 biocontrol strains of F....

  9. Discovery of secondary metabolites from Bacillus spp. biocontrol strains using genome mining and mass spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genome sequencing, data mining and mass spectrometry were used to identify secondary metabolites produced by several Bacillus spp. biocontrol strains. These biocontrol strains have shown promise in managing Fusarium head blight in wheat. Draft genomes were produced and screened in silico using genom...

  10. Proactive Management of Fermentation and Formulation Interactions to Improve Biocontrol Product Performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The key components of biocontrol product development—discovery, fermentation, and formulation—are interactively linked to each other and ultimately to product performance. To identify biocontrol agents suited for commercial development, our discovery programs utilize a cumulative ranking system tha...

  11. Cystofilobasidium infirmominiatum as a biocontrol agent of postharvest diseases of apple and citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two psycrotrophic yeasts isolated from the surface of lemons have been selected as biocontrol agents of the most common postharvest diseases of apples and citrus that develops during cold storage. The biocontrol yeasts were identified as Cystofilobasidium infirmominiatum and Leucosporidium scottii....

  12. Biocontrol in an impulsive predator-prey model.

    PubMed

    Terry, Alan J

    2014-10-01

    We study a model for biological pest control (or "biocontrol") in which a pest population is controlled by a program of periodic releases of a fixed yield of predators that prey on the pest. Releases are represented as impulsive increases in the predator population. Between releases, predator-pest dynamics evolve according to a predator-prey model with some fairly general properties: the pest population grows logistically in the absence of predation; the predator functional response is either of Beddington-DeAngelis type or Holling type II; the predator per capita birth rate is bounded above by a constant multiple of the predator functional response; and the predator per capita death rate is allowed to be decreasing in the predator functional response and increasing in the predator population, though the special case in which it is constant is permitted too. We prove that, when the predator functional response is of Beddington-DeAngelis type and the predators are not sufficiently voracious, then the biocontrol program will fail to reduce the pest population below a particular economic threshold, regardless of the frequency or yield of the releases. We prove also that our model possesses a pest-eradication solution, which is both locally and globally stable provided that predators are sufficiently voracious and that releases occur sufficiently often. We establish, curiously, that the pest-eradication solution can be locally stable whilst not being globally stable, the upshot of which is that, if we delay a biocontrol response to a new pest invasion, then this can change the outcome of the response from pest eradication to pest persistence. Finally, we state a number of specific examples for our model, and, for one of these examples, we corroborate parts of our analysis by numerical simulations.

  13. Modulation of Human Immune Response by Fungal Biocontrol Agents

    PubMed Central

    Konstantinovas, Cibele; de Oliveira Mendes, Tiago A.; Vannier-Santos, Marcos A.; Lima-Santos, Jane

    2017-01-01

    Although the vast majority of biological control agents is generally regarded as safe for humans and environment, the increased exposure of agriculture workers, and consumer population to fungal substances may affect the immune system. Those compounds may be associated with both intense stimulation, resulting in IgE-mediated allergy and immune downmodulation induced by molecules such as cyclosporin A and mycotoxins. This review discusses the potential effects of biocontrol fungal components on human immune responses, possibly associated to infectious, inflammatory diseases, and defective defenses. PMID:28217107

  14. Modulation of Human Immune Response by Fungal Biocontrol Agents.

    PubMed

    Konstantinovas, Cibele; de Oliveira Mendes, Tiago A; Vannier-Santos, Marcos A; Lima-Santos, Jane

    2017-01-01

    Although the vast majority of biological control agents is generally regarded as safe for humans and environment, the increased exposure of agriculture workers, and consumer population to fungal substances may affect the immune system. Those compounds may be associated with both intense stimulation, resulting in IgE-mediated allergy and immune downmodulation induced by molecules such as cyclosporin A and mycotoxins. This review discusses the potential effects of biocontrol fungal components on human immune responses, possibly associated to infectious, inflammatory diseases, and defective defenses.

  15. Indigenous bacteria may interfere with the biocontrol of plant diseases

    NASA Astrophysics Data System (ADS)

    Someya, Nobutaka; Akutsu, Katsumi

    2009-06-01

    Prodigiosin is a reddish antibiotic pigment that plays an important role in the biocontrol of plant diseases by the bacterium Serratia marcescens. However, its activity is unstable under agricultural conditions; further, it can be degraded by various environmental factors. To examine the effect of epiphytic microbes on the stability of prodigiosin used for biological control processes, we collected a total of 1,280 bacterial isolates from the phylloplane of cyclamen and tomato plants. Approximately 72% of the bacterial strains isolated from the cyclamen plants and 66% of those isolated from the tomato plants grew on minimal agar medium containing 100 μg ml-1 prodigiosin. Certain isolates obtained from both plant species exhibited prodigiosin-degrading activity. We compared the 16S rRNA gene sequences derived from the isolates with sequences in a database. The comparison revealed that the sequences determined for the prodigiosin-degrading isolates were homologous to those of the genera Pseudomonas, Caulobacter, Rhizobium, Sphingomonas, Janthinobacterium, Novosphingobium, and Rathayibacter. These results indicate that indigenous epiphytic microorganisms may interfere with the interaction between plant pathogens and biocontrol agents by degrading the antibiotics produced by the agents.

  16. Biocontrol of postharvest Rhizopus decay of peaches with Pichia caribbica.

    PubMed

    Xu, Baitian; Zhang, Hongyin; Chen, Keping; Xu, Qin; Yao, Yao; Gao, Hui

    2013-08-01

    A new yeast antagonist, Pichia caribbica, isolated in our laboratory from the soil collected from unsprayed orchards, was evaluated for its biocontrol capability against Rhizopus stolonifer on peaches and the possible mechanisms involved. The decay incidence and lesion diameter of Rhizopus decay of peaches treated by P. caribbica were significantly reduced compared with the control fruits, and the higher the concentration of P. caribbica, the better the efficacy of the biocontrol. Rapid colonization of the yeast in peach wounds stored at 25 °C was observed. In peaches, the activities of peroxidase (POD), catalase (CAT), and phenylalanine ammonia-lyase (PAL) were significantly induced by P. caribbica treatment compared to those of the control fruits. All these results indicated that P. caribbica has a great potential for the development of commercial formulations to control postharvest Rhizopus decay of peaches. Its modes of action were based on competition for space and nutrients with pathogens, inducement of activities of defense-related enzymes such as POD, CAT, and PAL of peaches.

  17. Differentiation and interchange of harlequin duck populations within the North Pacific. Restoration project 97161: Exxon Valdez oil spill restoration project -- Final report

    SciTech Connect

    Goatcher, B.; Zwiefelhofer, D.; Lanctot, R.; Talbot, S.; Pierson, B.

    1999-04-01

    Concerns about constraints to harlequin duck (Histrionicus histrionicus) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds in different molting and wintering areas belong to genetically distinct and, thus, demographically independent population segments. Genetic markers, which differed in mode of inheritance (two sex-linked Z-specific microsatellite loci, four biparentally inherited microsatellite loci and maternally inherited mitochondrial deoxyribonucleic acid sequences), were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound, Alaska Peninsula (Katmai National Park) and Kodiak Archipelago (Kodiak National Wildlife Refuge). The authors also used colored leg bands to detect population interchange within and among these regions. The authors` genetic results show that differences in genotype frequencies among wintering locations within Alaska were low and non-significant for all three classes of markers. An analysis of genetic samples collected throughout the West Coast of North America revealed significant structuring at larger geographic scales. No interchange of banded birds was observed among regions and movements within regions were uncommon.

  18. Phyllostictines A-D, Oxazatricycloalkenones Produced by Phyllosticta cirsii, A Potential Mycoherbicide for Cirsium arvense Biocontrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phyllosticta cirsii, a fungal pathogen isolated from Cirsium arvense and proposed as biocontrol agent of this noxious perennial weed, produces in liquid cultures different phytotoxic metabolites with potential herbicidal activity. Four new oxazatricycloalkenones, named phyllostictines A-D, were isol...

  19. Risk assessment: progress of quarantine biocontrol research on Chinese Tallow, Melaleuca, and Downy Rose Myrtle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Risk assessments of two biocontrol candidates for Chinese tallow, Triadica sebifera (Euphoriales: Euphorbiaceae), and one for Melaleuca, Melaleuca quinquenervia (Myrtales: Myrtaceae), were conducted during 2009 and continuing into 2010 by USDA scientists located at the Florida Department of Agricul...

  20. Proactive management of fermentation and formulation interactions to improve biocontrol product performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The key components of biocontrol product development; discovery, fermentation, and formulation, are interactively linked to each other and ultimately, to product performance. The fermentation environment can be managed to maximize the quantity and quality of biomass and bioproducts produced which, ...

  1. Liquid cultivation techniques for enhancing the effectiveness of yeast biocontrol agents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocontrol agents will gain broader acceptance into integrated pest management programs if products with enhanced efficacy and consistency of performance are developed. Though given comparatively little research attention, liquid cultivation environments and protocols can and should be optimized to...

  2. Identification, Development, and Release of Insect Biocontrol Agents for the Management of Phragmites australis

    DTIC Science & Technology

    2014-07-01

    ER D C/ EL C R- 14 -2 Aquatic Plant Control Research Program Identification, Development, and Release of Insect Biocontrol Agents for...ERDC/EL CR-14-2 July 2014 Identification, Development, and Release of Insect Biocontrol Agents for the Management of Phragmites australis Bernd...and (5) assess the extent of hybridization between native and introduced genotypes. All selected insect species are stem miners that overwinter as

  3. Novel Routes for Improving Biocontrol Activity of Bacillus Based Bioinoculants

    PubMed Central

    Wu, Liming; Wu, Hui-Jun; Qiao, Junqing; Gao, Xuewen; Borriss, Rainer

    2015-01-01

    Biocontrol (BC) formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of BC agents. PMID:26696998

  4. Biocontrol Activity of the Local Strain of Metschnikowia pulcherrima on Different Postharvest Pathogens.

    PubMed

    Türkel, Sezai; Korukluoğlu, Mihriban; Yavuz, Mümine

    2014-01-01

    The strains of the yeast Metschnikowia pulcherrima have strong biocontrol activity against various microorganisms. Biocontrol activity of M. pulcherrima largely depends on its iron immobilizing pigment pulcherrimin. Biocontrol activity of pulcherrimin producing strain, M. pulcherrima UMY15, isolated from local vineyards, was tested on different molds that cause food spoilage. M. pulcherrima UMY15 was a very effective biocontrol agent against Penicillium roqueforti, P. italicum, P. expansum, and Aspergillus oryzae in in-vitro plate tests. However, the inhibitory activity of M. pulcherrima UMY15 was less effective on Fusarium sp. and A. niger species in biocontrol assays. In addition, M. pulcherrima UMY15 strain completely inhibited the germination and mycelia growth of A. oryzae, A. parasiticus, and Fusarium sp. spores on artificial wounds of apples when they coinoculated with M. pulcherrima UMY15. Moreover, when coinoculated, M. pulcherrima UMY15 strain also inhibited the growth of P. roqueforti, P. italicum, P. expansum, A. oryzae, Fusarium sp., and Rhizopus sp. in grape juice, indicating that M. pulcherrima UMY15 can be used as a very effective biocontrol yeast against various species of postharvest pathogens, including Penicillium, Aspergillus, Fusarium, and Rhizopus.

  5. Biocontrol Activity of the Local Strain of Metschnikowia pulcherrima on Different Postharvest Pathogens

    PubMed Central

    Türkel, Sezai; Korukluoğlu, Mihriban; Yavuz, Mümine

    2014-01-01

    The strains of the yeast Metschnikowia pulcherrima have strong biocontrol activity against various microorganisms. Biocontrol activity of M. pulcherrima largely depends on its iron immobilizing pigment pulcherrimin. Biocontrol activity of pulcherrimin producing strain, M. pulcherrima UMY15, isolated from local vineyards, was tested on different molds that cause food spoilage. M. pulcherrima UMY15 was a very effective biocontrol agent against Penicillium roqueforti, P. italicum, P. expansum, and Aspergillus oryzae in in-vitro plate tests. However, the inhibitory activity of M. pulcherrima UMY15 was less effective on Fusarium sp. and A. niger species in biocontrol assays. In addition, M. pulcherrima UMY15 strain completely inhibited the germination and mycelia growth of A. oryzae, A. parasiticus, and Fusarium sp. spores on artificial wounds of apples when they coinoculated with M. pulcherrima UMY15. Moreover, when coinoculated, M. pulcherrima UMY15 strain also inhibited the growth of P. roqueforti, P. italicum, P. expansum, A. oryzae, Fusarium sp., and Rhizopus sp. in grape juice, indicating that M. pulcherrima UMY15 can be used as a very effective biocontrol yeast against various species of postharvest pathogens, including Penicillium, Aspergillus, Fusarium, and Rhizopus. PMID:24860671

  6. Molecular-based strategies to exploit Pseudomonas biocontrol strains for environmental biotechnology applications.

    PubMed

    Mark, Genevievel; Morrissey, John P; Higgins, P; O'gara, Fergal

    2006-05-01

    Exploitation of beneficial plant-microbe interactions in the rhizosphere can result in the promotion of plant health and have significant implications for low input sustainable agriculture applications such as biocontrol. Bacteria such as Bacillus and Pseudomonas, and fungi such as Trichoderma, have been developed as commercial biocontrol products. Registration of microbial inocualants as biocontrol agents in either the European Union or the United States requires production of extensive dossiers covering efficacy, safety and risk assessment. Despite the fact that a number of Pseudomonas biocontrol products have been marketed there are still some limitations hampering the development of this technology for widespread use in agriculture. Although many strains show good performance in specific trials, this is often not translated into consistent, effective biocontrol in diverse field situations. Advances in 'Omics' technology and the publication of complete genome sequences of a number of plant-associative bacterial strains, has facilitated investigations into the molecular basis underpinning the establishment of beneficial plant-microbe interactions in the rhizosphere. The understanding of these molecular signalling processes and the functions they regulate is fundamental to promoting beneficial microbe-plant interactions, to overcome existing limitations and to designing improved strategies for the development of novel Pseudmonas biocontrol inoculant consortia.

  7. Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes.

    PubMed

    Solans, Mariana; Scervino, Jose Martin; Messuti, María Inés; Vobis, Gernot; Wall, Luis Gabriel

    2016-11-01

    Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications.

  8. The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae).

    PubMed

    Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

    2017-01-01

    Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.

  9. An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes.

    PubMed

    Kandel, Shyam L; Firrincieli, Andrea; Joubert, Pierre M; Okubara, Patricia A; Leston, Natalie D; McGeorge, Kendra M; Mugnozza, Giuseppe S; Harfouche, Antoine; Kim, Soo-Hyung; Doty, Sharon L

    2017-01-01

    Microbial communities in the endosphere of Salicaceae plants, poplar (Populus trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum. Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas, and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.

  10. Indirect effects of biocontrol of an invasive riparian plant (Tamarix) alters habitat and reduces herpetofauna abundance

    USGS Publications Warehouse

    Bateman, H.L.; Merritt, D.M.; Glenn, E.P.; Nagler, P.L.

    2014-01-01

    The biological control agent (tamarisk leaf beetle, Diorhabda spp.) is actively being used to defoliate exotic saltcedar or tamarisk (Tamarix spp.) in riparian ecosystems in western USA. The Virgin River in Arizona and Nevada is a system where tamarisk leaf beetle populations are spreading. Saltcedar biocontrol, like other control methods, has the potential to affect non-target species. Because amphibians and reptiles respond to vegetation changes in habitat and forage in areas where beetles are active, herpetofauna are model taxa to investigate potential impacts of biocontrol defoliation. Our objectives related herpetofauna abundance to vegetation cover and indices (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI) and timing of biocontrol defoliation. We captured herpetofauna and ground-dwelling arthropods in trap arrays and measured vegetation using remotely sensed images and on-the-ground measurements at 16–21 sites 2 years before (2009–2010) and 2 years following (2011–2012) biocontrol defoliation. Following defoliation, riparian stands (including stands mixed with native and exotic trees and stands of monotypic exotic saltcedar) had significantly lower NDVI and EVI values and fewer captures of marked lizards. Total captures of herpetofauna (toads, lizards, and snakes) were related to higher vegetation cover and sites with a lower proportion of saltcedar. Our results suggest that effects of biocontrol defoliation are likely to be site-specific and depend upon the proportion of native riparian trees established prior to biocontrol introduction and defoliation. The mechanisms by which habitat structure, microclimate, and ultimately vertebrate species are affected by exotic plant biocontrol riparian areas should be a focus of natural-resource managers.

  11. The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae)

    PubMed Central

    Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M.; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

    2017-01-01

    Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10–30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents. PMID:28144236

  12. An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes

    PubMed Central

    Kandel, Shyam L.; Firrincieli, Andrea; Joubert, Pierre M.; Okubara, Patricia A.; Leston, Natalie D.; McGeorge, Kendra M.; Mugnozza, Giuseppe S.; Harfouche, Antoine; Kim, Soo-Hyung; Doty, Sharon L.

    2017-01-01

    Microbial communities in the endosphere of Salicaceae plants, poplar (Populus trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum. Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas, and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition. PMID:28348550

  13. Environmental factors affect the activity of biocontrol agents against ochratoxigenic Aspergillus carbonarius on wine grape.

    PubMed

    De Curtis, F; de Felice, D V; Ianiri, G; De Cicco, V; Castoria, R

    2012-09-17

    The influence of temperature and relative humidity (RH) on the activity of three biocontrol agents-the yeast Metschnikowia pulcherrima LS16 and two strains of the yeast-like fungus Aureobasidium pullulans LS30 and AU34-2-against infection by A. carbonarius and ochratoxin A (OTA) accumulation in wine grape berries was investigated in lab-scale experiments. The presence of wounds on grape skin dramatically favored infection of berries by A. carbonarius strain A1102, since unwounded berries showed very low levels of infection at all conditions of RH and temperature tested. Artificially wounded berries pre-treated with the biocontrol agents were inoculated with the ochratoxigenic A. carbonarius strain A1102 and were incubated for 5 days at two levels of RH (60% and 100%) and three different temperatures (20, 25 and 30 °C). The three biocontrol agents were able to prevent infections at 60% RH and 20 °C. At 60% RH and 25 °C only strain AU34-2 achieved some protection on day 5, whereas at 30 °C a limited biocontrol efficacy was evident only up to day 2. At 100% RH, LS16, LS30 and AU34-2 showed effective protection of grape berries at 20 °C until the 5th day of incubation. The three biocontrol agents achieved significant protection at higher temperatures only until the 2nd day after the beginning of the experiment: all three strains at 25 °C, and only strain LS16 at 30 °C. After 5 days, the three biocontrol agents were able to significantly reduce the level of OTA in berries at all the conditions tested. This occurred even when protection from infection was not significant, except at 30 °C and 100% of RH for all the three strains, and at 25 °C and 100% of RH for strain LS16. The biocontrol agents displayed a higher rate of colonization on grape berries at 20 and 25 °C than at 30 °C. The higher value of RH (100%) appeared to increase the rate of colonization, in particular at 20 and 25 °C. Taken together, our results emphasize the significant influence of

  14. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere

    PubMed Central

    Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

    2016-01-01

    Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer. PMID:27147933

  15. Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola.

    PubMed

    Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie; Hélias, Valérie; Faure, Denis

    2015-10-23

    Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers.

  16. Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

    PubMed Central

    Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie

    2015-01-01

    Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. PMID:26497457

  17. Ochratoxin A Management in Vineyards by Lobesia botrana Biocontrol

    PubMed Central

    Cozzi, Giuseppe; Somma, Stefania; Haidukowski, Miriam; Logrieco, Antonio F.

    2013-01-01

    Grape berries attacked by Lobesia botrana larvae are more easily infected by Aspergillus section Nigri (black aspergilli) ochratoxigenic species. Two-year field trials were carried out in Apulia (Italy) to evaluate a bioinsecticide control strategy against L. botrana and the indirect effect on reducing ochratoxin A (OTA) contamination in vineyards. A commercial Bacillus thuringiensis formulate and an experimental Beauveria bassiana (ITEM-1559) formulate were tested in two vineyards cultivated with the same grape variety, Negroamaro, but with two different training systems (espalier and little-arbor techniques). In both years and training systems the treatments by B. bassiana ITEM-1559 significantly controlled L. botrana larvae attacks with effectiveness similar to B. thuringensis (more than 20%). A significant reduction of OTA concentrations (up to 80% compared to untreated controls) was observed only in the first year in both training systems, when the metereological parameters prior to harvest were more favorable to the insect attack. Results of field trials showed that B. bassiana ITEM-1559 is a valid bioinsecticide against L. botrana and that grape moth biocontrol is a strategy to reduce OTA contamination in vineyard in seasons with heavy natural infestation. PMID:23282670

  18. Rhizobia: a potential biocontrol agent for soilborne fungal pathogens.

    PubMed

    Das, Krishnashis; Prasanna, Radha; Saxena, Anil Kumar

    2017-03-12

    Rhizobia are a group of organisms that are well known for their ability to colonize root surfaces and form symbiotic associations with legume plants. They not only play a major role in biological nitrogen fixation but also improve plant growth and reduce disease incidence in various crops. Rhizobia are known to control the growth of many soilborne plant pathogenic fungi belonging to different genera like Fusarium, Rhizoctonia, Sclerotium, and Macrophomina. Antagonistic activity of rhizobia is mainly attributed to production of antibiotics, hydrocyanic acid (HCN), mycolytic enzymes, and siderophore under iron limiting conditions. Rhizobia are also reported to induce systemic resistance and enhance expression of plant defense-related genes, which effectively immunize the plants against pathogens. Seed bacterization with appropriate rhizobial strain leads to elicitation and accumulation of phenolic compounds, isoflavonoid phytoalexins, and activation of enzymes like L-phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), peroxidase (POX), polyphenol oxidase (PPO), and others involved in phenylpropanoid and isoflavonoid pathways. Development of Rhizobium inoculants with dual attributes of nitrogen fixation and antagonism against phytopathogens can contribute to increased plant growth and productivity. This compilation aims to bring together the available information on the biocontrol facet of rhizobia and identify research gaps and effective strategies for future research in this area.

  19. [The prospects of using transgenic insects in biocontrol programs].

    PubMed

    Tkachuk, A P; Kim, M V; Savitskiĭ, V Iu; Savitskiĭ, M Iu

    2011-01-01

    Methods of biocontrol are widely used for suppression of pests and human disease vectors. One of the key methods is insects sterilization (sterile insect technique--SIT), which currently is accomplished by irradiation. Radiation-exposed insects have reduced fitness so theis competitive abilities are diminished as compared to insects from wild populations. Modern bioengineering is capable of producing transgenic insects with predetermined traits, and by now the schemes for getting sterile insects without exposure to radiation are developed. Another area of modern studies is producing insects that are unable to transmit diseases malaria, for example. In the present review the implementation and perspectives are outlined for replacement of Anopheles wild populations with transgenic mosquitos. The main way for delivering the genetic material to recipient's genome is using transposon-based constructs. The markers of transgenesis are described. The potential danger for the environment of transgenic constructs remobilization and the necessity of their stabilization within the genome are emphasized. The existing methods of stabilization which involve the deletion of transposon terminal inverted repeats are described.

  20. Ochratoxin A management in vineyards by Lobesia botrana biocontrol.

    PubMed

    Cozzi, Giuseppe; Somma, Stefania; Haidukowski, Miriam; Logrieco, Antonio F

    2013-01-02

    Grape berries attacked by Lobesia botrana larvae are more easily infected by Aspergillus section Nigri (black aspergilli) ochratoxigenic species. Two-year field trials were carried out in Apulia (Italy) to evaluate a bioinsecticide control strategy against L. botrana and the indirect effect on reducing ochratoxin A (OTA) contamination in vineyards. A commercial Bacillus thuringiensis formulate and an experimental Beauveria bassiana (ITEM-1559) formulate were tested in two vineyards cultivated with the same grape variety, Negroamaro, but with two different training systems (espalier and little-arbor techniques). In both years and training systems the treatments by B. bassiana ITEM-1559 significantly controlled L. botrana larvae attacks with effectiveness similar to B. thuringensis (more than 20%). A significant reduction of OTA concentrations (up to 80% compared to untreated controls) was observed only in the first year in both training systems, when the metereological parameters prior to harvest were more favorable to the insect attack. Results of field trials showed that B. bassiana ITEM-1559 is a valid bioinsecticide against L. botrana and that grape moth biocontrol is a strategy to reduce OTA contamination in vineyard in seasons with heavy natural infestation.

  1. Evaluation of recycled bioplastic pellets and a sprayable formulation for application of an Aspergillus flavus biocontrol strain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocontrol of Aspergillus flavus using inoculated bioplastic granules has been proven to be effective under laboratory and field conditions. In the present study, the use of low-density pellets from recycled bioplastic as a biocontrol strain carrier was evaluated. Applying recycled bioplastic pell...

  2. Cost modeling of pseudomonoas fluorescens and pseudomonoas chlororphis biocontrol for competitive exclusion of salmonella enterica on tomatoes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocontrol measures may enhance postharvest interventions, however; published research on process-based models for biocontrol of foodborne pathogens on produce is limited. The aim of this research was to develop cost model estimates for competitive exclusion process using Pseudomonas fluorescens and...

  3. Myco-Biocontrol of Insect Pests: Factors Involved, Mechanism, and Regulation

    PubMed Central

    Sandhu, Sardul Singh; Sharma, Anil K.; Beniwal, Vikas; Goel, Gunjan; Batra, Priya; Kumar, Anil; Jaglan, Sundeep; Sharma, A. K.; Malhotra, Sonal

    2012-01-01

    The growing demand for reducing chemical inputs in agriculture and increased resistance to insecticides have provided great impetus to the development of alternative forms of insect-pest control. Myco-biocontrol offers an attractive alternative to the use of chemical pesticides. Myco-biocontrol agents are naturally occurring organisms which are perceived as less damaging to the environment. Their mode of action appears little complex which makes it highly unlikely that resistance could be developed to a biopesticide. Past research has shown some promise of the use of fungi as a selective pesticide. The current paper updates us about the recent progress in the field of myco-biocontrol of insect pests and their possible mechanism of action to further enhance our understanding about the biological control of insect pests. PMID:22567344

  4. Biosynthetic Mechanism for Sunscreens of the Biocontrol Agent Lysobacter enzymogenes

    PubMed Central

    Li, Yaoyao; Wang, Yansheng; Wang, Yulan; Wright, Stephen; Li, Yuezhong; Shen, Yuemao; Liu, Fengquan; Du, Liangcheng

    2013-01-01

    Lysobacter are ubiquitous environmental bacteria emerging as novel biocontrol agents and new sources of anti-infectives. So far, very little effort has been invested in the study of the biology of these Gram-negative gliding bacteria. Many Lysobacter species are characterized by their yellow-orange appearance. Using transposon mutagenesis, we identified a stand-alone polyketide synthase (PKS) gene cluster required for the pigment production in L. enzymogenes OH11. The yellow pigments were abolished in the “white” mutants generated by target-specific deletions of ketosynthase (KS), acyl carrier protein, or ketoreductase. Spectroscopic data suggested that the pigments belong to xanthomonadin-like aryl polyenes. Polyene-type polyketides are known to be biosynthesized by modular PKS (Type I), not by stand-alone PKS (Type II) which always contain the heterodimer KS-CLF (chain-length factor) as the key catalytic component. Remarkably, this aryl polyene PKS complex only contains the KS (ORF17), but not the CLF. Instead, a hypothetical protein (ORF16) is located immediately next to ORF17. ORF16–17 homologs are widespread in numerous uncharacterized microbial genomes, in which an ORF17 homolog is always accompanied by an ORF16 homolog. The deletion of ORF16 eliminated pigment production, and homology modeling suggested that ORF16 shares a structural similarity to the N-terminal half of CLF. A point-mutation of glutamine (Q166A) that is the conserved active site of known CLF abolished pigment production. The “white” mutants are significantly more sensitive to UV/visible light radiation or H2O2 treatment than the wild type. These results unveil the first example of Type II PKS-synthesized polyene pigments and show that the metabolites serve as Lysobacter “sunscreens” that are important for the survival of these ubiquitous environmental organisms. PMID:23826105

  5. Bacteriophage cocktail for biocontrol of Salmonella in dried pet food.

    PubMed

    Heyse, Serena; Hanna, Leigh Farris; Woolston, Joelle; Sulakvelidze, Alexander; Charbonneau, Duane

    2015-01-01

    Human salmonellosis has been associated with contaminated pet foods and treats. Therefore, there is interest in identifying novel approaches for reducing the risk of Salmonella contamination within pet food manufacturing environments. The use of lytic bacteriophages shows promise as a safe and effective way to mitigate Salmonella contamination in various food products. Bacteriophages are safe, natural, highly targeted antibacterial agents that specifically kill bacteria and can be targeted to kill food pathogens without affecting other microbiota. In this study, we show that a cocktail containing six bacteriophages had a broadspectrum activity in vitro against a library of 930 Salmonella enterica strains representing 44 known serovars. The cocktail was effective against 95% of the strains in this tested library. In liquid culture dose-ranging experiments, bacteriophage cocktail concentrations of ≥10(8) PFU/ml inactivated more than 90% of the Salmonella population (10(1) to 10(3) CFU/ml). Dried pet food inoculated with a mixture containing equal proportions of Salmonella serovars Enteritidis (ATCC 4931), Montevideo (ATCC 8387), Senftenberg (ATCC 8400), and Typhimurium (ATCC 13311) and then surface treated with the six-bacteriophage cocktail (≥2.5 ± 1.5 × 10(6) PFU/g) achieved a greater than 1-log (P < 0.001) reduction compared with the phosphate-buffered saline-treated control in measured viable Salmonella within 60 min. Moreover, this bacteriophage cocktail reduced natural contamination in samples taken from an undistributed lot of commercial dried dog food that tested positive for Salmonella. Our results indicate that bacteriophage biocontrol of S. enterica in dried pet food is technically feasible.

  6. Bio-Control of Salmonella Enteritidis in Foods Using Bacteriophages.

    PubMed

    Bao, Hongduo; Zhang, Pengyu; Zhang, Hui; Zhou, Yan; Zhang, Lili; Wang, Ran

    2015-08-24

    Two lytic phages, vB_SenM-PA13076 (PA13076) and vB_SenM-PC2184 (PC2184), were isolated from chicken sewage and characterized with host strains Salmonella Enteritidis (SE) ATCC13076 and CVCC2184, respectively. Transmission electron microscopy revealed that they belonged to the family Myoviridae. The lytic abilities of these two phages in liquid culture showed 104 multiplicity of infection (MOI) was the best in inhibiting bacteria, with PC2184 exhibiting more activity than PA13076. The two phages exhibited broad host range within the genus Salmonella. Phage PA13076 and PC2184 had a lytic effect on 222 (71.4%) and 298 (95.8%) of the 311 epidemic Salmonella isolates, respectively. We tested the effectiveness of phage PA13076 and PC2184 as well as a cocktail combination of both in three different foods (chicken breast, pasteurized whole milk and Chinese cabbage) contaminated with SE. Samples were spiked with 1 × 10(4) CFU individual SE or a mixture of strains (ATCC13076 and CVCC2184), then treated with 1 × 10(8) PFU individual phage or a two phage cocktail, and incubated at 4 °C or 25 °C for 5 h. In general, the inhibitory effect of phage and phage cocktail was better at 4 °C than that at 25 °C, whereas the opposite result was observed in Chinese cabbage, and phage cocktail was better than either single phage. A significant reduction in bacterial numbers (1.5-4 log CFU/sample, p < 0.05) was observed in all tested foods. The two phages on the three food samples were relatively stable, especially at 4 ºC, with the phages exhibiting the greatest stability in milk. Our research shows that our phages have potential effectiveness as a bio-control agent of Salmonella in foods.

  7. Tick control: trapping, biocontrol, host management and other alternative strategies

    USGS Publications Warehouse

    Ginsberg, Howard S.; Edited by Sonenshine, Daniel E.; Roe, R. Michael

    2014-01-01

    Biology of Ticks is the most comprehensive work on tick biology and tick-borne diseases. This second edition is a multi-authored work, featuring the research and analyses of renowned experts across the globe. Spanning two volumes, the book examines the systematics, biology, structure, ecological adaptations, evolution, genomics and the molecular processes that underpin the growth, development and survival of these important disease-transmitting parasites. Also discussed is the remarkable array of diseases transmitted (or caused) by ticks, as well as modern methods for their control. This book should serve as a modern reference for students, scientists, physicians, veterinarians and other specialists. Volume I covers the biology of the tick and features chapters on tick systematics, tick life cycles, external and internal anatomy, and others dedicated to specific organ systems, specifically, the tick integument, mouthparts and digestive system, salivary glands, waste removal, salivary glands, respiratory system, circulatory system and hemolymph, fat body, the nervous and sensory systems and reproductive systems. Volume II includes chapters on the ecology of non-nidicolous and nidicolous ticks, genetics and genomics (including the genome of the Lyme disease vector Ixodes scapularis) and immunity, including host immune responses to tick feeding and tick-host interactions, as well as the tick's innate immune system that prevents and/or controls microbial infections. Six chapters cover in depth the many diseases caused by the major tick-borne pathogens, including tick-borne protozoa, viruses, rickettsiae of all types, other types of bacteria (e.g., the Lyme disease agent) and diseases related to tick paralytic agents and toxins. The remaining chapters are devoted to tick control using vaccines, acaricides, repellents, biocontrol, and, finally, techniques for breeding ticks in order to develop tick colonies for scientific study.

  8. Interplay between wheat cultivars, biocontrol pseudomonads, and soil.

    PubMed

    Meyer, Joana Beatrice; Lutz, Matthias Peter; Frapolli, Michele; Péchy-Tarr, Maria; Rochat, Laurène; Keel, Christoph; Défago, Geneviève; Maurhofer, Monika

    2010-09-01

    There is a significant potential to improve the plant-beneficial effects of root-colonizing pseudomonads by breeding wheat genotypes with a greater capacity to sustain interactions with these bacteria. However, the interaction between pseudomonads and crop plants at the cultivar level, as well as the conditions which favor the accumulation of beneficial microorganisms in the wheat rhizosphere, is largely unknown. Therefore, we characterized the three Swiss winter wheat (Triticum aestivum) cultivars Arina, Zinal, and Cimetta for their ability to accumulate naturally occurring plant-beneficial pseudomonads in the rhizosphere. Cultivar performance was measured also by the ability to select for specific genotypes of 2,4-diacetylphloroglucinol (DAPG) producers in two different soils. Cultivar-specific differences were found; however, these were strongly influenced by the soil type. Denaturing gradient gel electrophoresis (DGGE) analysis of fragments of the DAPG biosynthetic gene phlD amplified from natural Pseudomonas rhizosphere populations revealed that phlD diversity substantially varied between the two soils and that there was a cultivar-specific accumulation of certain phlD genotypes in one soil but not in the other. Furthermore, the three cultivars were tested for their ability to benefit from Pseudomonas inoculants. Interestingly, Arina, which was best protected against Pythium ultimum infection by inoculation with Pseudomonas fluorescens biocontrol strain CHA0, was the cultivar which profited the least from the bacterial inoculant in terms of plant growth promotion in the absence of the pathogen. Knowledge gained of the interactions between wheat cultivars, beneficial pseudomonads, and soil types allows us to optimize cultivar-soil combinations for the promotion of growth through beneficial pseudomonads. Additionally, this information can be implemented by breeders into a new and unique breeding strategy for low-input and organic conditions.

  9. Knockout of a transgene by transcription activator-like effector nucleases (TALENs) in the sawfly, Athalia rosae (Hymenoptera) and the ladybird beetle, Harmonia axyridis (Coleoptera).

    PubMed

    Hatakeyama, M; Yatomi, J; Sumitani, M; Takasu, Y; Sekiné, K; Niimi, T; Sezutsu, H

    2016-02-01

    Transcription activator-like effector nucleases (TALENs) are efficient tools for targeted genome editing and have been utilized in a number of insects. Here, we demonstrate the gene disruption (knockout) caused by TALENs targeting a transgene, 3xP3-driven enhanced green fluorescence protein (EGFP), that is integrated in the genome of two species, the sawfly Athalia rosae (Hymenoptera) and the ladybird beetle Harmonia axyridis (Coleoptera). Messenger RNAs of TALENs targeting the sequences adjacent to the chromophore region were microinjected into the eggs/embryos of each species. In At. rosae, when microinjection was performed at the posterior end of eggs, 15% of G(0) individuals showed a somatic mosaic phenotype for eye EGFP fluorescence. Three-quarters of the somatic mosaics produced EGFP-negative G(1) progeny. When eggs were injected at the anterior end, 63% of the G(0) individuals showed somatic mosaicism, and 17% of them produced EGFP-negative G(1) progeny. In H. axyridis, 25% of posterior-injected and 8% of anterior-injected G(0) individuals produced EGFP-negative G(1) progeny. In both species, the EGFP-negative progeny retained the EGFP gene, and various deletions were detected in the target sequences, indicating that gene disruption was successfully induced. Finally, for both species, 18-21% of G(0) founders produced gene knockout progeny sufficient for establishing knockout strains.

  10. Genotype characterization of the bacterium expressing the male-killing trait in the ladybird beetle Adalia bipunctata with specific rickettsial molecular tools.

    PubMed Central

    Balayeva, N M; Eremeeva, M E; Tissot-Dupont, H; Zakharov, I A; Raoult, D

    1995-01-01

    The male-killing ladybird beetle (LB) bacterium (AB bacterium) was analyzed with specific rickettsial molecular biology tools in the LB Adalia bipunctata strains. Eight phenotype-positive LB strains showing mortality of male embryos were amplified with rickettsial genus-specific primers from the gene for citrate synthase (CS) and the gene for a 17-kDa protein and spotted fever group-specific primers from the gene for the 120-kDa outer membrane protein (ompB). The specificity of amplification was confirmed by Southern hybridization and the absence of the above-listed gene products in three phenotype-negative LB strains. Restriction polymorphism patterns of three examined amplicons from the CS gene, 17-kDa-protein gene, and ompB gene were identical among the eight phenotype-positive LB strains and were unique among all known rickettsiae of the spotted fever and typhus groups. Amplified fragments of the CS genes of the AB bacterium, Rickettsia prowazekii Breinl, Rickettsia typhi Wilmington, Rickettsia canada 2678, and Rickettsia conorii 7 (Malish) were sequenced. The greatest differences among the above-listed rickettsial and AB bacterium CS gene sequences were between bp 1078 and 1110. Numerical analysis based on CS gene fragment sequences shows the close relationships of the AB bacterium to the genus Rickettsia. Expanding of knowledge about rickettsial arthropod vectors and participation of rickettsiae in the cytoplasmic maternal inheritance of arthropods is discussed. PMID:7747963

  11. Is there a difference between stripy journeys and stripy ladybirds? The N400 response to semantic and world-knowledge violations during sentence processing.

    PubMed

    Dudschig, Carolin; Maienborn, Claudia; Kaup, Barbara

    2016-03-01

    The distinction between linguistic and non-linguistic knowledge is particularly relevant because it is related to the principle of compositionality during sentence comprehension. Hagoort, Hald, Bastiaansen, and Petersson (2004) challenged the distinction between linguistic and non-linguistic knowledge. Here, we investigate how linguistic and non-linguistic violations are processed in a setting adapted from Hagoort et al., whilst in contrast to Hagoort, keeping the critical word identical. In line with the findings by Hagoort et al., our results showed largest N400 amplitudes for semantic violations ('Journeys are stripy'), followed by non-linguistic world-knowledge violations ('Ladybirds are stripy') and contingent sentences ('Trousers are stripy'), and finally by correct sentences ('Zebras are stripy'). Traditional fractional area and relative criterion measures of peak and onset latencies showed no effect of violation type. Interestingly, the semantic violation condition crossed a fixed criterion earlier than the word-knowledge violation condition. In conclusion, our data suggests that the question regarding the distinction between linguistic- and non-linguistic knowledge in terms of language integration remains open. Implications for future studies addressing the difference between linguistic and non-linguistic knowledge are discussed.

  12. Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis.

    PubMed

    Großkinsky, Dominik K; Tafner, Richard; Moreno, María V; Stenglein, Sebastian A; García de Salamone, Inés E; Nelson, Louise M; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

    2016-03-17

    Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.

  13. Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis

    PubMed Central

    Großkinsky, Dominik K.; Tafner, Richard; Moreno, María V.; Stenglein, Sebastian A.; García de Salamone, Inés E.; Nelson, Louise M.; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

    2016-01-01

    Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience. PMID:26984671

  14. Nutrient effects on biocontrol of Penicillium roqueforti by Pichia anomala J121 during airtight storage of wheat.

    PubMed

    Druvefors, Ulrika Adel; Passoth, Volkmar; Schnürer, Johan

    2005-04-01

    The biocontrol yeast Pichia anomala inhibits the growth of a variety of mold species. We examined the mechanism underlying the inhibition of the grain spoilage mold Penicillium roqueforti by the biocontrol yeast P. anomala J121 during airtight storage. The biocontrol effect in a model grain silo with moist wheat (water activity of 0.96) was enhanced when complex medium, maltose, or glucose was added. Supplementation with additional nitrogen or vitamin sources did not affect the biocontrol activity of the yeast. The addition of complex medium or glucose did not significantly influence the yeast cell numbers in the silos, whether in the presence or absence of P. roqueforti. Mold growth was not influenced by the addition of nutrients, if cultivated without yeast. The products of glucose metabolism, mainly ethanol and ethyl acetate, increased after glucose addition to P. anomala-inoculated treatments. Our results suggest that neither competition for nutrients nor production of a glucose-repressible cell wall lytic enzyme is the main mode of action of biocontrol by P. anomala in this grain system. Instead, the mold-inhibiting effect probably is due to the antifungal action of metabolites, most likely a combination of ethyl acetate and ethanol, derived from glycolysis. The discovery that sugar amendments enhance the biocontrol effect of P. anomala suggests novel ways of formulating biocontrol yeasts.

  15. Complete Genome Sequence of Ralstonia solanacearum FJAT-1458, a Potential Biocontrol Agent for Tomato Wilt

    PubMed Central

    Chen, Deju; Zhu, Yujing; Wang, Jieping; Chen, Zheng; Che, Jiamei; Zheng, Xuefang; Chen, Xiaoqiang

    2017-01-01

    ABSTRACT An avirulent strain of Ralstonia solanacearum FJAT-1458 was isolated from a living tomato. Here, we report the complete R. solanacearum FJAT-1458 genome sequence of 6,059,899 bp and 5,241 genes. This bacterial strain is a potential candidate as a biocontrol agent in the form of a plant vaccine for bacterial wilt. PMID:28385834

  16. Genome Sequence of the Biocontrol Agent Microbacterium barkeri Strain 2011-R4

    PubMed Central

    Liu, Jian; Zhou, Qing; Ibrahim, Muhammad; Liu, He; Jin, Gulei

    2012-01-01

    Microbacterium barkeri strain 2011-R4 is a Gram-positive epiphyte which has been confirmed as a biocontrol agent against several plant pathogens in our previous studies. Here, we present the draft genome sequence of this strain, which was isolated from the rice rhizosphere in Tonglu city, Zhejiang province, China. PMID:23144410

  17. What magnitude are observed non-target impacts from weed biocontrol?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a ...

  18. Metschnikowia fructicola, a new ascosporic yeast with potential for biocontrol of postharvest fruit rots.

    PubMed

    Kurtzman, C P; Droby, S

    2001-11-01

    A new ascosporic yeast, Metschnikowia fructicola (type strain NRRL Y-27328, CBS 8853), is described and was isolated from grapes grown in central Israel. Preliminary tests indicate the new species has biocontrol activity against Botrytis rot of stored grapes. Phylogenetic analysis of domain D1/D2 26S rDNA sequences showed M. fructicola to be a sister species of M. pulcherrima.

  19. Transcriptome analysis of grapefruit flavedo in response to application of the yeast biocontrol agent Metschnikowia fructicola

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yeasts used to control postharvest pathogens have been shown to induce several biochemical defense responses in surface wounds of fruit. The capability to elicit these responses in fruit tissue has been regarded as one of the possible mechanisms of action by which yeast biocontrol agent inhibit the...

  20. Genomic Diversity of Biocontrol Strains of Pseudomonas spp. Isolated from Aerial or Root Surfaces of Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The striking ecological, metabolic, and biochemical diversity of Pseudomonas has intrigued microbiologists for many decades. To explore the genomic diversity of biocontrol strains of Pseudomonas spp., we derived high quality draft sequences of seven strains known to suppress plant disease. The str...

  1. [Correction of autonomic reactions parameters in organism of cosmonaut with adaptive biocontrol method].

    PubMed

    Kornilova, L N; Cowings, P S; Toscano, W B; Arlashchenko, N I; Korneev, D Iu; Ponomarenko, A V; Salagovich, S V; Sarantseva, A V; Kozlovskaia, I B

    2000-01-01

    Presented are results of testing the method of adaptive biocontrol during preflight training of cosmonauts. Within the MIR-25 crew, a high level of controllability of the autonomous reactions was characteristic of Flight Commanders MIR-23 and MIR-25 and flight Engineer MIR-23, while Flight Engineer MIR-25 displayed a weak intricate dependence of these reactions on the depth of relaxation or strain.

  2. Yeast Biocontrol of a Fungal Plant Disease: A Model for Studying Organism Interrelationships

    ERIC Educational Resources Information Center

    Chanchaichaovivat, Arun; Panijpan, Bhinyo; Ruenwongsa, Pintip

    2008-01-01

    An experiment on the action of the yeast, "Saccharomyces cerevisiae", against a fungal plant disease is proposed for secondary students (Grade 11) to support their study of organism interrelationship. This biocontrol experiment serves as the basis for discussing relationships among three organisms (red chilli fruit, "Saccharomyces cerevisiae," and…

  3. Heat shock improves stress tolerance and biocontrol performance of Rhodotorula mucilaginosa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeasts, is a research topic and eco-friendly management approach that has received considerable attention. A few yeast-based biocontrol products are available in the market. Ecological fitness, stress to...

  4. Pantoea applied genomics to understand and improve biocontrol activity against fire blight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pantoea agglomerans and P. vagans (ex. Erwinia herbicola) are common epiphytes of pome fruit flowers and three strains (E325, P10c, C9-1) have been commercially developed as effective biocontrol products for managing fire blight (Erwinia amylovora). Antibiotics as a standard, reliable chemical optio...

  5. Cucumber rhizosphere microbial community response to biocontrol agent Bacillus subtilis B068150

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum f. sp. Cucumerinum. However, their survival ability in cucumber rhizosphere and non-rhizosphere as well as their influence on native microbial communities has not been fully i...

  6. Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

  7. Linking habitat management and conservation biocontrol through gut-content analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing the habitat diversity of agricultural fields can lead to more effective biocontrol of arthropod pests. Annual cropping systems are exposed to frequent disturbance and lack habitat diversity; therefore it is important to develop strategies that can improve ecosystem services such as bioco...

  8. Efficacy of water dispersible formulations of biocontrol strains of Aspergillus flavus for aflatoxin management in corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field experiments were conducted in 2011 and 2012 to evaluate the efficacy of water dispersible granule (WDG) formulations of biocontrol strains of Aspergillus flavus in controlling aflatoxin contamination of corn. In 2011, when aflatoxin was present at very high levels, no WDG treatment provided s...

  9. [Effect of adaptive biocontrol sessions in the presence of strong professional skill].

    PubMed

    Antonov, A A; Ershova, T A; Dudukin, A V

    2011-01-01

    Effect of adaptive biocontrol on efficiency of the operator possessing stable skills in simulating manual control of Soyuz hang-up and berthing to the International space station (ISS) was studied. Job quality was evaluated by the time, energy and precision parameters. The investigation used an ISS computer model and mock-ups of the board operating controls.

  10. [Correction of autonomic reactions parameters in organism of cosmonaut with adaptive biocontrol method

    NASA Technical Reports Server (NTRS)

    Kornilova, L. N.; Cowings, P. S.; Toscano, W. B.; Arlashchenko, N. I.; Korneev, D. Iu; Ponomarenko, A. V.; Salagovich, S. V.; Sarantseva, A. V.; Kozlovskaia, I. B.

    2000-01-01

    Presented are results of testing the method of adaptive biocontrol during preflight training of cosmonauts. Within the MIR-25 crew, a high level of controllability of the autonomous reactions was characteristic of Flight Commanders MIR-23 and MIR-25 and flight Engineer MIR-23, while Flight Engineer MIR-25 displayed a weak intricate dependence of these reactions on the depth of relaxation or strain.

  11. Functional and structural microbial diversity in organic and conventional viticulture: organic farming benefits natural biocontrol agents.

    PubMed

    Schmid, Florian; Moser, Gerit; Müller, Henry; Berg, Gabriele

    2011-03-01

    Statistically significant differences in the structure and function of above-ground grapevine-associated microorganisms from organically and conventionally managed vineyards were found. Aureobasidium pullulans, a copper-detoxifying fungus and biocontrol agent, plays a key role in explaining these differences. The black fungus was strongly enriched in the communities of organically managed plants and yielded a higher indigenous antiphytopathogenic potential.

  12. Draft Genome Sequence of Biocontrol Agent Pythium oligandrum Strain Po37, an Oomycota

    PubMed Central

    Berger, Harald; Yacoub, Amira; Gerbore, Jonathan; Grizard, Damien; Rey, Patrice; Sessitsch, Angela

    2016-01-01

    The oomycota Pythium oligandrum Po37 is used as a biocontrol agent of plant diseases. Here, we present the first draft of the P. oligandrum Po37 genome sequence, which comprises 725 scaffolds with a total length of 35.9 Mb and 11,695 predicted protein-coding genes. PMID:27081125

  13. Identification of Biocontrol Agents to Control the Fungal Pathogen, Geomyces destructans, in Bats

    NASA Astrophysics Data System (ADS)

    Braunstein, S.; Cheng, T.

    2013-12-01

    The fungal pathogen Geomyces destructans (Gd) causes the disease White-nose Syndrome (WNS) in bats and is estimated to have killed millions of bats since its emergence in North America in 2006. Gd is predicted to cause the local extinction of at least three bat species if rates of decline continue unabated. Given the devastating impacts of Gd to bat populations, identifying a viable method for controlling the pathogen is pertinent for conservation of affected bat species. Our work focuses on identifying naturally-occurring skin bacteria on bats that are antagonistic to Gd that could potentially be used as a biocontrol. We cultured bacteria from skin swabs taken from wild bats (Myotis lucifugus, Eptesicus fuscus, Myotis sodalis, Perimyotis subflavus). We conducted challenge experiments to identify bacterial strains that inhibited Gd growth. Bacteria that exhibited antifungal properties were identified using 16S and gyrB markers. Our methods identified several bacteria in the Pseudomonas fluorescens complex as potential biocontrol agents. Future work will continue to test the viability of these bacteria as biocontrol agents via experimental treatments with live captive bats. The failure of previous non-biocontrol methods highlights the importance of developing these bacteria as a biologically-friendly method for controlling Gd. A bat infected with Geomyces destructans. Photo by West Virginia Division of Natural Resources Bacterial culture from the swab of a bat's wings

  14. Ecological Considerations in Producing and Formulating Fungal Entomopathogens for Use in Insect Biocontrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect pests persist in a wide variety of agricultural, arboreal, and urban environments. Effective control with fungal entomopathogens using inundation biocontrol requires an understanding of the ecology of the target insect, fungal pathogen, and the insect-pathogen interaction. Historically, the...

  15. Ecological Considerations in Producing and Formulating Fungal Entomopathogens for Use in Insect Biocontrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect pests persist in a wide-variety of agricultural, arboreal, and urban environments. Effective control with fungal entomopathogens using inundation biocontrol requires an understanding of the ecology of the target insect, fungal pathogen, and the insect-pathogen interaction. Historically, the d...

  16. Attachment Capability of Antagonistic Yeast Rhodotorula glutinis to Botrytis cinerea Contributes to Biocontrol Efficacy

    PubMed Central

    Li, Boqiang; Peng, Huaimin; Tian, Shiping

    2016-01-01

    Rhodotorula glutinis as an antagonism show good biocontrol performance against various post-harvest diseases in fruits. In the present study, strong attachment capability of R. glutinis to spores and hyphae of Botrytis cinerea was observed. Further analysis showed that certain protein components on the yeast cell surface played critical role during the interaction between R. glutinis and B. cinerea. The components mainly distributed at the poles of yeast cells and might contain glycosylation modification, as tunicamycin treated yeast cells lost attachment capability to B. cinerea. To investigate contributions of attachment capability of R. glutinis to its biocontrol efficacy, yeast cells were mutagenized with 3% methane-sulfonic acid ethyl ester (EMS), and a mutant CE4 with stable non-attaching phenotype was obtained. No significant difference was found on colony, cell morphology, reproductive ability, and capsule formation between the mutant and wild-type. However, there was a distinct difference in India ink positive staining patterns between the two strains. Moreover, wild-type strain of R. glutinis showed better performance on inhibiting spore germination and mycelial growth of B. cinerea than CE4 strain when yeast cells and B. cinerea were co-cultured in vitro. In biocontrol assay, both wild-type and CE4 strains showed significant biocontrol efficacy against gray mold caused by B. cinerea in apple fruit, whereas, control effect of CE4 strain was lower than that of wild-type. Our findings provided new evidences that attachment capability of R. glutinis to B. cinerea contributed to its biocontrol efficacy. PMID:27199931

  17. Biocontrol potential of Trichoderma harzianum isolate T-aloe against Sclerotinia sclerotiorum in soybean.

    PubMed

    Zhang, Fuli; Ge, Honglian; Zhang, Fan; Guo, Ning; Wang, Yucheng; Chen, Long; Ji, Xiue; Li, Chengwei

    2016-03-01

    Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2(-)) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants.

  18. Lentinula edodes enhances the biocontrol activity of Cryptococcus laurentii against Penicillium expansum contamination and patulin production in apple fruits.

    PubMed

    Tolaini, V; Zjalic, S; Reverberi, M; Fanelli, C; Fabbri, A A; Del Fiore, A; De Rossi, P; Ricelli, A

    2010-04-15

    Penicillium expansum is a post-harvest pathogen of apples which can produce the hazardous mycotoxin patulin. The yeast Cryptococcus laurentii (LS28) is a biocontrol agent able to colonize highly oxidative environments such as wounds in apples. In this study culture filtrates of the basidiomycete Lentinula edodes (LF23) were used to enhance the biocontrol activity of LS28. In vitro L. edodes culture filtrates improved the growth of C. laurentii and the activity of its catalase, superoxide dismutase and glutathione peroxidase, which play a key role in oxidant scavenging. In addition, LF23 also delayed P. expansum conidia germination. The biocontrol effect of LS28 used together with LF23 in wounded apples improved the inhibition of P. expansum growth and patulin production in comparison with LS28 alone, under both experimental and semi-commercial conditions. The biocontrol effect was confirmed by a semi-quantitative PCR analysis set up for monitoring the growth of P. expansum.

  19. Growth kinetics and efficacy as parameters for ranking and selecting biocontrol agents that reduce pink rot in stored potatoes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased production of organic agricultural products and the relative ineffectiveness of traditional control measures support development of new biocontrol technologies for use against pink rot infections in storage. The microbiota of 84 different agricultural soils was individually transferred to...

  20. Biocontrol efficacy of different isolates of Trichoderma against soil borne pathogen Rhizoctonia solani.

    PubMed

    Asad, Saeed Ahmad; Ali, Naeem; Hameed, Abdul; Khan, Sabaz Ali; Ahmad, Rafiq; Bilal, Muhammad; Shahzad, Muhammad; Tabassum, Ayesha

    2014-01-01

    In this study, the biocontrol abilities of water-soluble and volatile metabolites of three different isolates of Trichoderma (T. asperellum, T. harzianum and Trichoderma spp.) against soil borne plant pathogen Rhizoctonia solani were investigated both in vitro and in vivo. The results showed for the first time that mycelial growth inhibition of the pathogen was 74.4-67.8% with water-soluble metabolites as compared to 15.3-10.6% with volatile metabolites in vitro. In vivo antagonistic activity of Trichoderma isolates against R. solani was evaluated on bean plants under laboratory and greenhouse conditions. We observed that T. asperellum was more effective and consistent, lowering disease incidence up to 19.3% in laboratory and 30.5% in green house conditions. These results showed that three isolates of Trichoderma could be used as effective biocontrol agents against R. solani.

  1. Genetic engineering of fungal biocontrol agents to achieve greater efficacy against insect pests.

    PubMed

    St Leger, Raymond J; Wang, Chengshu

    2010-01-01

    Molecular biology methods have elucidated pathogenic processes in several fungal biocontrol agents including two of the most commonly applied entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana. In this review, we describe how a combination of molecular techniques has: (1) identified and characterized genes involved in infection; (2) manipulated the genes of the pathogen to improve biocontrol performance; and (3) allowed expression of a neurotoxin from the scorpion Androctonus australis. The complete sequencing of four exemplar species of entomopathogenic fungi including B. bassiana and M. anisopliae will be completed in 2010. Coverage of these genomes will help determine the identity, origin, and evolution of traits needed for diverse lifestyles and host switching. Such knowledge combined with the precision and malleability of molecular techniques will allow design of multiple pathogens with different strategies to be used for different ecosystems and avoid the possibility of the host developing resistance.

  2. Unrecognized impact of a biocontrol agent on the spread rate of an invasive thistle.

    PubMed

    Marchetto, Katherine M; Shea, Katriona; Kelly, Dave; Groenteman, Ronny; Sezen, Zeynep; Jongejans, Eelke

    2014-07-01

    Herbivores may significantly reduce plant populations by reducing seed set; however, we know little of their impact on seed movement. We show for the first time that the receptacle-feeding weevil Rhinocyllus conicus not only reduces seed production by the invasive thistle Carduus nutans but also inhibits release and subsequent wind dispersal of seeds. These effects generate large, though different, impacts on spatial spread and local abundance in two populations with differing demography, located in the United States and New Zealand. Furthermore, the mechanism is context dependent, with the largest effects through increased terminal velocity in the United States but through reduced seed production in New Zealand. Our results show that the benefit of biocontrol programs may have been underestimated; screenings of potential biocontrol agents should examine effects on pest dispersal and spread, as well as on abundance.

  3. Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes

    PubMed Central

    Landis, Douglas A.; Gardiner, Mary M.; van der Werf, Wopke; Swinton, Scott M.

    2008-01-01

    Increased demand for corn grain as an ethanol feedstock is altering U.S. agricultural landscapes and the ecosystem services they provide. From 2006 to 2007, corn acreage increased 19% nationally, resulting in reduced crop diversity in many areas. Biological control of insects is an ecosystem service that is strongly influenced by local landscape structure. Here, we estimate the value of natural biological control of the soybean aphid, a major pest in agricultural landscapes, and the economic impacts of reduced biocontrol caused by increased corn production in 4 U.S. states (Iowa, Michigan, Minnesota, and Wisconsin). For producers who use an integrated pest management strategy including insecticides as needed, natural suppression of soybean aphid in soybean is worth an average of $33 ha−1. At 2007–2008 prices these services are worth at least $239 million y−1 in these 4 states. Recent biofuel-driven growth in corn planting results in lower landscape diversity, altering the supply of aphid natural enemies to soybean fields and reducing biocontrol services by 24%. This loss of biocontrol services cost soybean producers in these states an estimated $58 million y−1 in reduced yield and increased pesticide use. For producers who rely solely on biological control, the value of lost services is much greater. These findings from a single pest in 1 crop suggest that the value of biocontrol services to the U.S. economy may be underestimated. Furthermore, we suggest that development of cellulosic ethanol production processes that use a variety of feedstocks could foster increased diversity in agricultural landscapes and enhance arthropod-mediated ecosystem services. PMID:19075234

  4. Draft Genome Sequence of the Pediocin-Encoding Biopreservative and Biocontrol Strain Pediococcus acidilactici D3

    PubMed Central

    Rajendran, Mahitha; Altermann, Eric

    2013-01-01

    We describe a draft genome sequence for Pediococcus acidilactici strain D3, a component of multistrain commercial cultures with biopreservative and biocontrol properties in food-based applications. Strain D3 encodes at least one antimicrobial peptide, pediocin AMPd3. The AMPd3-encoding operon exhibits high sequence similarity to the archetype pediocin, PA-1, encoded by P. acidilactici PAC 1.0. PMID:23788534

  5. Influence of Oxidative Stress on Biocontrol Activity of Cryptococcus laurentii against Blue Mold on Peach Fruit

    PubMed Central

    Zhang, Zhanquan; Chen, Jian; Li, Boqiang; He, Chang; Chen, Yong; Tian, Shiping

    2017-01-01

    The limitations of chemical fungicides for the control of postharvest diseases have recently become more apparent. The utilization of antagonistic microorganisms is a promising alternative to that of fungicides to control postharvest decay. In previous studies, the antagonistic yeast Cryptococcus laurentii has shown excellent effects of biocontrol and great potential for practical application. Adverse conditions, such as oxidative stress, limit the practical application of antagonistic yeast. In this study, we investigated the oxidative stress tolerance of C. laurentii and the associated mechanisms. The results indicated that exogenous oxidative stress has a significant effect on the viability and biocontrol efficiency of C. laurentii. H2O2-induced oxidative stress led to the accumulation of reactive oxygen species. The results of flow cytometric analysis suggested that apoptosis is responsible for the reduced survival rate of C. laurentii under oxidative stress. Using tests of antioxidant activity, we found that C. laurentii could employ enzymatic systems to resist exogenous oxidative stress. The addition of exogenous glutathione, a non-enzymatic antioxidant, to the media can significantly enhance oxidative tolerance and biocontrol efficiency of C. laurentii. PMID:28210254

  6. Evaluation of indigenous Trichoderma isolates from Manipur as biocontrol agent against Pythium aphanidermatum on common beans.

    PubMed

    Kamala, Th; Indira, S

    2011-12-01

    Pythium aphanidermatum is one of the common causal pathogen of damping-off disease of beans (Phaseolus vulgaris L.) grown in Manipur. A total of 110 indigenous Trichoderma isolates obtained from North east India were screened for their biocontrol activity which can inhibit the mycelial growth of P. aphanidermatum, the causal organism of damping-off in beans. Out of the total isolates, 32% of them showed strong antagonistic activity against P. aphanidermatum under in vitro condition and subsequently 20 best isolates were selected based on their mycelial inhibition capacity against P. aphanidermatum for further analysis. Different biocontrol mechanisms such as protease, chitinase, β-1,3-glucanase activity, cellulase and production of volatile and non-volatile compounds were also assayed. Based on their relative biocontrol potency, only three indigenous Trichoderma isolates (T73, T80 and T105) were selected for pot culture experiment against damping-off diseases in common beans. In greenhouse experiment, Trichoderma isolates T-105 significantly reduced the pre- and post-emergence damping-off disease incidence under artificial infection with P. aphanidermatum and showed highest disease control percentage.

  7. Influence of Oxidative Stress on Biocontrol Activity of Cryptococcus laurentii against Blue Mold on Peach Fruit.

    PubMed

    Zhang, Zhanquan; Chen, Jian; Li, Boqiang; He, Chang; Chen, Yong; Tian, Shiping

    2017-01-01

    The limitations of chemical fungicides for the control of postharvest diseases have recently become more apparent. The utilization of antagonistic microorganisms is a promising alternative to that of fungicides to control postharvest decay. In previous studies, the antagonistic yeast Cryptococcus laurentii has shown excellent effects of biocontrol and great potential for practical application. Adverse conditions, such as oxidative stress, limit the practical application of antagonistic yeast. In this study, we investigated the oxidative stress tolerance of C. laurentii and the associated mechanisms. The results indicated that exogenous oxidative stress has a significant effect on the viability and biocontrol efficiency of C. laurentii. H2O2-induced oxidative stress led to the accumulation of reactive oxygen species. The results of flow cytometric analysis suggested that apoptosis is responsible for the reduced survival rate of C. laurentii under oxidative stress. Using tests of antioxidant activity, we found that C. laurentii could employ enzymatic systems to resist exogenous oxidative stress. The addition of exogenous glutathione, a non-enzymatic antioxidant, to the media can significantly enhance oxidative tolerance and biocontrol efficiency of C. laurentii.

  8. Characterization of Alcaligenes faecalis strain AD15 indicating biocontrol activity against plant pathogens.

    PubMed

    Yokoyama, Shin-ichiro; Adachi, Yoshitomi; Asakura, Shuichi; Kohyama, Erina

    2013-01-01

    Bacterial strain possessing both bacteriostatic and fungistatic activity (biocontrol activity) against pathogens of cyclamen (Cyclamen sp.) was isolated from the soil in Gifu Prefecture, Japan, and characterized with respect to its taxonomic and biocontrol properties. The sequence of its 16S rRNA gene, morphology, biochemistry, and fatty acid composition demonstrated that it is a strain most closely related to Alcaligenes faecalis subsp. faecalis LMG 1229(T). The isolate was named A. faecalis strain AD15. A. faecalis AD15 produced hydroxylamine at maximum yields of 33.3±1.7 mg/L after 16 h cultivation in LB medium and 19.0±0.44 mg/L after 19 h cultivation in synthetic medium. Moreover, minimum inhibitory concentrations of hydroxylamine against the cyclamen pathogens Pantoea agglomerans and Colletotrichum gloeosporioides were 4.20±0.98 and 16.5±0.67 mg/L. These results indicated that the biocontrol activity of strain AD15 might be attributed to hydroxylamine, a metabolite in the culture medium, and it had the potential for biopesticide application.

  9. Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages

    PubMed Central

    Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

    2015-01-01

    One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains. PMID:26413062

  10. Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

    PubMed

    Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

    2015-01-01

    One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

  11. Evaluation of the Biocontrol Potential of Purpureocillium lilacinum QLP12 against Verticillium dahliae in Eggplant

    PubMed Central

    Zhang, Jing; Zong, Zhaofeng

    2017-01-01

    A fungus with broad spectrum antifungal activity was isolated from the soil in Qinling Mountain, Shaanxi Province, in China. The fungus was identified as Purpureocillium lilacinum based on ITS rDNA gene analysis. The strain, coded as QLP12, showed high inhibition activity on fungal mycelium growth in vitro, especially to Mucor piriformis, Trichothecium roseum, Rhizoctonia solani, and Verticillium dahliae, and its potential for biocontrol efficacy of eggplant. Verticillium wilt disease caused by Verticillium dahliae among 10 fungal species tested was explored. In greenhouse experiments, QLP12 showed an excellent growth-promoting effect on eggplant seed germination (76.7%), bud growth (79.4%), chlorophyll content (47.83%), root activity (182.02%), and so on. QLP12 can colonize the eggplant interior and also develop in rhizosphere soil. In greenhouse, the incidence of Verticillium wilt decreased by 83.82% with pretreated QLP12 fermentation broth in the soil. In the field, QLP12 showed prominent biocontrol effects on Verticillium wilt by reducing the disease index over the whole growth period, a decline of 40.1%. This study showed that the strain QLP12 is not only an effective biocontrol agent for controlling Verticillium wilt of eggplant, but also a plant growth-promoting fungus that deserves to be further developed. PMID:28303252

  12. Method To Enhance Growth and Sporulation of Pelletized Biocontrol Fungi †

    PubMed Central

    Knudsen, G. R.; Eschen, D. J.; Dandurand, L. M.; Wang, Z. G.

    1991-01-01

    The biocontrol fungi Trichoderma harzianum, used to control soilborne plant pathogens, and Beauveria bassiana, used to control insect pests, were formulated as mycelial biomass in alginate pellets with wheat bran added. After drying for 0, 4, or 16 h, pellets were placed in water or in aqueous solutions of polyethylene glycol (PEG) 8000 for 4 to 24 h and then allowed to continue drying. PEG-treated pellets containing T. harzianum showed significantly greater proliferation of hyphae in soil than untreated pellets or pellets treated with water. Production of conidia of T. harzianum from PEG-treated pellets was lower than production from untreated pellets after 4 days, although rates were equivalent after 7 days. In contrast, production of conidia of B. bassiana was significantly more rapid from PEG-treated pellets than from untreated pellets. Biocontrol of soilborne plant pathogens or insect pests may be enhanced by rapid hyphal growth of T. harzianum in soil or rapid sporulation of B. bassiana on foliage, respectively. Therefore, PEG treatment may improve the efficacy of these biocontrol agents. PMID:16348562

  13. Evaluation of the Biocontrol Potential of Purpureocillium lilacinum QLP12 against Verticillium dahliae in Eggplant.

    PubMed

    Lan, Xingjie; Zhang, Jing; Zong, Zhaofeng; Ma, Qing; Wang, Yang

    2017-01-01

    A fungus with broad spectrum antifungal activity was isolated from the soil in Qinling Mountain, Shaanxi Province, in China. The fungus was identified as Purpureocillium lilacinum based on ITS rDNA gene analysis. The strain, coded as QLP12, showed high inhibition activity on fungal mycelium growth in vitro, especially to Mucor piriformis, Trichothecium roseum, Rhizoctonia solani, and Verticillium dahliae, and its potential for biocontrol efficacy of eggplant. Verticillium wilt disease caused by Verticillium dahliae among 10 fungal species tested was explored. In greenhouse experiments, QLP12 showed an excellent growth-promoting effect on eggplant seed germination (76.7%), bud growth (79.4%), chlorophyll content (47.83%), root activity (182.02%), and so on. QLP12 can colonize the eggplant interior and also develop in rhizosphere soil. In greenhouse, the incidence of Verticillium wilt decreased by 83.82% with pretreated QLP12 fermentation broth in the soil. In the field, QLP12 showed prominent biocontrol effects on Verticillium wilt by reducing the disease index over the whole growth period, a decline of 40.1%. This study showed that the strain QLP12 is not only an effective biocontrol agent for controlling Verticillium wilt of eggplant, but also a plant growth-promoting fungus that deserves to be further developed.

  14. Genetics Home Reference: harlequin ichthyosis

    MedlinePlus

    ... Taylor AE, Ilchyshyn A, Kennedy CT, Goodyear H, Moss C, Paige D, Harper JI, Young BD, Leigh ... D, Elias PM, Williams ML. Pathophysiologic basis for growth failure in children with ichthyosis: an evaluation of ...

  15. "Repent, Harlequin!" Said the Ticktockman

    ERIC Educational Resources Information Center

    Ellison, Harlan

    1973-01-01

    Topic 8, Our Contemporary World: Problems and Issues, in a theme issue on Teaching World History Through Science Fiction, presents this short story to motivate discussion on dehumanization, resulting in a society where the single driving force is order and unity and promptness and clocklike precision. (JB)

  16. Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers.

    PubMed

    Nzioki, Henry S; Oyosi, Florence; Morris, Cindy E; Kaya, Eylul; Pilgeram, Alice L; Baker, Claire S; Sands, David C

    2016-01-01

    Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize

  17. Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers

    PubMed Central

    Nzioki, Henry S.; Oyosi, Florence; Morris, Cindy E.; Kaya, Eylul; Pilgeram, Alice L.; Baker, Claire S.; Sands, David C.

    2016-01-01

    Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize

  18. Demographic models inform selection of biocontrol agents for garlic mustard (Alliaria petiolata).

    PubMed

    Davis, Adam S; Landis, Douglas A; Nuzzo, Victoria; Blossey, Bernd; Gerber, Esther; Hinz, Hariet L

    2006-12-01

    Nonindigenous invasive plants pose a major threat to natural communities worldwide. Biological control of weeds via selected introduction of their natural enemies can affect control over large spatial areas but also risk nontarget effects. To maximize effectiveness while minimizing risk, weed biocontrol programs should introduce the minimum number of host-specific natural enemies necessary to control an invasive nonindigenous plant. We used elasticity analysis of a matrix model to help inform biocontrol agent selection for garlic mustard (Alliaria petiolata (M. Bieb.) Cavara and Grande). The Eurasian biennial A. petiolata is considered one of the most problematic invaders of temperate forests in North America. Four weevil species in the genus Ceutorhynchus (Coleoptera: Curculionidae) are currently considered potential biocontrol agents. These species attack rosettes (C. scrobicollis), stems (C. roberti, C. alliariae), and seeds (C. constrictus) of A. petiolata. Elasticity analyses using A. petiolata demographic parameters from North America indicated that changes in the rosette-to-flowering-plant transition and changes in fecundity consistently had the greatest impact on population growth rate. These results suggest that attack by the rosette-feeder C. scrobicollis, which reduces overwintering survival, and seed or stem feeders that reduce seed output should be particularly effective. Model outcomes differed greatly as A. petiolata demographic parameters were varied within ranges observed in North America, indicating that successful control of A. petiolata populations may occur under some, but not all, conditions. Using these a priori analyses we predict: (1) rosette mortality and reduction of seed output will be the most important factors determining A. petiolata demography; (2) the root-crown feeder C. scrobicollis will have the most significant impact on A. petiolata demography; (3) releases of single control agents are unlikely to control A. petiolata across

  19. Functional Investigation of a Non-coding Variant Associated with Adolescent Idiopathic Scoliosis in Zebrafish: Elevated Expression of the Ladybird Homeobox Gene Causes Body Axis Deformation.

    PubMed

    Guo, Long; Yamashita, Hiroshi; Kou, Ikuyo; Takimoto, Aki; Meguro-Horike, Makiko; Horike, Shin-ichi; Sakuma, Tetsushi; Miura, Shigenori; Adachi, Taiji; Yamamoto, Takashi; Ikegawa, Shiro; Hiraki, Yuji; Shukunami, Chisa

    2016-01-01

    Previously, we identified an adolescent idiopathic scoliosis susceptibility locus near human ladybird homeobox 1 (LBX1) and FLJ41350 by a genome-wide association study. Here, we characterized the associated non-coding variant and investigated the function of these genes. A chromosome conformation capture assay revealed that the genome region with the most significantly associated single nucleotide polymorphism (rs11190870) physically interacted with the promoter region of LBX1-FLJ41350. The promoter in the direction of LBX1, combined with a 590-bp region including rs11190870, had higher transcriptional activity with the risk allele than that with the non-risk allele in HEK 293T cells. The ubiquitous overexpression of human LBX1 or either of the zebrafish lbx genes (lbx1a, lbx1b, and lbx2), but not FLJ41350, in zebrafish embryos caused body curvature followed by death prior to vertebral column formation. Such body axis deformation was not observed in transcription activator-like effector nucleases mediated knockout zebrafish of lbx1b or lbx2. Mosaic expression of lbx1b driven by the GATA2 minimal promoter and the lbx1b enhancer in zebrafish significantly alleviated the embryonic lethal phenotype to allow observation of the later onset of the spinal curvature with or without vertebral malformation. Deformation of the embryonic body axis by lbx1b overexpression was associated with defects in convergent extension, which is a component of the main axis-elongation machinery in gastrulating embryos. In embryos overexpressing lbx1b, wnt5b, a ligand of the non-canonical Wnt/planar cell polarity (PCP) pathway, was significantly downregulated. Injection of mRNA for wnt5b or RhoA, a key downstream effector of Wnt/PCP signaling, rescued the defective convergent extension phenotype and attenuated the lbx1b-induced curvature of the body axis. Thus, our study presents a novel pathological feature of LBX1 and its zebrafish homologs in body axis deformation at various stages of

  20. Functional Investigation of a Non-coding Variant Associated with Adolescent Idiopathic Scoliosis in Zebrafish: Elevated Expression of the Ladybird Homeobox Gene Causes Body Axis Deformation

    PubMed Central

    Guo, Long; Yamashita, Hiroshi; Kou, Ikuyo; Takimoto, Aki; Meguro-Horike, Makiko; Horike, Shin-ichi; Sakuma, Tetsushi; Miura, Shigenori; Adachi, Taiji; Yamamoto, Takashi; Ikegawa, Shiro; Hiraki, Yuji; Shukunami, Chisa

    2016-01-01

    Previously, we identified an adolescent idiopathic scoliosis susceptibility locus near human ladybird homeobox 1 (LBX1) and FLJ41350 by a genome-wide association study. Here, we characterized the associated non-coding variant and investigated the function of these genes. A chromosome conformation capture assay revealed that the genome region with the most significantly associated single nucleotide polymorphism (rs11190870) physically interacted with the promoter region of LBX1-FLJ41350. The promoter in the direction of LBX1, combined with a 590-bp region including rs11190870, had higher transcriptional activity with the risk allele than that with the non-risk allele in HEK 293T cells. The ubiquitous overexpression of human LBX1 or either of the zebrafish lbx genes (lbx1a, lbx1b, and lbx2), but not FLJ41350, in zebrafish embryos caused body curvature followed by death prior to vertebral column formation. Such body axis deformation was not observed in transcription activator-like effector nucleases mediated knockout zebrafish of lbx1b or lbx2. Mosaic expression of lbx1b driven by the GATA2 minimal promoter and the lbx1b enhancer in zebrafish significantly alleviated the embryonic lethal phenotype to allow observation of the later onset of the spinal curvature with or without vertebral malformation. Deformation of the embryonic body axis by lbx1b overexpression was associated with defects in convergent extension, which is a component of the main axis-elongation machinery in gastrulating embryos. In embryos overexpressing lbx1b, wnt5b, a ligand of the non-canonical Wnt/planar cell polarity (PCP) pathway, was significantly downregulated. Injection of mRNA for wnt5b or RhoA, a key downstream effector of Wnt/PCP signaling, rescued the defective convergent extension phenotype and attenuated the lbx1b-induced curvature of the body axis. Thus, our study presents a novel pathological feature of LBX1 and its zebrafish homologs in body axis deformation at various stages of

  1. Is the ability of biocontrol fluorescent pseudomonads to produce the antifungal metabolite 2,4-diacetylphloroglucinol really synonymous with higher plant protection?

    PubMed

    Rezzonico, Fabio; Zala, Marcello; Keel, Christoph; Duffy, Brion; Moënne-Loccoz, Yvan; Défago, Geneviève

    2007-01-01

    The antifungal compound 2,4-diacetylphloroglucinol (Phl) contributes to biocontrol in pseudomonads, but whether or not Phl(+) biocontrol pseudomonads display higher plant-protecting activity than Phl(-) biocontrol pseudomonads remains to be demonstrated. This issue was addressed by assessing 230 biocontrol fluorescent pseudomonads selected from a collection of 3132 bacterial isolates obtained from 63 soils worldwide. One-third of the biocontrol pseudomonads were Phl(+) and almost all Phl(+) isolates also produced hydrogen cyanide (HCN). The only Phl(+) HCN(-) strain did harbor hcn genes, but with the deletion of a 134 bp hcnC fragment corresponding to an ADP-binding motif. Statistical analysis of biocontrol isolate distributions indicated that Phl production ability was associated with superior disease suppression activity in the Pythium-cucumber and Fusarium-tomato pathosystems, but this was also the case with HCN production ability. However, HCN significance was not as strong, as indicated both by the comparison of Phl(-) HCN(+) and Phl(-) HCN(-) strains and by correlation analyses. This is the first population-level demonstration of the higher plant-protecting activity of Phl(+) biocontrol pseudomonads in comparison with Phl(-) biocontrol pseudomonads.

  2. Hrp mutant bacteria as biocontrol agents: toward a sustainable approach in the fight against plant pathogenic bacteria.

    PubMed

    Hanemian, Mathieu; Zhou, Binbin; Deslandes, Laurent; Marco, Yves; Trémousaygue, Dominique

    2013-10-01

    Sustainable agriculture necessitates development of environmentally safe methods to protect plants against pathogens. Among these methods, application of biocontrol agents has been efficiently used to minimize disease development. Here we review current understanding of mechanisms involved in biocontrol of the main Gram-phytopathogenic bacteria-induced diseases by plant inoculation with strains mutated in hrp (hypersensitive response and pathogenicity) genes. These mutants are able to penetrate plant tissues and to stimulate basal resistance of plants. Novel protection mechanisms involving the phytohormone abscisic acid appear to play key roles in the biocontrol of wilt disease induced by Ralstonia solanacearum in Arabidopsis thaliana. Fully understanding these mechanisms and extending the studies to other pathosystems are still required to evaluate their importance in disease protection.

  3. The double life of Ceratobasidium: orchid mycorrhizal fungi and their potential for biocontrol of Rhizoctonia solani sheath blight of rice.

    PubMed

    Mosquera-Espinosa, Ana Teresa; Bayman, Paul; Prado, Gustavo A; Gómez-Carabalí, Arnulfo; Otero, J Tupac

    2013-01-01

    Ceratobasidium includes orchid mycorrhizal symbionts, plant pathogens and biocontrol agents of soilborne plant pathogens. It is not known to what extent members of the first guild also can participate in the others. Ceratobasidium spp. were isolated from roots of Colombian orchids and identified by phylogeny based on nrITS sequences. Phylogenetic grouping of Ceratobasidium spp. isolates corresponded to orchid host substrate (epiphytic vs. terrestrial). Isolates were tested for virulence on rice and for biocontrol of Rhizoctonia solani, causal agent of sheath blight of rice. All Ceratobasidium spp. isolates caused some signs of sheath blight but significantly less than a pathogenic R. solani used as a positive control. When Ceratobasidium spp. isolates were inoculated on rice seedlings 3 d before R. solani, they significantly reduced disease expression compared to controls inoculated with R. solani alone. The use of Ceratobasidium spp. from orchids for biological control is novel, and biodiverse countries such as Colombia are promising places to look for new biocontrol agents.

  4. Production of the biocontrol agent Pantoea agglomerans strain CPA-2 using commercial products and by-products.

    PubMed

    Costa, E; Teixidó, N; Usall, J; Atarés, E; Viñas, I

    2001-08-01

    The aim of this paper was to find the nitrogen and carbon sources that provide maximum biomass production of strain CPA-2 of the biocontrol agent Pantoea agglomerans and minimum cost of media, whilst maintaining biocontrol efficacy. To reduce the cost of media, commercial products and by-products were tested. P. agglomerans can be produced using a combination of nitrogen sources such as yeast extract (5 g l(-1)) and dry beer yeast (10 g l(-1)) with inexpensive carbohydrates such as sucrose (10 g l(-1)) and molasses (20 g l(-1)), respectively, maintaining the efficacy of the biocontrol agent against Penicillium digitatum and P. italicum on oranges. The results obtained in this study could be used to provide a reliable basis for a scale-up of this fermentation process to an industrial level.

  5. Preliminary in vitro insights into the use of natural fungal pathogens of leaf-cutting ants as biocontrol agents.

    PubMed

    Folgarait, Patricia; Gorosito, Norma; Poulsen, Michael; Currie, Cameron R

    2011-09-01

    Leaf-cutting ants are one of the main herbivores of the Neotropics, where they represent an important agricultural pest. These ants are particularly difficult to control because of the complex network of microbial symbionts. Leaf-cutting ants have traditionally been controlled through pesticide application, but there is a need for alternative, more environmentally friendly, control methods such as biological control. Potential promising biocontrol candidates include the microfungi Escovopsis spp. (anamorphic Hypocreales), which are specialized pathogens of the fungi the ants cultivate for food. These pathogens are suppressed through ant behaviors and ant-associated antibiotic-producing Actinobacteria. In order to be an effective biocontrol agent, Escovopsis has to overcome these defenses. Here, we evaluate, using microbial in vitro assays, whether defenses in the ant-cultivated fungus strain (Leucoagaricus sp.) and Actinobacteria from the ant pest Acromyrmex lundii have the potential to limit the use of Escovopsis in biocontrol. We also explore, for the first time, possible synergistic biocontrol between Escovopsis and the entomopathogenic fungus Lecanicillium lecanii. All strains of Escovopsis proved to overgrow A. lundii cultivar in less than 7 days, with the Escovopsis strain isolated from a different leaf-cutting ant species being the most efficient. Escovopsis challenged with a Streptomyces strain isolated from A. lundii did not exhibit significant growth inhibition. Both results are encouraging for the use of Escovopsis as a biocontrol agent. Although we found that L. lecanii can suppress the growth of the cultivar, it also had a negative impact on Escovopsis, making the success of simultaneous use of these two fungi for biocontrol of A. lundii questionable.

  6. Small RNAs regulate the biocontrol property of fluorescent Pseudomonas strain Psd.

    PubMed

    Upadhyay, Anamika; Kochar, Mandira; Upadhyay, Ashutosh; Tripathy, Soumya; Rajam, Manchikatla Venkat; Srivastava, Sheela

    2017-03-01

    The production of biocontrol factors by Pseudomonads is reported to be controlled at the post-transcriptional level by the GacS/GacA signal transduction pathway. This involves RNA-binding translational repressor proteins, RsmA and RsmE, and the small regulatory RNAs (sRNAs) RsmX, RsmY, and RsmZ. While the former represses genes involved in secondary metabolite production, the latter relieves this repression at the end of exponential growth. We have studied the fluorescent Pseudomonas strain Psd, possessing good biocontrol potential, and confirmed the presence of rsmY and rsmZ by PCR amplification. Gene constructs for all the three small RNAs (RsmX, RsmY and RsmZ) carried on broad host-range plasmid, pME6032 were mobilized into strain Psd. Expression analysis of gacA in the recombinant strains over-expressing rsmX (Psd-pME7320), rsmY (Psd-pME6359) and rsmZ (Psd-pME6918) revealed a significant upregulation of the response regulator. Besides, a remarkable down-regulation of rsmA was also reported in all the strains. The variant strains were found to produce comparatively higher levels of phenazines. Indole acetic acid levels were higher to some extent, and strain Psd-pME6918 also showed elevated production of HCN. The tomato seedlings infected with Fusarium oxysporum and Verticillium dahliae in the presence of culture filtrate of the recombinant strains showed better plant protection response in comparison to the wild-type strain Psd. These results suggest that small RNAs are important determinants in regulation of the biocontrol property of strain Psd.

  7. Characterization of the biocontrol activity of pseudomonas fluorescens strain X reveals novel genes regulated by glucose.

    PubMed

    Kremmydas, Gerasimos F; Tampakaki, Anastasia P; Georgakopoulos, Dimitrios G

    2013-01-01

    Pseudomonas fluorescens strain X, a bacterial isolate from the rhizosphere of bean seedlings, has the ability to suppress damping-off caused by the oomycete Pythium ultimum. To determine the genes controlling the biocontrol activity of strain X, transposon mutagenesis, sequencing and complementation was performed. Results indicate that, biocontrol ability of this isolate is attributed to gcd gene encoding glucose dehydrogenase, genes encoding its co-enzyme pyrroloquinoline quinone (PQQ), and two genes (sup5 and sup6) which seem to be organized in a putative operon. This operon (named supX) consists of five genes, one of which encodes a non-ribosomal peptide synthase. A unique binding site for a GntR-type transcriptional factor is localized upstream of the supX putative operon. Synteny comparison of the genes in supX revealed that they are common in the genus Pseudomonas, but with a low degree of similarity. supX shows high similarity only to the mangotoxin operon of Ps. syringae pv. syringae UMAF0158. Quantitative real-time PCR analysis indicated that transcription of supX is strongly reduced in the gcd and PQQ-minus mutants of Ps. fluorescens strain X. On the contrary, transcription of supX in the wild type is enhanced by glucose and transcription levels that appear to be higher during the stationary phase. Gcd, which uses PQQ as a cofactor, catalyses the oxidation of glucose to gluconic acid, which controls the activity of the GntR family of transcriptional factors. The genes in the supX putative operon have not been implicated before in the biocontrol of plant pathogens by pseudomonads. They are involved in the biosynthesis of an antimicrobial compound by Ps. fluorescens strain X and their transcription is controlled by glucose, possibly through the activity of a GntR-type transcriptional factor binding upstream of this putative operon.

  8. A new method to evaluate the biocontrol potential of single spore isolates of fungal entomopathogens

    PubMed Central

    Posada, Francisco J.; Vega, Fernando E.

    2005-01-01

    Fifty Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) strains isolated from the coffee berry borer were used to develop a novel screening method aimed at selecting strains with the highest biocontrol potential. The screening method is based on percent insect mortality, average survival time, mortality distribution, percent spore germination, fungal life cycle duration, and spore production on the insect. Based on these parameters, only 11 strains merited further study. The use of a sound scientific protocol for the selection of promising fungal entomopathogens should lead to more efficient use of time, labor, and financial resources in biological control programs. PMID:17119619

  9. [Optimization of biocontrol agent Burkholderia pyrrocinia strain JK-SH007 fermentation by response surface methodology].

    PubMed

    Li, Hao; Ren, Jiahong; Ye, Jianren

    2013-02-01

    In order to improve ferment efficiency of biocontrol agent Burkholderia pyrrocinia JK-SH007, the fermentation conditions of this strain were optimized. The optimal fermentation conditions were corn steep liquor (13.88 g/L) and glucose (3.37 g/L) by screening test, steepest ascent experiments and response surface analysis. The results showed that the cell density of JK-SH007 (1.18 x 10(9) CFU/mL) increased 1.35 times than before, and there was a 28.84% increase in antifungal activity.

  10. Isolation, characterization, and production of red pigment from Cercospora piaropi a biocontrol agent for waterhyacinth.

    PubMed

    Jiménez, Maricela Martínez; Bahena, Selenia Miranda; Espinoza, César; Trigos, Angel

    2010-04-01

    A red pigment produced by a Mexican isolate of Cercospora piaropi (waterhyacinth pathogen) has been isolated and identified as cercosporin. The kinetic of cercosporin production in culture media during dark/light regimes was evaluated. When C. piaropi was cultivated in continuous light and potato dextrose broth culture, a maximum of cercosporin production was observed (72.59 mg/l). Despite other reports, C piaropi Mexican isolate produce cercosporin in dark conditions (25.70 mg/l). The results suggest that production of cercosporin in C. piaropi-waterhyacinth pathogenesis is an important factor to take into account in biocontrol strategies.

  11. A new method to evaluate the biocontrol potential of single spore isolates of fungal entomopathogens.

    PubMed

    Posada, Francisco J; Vega, Fernando E

    2005-12-06

    Fifty Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) strains isolated from the coffee berry borer were used to develop a novel screening method aimed at selecting strains with the highest biocontrol potential. The screening method is based on percent insect mortality, average survival time, mortality distribution, percent spore germination, fungal life cycle duration, and spore production on the insect. Based on these parameters, only 11 strains merited further study. The use of a sound scientific protocol for the selection of promising fungal entomopathogens should lead to more efficient use of time, labor, and financial resources in biological control programs.

  12. Alternethanoxins A and B, polycyclic ethanones produced by Alternaria sonchi , potential mycoherbicides for Sonchus arvensis biocontrol.

    PubMed

    Evidente, Antonio; Punzo, Biancavaleria; Andolfi, Anna; Berestetskiy, Alexander; Motta, Andrea

    2009-08-12

    Alternaria sonchi is a fungal pathogen isolated from Sonchus arvensis and proposed as a biocontrol agent of this noxious perennial weed. Different phytotoxic metabolites were isolated from solid culture of the fungus. Two new polycyclic ethanones, named alternethanoxins A and B, were characterized using essentially spectroscopic and chemical methods. Tested by leaf disk-puncture assay on the fungal host plant and a number of nonhost plants, alternethanoxins A and B were shown to be phytotoxic, whereas they did not possess antimicrobial activity tested at 100 microg/disk. Hence, alternethanoxins A and B have potential as nonselective natural herbicides. Some structure-activity relationship observations were also made.

  13. Rhizoxin analogs contribute to the biocontrol activity of a newly isolated pseudomonas strain.

    PubMed

    Takeuchi, Kasumi; Noda, Naomi; Katayose, Yuichi; Mukai, Yoshiyuki; Numa, Hisataka; Yamada, Kosumi; Someya, Nobutaka

    2015-03-01

    Two strains of Pseudomonas sp., Os17 and St29, were newly isolated from the rhizosphere of rice and potato, respectively, by screening for 2,4-diacetylphloroglucinol producers. These strains were found to be the same species and were the closest to but different from Pseudomonas protegens among the sequenced pseudomonads, based on 16S ribosomal RNA gene and whole-genome analyses. Strain Os17 was as effective a biocontrol agent as reported for P. protegens Cab57, whereas strain St29 was less effective. The whole-genome sequences of these strains were obtained: the genomes are organized into a single circular chromosome with 6,885,464 bp, 63.5% G+C content, and 6,195 coding sequences for strain Os17; and with 6,833,117 bp, 63.3% G+C content, and 6,217 coding sequences for strain St29. Comparative genome analysis of these strains revealed that the complete rhizoxin analog biosynthesis gene cluster (approximately 79 kb) found in the Os17 genome was absent from the St29 genome. In an rzxB mutant, which lacks the polyketide synthase essential for the production of rhizoxin analogs, the growth inhibition activity against fungal and oomycete pathogens and the plant protection efficacy were attenuated compared with those of wild-type Os17. These findings suggest that rhizoxin analogs are important biocontrol factors of this strain.

  14. Tamarisk biocontrol using tamarisk beetles: Potential consequences for riparian birds in the southwestern United States

    USGS Publications Warehouse

    Paxton, E.H.; Theimer, T.C.; Sogge, M.K.

    2011-01-01

    The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a wellstudied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.) and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment. ?? The Cooper Ornithological Society 2011.

  15. Tamarisk biocontrol using tamarisk beetles: Potential consequences for riparian birds in the southwestern United States

    USGS Publications Warehouse

    Paxton, Eben H.; Theimer, Tad C.; Sogge, Mark K.

    2011-01-01

    The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a well-studied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.) and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment.

  16. Phaeobacter inhibens as biocontrol agent against Vibrio vulnificus in oyster models.

    PubMed

    Porsby, Cisse Hedegaard; Gram, Lone

    2016-08-01

    Molluscan shellfish can cause food borne diseases and here we investigated if addition of Vibrio-antagonising bacteria could reduce Vibrio vulnificus in model oyster systems and prevent its establishment in live animals. Phaeobacter inhibens, which produces an antibacterial compound, tropodithietic acid (TDA), inhibited V. vulnificus as did pure TDA (MIC of 1-3.9 μM). P. inhibens DSM 17395 (at 10(6) cfu/ml) eradicated 10(5) cfu/ml V. vulnificus CMCP6 (a rifampicin resistant variant) from a co-culture oyster model system (oyster juice) whereas the pathogen grew to 10(7) cfu/ml when co-cultured with a TDA negative Phaeobacter mutant. P. inhibens grew well in oyster juice to 10(8) CFU/ml and sterile filtered samples from these cultures were inhibitory to Vibrio spp. P. inhibens established itself in live European flat oysters (Ostrea edulis) and remained at 10(5) cfu/g for five days. However, the presence of P. inhibens could not prevent subsequently added V. vulnificus from entering the live animals, likely because of too low levels of the biocontrol strain. Whilst the oyster model studies provided indication that P. inhibens DSM 17395 could be a good candidate as biocontrol agent against V. vulnificus further optimization is need in the actual animal rearing situation.

  17. Structural characterization of antibiotic self-immunity tRNA synthetase in plant tumour biocontrol agent

    PubMed Central

    Chopra, Shaileja; Palencia, Andrés; Virus, Cornelia; Schulwitz, Sarah; Temple, Brenda R.; Cusack, Stephen; Reader, John

    2016-01-01

    Antibiotic-producing microbes evolved self-resistance mechanisms to avoid suicide. The biocontrol Agrobacterium radiobacter K84 secretes the Trojan Horse antibiotic agrocin 84 that is selectively transported into the plant pathogen A. tumefaciens and processed into the toxin TM84. We previously showed that TM84 employs a unique tRNA-dependent mechanism to inhibit leucyl-tRNA synthetase (LeuRS), while the TM84-producer prevents self-poisoning by expressing a resistant LeuRS AgnB2. We now identify a mechanism by which the antibiotic-producing microbe resists its own toxin. Using a combination of structural, biochemical and biophysical approaches, we show that AgnB2 evolved structural changes so as to resist the antibiotic by eliminating the tRNA-dependence of TM84 binding. Mutagenesis of key resistance determinants results in mutants adopting an antibiotic-sensitive phenotype. This study illuminates the evolution of resistance in self-immunity genes and provides mechanistic insights into a fascinating tRNA-dependent antibiotic with applications for the development of anti-infectives and the prevention of biocontrol emasculation. PMID:27713402

  18. Plant growth-promoting rhizobacteria (PGPR): Their potential as antagonists and biocontrol agents

    PubMed Central

    Beneduzi, Anelise; Ambrosini, Adriana; Passaglia, Luciane M.P.

    2012-01-01

    Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR). PGPR are highly diverse and in this review we focus on rhizobacteria as biocontrol agents. Their effects can occur via local antagonism to soil-borne pathogens or by induction of systemic resistance against pathogens throughout the entire plant. Several substances produced by antagonistic rhizobacteria have been related to pathogen control and indirect promotion of growth in many plants, such as siderophores and antibiotics. Induced systemic resistance (ISR) in plants resembles pathogen-induced systemic acquired resistance (SAR) under conditions where the inducing bacteria and the challenging pathogen remain spatially separated. Both types of induced resistance render uninfected plant parts more resistant to pathogens in several plant species. Rhizobacteria induce resistance through the salicylic acid-dependent SAR pathway, or require jasmonic acid and ethylene perception from the plant for ISR. Rhizobacteria belonging to the genera Pseudomonas and Bacillus are well known for their antagonistic effects and their ability to trigger ISR. Resistance-inducing and antagonistic rhizobacteria might be useful in formulating new inoculants with combinations of different mechanisms of action, leading to a more efficient use for biocontrol strategies to improve cropping systems. PMID:23411488

  19. Should the biofilm mode of life be taken into consideration for microbial biocontrol agents?

    PubMed

    Pandin, Caroline; Le Coq, Dominique; Canette, Alexis; Aymerich, Stéphane; Briandet, Romain

    2017-02-16

    Almost one-third of crop yields are lost every year due to microbial alterations and diseases. The main control strategy to limit these losses is the use of an array of chemicals active against spoilage and unwanted pathogenic microorganisms. Their massive use has led to extensive environmental pollution, human poisoning and a variety of diseases. An emerging alternative to this chemical approach is the use of microbial biocontrol agents. Biopesticides have been used with success in several fields, but a better understanding of their mode of action is necessary to better control their activity and increase their use. Very few studies have considered that biofilms are the preferred mode of life of microorganisms in the target agricultural biotopes. Increasing evidence shows that the spatial organization of microbial communities on crop surfaces may drive important bioprotection mechanisms. The aim of this review is to summarize the evidence of biofilm formation by biocontrol agents on crops and discuss how this surface-associated mode of life may influence their biology and interactions with other microorganisms and the host and, finally, their overall beneficial activity.

  20. Systematics of the Trichoderma harzianum species complex and the re-identification of commercial biocontrol strains

    PubMed Central

    Jaklitsch, Walter; Gazis, Romina; Degenkolb, Thomas; Samuels, Gary J.

    2016-01-01

    Trichoderma harzianum is known as a cosmopolitan, ubiquitous species associated with a wide variety of substrates. It is possibly the most commonly used name in agricultural applications involving Trichoderma, including biological control of plant diseases. While various studies have suggested that T. harzianum is a species complex, only a few cryptic species are named. In the present study the taxonomy of the T. harzianum species complex is revised to include at least 14 species. Previously named species included in the complex are T. guizhouense, T. harzianum, and T. inhamatum. Two new combinations are proposed, T. lentiforme and T. lixii. Nine species are described as new, T. afarasin, T. afroharzianum, T. atrobrunneum, T. camerunense, T. endophyticum, T. neotropicale, T. pyramidale, T. rifaii and T. simmonsii. We isolated Trichoderma cultures from four commercial biocontrol products reported to contain T. harzianum. None of the biocontrol strains were identified as T. harzianum s. str. In addition, the widely applied culture ‘T. harzianum T22’ was determined to be T. afroharzianum. Some species in the T. harzianum complex appear to be exclusively endophytic, while others were only isolated from soil. Sexual states are rare. Descriptions and illustrations are provided. A secondary barcode, nuc translation elongation factor 1-α (TEF1) is needed to identify species in this complex. PMID:25661720

  1. Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 – a review

    PubMed Central

    Chowdhury, Soumitra Paul; Hartmann, Anton; Gao, XueWen; Borriss, Rainer

    2015-01-01

    Bacillus amyloliquefaciens subsp. plantarum FZB42 is a Gram-positive model bacterium for unraveling plant–microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that – except surfactin – the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli. Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR), which protect plants against attacks of pathogenic microbes, viruses, and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42. PMID:26284057

  2. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes.

    PubMed

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2015-09-07

    Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination.

  3. Carbon requirements of some nematophagous, entomopathogenic and mycoparasitic hyphomycetes as fungal biocontrol agents.

    PubMed

    Sun, ManHong; Liu, XingZhong

    2006-05-01

    Thirty-three carbon sources were evaluated for their effects on spore germination, hyphal growth and sporulation of 11 fungal biocontrol agents, i.e. the nematophagous fungi Paecilomyces lilacinus, Pochonia chlamydosporia, Hirsutella rhossiliensis, H. minnesotensis and Arkansas Fungus 18, the entomopathogenic fungi Lecanicillium lecanii, Beauveria bassiana and Metarhizium anisopliae, and the mycoparasitic fungus Trichoderma viride. Variations in carbon requirements were found among the fungal species or strains tested. All strains studied except for T. viride grew on most carbon sources, although B. bassiana had more fastidious requirements for spore germination. Monosaccharides and disaccharides were suitable for fungal growth. For most isolates, D-glucose, D-mannose, sucrose and trehalose were superior to pectin and soluble starch among the polysaccharides and lactic acid among the organic acids. Both ethanol and methanol could accelerate growth of most isolates but not biomass. D-mannose, D-fructose and D-xylose were excellent carbon sources for sporulation, while D-glucose, sucrose, cellobiose, trehalose, chitin, dextrin, gelatin and lactic acid were better for some isolates. Neither sorbic acid nor linoleic acid could be utilized as a single carbon source. These findings provided a better understanding of the nutritional requirements of different fungal biocontrol agents that can benefit the mass production process.

  4. Relationship between mycoparasites lifestyles and biocontrol behaviors against Fusarium spp. and mycotoxins production.

    PubMed

    Kim, Seon Hwa; Vujanovic, Vladimir

    2016-06-01

    Global food security research is seeking eco-friendly solutions to control mycotoxins in grain infected by fungi (molds). In particular, mycotoxigenic Fusarium spp. outbreak is a chronic threat for cereal grain production, human, and animal health. In this review paper, we discuss up-to-date biological control strategies in applying mycoparasites as biological control agents (BCA) to prevent plant diseases in crops and mycotoxins in grain, food, and feed. The aim is to increase food safety and to minimize economic losses due to the reduced grain yield and quality. However, recent papers indicate that the study of the BCA specialists with biotrophic lifestyle lags behind our understanding of the BCA generalists with necrotrophic lifestyle. We examine critical behavioral traits of the two BCA groups of mycoparasites. The goal is to highlight their major characteristics in the context of future research towards an efficient biocontrol strategy against mycotoxin-producing Fusarium species. The emphasis is put on biocontrol of Fusarium graminearum, F. avenaceum, and F. culmorum causing Fusarium head blight (FHB) in cereals and their mycotoxins.

  5. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

    PubMed Central

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2015-01-01

    Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

  6. Biocontrol of Burkholderia cepacia complex bacteria and bacterial phytopathogens by Bdellovibrio bacteriovorus.

    PubMed

    McNeely, Damian; Chanyi, Ryan M; Dooley, James S; Moore, John E; Koval, Susan F

    2017-04-01

    Bdellovibrio and like organisms are predatory bacteria that have the unusual property of using the cytoplasmic constituents of other Gram-negative bacteria as nutrients. These predators may thus provide an alternative approach to the biocontrol of human and plant pathogens. Predators were isolated on Burkholderia cenocepacia K56-2 and J2315 as prey cells, in enrichment cultures with soil and sewage. Three isolates (DM7C, DM8A, and DM11A) were identified as Bdellovibrio bacteriovorus on the basis of morphology, a periplasmic life cycle, and 16S rRNA gene sequencing. The prey range of these isolates was tested on Burkholderia cepacia complex bacteria and several phytopathogenic bacteria of agricultural importance. Of 31 strains of the Burkholderia cepacia complex tested, only 4 were resistant to predation by strain DM7C. A subset of 9 of the prey tested were also susceptible to strains DM8A and DM11A. Of 12 phytopathogens tested, 4 were resistant to strains DM7C and DM8A, and only 2 were resistant to strain DM11A. Thus, Bdellovibrio bacteriovorus strains retrieved from environmental samples on 2 Burkholderia cenocepacia isolates from cystic fibrosis patients did not distinguish in their prey range between other isolates of that pathogen or phytopathogens. Such strains hold promise as potential wide-spectrum biocontrol agents.

  7. Diversity, Biocontrol, and Plant Growth Promoting Abilities of Xylem Residing Bacteria from Solanaceous Crops

    PubMed Central

    Achari, Gauri A.

    2014-01-01

    Eggplant (Solanum melongena L.) is one of the solanaceous crops of economic and cultural importance and is widely cultivated in the state of Goa, India. Eggplant cultivation is severely affected by bacterial wilt caused by Ralstonia solanacearum that colonizes the xylem tissue. In this study, 167 bacteria were isolated from the xylem of healthy eggplant, chilli, and Solanum torvum Sw. by vacuum infiltration and maceration. Amplified rDNA restriction analysis (ARDRA) grouped these xylem residing bacteria (XRB) into 38 haplotypes. Twenty-eight strains inhibited growth of R. solanacearum and produced volatile and diffusible antagonistic compounds and plant growth promoting substances in vitro. Antagonistic strains XB86, XB169, XB177, and XB200 recorded a biocontrol efficacy greater than 85% against BW and exhibited 12%–22 % increase in shoot length in eggplant in the greenhouse screening. 16S rRNA based identification revealed the presence of 23 different bacterial genera. XRB with high biocontrol and plant growth promoting activities were identified as strains of Staphylococcus sp., Bacillus sp., Streptomyces sp., Enterobacter sp., and Agrobacterium sp. This study is the first report on identity of bacteria from the xylem of solanaceous crops having traits useful in cultivation of eggplant. PMID:24963298

  8. Plant growth-promoting rhizobacteria (PGPR): Their potential as antagonists and biocontrol agents.

    PubMed

    Beneduzi, Anelise; Ambrosini, Adriana; Passaglia, Luciane M P

    2012-12-01

    Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR). PGPR are highly diverse and in this review we focus on rhizobacteria as biocontrol agents. Their effects can occur via local antagonism to soil-borne pathogens or by induction of systemic resistance against pathogens throughout the entire plant. Several substances produced by antagonistic rhizobacteria have been related to pathogen control and indirect promotion of growth in many plants, such as siderophores and antibiotics. Induced systemic resistance (ISR) in plants resembles pathogen-induced systemic acquired resistance (SAR) under conditions where the inducing bacteria and the challenging pathogen remain spatially separated. Both types of induced resistance render uninfected plant parts more resistant to pathogens in several plant species. Rhizobacteria induce resistance through the salicylic acid-dependent SAR pathway, or require jasmonic acid and ethylene perception from the plant for ISR. Rhizobacteria belonging to the genera Pseudomonas and Bacillus are well known for their antagonistic effects and their ability to trigger ISR. Resistance-inducing and antagonistic rhizobacteria might be useful in formulating new inoculants with combinations of different mechanisms of action, leading to a more efficient use for biocontrol strategies to improve cropping systems.

  9. Screening of novel microorganisms for biosurfactant and biocontrol activity against Phytophthora infestans.

    PubMed

    Tomar, Sonica; Singh, B P; Lal, Mehi; Ma, Khan; Hussain, Touseef; Sharma, Sanjeev; Kaushik, S K; Kumar, Satish

    2014-09-01

    In the present study, 95 isolates of bacteria were tested for their biosurfactant as well as biocontrol activity against Phytophthora infestans. The results revealed that only 15.8% isolates showed biosurfactant activity. The emulsification index ranged from 0-68% and 24.2% isolates showed positive reaction for biosurfactant properties. In emulsification assay and oil spreading test, 18.95% and 5.26% isolates, respectively scored positive for biosurfactant production. Among all, only five isolates were found effective against P. infestans, for biocontrol properties. Pseudomonas aeruginosa-1 showed 62.22% inhibition zone after 72 hrs while P. aeruginosa-3 showed 46.42%. Forty-eight hrs old culture supernatants were highly effective in food-poisoning test, tuber slice test and detached leaf method against P. infestans. In whole potato plant test, bacterial cell based formulation, culture supernatant and bacterial cell suspension of P. aeruginosa-1 showed 10.42%, 9.94% and 17.96% diseases severity respectively, as against 53.96% in control. This isolate holds promise as biological control agent against P. infestans in field.

  10. Endemic plants harbour specific Trichoderma communities with an exceptional potential for biocontrol of phytopathogens.

    PubMed

    Zachow, Christin; Berg, Christian; Müller, Henry; Monk, Jana; Berg, Gabriele

    2016-10-10

    Trichoderma strains exhibit enormous potential for applications in biotechnology, in particular as biocontrol agents against pathogens. However, little is known about the diversity of plant-associated Trichoderma communities at a global scale and their antagonistic spectrum. In order to gather information about structure and function, we compared Trichoderma biomes of endemic (Aeonium, Diospyros, Hebe, Rhododendron) and cosmopolitan plants (Zea mays) in a global study encompassing the area Northwest Africa to New Zealand via the European Alps and Madagascar. At the quantitative level we found no differences between cosmopolitan and endemic plants. Statistically significant differences were detected at the qualitative level: Trichoderma populations of endemic plants were highly specific and diverse with hot spots appearing in Madagascar and New Zealand. By contrast, maize plants from all sites shared the majority of Trichoderma species (65.5%). Interestingly, the high above ground biodiversity in ecosystems containing endemic plants was confirmed by a high below ground Trichoderma diversity. Despite the differences, we found a global Trichoderma core community shared by all analysed plants, which was dominated by T. koningii and T. koningiopsis. Amplicon-based network analyses revealed a high similarity between maize Trichoderma grown world-wide and distinct populations of endemic plants. Furthermore, Trichoderma strains from endemic plants showed a higher antagonistic activity against fungal pathogens compared to maize-associated strains. Our results showed that endemic plants are associated with a specific Trichoderma microbiome which possesses a high antagonistic activity indicating that it has potential to be used for biocontrol purposes.

  11. Biofertilization and Biocontrol in the fight against soilborne fungal root pathogens in Australian soils

    NASA Astrophysics Data System (ADS)

    Cooper, Sarah; Agnew, Linda; Pereg, Lily

    2015-04-01

    Control of soilborne fungal root pathogens that severely compromise cotton production and other crops worldwide has historically been through the use of synthetic fungicides and fertilizers, these often have hazardous implications for environmental and soil health. The search for sustainable alternatives has lead to heightened interest in biocontrol, using soil microorganisms that suppress the growth of phytopathogens directly and biofertilization, the use of microorganisms to increasing the nutrient availability in soils, increasing seedling vigour. Soil properties and consequently soil microbial properties are strongly impacted by agricultural practices, therefore we are isolating indigenous microorganisms from soils collected from ten different geographical locations within the Australian cotton-growing region. These differ vastly in soil type and management practices. Soils are being analysed to compare the abundance of phosphate solubilising, auxin producing and nitrogen cycling bacteria. Rhizospheric bacteria capable of plant growth promoting through a multiple actions are being isolated. In addition, a method for isolating soilborne fungal suppressive microbes directly from soil samples has been designed and is currently being used. Comparisons between agricultural practices and the plant growth promoting microbial component of soil microbiome will be reported on. We will discuss the microbial isolates identified, their modes of action and their potential use as biocontrol agents and/or biofertilizers in Australian cotton growing soils.

  12. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight disease of apple.

    PubMed

    Kim, In-Yong; Pusey, Paul Lawrence; Zhao, Youfu; Korban, Schuyler S; Choi, Hyungsoo; Kim, Kyekyoon Kevin

    2012-07-10

    Microencapsulation and controlled release of the biocontrol agent Pantoea agglomerans strain E325 (E325), an antagonist to the bacterial plant pathogen Erwinia amylovora that causes fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 μm in diameter, were fabricated to encapsulate E325 within the core, along with nutrients, to preserve viability and promote proliferation. Controlled release of E325 was achieved by separately adjusting alginate concentrations in the shell and core solutions, and by modifying the AMC size. Viability of E325 was monitored via fluorescent staining, revealing either lack of or minimal stress during or after encapsulation. Proliferation of E325 within AMCs, followed by their subsequent release, and colonization activities within confines of apple flowers were studied under different encapsulation conditions using rfp-labeled E325 to obtain highly promising results. This study provided a 'proof of concept' of the successful use of a microencapsulated biocontrol agent, E325, against E. amylovora, and could serve as a model for further studies on the development of effective plant disease management strategies.

  13. Endophytic colonization of olive roots by the biocontrol strain Pseudomonas fluorescens PICF7.

    PubMed

    Prieto, Pilar; Mercado-Blanco, Jesús

    2008-05-01

    Confocal microscopy combined with three-dimensional olive root tissue sectioning was used to provide evidence of the endophytic behaviour of Pseudomonas fluorescens PICF7, an effective biocontrol strain against Verticillium wilt of olive. Two derivatives of the green fluorescent protein (GFP), the enhanced green and the red fluorescent proteins, have been used to visualize simultaneously two differently fluorescently tagged populations of P. fluorescens PICF7 within olive root tissues at the single cell level. The time-course of colonization events of olive roots cv. Arbequina by strain PICF7 and the localization of tagged bacteria within olive root tissues are described. First, bacteria rapidly colonized root surfaces and were predominantly found in the differentiation zone. Thereafter, microscopy observations showed that PICF7-tagged populations eventually disappeared from the root surface, and increasingly colonized inner root tissues. Localized and limited endophytic colonization by the introduced bacteria was observed over time. Fluorescent-tagged bacteria were always visualized in the intercellular spaces of the cortex region, and no colonization of the root xylem vessels was detected at any time. To the best of our knowledge, this is the first time this approach has been used to demonstrate endophytism of a biocontrol Pseudomonas spp. strain in a woody host such as olive using a nongnotobiotic system.

  14. Systematics of the Trichoderma harzianum species complex and the re-identification of commercial biocontrol strains.

    PubMed

    Chaverri, Priscila; Branco-Rocha, Fabiano; Jaklitsch, Walter; Gazis, Romina; Degenkolb, Thomas; Samuels, Gary J

    2015-01-01

    Trichoderma harzianum is known as a cosmopolitan, ubiquitous species associated with a wide variety of substrates. It is possibly the most commonly used name in agricultural applications involving Trichoderma, including biological control of plant diseases. While various studies have suggested that T. harzianum is a species complex, only a few cryptic species are named. In the present study the taxonomy of the T. harzianum species complex is revised to include at least 14 species. Previously named species included in the complex are T. guizhouense, T. harzianum, and T. inhamatum. Two new combinations are proposed, T. lentiforme and T. lixii. Nine species are described as new, T. afarasin, T. afroharzianum, T. atrobrunneum, T. camerunense, T. endophyticum, T. neotropicale, T. pyramidale, T. rifaii and T. simmonsii. We isolated Trichoderma cultures from four commercial biocontrol products reported to contain T. harzianum. None of the biocontrol strains were identified as T. harzianum s. str. In addition, the widely applied culture 'T. harzianum T22' was determined to be T. afroharzianum. Some species in the T. harzianum complex appear to be exclusively endophytic, while others were only isolated from soil. Sexual states are rare. Descriptions and illustrations are provided. A secondary barcode, nuc translation elongation factor 1-α (TEF1) is needed to identify species in this complex.

  15. Influence of Pythium oligandrum Biocontrol on Fungal and Oomycete Population Dynamics in the Rhizosphere▿

    PubMed Central

    Vallance, Jessica; Le Floch, Gaétan; Déniel, Franck; Barbier, Georges; Lévesque, C. André; Rey, Patrice

    2009-01-01

    Fungal and oomycete populations and their dynamics were investigated following the introduction of the biocontrol agent Pythium oligandrum into the rhizosphere of tomato plants grown in soilless culture. Three strains of P. oligandrum were selected on the basis of their ability to form oospores (resting structures) and to produce tryptamine (an auxin-like compound) and oligandrin (a glycoprotein elicitor). Real-time PCR and plate counting demonstrated the persistence of large amounts of the antagonistic oomycete in the rhizosphere throughout the cropping season (April to September). Inter-simple-sequence-repeat analysis of the P. oligandrum strains collected from root samples at the end of the cropping season showed that among the three strains used for inoculation, the one producing the smallest amount of oospores was detected at 90%. Single-strand conformational polymorphism analysis revealed increases in the number of members and the complexity of the fungal community over time. There were no significant differences between the microbial ecosystems inoculated with P. oligandrum and those that were not treated, except for a reduction of Pythium dissotocum (ubiquitous tomato root minor pathogen) populations in inoculated systems during the last 3 months of culture. These findings raise interesting issues concerning the use of P. oligandrum strains producing elicitor and auxin molecules for plant protection and the development of biocontrol. PMID:19447961

  16. Global changes in expression of grapefruit peel tissue in response to the yeast biocontrol agent, Metschnikowia fructicola

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To gain a better understanding of the molecular changes taking place in citrus fruit tissue following the application of the yeast biocontrol agent, Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. Using a cut off of p<0.0...

  17. Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast Pichia anomala for aflatoxin reduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pichia anomala WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of mycotoxin in the food chain...

  18. Biocontrol potential of Steinernema thermophilum and its symbiont Xenorhabdus indica against lepidopteran pests: virulence to egg and larval stages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Under laboratory conditions, the biocontrol potential of Steinernema thermophilum was tested against eggs and larval stages of two important lepidopteran insect pests, Helicoverpa armigera and Spodoptera litura (polyphagous pests), as well as Galleria mellonella (used as a model host) . In terms of ...

  19. Complete Genome Sequence of Pseudomonas fluorescens LBUM636, a Strain with Biocontrol Capabilities against Late Blight of Potato

    PubMed Central

    Morrison, Christopher K.; Novinscak, Amy; Gadkar, Vijay J.; Joly, David L.

    2016-01-01

    Herein provided is the full-genome sequence of Pseudomonas fluorescens LBUM636. This strain is a plant growth-promoting rhizobacterium (PGPR) which produces phenazine-1-carboxylic acid, an antibiotic involved in the biocontrol of numerous plant pathogens, including late blight of potato caused by the plant pathogen Phytophthora infestans. PMID:27231373

  20. Potential for bio-control of food-borne pathogens with Bacteriovorax spp. and implications for food safety

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteriovorax spp. (Bvx) are delta proteobacteria adapted to marine ecosystems where salinity concentration range from 1-3%. Due to their predation of Gram-negative bacteria, Bvx may have great potential for biocontrol of food-borne pathogens on fruits and leafy greens. The goal of this research was...

  1. Survival of Salmonella Typhimurium on soybean sprouts after treatment with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of Salmonella Typhimurium on sprouts and minimally processed produce is crucial for food and consumer safety. The aim of this research was to assess natural microflora populations on soybean and evaluate the effects of gaseous chlorine dioxide (ClO2) and biocontrol Pseudomonas on the surviva...

  2. Survival of Salmonella enterica on soybean sprouts following treatments with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of Salmonella enterica on sprouts and minimally processed, ready-to-eat fruits and vegetables is important for food and consumer safety. The aim of this research was to assess the effects of gaseous chlorine dioxide(ClO2)and biocontrol microorganisms (Pseudomonas chlororaphis and P. fluoresc...

  3. Reduction of aflatoxins, cyclopiazonic acid and fumonisins in corn by biocontrol strains of non-aflatoxigenic Aspergillus flavus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of field studies in corn (maize) evaluated the ability of non-aflatoxigenic biocontrol strains of Aspergillus flavus to reduce, through competitive exclusion, production in kernels of aflatoxins and cyclopiazonic acid (CPA) by A. flavus and fumonisins by Fusarium verticillioides. The abili...

  4. Involvement of phenazines and biosurfactants in biocontrol of Pythium myriotylum root rot on cocoyam by Pseudomonas sp. CMR12A

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas sp. CMR12a was isolated from the rhizosphere of the tropical tuber crop cocoyam and produces both phenazines and cyclic lipopeptide (CLP) biosurfactants. CMR12a was shown to be an efficient biocontrol agent of P. myriotylum on cocoyam. To assess the importance of phenazine and biosurfact...

  5. Use of biocontrol organisms and compost amendments for improved control of soilborne diseases and increased potato production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evalua...

  6. Functional and Structural Microbial Diversity in Organic and Conventional Viticulture: Organic Farming Benefits Natural Biocontrol Agents ▿ †

    PubMed Central

    Schmid, Florian; Moser, Gerit; Müller, Henry; Berg, Gabriele

    2011-01-01

    Statistically significant differences in the structure and function of above-ground grapevine-associated microorganisms from organically and conventionally managed vineyards were found. Aureobasidium pullulans, a copper-detoxifying fungus and biocontrol agent, plays a key role in explaining these differences. The black fungus was strongly enriched in the communities of organically managed plants and yielded a higher indigenous antiphytopathogenic potential. PMID:21278278

  7. Combinations of Biocontrol Agents for Management of Plant-Parasitic Nematodes and Soilborne Plant-Pathogenic Fungi

    PubMed Central

    Meyer, Susan L. F.; Roberts, Daniel P.

    2002-01-01

    Numerous microbes are antagonistic to plant-parasitic nematodes and soilborne plant-pathogenic fungi, but few of these organisms are commercially available for management of these pathogens. Inconsistent performance of applied biocontrol agents has proven to be a primary obstacle to the development of successful commercial products. One of the strategies for overcoming inconsistent performance is to combine the disease-suppressive activity of two (or more) beneficial microbes in a biocontrol preparation. Such combinations have potential for more extensive colonization of the rhizosphere, more consistent expression of beneficial traits under a broad range of soil conditions, and antagonism to a larger number of plant pests or pathogens than strains applied individually. Conversely, microbes applied in combination also may have antagonistic interactions with each other. Increased, decreased, and unaltered suppression of the target pathogen or pest has been observed when biocontrol microbes have been applied in combination. Unfortunately, the ecological basis for increased or decreased suppression has not been determined in many cases and needs further consideration. The complexity of interactions involved in the application of multiple organisms for biological control has slowed progress toward development of successful formulations. However, this approach has potential for overcoming some of the efficacy problems that occur with application of individual biocontrol agents. PMID:19265899

  8. The Xylella fastidiosa biocontrol strain EB92-1 genome is very similar and syntenic to Pierce's disease strains.

    PubMed

    Zhang, Shujian; Flores-Cruz, Zomary; Kumar, Dibyendu; Chakrabarty, Pranjib; Hopkins, Donald L; Gabriel, Dean W

    2011-10-01

    Xylella fastidiosa infects a wide range of plant hosts and causes economically serious diseases, including Pierce's disease (PD) of grapevines. X. fastidiosa biocontrol strain EB92-1 is infectious to grapevines but does not cause symptoms. The draft genome of EB92-1 reveals that it may be missing 10 potential pathogenicity effectors.

  9. Impacts of biocontrol products on Rhizoctonia disease of potato and soil microbial communities, and their persistence in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four commercial biocontrol formulations (Bacillus subtilis GB03, Burkholderia ambifaria type Wisconsin isolate J82, Trichoderma virens Gl-21, and Trichoderma harzianum strain T-22), a chemical seed treatment (Topsin, mancozeb, and cymoxanil mixture, TMC), and a combination chemical/biological treatm...

  10. Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...

  11. Biocontrol Potential of Metchnikowia pulcherrima Strains Against Blue Mold of Apple.

    PubMed

    Janisiewicz, W J; Tworkoski, T J; Kurtzman, C P

    2001-11-01

    ABSTRACT Eight strains of Metschnikowia pulcherrima isolated over a 4-year period from an unmanaged orchard and selected for their biocontrol activity against blue mold (caused by Penicillium expansum) of apples were characterized phenotypically, genetically, and for their biocontrol potential against blue mold on apples. All strains grew well and only differed slightly in their growth in nutrient yeast dextrose broth medium at 1 degrees C after 216 h, but large differences occurred at 0 degrees C, with strain T5-A2 outgrowing other strains by more than 25% transmittance after 360 h. This strain was also one of the most resistant to diphenylamine (DPA), a postharvest antioxidant treatment. All strains required biotin for growth in minimum salt (MS) medium, although strain ST2-A10 grew slightly in MS medium containing riboflavin or folic acid, as did ST3-E1 in MS medium without vitamins. None of the strains produced killer toxins against an indicator strain of Saccharomyces cerevisiae. Analysis of Biolog data from YT plates for all eight strains using the MLCLUST program resulted in separation of the strains into one major cluster containing four strains and four scattered strains from which strain ST1-D10 was the most distant from all other strains. This was particularly apparent in 3-D and principle component analysis. Genetic differentiation of the eight strains using maximum parsimony analysis of nucleotide sequences from domain D1/D2 of nuclear large subunit (26S) ribosomal DNA resulted in detection of two clades. Strain ST1-D10 grouped with the type strain of M. pulcherrima but the remaining seven strains grouped separately, which might possibly represent a new species. All strains significantly reduced blue mold on mature Golden Delicious apples during 1 month of storage at 1 degrees C followed by 7 days at room temperature, but strains T5-A2 and T4-A2 were distinctly more effective under these conditions. Strain T5-A2 also was the most effective in tests on

  12. Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis

    PubMed Central

    Zhang, Yanzhou; Wei, Zhiwen; Guan, Zhengbing; Cai, Yujie; Liao, Xiangru

    2016-01-01

    The gummosis disease is caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., and it is one of the most important diseases of stone fruits worldwide. The use of biocontrol as an alternative approach to synthetic chemical fungicides has aroused general concern about how to control plant diseases that are caused by phytopathogens. The aim of this study is to isolate Bacillus strains from raw honeys with the capacity to inhibit B. dothidea and to explore the mechanisms by which they could be used in the biocontrol of peach gummosis. Bacillus amyloliquefaciens SYBC H47 was isolated and identified on the basis of its physiological and biochemical characteristics and its 16S rRNA and gyrB gene sequences. The cell suspension and the cell-free supernatant of its culture showed significant antifungal activity against Aspergillus niger, Mucor racemosus, Fusarium oxysporum, Penicillium citrinum, and Candida albicans by agar-diffusion assays. The primary antifungal substances were bacillomycin L, fengycin, and surfactin, which were analyzed by HPLC LC/ESI-MS/MS. Bacillomycin L showed the best inhibitory effect against conidial germination of B. dothidea, followed by fengycin and surfactin. Surfactin had limited effects on mycelial growth, contrary to those of bacillomycin L and fengycin. However, a mixture of the three lipopeptides had a synergistic effect that disrupted the structure of the conidia and mycelia. In order to reduce the production cost, the use of waste frying peanut oil and soy oil as the sole carbon source increased the lipopeptide yield levels by approximately 17% (2.42 g/L) and 110% (4.35 g/L), respectively. In a field trial, the decreases in the infected gummosis rate (IGR) and the disease severity index (DSI) through cell suspension treatments were 20% and 57.5% (in 2014), respectively, and 40% and 57.5% (in 2015), respectively, in comparison with the control. In conclusion, B. amyloliquefaciens SYBC H47 could inhibit the germination of conidia

  13. Is Quorum Signaling by Mycotoxins a New Risk-Mitigating Strategy for Bacterial Biocontrol of Fusarium verticillioides and Other Endophytic Fungal Species?

    PubMed

    Bacon, Charles W; Hinton, Dorothy M; Mitchell, Trevor R

    2016-12-13

    Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. In this work, we hypothesize and review work that quorum sensing inhibitors are produced either by fungi or by pathogenic bacteria for competitive purposes, altering the efficiency of the biocontrol organisms. Recently, quorum sensing inhibitors have been isolated from several fungi, including Fusarium species, three of which are mycotoxins. Thus, we further postulate that other mycotoxins are inhibitors or quenching metabolites that prevent the protective abilities and activities of endophytic biocontrol bacteria within intercellular spaces. To test the aforementioned suppositions, we review work detailing the use of bioassay bacteria for several mycotoxins for quorum activity. We specifically focus on the quorum use of endophytic bacteria as biocontrols for mycotoxic fungal endophytes, such as the Fusarium species and the fumonisin mycotoxins.

  14. Shallot aphids, Myzus ascalonicus, in strawberry: biocontrol potential of three predators and three parasitoids.

    PubMed

    Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

    2013-01-01

    The parasitization capacity of 3 parasitoids and the predation capacity of 3 predators towards the shallot aphid, Myzus ascalonicus Doncaster (Homoptera: Aphididae), on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae) cv. Honeoye, were examined in laboratory experiments. In Petri dish assays, both Aphidius colemani Viereck (Hymenoptera: Aphidiidae) and A. ervi Haliday readily stung shallot aphids, with no significant difference in stinging frequency between the two species. A. ervi induced a significantly higher mortality (79.0 ± 7.2%) in terms of stung aphids compared with A. colemani (55.3 ± 4.1%); however, only a minor fraction (2.7 ± 1.8% and 7.1 ± 3.1%, respectively) of the killed aphids resulted in formation of mummies, presumably due to a physiological response to parasitism. The low percentage of mummification precludes the use of either Aphidius species in anything but inundative biocontrol. In similar set-ups, Aphelinus abdominalis (Dalman) (Hymenoptera: Aphelinidae) killed almost half (49.6 ± 5.3%) of the exposed aphids through host feeding. In addition, 23.2 ± 7.3% of non-host-fed aphids developed into mummified aphids, and 38.1 ± 13.2% of non-host-fed aphids died from other parasitoid-induced causes. However, the host feeding rate was reduced to only 1.2 ± 0.8%, and no significant parasitization mortality was observed on strawberry plants, suggesting that host plants interfered with A. abdominalis activity. This parasitoid does not, therefore, seem to be suited to either inoculative or inundative biocontrol of shallot aphids in strawberry. The three predators studied were the green lacewing, Chrysoperla carnea Steph. (Neuroptera: Chrysopidae), the two-spotted lady beetle, Adalia bipunctata L. (Coleoptera: Coccinellidae), and the gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). Third instars of all 3 predators readily preyed upon the shallot aphid in Petri dish set-ups with significant differences in daily

  15. Isolation and identification of biocontrol agent Streptomyces rimosus M527 against Fusarium oxysporum f. sp. cucumerinum.

    PubMed

    Lu, Dandan; Ma, Zheng; Xu, Xianhao; Yu, Xiaoping

    2016-08-01

    Actinomycetes have received considerable attention as biocontrol agents against fungal plant pathogens and as plant growth promoters. In this study, a total of 320 actinomycetes were isolated from various habitats in China. Among which, 77 strains have been identified as antagonistic activities against Fusarium oxysporum f. sp. cucumerinum which usually caused fusarium wilt of cucumber. Of these, isolate actinomycete M527 not only displayed broad-spectrum antifungal activity but also showed the strongest antagonistic activity against the spore germination of F. oxysporum f. sp. cucumerinum. In pot experiments, the results indicated that isolate M527 could promote the shoot growth and prevent the development of the disease on cucumber caused by F. oxysporum f. sp. cucumerinum. The control efficacy against seedling fusarium wilt of cucumber after M527 fermentation broth root-irrigation was up to 72.1% as compared to control. Based on 16S rDNA sequence analysis, the isolate M527 was identified as Streptomyces rimosus.

  16. Biocontrol efficacy of Cestrum diurnum L. (Solanaceae: Solanales) against the larval forms of Anopheles stephensi.

    PubMed

    Ghosh, Anupam; Chandra, Goutam

    2006-04-01

    Cestrum diurnum L. (Solanaceae: Solanales) is a multistemmed shrub that is also known as 'Day Jasmine'. The efficacy of the plant as a strong biocontrol agent of the larval anopheline mosquito was evaluated in the laboratory and bioactive ingredients were characterized by thin layer chromatography (TLC) and infrared (IR) analysis. Thin layer chromatographic analysis revealed the presence of steroidal compound as a bioactive ingredient and IR analysis reported the presence of O-H group, C-S bond as a -CH2S group, H bonded -C=O group and carbonyl stress of esters. The LC50 value of the active ingredient was determined as 0.70, 0.89, 0.90 and 1.03 mg/100 mL-1, for 1st, 2nd, 3rd and 4th instar larva respectively in 24 h study period. The active component was analyzed by GLC and GLC-MS and altogether 14 components were detected.

  17. Yeast biocontrol of fungal spoilage of pears stored at low temperature.

    PubMed

    Robiglio, Andrea; Sosa, M Cristina; Lutz, M Cecilia; Lopes, Christian A; Sangorrín, Marcela P

    2011-06-30

    To reduce the use of fungicides, biological control with yeasts has been proposed in postharvest pears. Most studies of antagonists selection have been carried out at room temperature. However, in regions like North Patagonia where fruits are stored at -1/0 °C during 5-7 months the selection of potential antagonist agents must be carried out at low temperature. In this study, 75 yeast cultures were isolated from healthy pears from two Patagonian cold-storage packinghouses. Aureobasidium pullulans, Cryptococcus albidus, Cryptococcus difluens, Pichia membranifaciens, Pichia philogaea, Rhodotorula mucilaginosa and Saccharomyces cerevisiae yeast species were identified. Additionally, 13 indigenous isolates of Penicillium expansum and 10 isolates of Botrytis cinerea were obtained from diseased pears, characterized by aggressiveness and tested for sensitivity to postharvest fungicides. The yeasts were pre-selected for their ability to grow at low temperature. In a first biocontrol assay using the most aggressive and the most sensitive isolate of each pathogen, two epiphytic isolates of A. pullulans and R. mucilaginosa were the most promising isolates to be used as biocontrol agents. They reduced the decay incidence by P. expansum to 33% and the lesion diameter in 88% after 60 days of incubation in cold. Foreign commercial yeast used as a reference in assays, only reduced 30% of lesion diameter in the same conditions. Yeasts were not able to reduce the incidence of B. cinerea decay. The control activity of the best two yeasts was compared with the control caused by the fungicides in a second bioassay, obtaining higher levels of protection against P. expansum by the yeasts. These two regional yeasts isolates could be promising tools for the future development of commercial products for biological control.

  18. The global regulator ANR is essential for Pseudomonas chlororaphis strain PA23 biocontrol.

    PubMed

    Nandi, Munmun; Selin, Carrie; Brawerman, Gabriel; Fernando, W G Dilantha; de Kievit, Teresa R

    2016-12-01

    Pseudomonas chlororaphis PA23 is a biocontrol agent capable of protecting canola from stem rot disease caused by the fungus Sclerotinia sclerotiorum. The focus of the current study was to elucidate the role of the transcriptional regulator ANR in the biocontrol capabilities of this bacterium. An anr mutant was created, PA23anr, that was devoid antifungal activity. In other pseudomonads, ANR is essential for regulating HCN production. Characterization of PA23anr revealed that, in addition to HCN, ANR controls phenazine (PHZ), pyrrolnitrin (PRN), protease and autoinducer (AHL) signal molecule production. In gene expression studies, hcnA, phzA, prnA and phzI were found to be downregulated, consistent with our endproduct analysis. Because the phenotype of PA23anr closely resembles that of quorum sensing (QS)-deficient strains, we explored whether there is a connection between ANR and the PhzRI QS system. Both phzI and phzR are positively regulated by ANR, whereas PhzR represses anr transcription. Complementation of PA23anr with pUCP-phzR, C6-HSL or both yielded no change in phenotype. Conversely, PA23phzR harbouring pUCP23-anr exhibited partial-to-full restoration of antifungal activity, HCN, PRN and AHL production together with hcnA, prnA, phzI and rpoS expression. PHZ and protease production remained unchanged indicating that ANR can complement the QS-deficient phenotype with respect to some but not all traits. Our experiments were conducted at atmospheric O2 levels underscoring the fact that ANR has a profound effect on PA23 physiology under aerobic conditions.

  19. The importance of chorismate mutase in the biocontrol potential of Trichoderma parareesei.

    PubMed

    Pérez, Esclaudys; Rubio, M Belén; Cardoza, Rosa E; Gutiérrez, Santiago; Bettiol, Wagner; Monte, Enrique; Hermosa, Rosa

    2015-01-01

    Species of Trichoderma exert direct biocontrol activity against soil-borne plant pathogens due to their ability to compete for nutrients and to inhibit or kill their targets through the production of antibiotics and/or hydrolytic enzymes. In addition to these abilities, Trichoderma spp. have beneficial effects for plants, including the stimulation of defenses and the promotion of growth. Here we study the role in biocontrol of the T. parareesei Tparo7 gene, encoding a chorismate mutase (CM), a shikimate pathway branch point leading to the production of aromatic amino acids, which are not only essential components of protein synthesis but also the precursors of a wide range of secondary metabolites. We isolated T. parareesei transformants with the Tparo7 gene silenced. Compared with the wild-type, decreased levels of Tparo7 expression in the silenced transformants were accompanied by reduced CM activity, lower growth rates on different culture media, and reduced mycoparasitic behavior against the phytopathogenic fungi Rhizoctonia solani, Fusarium oxysporum and Botrytis cinerea in dual cultures. By contrast, higher amounts of the aromatic metabolites tyrosol, 2-phenylethanol and salicylic acid were detected in supernatants from the silenced transformants, which were able to inhibit the growth of F. oxysporum and B. cinerea. In in vitro plant assays, Tparo7-silenced transformants also showed a reduced capacity to colonize tomato roots. The effect of Tparo7-silencing on tomato plant responses was examined in greenhouse assays. The growth of plants colonized by the silenced transformants was reduced and the plants exhibited an increased susceptibility to B. cinerea in comparison with the responses observed for control plants. In addition, the plants turned yellowish and were defective in jasmonic acid- and ethylene-regulated signaling pathways which was seen by expression analysis of lipoxygenase 1 (LOX1), ethylene-insensitive protein 2 (EIN2) and pathogenesis

  20. CHARACTERIZATION AND BIOCONTROL POTENT OF STREPTOMYCES SP. ISOLATED FROM THE RHIZOSPHERE OF ONONIS ANGUSTISSIMA LAM.

    PubMed

    Ghadbane, M; Belhadj, H; Medjekal, S; Harzallah, D

    2015-01-01

    A total of 40 actinomycetes isolated from rhizosphere soils of Ononis angustissima Lam. were in vitro tested for their antagonism against deferent pathogenic microorganisms by streak assay. Among the isolates, four (21, 2A26, 1B10 and 2C34) present a potent antagonism against both pathogenic bacteria and fungi, they were selected, identified by 16S rDNA sequence analysis and phenotypic properties, and tested for their antimicrobial activity as well as their biocontrol potential against Chickpea (Cicer arietinum L.) pathogenic fungus (Fusarium oxysporum). Cultural characteristic studies strongly suggested that these strains belong to the genus Streptomyces. The four Streptomyces sp., solubilize phosphate and produce extracellular fungal cell-wall degrading enzymes chitinase and protease, as well as a marked production of acid-β-indole acetic (AIA). The nucleotide sequence of the 16S rRNA gene of Streptomyces sp. strains 21, 2A26, 1B10 and 2C34 exhibited close similarity (62-75%) with Streptomyces parvulus MARS 16S rRNA genes. The inhibition was higher against fungi and Gram+ bacteria, while Gram- bacteria were less inhibited. The growth of the plant pathogenic fungus Fusarium oxysporum was considerably inhibited in the presence of the strains 21, 2A26, 1B10 and 2C34 culture supernatant. These studies revealed that the presence of the Streptomyces strains in the soil significantly promoted the growth of the Chickpea plants. These results indicate that the Streptomyces strains isolated for rhizosphere from Ononis angustissima Lam. growing in arid conditions in southern Algeria (Sahara) could be an interesting source for antimicrobial bioactive substances and as biocontrol agents.

  1. Biocontrol of Fusarium wilt disease in tomato by Paenibacillus ehimensis KWN38.

    PubMed

    Naing, Kyaw Wai; Nguyen, Xuan Hoa; Anees, Muhammad; Lee, Yong Seong; Kim, Yong Cheol; Kim, Sang Jun; Kim, Myung Hee; Kim, Yong Hwan; Kim, Kil Yong

    2015-01-01

    This study was conducted to investigate biocontrol potential of Paenibacillus ehimensis KWN38 against Fusarium oxysporum f.sp. lycopersici causing Fusarium wilt disease in tomato. Our result showed that P. ehimensis KWN38 produced extracellular organic compounds and crude enzyme to inhibit F. oxysporum f.sp. lycopersici conidial germination in in vitro assays. Tomato seedlings were treated with water (W), grass medium (G), G with P. ehimensis KWN38 inoculation (GP) and G along with synthetic fungicide (GSf). Disease symptoms were was first observed in G and W at 12 days after infection (DAI) while symptoms were noticeable in the GP and GSf treatments at 20 and 24 DAI, respectively. Tomato plants treated with P. ehimensis KWN38 or fungicide significantly reduced Fusarium wilt disease incidence and severity as compared to control tomato plants treated with water and grass medium. The similar results were also found in the root mortality of tomato plants. At 25 DAI, most plants in control treatments (W and G) wilted and the brown vascular systems of infected plants was clearly differentiable from normal green vascular system of healthy plants from GP and GSf. Plants in the GP showed higher fresh and dry weights of both root and shoots than those in W and G treatments. Leaf peroxidase and polyphenol oxidase activities of tomato plants in G and W were higher than those in GP and GSf. Root enzyme activities showed a similar pattern but the values were higher than leaf enzyme. The results clearly demonstrated that P. ehimensis KWN38 may be considered as biocontrol agent of Fusarium wilt disease in tomato.

  2. Interactions between conventional and organic farming for biocontrol services across the landscape.

    PubMed

    Bianchi, F J J A; Ives, A R; Schellhorn, N A

    2013-10-01

    While the area of organic crop production increases at a global scale, the potential interactions between pest management in organic and conventionally managed systems have so far received little attention. Here, we evaluate the landscape-level codependence of insecticide-based and natural enemy-based pest management using a simulation model for parasitoid-host interactions in landscapes consisting of conventionally and organically managed fields. In our simulations conventional management consists of broad-spectrum or selective insecticide application, while organic management involves no insecticides. Simulations indicate that insecticide use can easily result in lose-lose scenarios whereby both organically and conventionally managed fields suffer from increased pest loads as compared to a scenario where no insecticides are used, but that under some conditions insecticide use can be compatible with biocontrol. Simulations also suggest that the pathway to achieve the insecticide reduction without triggering additional pest pressure is not straightforward, because increasing the proportion of organically managed fields or reducing the spray frequency in conventional fields can potentially give rise to dramatic increases in pest load. The disruptive effect of insecticide use, however, can be mitigated by spatially clustering organic fields and using selective insecticides, although the effectiveness of this mitigation depends on the behavioral traits of the biocontrol agents. Poorly dispersing parasitoids and parasitoids with high attack rates required a lower amount of organically managed fields for effective pest suppression. Our findings show that the transition from a landscape dominated by conventionally managed crops to organic management has potential pitfalls; intermediate levels of organic management may lead to higher pest burdens than either low or high adoption of organic management.

  3. Biocontrol of geosmin-producing Streptomyces spp. by two Bacillus strains from Chinese liquor.

    PubMed

    Zhi, Yan; Wu, Qun; Du, Hai; Xu, Yan

    2016-08-16

    Streptomyces spp. producing geosmin have been regarded as the most frequent and serious microbial contamination causing earthy off-flavor in Chinese liquor. It is therefore necessary to control the Streptomyces community during liquor fermentation. Biological control, using the native microbiota present in liquor making, appears to be a better solution than chemical methods. The objective of this study was to isolate native microbiota antagonistic toward Streptomyces spp. and then to evaluate the possible action mode of the antagonists. Fourteen Bacillus strains isolated from different Daqu (the fermentation starter) showed antagonistic activity against Streptomyces sampsonii, which is one of the dominant geosmin producers. Bacillus subtilis 2-16 and Bacillus amyloliquefaciens 1-45 from Maotai Daqu significantly inhibited the growth of S. sampsonii by 57.8% and 84.3% respectively, and effectively prevented the geosmin production in the simulated fermentation experiments (inoculation ratio 1:1). To probe the biocontrol mode, the ability of strain 2-16 and 1-45 to produce antimicrobial metabolites and to reduce geosmin in the fermentation system was investigated. Antimicrobial substances were identified as lipopeptides by ultra-performance liquid chromatography tandem electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI/Q-TOF MS) and in vitro antibiotic assay. In addition, strains 2-16 and 1-45 were able to remove 45% and 15% of the geosmin respectively in the simulated solid-state fermentation. This study highlighted the potential of biocontrol, and how the use of native Bacillus species in Daqu could provide an eco-friendly method to prevent growth of Streptomyces spp. and geosmin contamination in Chinese liquor fermentation.

  4. Method To immobilize the aphid-pathogenic fungus erynia neoaphidis in an alginate matrix for biocontrol

    PubMed

    Shah; Aebi; Tuor

    1998-11-01

    Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.

  5. Genome Sequencing and Comparative Analysis of the Biocontrol Agent Trichoderma harzianum sensu stricto TR274

    SciTech Connect

    Steindorff, Andrei S.; Noronha, Elilane F.; Ulhoa, Cirano J.; Kuo, Alan; Salamov, Asaf A.; Haridas, Sajeet; Riley, Robert W.; Druzhinina, Irina S.; Kubicek, Christian P.; Grigoriev, Igor V.

    2015-03-17

    Biological control is a complex process which requires many mechanisms and a high diversity of biochemical pathways. The species of Trichoderma harzianum are well known for their biocontrol activity against many plant pathogens. To gain new insights into the biocontrol mechanism used by T. harzianum, we sequenced the isolate TR274 genome using Illumina. The assembly was performed using AllPaths-LG with a maximum coverage of 100x. The assembly resulted in 2282 contigs with a N50 of 37033bp. The genome size generated was 40.8 Mb and the GC content was 47.7%, similar to other Trichoderma genomes. Using the JGI Annotation Pipeline we predicted 13,932 genes with a high transcriptome support. CEGMA tests suggested 100% genome completeness and 97.9% of RNA-SEQ reads were mapped to the genome. The phylogenetic comparison using orthologous proteins with all Trichoderma genomes sequenced at JGI, corroborates the Trichoderma (T. asperellum and T. atroviride), Longibrachiatum (T. reesei and T. longibrachiatum) and Pachibasium (T. harzianum and T. virens) section division described previously. The comparison between two Trichoderma harzianum species suggests a high genome similarity but some strain-specific expansions. Analyses of the secondary metabolites, CAZymes, transporters, proteases, transcription factors were performed. The Pachybasium section expanded virtually all categories analyzed compared with the other sections, specially Longibrachiatum section, that shows a clear contraction. These results suggests that these proteins families have an important role in their respective phenotypes. Future analysis will improve the understanding of this complex genus and give some insights about its lifestyle and the interactions with the environment.

  6. The importance of chorismate mutase in the biocontrol potential of Trichoderma parareesei

    PubMed Central

    Pérez, Esclaudys; Rubio, M. Belén; Cardoza, Rosa E.; Gutiérrez, Santiago; Bettiol, Wagner; Monte, Enrique; Hermosa, Rosa

    2015-01-01

    Species of Trichoderma exert direct biocontrol activity against soil-borne plant pathogens due to their ability to compete for nutrients and to inhibit or kill their targets through the production of antibiotics and/or hydrolytic enzymes. In addition to these abilities, Trichoderma spp. have beneficial effects for plants, including the stimulation of defenses and the promotion of growth. Here we study the role in biocontrol of the T. parareesei Tparo7 gene, encoding a chorismate mutase (CM), a shikimate pathway branch point leading to the production of aromatic amino acids, which are not only essential components of protein synthesis but also the precursors of a wide range of secondary metabolites. We isolated T. parareesei transformants with the Tparo7 gene silenced. Compared with the wild-type, decreased levels of Tparo7 expression in the silenced transformants were accompanied by reduced CM activity, lower growth rates on different culture media, and reduced mycoparasitic behavior against the phytopathogenic fungi Rhizoctonia solani, Fusarium oxysporum and Botrytis cinerea in dual cultures. By contrast, higher amounts of the aromatic metabolites tyrosol, 2-phenylethanol and salicylic acid were detected in supernatants from the silenced transformants, which were able to inhibit the growth of F. oxysporum and B. cinerea. In in vitro plant assays, Tparo7-silenced transformants also showed a reduced capacity to colonize tomato roots. The effect of Tparo7-silencing on tomato plant responses was examined in greenhouse assays. The growth of plants colonized by the silenced transformants was reduced and the plants exhibited an increased susceptibility to B. cinerea in comparison with the responses observed for control plants. In addition, the plants turned yellowish and were defective in jasmonic acid- and ethylene-regulated signaling pathways which was seen by expression analysis of lipoxygenase 1 (LOX1), ethylene-insensitive protein 2 (EIN2) and pathogenesis

  7. Native isolate of Trichoderma: a biocontrol agent with unique stress tolerance properties.

    PubMed

    Mishra, N; Khan, S S; Sundari, S Krishna

    2016-08-01

    Species of Trichoderma are widely recognized for their biocontrol abilities, but seldom studied collectively, for their plant growth promotion, abiotic stress tolerance and bioremediation properties. Our study is a concentrated effort to establish the potential of native isolate Trichoderma harzianum KSNM (T103) to tolerate biotic (root pathogens) and abiotic stresses [high salt (100-1000 mM); heavy metal (chromium, nickel and zinc: 1-10 mM); pesticides: malathion (100-600 ppm), carbofuran (100-600 ppb)], along with its ability to support plant growth. In vitro growth promotion assays with T103 treated Vigna radiata, Vigna mungo and Hordeum vulgare confirmed 'non-species specific' growth promotion effects of T103. At lower metal concentration, T103 treatment was found to completely negate the impact of metal stress [60 % increase in radicle length (RL) with no significant decrease in %germination (%G)]. Even at 10 mM metal, T103 inoculation gave 80 % increase in %G and >50 % increase in RL. In vitro experiments confirmed high metal reduction capacity (47 %-Cr, 35 %-Ni and 42 %-Zn) of T103 at concentrations as high as 4 mM. At maximum residual concentrations of malathion (440 ppm) and carbofuran (100 ppb) reported in agricultural soils, T103 maintained 80 and 100 % survivability, respectively. T103 treatment has improved %G and RL in all three hosts challenged with pesticide. Isolate T103 was found to effectively suppress growth of three major root pathogens: Macrophomina phaseolina (65.83 %) followed by Sclerotium rolfsii (19.33 %) and Fusarium oxysporum (19.18 %). In the light of these observations, native T. harzianum (T103) seems to be a competent biocontrol agent for tropical agricultural soils contaminated with residual pesticides and heavy metals.

  8. Pseudomonas protegens CS1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent.

    PubMed

    Michavila, G; Adler, C; De Gregorio, P R; Lami, M J; Caram Di Santo, M C; Zenoff, A M; de Cristobal, R E; Vincent, P A

    2017-02-14

    Citrus canker is a worldwide-distributed disease caused by Xanthomonas citri subsp. citri. One of the most used strategies to control the disease is centred on copper-based compounds that cause environmental problems. Therefore, it is of interest to develop new strategies to manage the disease. Previously, we reported the ability of the siderophore pyochelin, produced by the opportunistic human pathogen Pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including X. citri subsp. citri. The action mechanism, addressed with the model bacterium Escherichia coli, was connected to the generation of reactive oxygen species (ROS). This work aimed to find a non-pathogenic strain from the lemon phyllosphere that would produce pyochelin and therefore serve in canker biocontrol. An isolate that retained its capacity to colonise the lemon phyllosphere and inhibit X. citri subsp. citri was selected and characterised as Pseudomonas protegens CS1. From a liquid culture of this strain, the active compound was purified and identified as the pyochelin enantiomer, enantio-pyochelin. Using the producing strain and the pure compound, both in vitro and in vivo, we determined that the action mechanism of X. citri subsp. citri inhibition also involved the generation of ROS. Finally, the potential application of P. protegens CS1 was evaluated by spraying the bacterium in a model that mimics the natural X. citri subsp. citri infection. The ability of P. protegens CS1 to reduce canker formation makes this strain an interesting candidate as a biocontrol agent.

  9. Effect of rice husbandry on mosquito breeding at Mwea Rice Irrigation Scheme with reference to biocontrol strategies.

    PubMed

    Asimeng, E J; Mutinga, M J

    1993-03-01

    A study was carried out at Mwea Rice Irrigation Scheme, Kenya, to assess the impact of rice husbandry on mosquito breeding and identify indigenous biocontrol agents with potential for controlling mosquito breeding in the scheme. The study established a close relationship between the schedule of the farming practices (particularly the flooding phase) and mosquito breeding. Two groups of agents, entomopathogenic bacteria (Bacillus thuringiensis var. israelensis) and larvivorous fish, were identified. Laboratory evaluation of the agents produced encouraging results. The bacterial isolates showed broad-spectrum larvicidal potency against Anopheles, Culex and Aedes mosquito larvae and 2 of the fish species, Tilapia zilli and Oreochromis niloticus, demonstrated a strong predation for a mosquito larval diet. To facilitate their use in effective biocontrol strategies, the agents would require further evaluation under field conditions.

  10. Biocontrol of Bacillus subtilis against infection of Arabidopsis roots by Pseudomonas syringae is facilitated by biofilm formation and surfactin production.

    PubMed

    Bais, Harsh Pal; Fall, Ray; Vivanco, Jorge M

    2004-01-01

    Relatively little is known about the exact mechanisms used by Bacillus subtilis in its behavior as a biocontrol agent on plants. Here, we report the development of a sensitive plant infection model demonstrating that the bacterial pathogen Pseudomonas syringae pv tomato DC3000 is capable of infecting Arabidopsis roots both in vitro and in soil. Using this infection model, we demonstrated the biocontrol ability of a wild-type B. subtilis strain 6051 against P. syringae. Arabidopsis root surfaces treated with B. subtilis were analyzed with confocal scanning laser microscopy to reveal a three-dimensional B. subtilis biofilm. It is known that formation of biofilms by B. subtilis is a complex process that includes secretion of surfactin, a lipopeptide antimicrobial agent. To determine the role of surfactin in biocontrol by B. subtilis, we tested a mutant strain, M1, with a deletion in a surfactin synthase gene and, thus, deficient in surfactin production. B. subtilis M1 was ineffective as a biocontrol agent against P. syringae infectivity in Arabidopsis and also failed to form robust biofilms on either roots or inert surfaces. The antibacterial activity of surfactin against P. syringae was determined in both broth and agar cultures and also by live-dead staining methods. Although the minimum inhibitory concentrations determined were relatively high (25 microg mL(-1)), the levels of the lipopeptide in roots colonized by B. subtilis are likely to be sufficient to kill P. syringae. Our results collectively indicate that upon root colonization, B. subtilis 6051 forms a stable, extensive biofilm and secretes surfactin, which act together to protect plants against attack by pathogenic bacteria.

  11. Interaction of media on production and biocontrol efficacy of Pseudomonas fluorescens and Bacillus subtilis against grey mould of apple.

    PubMed

    Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

    2008-01-01

    The medium has a profound effect on biocontrol agents, including ability to grow and effectiveness in disease control. In this study, growth and antagonistic efficacy of strains P-5 and P-35 (P. fluorescens), B-3 and B-16 (B. subtilis) were evaluated in combinations of two carbon (sucrose and molasses) and two nitrogen (urea and yeast extract) sources to optimize control of Botrytis cinerea on apple. All of the strains were grown in different liquid media (pH = 6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, molasses, malt extract and nutrient broth. Apples (Golden Delicious) were inoculated by a 25-microl suspension of 10(6) spores of B. cinerea per ml, wounding each fruit (in two sites separately). Then a 25-microl suspension of each strain, containing 2 x 10(8) cfu ml(-1) grown in each of the above culture media, was applied to each wound. Results indicated that Molasses + Yeast extract (1:1 w/w) medium supported rapid growth in all of the strains. The final growth of B. subtilis B-16 in Molasses + Yeast extract (1:1 w/w) medium was 5 x 10(9) cfu ml(-1). After ten days, all of the strains significantly inhibited pathogenicity of B. cinerea on apples. The biocontrol efficacy of B. subtilis B-3 in Molasses + Yeast extract (1:1 w/w) medium reduced the severity of grey mould from 100% (inoculated control) to less than 26.9%. After 20 days, Strain B-3 showed a considerable biocontrol efficacy in Molasses medium and reduced the severity of grey mould from 100% (inoculated control) to less than 38.2%. The results obtained in this study could be used to provide a reliable basis for the increase of population of biocontrol agents in fermentation process.

  12. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    NASA Astrophysics Data System (ADS)

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-10-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

  13. Citrus compost and its water extract for cultivation of melon plants in greenhouse nurseries. Evaluation of nutriactive and biocontrol effects.

    PubMed

    Bernal-Vicente, A; Ros, M; Tittarelli, F; Intrigliolo, F; Pascual, J A

    2008-12-01

    Two different types of citrus composts, and their water extracts, were tested with regard to their utilisations as partial substitutes for peat in growing media for melon seedlings in greenhouse nurseries. Both compost showed higher plant growth than peat. Compost composed by citrus waste and green residue (C2) showed greater plant growth than compost obtained from the same organic matrices mentioned above further the addition of sludge obtained from citrus industry (C1). Compost C2 showed a greater auxinic effect than C1 and it was the only one that showed cytokinic effect. Both composts also demonstrated a biocontrol effect against Fusarium oxysporum for melon plants: the effects were also higher in C2 than in C1. Higher number of isolated fungi was active against F. oxysporum in compost C2, than compost C1. No different bacterial biocontrol efficacy was observed between both composts. The water extracts of both composts gave lower plant yields than their solid matrices, their relative effects being similar to those of the solid composts (C2 extract gave higher plant yields than the extract from C1). The biocontrol effects of compost water extracts followed the same trend.

  14. [Colonization characteristics of endophytic bacteria NJ13 in Panax ginseng and its biocontrol efficiency against Alternaria leaf spot of ginseng].

    PubMed

    Chen, Chang-Qing; Li, Tong; Li, Xin-Lian; Jiang, Yun; Tian, Lei; Xu, Peng

    2014-05-01

    To reveal the colonization characteristics in host of endophytic biocontrol bacteria NJ13 isolated from Panax ginseng, this study obtained the marked strain NJ13-R which was double antibiotic resistant to rifampicin and streptomycin through enhancing the method of inducing antibiotic. The colonization characteristics in ginseng and its biocontrol efficiency against Alternaria spot of ginseng in the field were studied. The results showed that the strain could colonize in root, stem and leaf of ginseng and the colonization amount was positive correlated with inoculation concentration. Meanwhile, the strain could infect and then transfer in different tissues of ginseng The colonization amount of strain in roots and leaves of ginseng increased first and then decreased. However, the tendency of colonization amount of strain in stems was ascend at first and then descend slowly, and was more than that in roots and leaves along with time, which had a preference to specific tissue of its host. In field experiment, the endophytic bacteria NJ13 was proved to be effective in controlling Alternaria leaf spot of ginseng. The biocontrol efficiency of fermentation broth at the concentration of 0.76 x 10(8) cfu x mL(-1) reached 75.62%, which was close to the controlling level (73.06%) of 0.67 mg x L(-1) 50% cyprodinil WG.

  15. Arbuscular Mycorrhizal Fungi for the Biocontrol of Plant-Parasitic Nematodes: A Review of the Mechanisms Involved

    PubMed Central

    Schouteden, Nele; De Waele, Dirk; Panis, Bart; Vos, Christine M.

    2015-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate root symbionts that can protect their host plant against biotic stress factors such as plant-parasitic nematode (PPN) infection. PPN consist of a wide range of species with different life styles that can cause major damage in many important crops worldwide. Various mechanisms have been proposed to play a role in the biocontrol effect of AMF against PPN. This review presents an overview of the different mechanisms that have been proposed, and discusses into more detail the plausibility of their involvement in the biocontrol against PPN specifically. The proposed mechanisms include enhanced plant tolerance, direct competition for nutrients and space, induced systemic resistance (ISR) and altered rhizosphere interactions. Recent studies have emphasized the importance of ISR in biocontrol and are increasingly placing rhizosphere effects on the foreground as well, both of which will be the focal point of this review. Though AMF are not yet widely used in conventional agriculture, recent data help to develop a better insight into the modes of action, which will eventually lead toward future field applications of AMF against PPN. The scientific community has entered an exciting era that provides the tools to actually unravel the underlying molecular mechanisms, making this a timely opportunity for a review of our current knowledge and the challenges ahead. PMID:26635750

  16. Development of species-, strain- and antibiotic biosynthesis-specific quantitative PCR assays for Pantoea agglomerans as tools for biocontrol monitoring.

    PubMed

    Braun-Kiewnick, Andrea; Lehmann, Andreas; Rezzonico, Fabio; Wend, Chris; Smits, Theo H M; Duffy, Brion

    2012-09-01

    Pantoea agglomerans is a cosmopolitan plant epiphytic bacterium that includes some of the most effective biological antagonists against the fire blight pathogen Erwinia amylovora, a major threat to pome fruit production worldwide. Strain E325 is commercially available as Bloomtime Biological™ in the USA and Canada. New quantitative PCR (qPCR) assays were developed for species- and strain -specific detection in the environment, and for detection of indigenous strains carrying the biocontrol antibacterial peptide biosynthesis gene paaA. The qPCR assays were highly specific, efficient and sensitive, detecting fewer than three cells per reaction or 700 colony forming units per flower, respectively. The qPCR assays were tested on field samples, giving first indications to the incidence of P. agglomerans E325 related strains, total P. agglomerans and pantocin A producing bacteria in commercial orchards. These assays will facilitate monitoring the environmental behavior of biocontrol P. agglomerans after orchard application for disease protection, proprietary strain-tracking, and streamlined screening for discovery of new biocontrol strains.

  17. Comparative Genomic Analysis of Pseudomonas chlororaphis PCL1606 Reveals New Insight into Antifungal Compounds Involved in Biocontrol.

    PubMed

    Calderón, Claudia E; Ramos, Cayo; de Vicente, Antonio; Cazorla, Francisco M

    2015-03-01

    Pseudomonas chlororaphis PCL1606 is a rhizobacterium that has biocontrol activity against many soilborne phytopathogenic fungi. The whole genome sequence of this strain was obtained using the Illumina Hiseq 2000 sequencing platform and was assembled using SOAP denovo software. The resulting 6.66-Mb complete sequence of the PCL1606 genome was further analyzed. A comparative genomic analysis using 10 plant-associated strains within the fluorescent Pseudomonas group, including the complete genome of P. chlororaphis PCL1606, revealed a diverse spectrum of traits involved in multitrophic interactions with plants and microbes as well as biological control. Phylogenetic analysis of these strains using eight housekeeping genes clearly placed strain PCL1606 into the P. chlororaphis group. The genome sequence of P. chlororaphis PCL1606 revealed the presence of sequences that were homologous to biosynthetic genes for the antifungal compounds 2-hexyl, 5-propyl resorcinol (HPR), hydrogen cyanide, and pyrrolnitrin; this is the first report of pyrrolnitrin encoding genes in this P. chlororaphis strain. Single-, double-, and triple-insertional mutants in the biosynthetic genes of each antifungal compound were used to test their roles in the production of these antifungal compounds and in antagonism and biocontrol of two fungal pathogens. The results confirmed the function of HPR in the antagonistic phenotype and in the biocontrol activity of P. chlororaphis PCL1606.

  18. Four-trophic level food webs reveal the cascading impacts of an invasive plant targeted for biocontrol.

    PubMed

    López-Núñez, Francisco A; Heleno, Ruben H; Ribeiro, Sérgio; Marchante, Hélia; Marchante, Elizabete

    2017-03-01

    Biological invasions are a major threat to biodiversity and as such understanding their impacts is a research priority. Ecological networks provide a valuable tool to explore such impacts at the community level, and can be particularly insightful for planning and monitoring biocontrol programmes, including the potential for their seldom evaluated indirect non-target effects. Acacia longifolia is among the worst invasive species in Portugal, and has been recently targeted for biocontrol by a highly specific gall-wasp. Here we use an ambitious replicated network approach to: (1) identify the mechanisms by which direct and indirect impacts of A. longifolia can cascade from plants to higher trophic levels, including gallers, their parasitoids and inquilines; (2) reveal the structure of the interaction networks between plants, gallers, parasitoids and inquilines before the biocontrol; and (3) explore the potential for indirect interactions among gallers, including those established with the biocontrol agent, via apparent competition. Over a 15-month period, we collected 31,737 galls from native plants and identified all emerging insects, quantifying the interactions between 219 plant-, 49 galler-, 65 parasitoid- and 87 inquiline-species-one of the largest ecological networks to date. No galls were found on any of the 16 alien plant species. Invasion by A. longifolia caused an alarming simplification of plant communities, with cascading effects to higher trophic levels, namely: a decline of overall gall biomass, and on the richness, abundance and biomass of galler insects, their parasitoids, and inquilines. Correspondingly, we detected a significant decline in the richness of interactions between plants and galls. The invasion tended to increase overall interaction evenness by promoting the local extinction of the native plants that sustained more gall species. However, highly idiosyncratic responses hindered the detection of further consistent changes in network

  19. Nontarget herbivory by a weed biocontrol insect is limited to spillover, reducing the chance of population-level impacts.

    PubMed

    Catton, Haley A; Lalonde, Robert G; De Clerck-Floate, Rosemarie A

    2015-03-01

    Insects approved for classical biocontrol of weeds are often capable of using close relatives of their target weed for feeding, oviposition, or larval development, with reduced preference and performance. When nontarget herbivory occurs and is suspected to reduce survival, growth, or fecundity of individual plants, and insects are capable of reproducing on their nontarget host, characterization of spatial and temporal patterns of the occurrence and intensity of herbivory is valuable for predicting potential population-level effects. Here, we perform a novel post-release manipulative field experiment with a root-feeding biocontrol weevil, Mogulones crucifer, released in Canada to control the rangeland weed Cynoglossum officinale, to test for its ability to establish on the nontarget plant Hackelia micrantha. After Cynoglossum, M. crucifer exhibits its highest preference for and performance on Hackelia spp. We released M. crucifer on Canadian rangeland sites with naturally occurring populations of H. micrantha growing interspersed with the target weed or in the near absence of the target weed. Adult weevil feeding on surrounding plants was monitored for three summers after release (years 0, 1, and 2), and, subsequently, subsets of plants were destructively sampled to determine M. crucifer oviposition levels. Additional oviposition and larval development data were obtained from seven non-experimental sites where weevils were released zero, three, or four years earlier. M. crucifer was not detected on experimental sites without C. officinale after two years, and nontarget herbivory was restricted to rare, low-level spillover. Visible evidence of adult herbivory (i.e., scars on shoots) was associated with oviposition in 90% of targets but only 30% of nontarget plants. We infer, through ecological refuge theory, that nontarget population-level impacts from M. crucifer spillover are unlikely because of temporal, spatial, and probabilistic refuges from herbivory, and make

  20. Comparative transcriptome analysis of the biocontrol strain Bacillus amyloliquefaciens FZB42 as response to biofilm formation analyzed by RNA sequencing.

    PubMed

    Kröber, Magdalena; Verwaaijen, Bart; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schlüter, Andreas

    2016-08-10

    The strain Bacillus amyloliquefaciens FZB42 is a plant growth promoting rhizobacterium (PGPR) and biocontrol agent known to keep infections of lettuce (Lactuca sativa) by the phytopathogen Rhizoctonia solani down. Several mechanisms, including the production of secondary metabolites possessing antimicrobial properties and induction of the host plant's systemic resistance (ISR), were proposed to explain the biocontrol effect of the strain. B. amyloliquefaciens FZB42 is able to form plaques (biofilm-like structures) on plant roots and this feature was discussed to be associated with its biocontrol properties. For this reason, formation of B. amyloliquefaciens biofilms was studied at the transcriptional level using high-throughput sequencing of whole transcriptome cDNA libraries from cells grown under biofilm-forming conditions vs. planktonic growth. Comparison of the transcriptional profiles of B. amyloliquefaciens FZB42 under these growth conditions revealed a common set of highly transcribed genes mostly associated with basic cellular functions. The lci gene, encoding an antimicrobial peptide (AMP), was among the most highly transcribed genes of cells under both growth conditions suggesting that AMP production may contribute to biocontrol. In contrast, gene clusters coding for synthesis of secondary metabolites with antimicrobial properties were only moderately transcribed and not induced in biofilm-forming cells. Differential gene expression revealed that 331 genes were significantly up-regulated and 230 genes were down-regulated in the transcriptome of B. amyloliquefaciens FZB42 under biofilm-forming conditions in comparison to planktonic cells. Among the most highly up-regulated genes, the yvqHI operon, coding for products involved in nisin (class I bacteriocin) resistance, was identified. In addition, an operon whose products play a role in fructosamine metabolism was enhanced in its transcription. Moreover, genes involved in the production of the extracellular

  1. Characterization of Biocontrol Traits in Heterorhabditis floridensis: A Species with Broad Temperature Tolerance.

    PubMed

    Shapiro-Ilan, David I; Blackburn, Dana; Duncan, Larry; El-Borai, Fahiem E; Koppenhöfer, Heather; Tailliez, Patrick; Adams, Byron J

    2014-12-01

    Biological characteristics of two strains of the entomopathogenic nematode, Heterorhabditis floridensis (332 isolated in Florida and K22 isolated in Georgia) were described. The identity of the nematode's symbiotic bacteria was elucidated and found to be Photorhabdus luminescens subsp. luminescens. Beneficial traits pertinent to biocontrol (environmental tolerance and virulence) were characterized. The range of temperature tolerance in the H. floridensis strains was broad and showed a high level of heat tolerance. The H. floridensis strains caused higher mortality or infection in G. mellonella at 30°C and 35°C compared with S. riobrave (355), a strain widely known to be heat tolerant, and the H. floridensis strains were also capable of infecting at 17°C whereas S. riobrave (355) was not. However, at higher temperatures (37°C and 39°C), though H. floridensis readily infected G. mellonella, S. riobrave strains caused higher levels of mortality. Desiccation tolerance in H. floridensis was similar to Heterorhabditis indica (Hom1) and S. riobrave (355) and superior to S. feltiae (SN). H. bacteriophora (Oswego) and S. carpocapsae (All) exhibited higher desiccation tolerance than the H. floridensis strains. The virulence of H. floridensis to four insect pests (Aethina tumida, Conotrachelus nenuphar, Diaprepes abbreviatus, and Tenebrio molitor) was determined relative to seven other nematodes: H. bacteriophora (Oswego), H. indica (Hom1), S. carpocapsae (All), S. feltiae (SN), S. glaseri (4-8 and Vs strains), and S. riobrave (355). Virulence to A. tumida was similar among the H. floridensis strains and other nematodes except S. glaseri (Vs), S. feltiae, and S. riobrave failed to cause higher mortality than the control. Only H. bacteriophora, H. indica, S. feltiae, S. riobrave, and S. glaseri (4-8) caused higher mortality than the control in C. nenuphar. All nematodes were pathogenic to D. abbreviatus though S. glaseri (4-8) and S. riobrave (355) were the most virulent

  2. The Potential Use of Wolbachia-Based Mosquito Biocontrol Strategies for Japanese Encephalitis

    PubMed Central

    Jeffries, Claire L.; Walker, Thomas

    2015-01-01

    Japanese encephalitis virus (JEV) is a zoonotic pathogen transmitted by the infectious bite of Culex mosquitoes. The virus causes the development of the disease Japanese encephalitis (JE) in a small proportion of those infected, predominantly affecting children in eastern and southern Asia. Annual JE incidence estimates range from 50,000–175,000, with 25%–30% of cases resulting in mortality. It is estimated that 3 billion people live in countries in which JEV is endemic. The virus exists in an enzootic transmission cycle, with mosquitoes transmitting JEV between birds as reservoir hosts and pigs as amplifying hosts. Zoonotic infection occurs as a result of spillover events from the main transmission cycle. The reservoir avian hosts include cattle egrets, pond herons, and other species of water birds belonging to the family Ardeidae. Irrigated rice fields provide an ideal breeding ground for mosquitoes and attract migratory birds, maintaining the transmission of JEV. Although multiple vaccines have been developed for JEV, they are expensive and require multiple doses to maintain efficacy and immunity. As humans are a “dead-end” host for the virus, vaccination of the human population is unlikely to result in eradication. Therefore, vector control of the principal mosquito vector, Culex tritaeniorhynchus, represents a more promising strategy for reducing transmission. Current vector control strategies include intermittent irrigation of rice fields and space spraying of insecticides during outbreaks. However, Cx. Tritaeniorhynchus is subject to heavy exposure to pesticides in rice fields, and as a result, insecticide resistance has developed. In recent years, significant advancements have been made in the potential use of the bacterial endosymbiont Wolbachia for mosquito biocontrol. The successful transinfection of Wolbachia strains from Drosophila flies to Aedes (Stegomyia) mosquitoes has resulted in the generation of “dengue-refractory” mosquito lines

  3. Comparative Genomics Within the Bacillus Genus Reveal the Singularities of Two Robust Bacillus amyloliquefaciens Biocontrol Strains.

    PubMed

    Magno-Pérez-Bryan, M C; Martínez-García, P M; Hierrezuelo, J; Rodríguez-Palenzuela, P; Arrebola, E; Ramos, C; de Vicente, A; Pérez-García, A; Romero, D

    2015-10-01

    Bacillus amyloliquefaciens CECT 8237 and CECT 8238, formerly known as Bacillus subtilis UMAF6639 and UMAF6614, respectively, contribute to plant health by facing microbial pathogens or inducing the plant's defense mechanisms. We sequenced their genomes and developed a set of ad hoc scripts that allowed us to search for the features implicated in their beneficial interaction with plants. We define a core set of genes that should ideally be found in any beneficial Bacillus strain, including the production of secondary metabolites, volatile compounds, metabolic plasticity, cell-to-cell communication systems, and biofilm formation. We experimentally prove that some of these genetic elements are active, such as i) the production of known secondary metabolites or ii) acetoin and 2-3-butanediol, compounds that stimulate plant growth and host defense responses. A comparison with other Bacillus genomes permits us to find differences in the cell-to-cell communication system and biofilm formation and to hypothesize variations in their persistence and resistance ability in diverse environmental conditions. In addition, the major protection provided by CECT 8237 and CECT 8238, which is different from other Bacillus strains against bacterial and fungal melon diseases, permits us to propose a correlation with their singular genetic background and determine the need to search for additional blind biocontrol-related features.

  4. Biocontrol and plant growth-promoting activity of rhizobacteria from Chinese fields with contaminated soils

    PubMed Central

    Wang, Xuefei; Mavrodi, Dmitri V; Ke, Linfeng; Mavrodi, Olga V; Yang, Mingming; Thomashow, Linda S; Zheng, Na; Weller, David M; Zhang, Jibin

    2015-01-01

    The aim of this study was to inventory the types of plant growth-promoting rhizobacteria (PGPR) present in the rhizosphere of plants grown in soils contaminated with heavy metals, recalcitrant organics, petroleum sewage or salinity in China. We screened 1223 isolates for antifungal activity and about 24% inhibited Rhizoctonia solani or Sclerotinia sclerotiorum. Twenty-four strains inhibitory to R. solani, Gaeumannomyces graminis var. tritici and/or S. sclerotiorum and representing the dominant morphotypes were assayed for PGPR activity. Seven strains contained phlD, prnD, pltC or phzF genes and produced the antibiotics 2,4-diacetylphloroglucinol, pyrrolnitrin, pyoluteorin and phenazines respectively. Six strains contained acdS, which encodes 1-aminocyclopropane-1-carboxylic acid deaminase. Phylogenetic analysis of 16S rDNA and phlD, phzF and acdS genes demonstrated that some strains identified as Pseudomonas were similar to model PGPR strains Pseudomonas protegens Pf-5, Pseudomonas chlororaphis subsp. aureofaciens 30–84 and P. brassicacearum Q8r1-96. Pseudomonas protegens- and P. chlororaphis-like strains had the greatest biocontrol activity against Rhizoctonia root rot and take-all of wheat. Pseudomonas protegens and P. brassicacearum-like strains showed the greatest promotion of canola growth. Our results indicate that strains from contaminated soils are similar to well-described PGPR found in agricultural soils worldwide. Growth-promoting rhizobacteria in polluted soils PMID:25219642

  5. Host-Range Dynamics of Cochliobolus lunatus: From a Biocontrol Agent to a Severe Environmental Threat

    PubMed Central

    Louis, Bengyella; Waikhom, Sayanika Devi; Roy, Pranab; Bhardwaj, Pardeep Kumar; Sharma, Chandradev K.; Singh, Mohendro Wakambam; Talukdar, Narayan Chandra

    2014-01-01

    We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L) farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide. PMID:24987680

  6. Native Killer Yeasts as Biocontrol Agents of Postharvest Fungal Diseases in Lemons.

    PubMed

    Perez, María Florencia; Contreras, Luciana; Garnica, Nydia Mercedes; Fernández-Zenoff, María Verónica; Farías, María Eugenia; Sepulveda, Milena; Ramallo, Jacqueline; Dib, Julián Rafael

    2016-01-01

    Economic losses caused by postharvest diseases represent one of the main problems of the citrus industry worldwide. The major diseases affecting citrus are the "green mold" and "blue mold", caused by Penicillium digitatum and P. italicum, respectively. To control them, synthetic fungicides are the most commonly used method. However, often the emergence of resistant strains occurs and their use is becoming more restricted because of toxic effects and environmental pollution they generate, combined with trade barriers to international markets. The aim of this work was to isolate indigenous killer yeasts with antagonistic activity against fungal postharvest diseases in lemons, and to determine their control efficiency in in vitro and in vivo assays. Among 437 yeast isolates, 8.5% show to have a killer phenotype. According to molecular identification, based on the 26S rDNA D1/D2 domain sequences analysis, strains were identified belonging to the genera Saccharomyces, Wickerhamomyces, Kazachstania, Pichia, Candida and Clavispora. Killers were challenged with pathogenic molds and strains that caused the maximum in vitro inhibition of P. digitatum were selected for in vivo assays. Two strains of Pichia and one strain of Wickerhamomyces depicted a significant protection (p <0.05) from decay by P. digitatum in assays using wounded lemons. Thus, the native killer yeasts studied in this work showed to be an effective alternative for the biocontrol of postharvest fungal infections of lemons and could be promising agents for the development of commercial products for the biological control industry.

  7. Candida parapsilosis as a Potent Biocontrol Agent against Growth and Aflatoxin Production by Aspergillus Species

    PubMed Central

    Niknejad, F; Zaini, F; Faramarzi, MA; Amini, M; Kordbacheh, P; Mahmoudi, M; Safara, M

    2012-01-01

    Background: Aflatoxin contamination of food and feed stuff is a serious health problem and significant economic concerns. In the present study, the inhibitory effect of Candida parapsilosis IP1698 on mycelial growth and aflatoxin production in aflatoxigenic strains of Aspergillus species was investigated. Methods: Mycelial growth inhibitions of nine strains of aflatoxigenic and non-aflatoxigenic Aspergillus species in the presence of C. parapsilosis investigated by pour plate technique at different pH, temperature and time of incubation. Reduction of aflatoxin was evaluated in co-cultured fungi in yeast extract sucrose broth after seven days of incubation using HPLC method. The data were analyzed by SPSS 11.5. Results: The presence of the C. parapsilosis at different pH did not affect significantly the growth rate of Aspergillus isolates. On the other hand, temperature and time of incubation showed to be significantly effective when compared to controls without C. parapsilosis (P≤0.05). In aflatoxigenic strains, minimum percentage of reductions in total aflatoxin and B1, B2, G1, G2 fractions were 92.98, 92.54, 77.48, 54.54 and 72.22 and maximum percentage of reductions were 99.59, not detectable, 94.42, and not detectable in both G1 and G2, respectively. Conclusion: C. parapsilosis might employ as a good biocontrol agent against growth and aflatoxin production by aflatoxigenic Aspergillus species PMID:23308351

  8. Native Killer Yeasts as Biocontrol Agents of Postharvest Fungal Diseases in Lemons

    PubMed Central

    Garnica, Nydia Mercedes; Fernández-Zenoff, María Verónica; Farías, María Eugenia; Sepulveda, Milena; Ramallo, Jacqueline; Dib, Julián Rafael

    2016-01-01

    Economic losses caused by postharvest diseases represent one of the main problems of the citrus industry worldwide. The major diseases affecting citrus are the "green mold" and "blue mold", caused by Penicillium digitatum and P. italicum, respectively. To control them, synthetic fungicides are the most commonly used method. However, often the emergence of resistant strains occurs and their use is becoming more restricted because of toxic effects and environmental pollution they generate, combined with trade barriers to international markets. The aim of this work was to isolate indigenous killer yeasts with antagonistic activity against fungal postharvest diseases in lemons, and to determine their control efficiency in in vitro and in vivo assays. Among 437 yeast isolates, 8.5% show to have a killer phenotype. According to molecular identification, based on the 26S rDNA D1/D2 domain sequences analysis, strains were identified belonging to the genera Saccharomyces, Wickerhamomyces, Kazachstania, Pichia, Candida and Clavispora. Killers were challenged with pathogenic molds and strains that caused the maximum in vitro inhibition of P. digitatum were selected for in vivo assays. Two strains of Pichia and one strain of Wickerhamomyces depicted a significant protection (p <0.05) from decay by P. digitatum in assays using wounded lemons. Thus, the native killer yeasts studied in this work showed to be an effective alternative for the biocontrol of postharvest fungal infections of lemons and could be promising agents for the development of commercial products for the biological control industry. PMID:27792761

  9. AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

    PubMed

    Elsen, A; Gervacio, D; Swennen, R; De Waele, D

    2008-07-01

    Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

  10. Postharvest biocontrol ability of killer yeasts against Monilinia fructigena and Monilinia fructicola on stone fruit.

    PubMed

    Grzegorczyk, Monika; Żarowska, Barbara; Restuccia, Cristina; Cirvilleri, Gabriella

    2017-02-01

    The antagonistic effects of Debaryomyces hansenii KI2a, D. hansenii MI1a and Wickerhamomyces anomalus BS91 were tested against Monilinia fructigena and Monilinia fructicola in in vitro and in vivo trials. All yeast strains demonstrated antifungal activity at different levels depending on species, strain and pathogen. D hansenii KI2a and W. anomalus BS91 showed the highest biocontrol activity in vitro; the production of hydrolytic enzymes, killer toxins and volatile organic compounds (VOCs) were hypothesized as their main mechanisms of action against pathogens. D hansenii KI2a and W. anomalus BS91 significantly reduced brown rot incidence and severity on peach and plum fruits artificially inoculated with M. fructigena and M. fructicola, especially when applied 24 h before pathogen inoculation. On the opposite, D. hansenii MI1a exhibited weak antagonistic activity towards M. fructigena on peach and plum fruits and was ineffective against M. fructicola. The noticeable ability of W. anomalus BS91 to control brown rot could be also correlated with its high capacity to colonize the wound tissue and to increase its population density. Accordingly, the antagonistic strains of D. hansenii and W. anomalus could be proposed as active ingredients for the development of biofungicides against Monilinia species that are responsible for considerable economic losses in stone fruit crops.

  11. Characterization of Novel Trichoderma asperellum Isolates to Select Effective Biocontrol Agents Against Tomato Fusarium Wilt

    PubMed Central

    El_Komy, Mahmoud H.; Saleh, Amgad A.; Eranthodi, Anas; Molan, Younes Y.

    2015-01-01

    The use of novel isolates of Trichoderma with efficient antagonistic capacity against Fusarium oxysporum f. sp. lycopersici (FOL) is a promising alternative strategy to pesticides for tomato wilt management. We evaluated the antagonistic activity of 30 isolates of T. asperellum against 4 different isolates of FOL. The production of extracellular cell wall degrading enzymes of the antagonistic isolates was also measured. The random amplified polymorphic DNA (RAPD) method was applied to assess the genetic variability among the T. asperellum isolates. All of the T. asperellum isolates significantly reduced the mycelial growth of FOL isolates but the amount of growth reduction varied significantly as well. There was a correlation between the antagonistic capacity of T. asperellum isolates towards FOL and their lytic enzyme production. Isolates showing high levels of chitinase and β-1,3-glucanase activities strongly inhibited the growth of FOL isolates. RAPD analysis showed a high level of genetic variation among T. asperellum isolates. The UPGMA dendrogram revealed that T. asperellum isolates could not be grouped by their anta- gonistic behavior or lytic enzymes production. Six isolates of T. asperellum were highly antagonistic towards FOL and potentially could be used in commercial agriculture to control tomato wilt. Our results are consistent with the conclusion that understanding the genetic variation within Trichoderma isolates and their biochemical capabilities are required for the selection of effective indigenous fungal strains for the use as biocontrol agents. PMID:25774110

  12. Synergistic effect of beneficial rhizosphere microflora in biocontrol and plant growth promotion.

    PubMed

    Kannan, Vijayaragahavan; Sureendar, Raman

    2009-04-01

    Biological systems are getting more relevance than chemical control of plant pathogens as they are not only eco-friendly and economic in approach but are also involved in improving the soil consistency and maintenance of natural soil flora. Plant growth promoting rhizosphere microorganisms were isolated from three different tree rhizospheres using selective culture media. Five microorganisms were selected from each rhizosphere soil based on their efficiency and screened for their ability to promote plant growth as a consortium. Each of the developed consortium has a phosphate solubilizer, nitrogen fixer, growth hormone producer, heterotrophic member and an antagonist. The plant growth promoting ability of the microbial members present in the consortium was observed by estimating the IAA production level and also by the nitrogenase activity of the nitrogen fixers. The biocontrol potentiality of the consortium and the antagonist present in the consortium were checked by both dual plate assay and cross-streaking technique. Consortial treatments effected very good growth promotion in Lycopersicon esculentum Mill and the treated plants also developed resistance against wilt pathogen, Fusarium oxysporum f. sp. lycopersici though the effect was well pronounced with consortium developed from Santalum album.

  13. Molecular characterization of alkaline protease of Bacillus amyloliquefaciens SP1 involved in biocontrol of Fusarium oxysporum.

    PubMed

    Guleria, Shiwani; Walia, Abhishek; Chauhan, Anjali; Shirkot, C K

    2016-09-02

    An alkaline protease gene was amplified from genomic DNA of Bacillus amyloliquefaciens SP1 which was involved in effective biocontrol of Fusarium oxysporum. We investigated the antagonistic capacity of protease of B. amyloliquifaciens SP1, under in vitro conditions. The 5.62 fold purified enzyme with specific activity of 607.69U/mg reported 24.14% growth inhibition of F. oxysporum. However, no antagonistic activity was found after addition of protease inhibitor i.e. PMSF (15mM) to purified enzyme. An 1149bp nucleotide sequence of protease gene encoded 382 amino acids of 43kDa and calculated isoelectric point of 9.29. Analysis of deduced amino acid sequence revealed high homology (86%) with subtilisin E of Bacillus subtilis. The B. amyloliquefaciens SP1 protease gene was expressed in Escherichiax coli BL21. The expressed protease was secreted into culture medium by E. coli and exhibited optimum activity at pH8.0 and 60°C. The most reliable three dimensional structure of alkaline protease was determined using Phyre 2 server which was validated on the basis of Ramachandran plot and ERRAT value. The expression and structure prediction of the enzyme offers potential value for commercial application in agriculture and industry.

  14. Ecology of Anti-Biofilm Agents II: Bacteriophage Exploitation and Biocontrol of Biofilm Bacteria

    PubMed Central

    Abedon, Stephen T.

    2015-01-01

    Bacteriophages are the viruses of bacteria. In the guise of phage therapy they have been used for decades to successfully treat what are probable biofilm-containing chronic bacterial infections. More recently, phage treatment or biocontrol of biofilm bacteria has been brought back to the laboratory for more rigorous assessment as well as towards the use of phages to combat environmental biofilms, ones other than those directly associated with bacterial infections. Considered in a companion article is the inherent ecological utility of bacteriophages versus antibiotics as anti-biofilm agents. Discussed here is a model for phage ecological interaction with bacteria as they may occur across biofilm-containing ecosystems. Specifically, to the extent that individual bacterial types are not highly abundant within biofilm-containing environments, then phage exploitation of those bacteria may represent a “Feast-or-famine” existence in which infection of highly localized concentrations of phage-sensitive bacteria alternate with treacherous searches by the resulting phage progeny virions for new concentrations of phage-sensitive bacteria to infect. An updated synopsis of the literature concerning laboratory testing of phage use to combat bacterial biofilms is then provided along with tips on how “Ecologically” such phage-mediated biofilm control can be modified to more reliably achieve anti-biofilm efficacy. PMID:26371011

  15. Identification of Aspergillus flavus isolates as potential biocontrol agents of aflatoxin contamination in crops.

    PubMed

    Rosada, L J; Sant'anna, J R; Franco, C C S; Esquissato, G N M; Santos, P A S R; Yajima, J P R S; Ferreira, F D; Machinski, M; Corrêa, B; Castro-Prado, M A A

    2013-06-01

    Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.

  16. Biocontrol and plant growth-promoting activity of rhizobacteria from Chinese fields with contaminated soils.

    PubMed

    Wang, Xuefei; Mavrodi, Dmitri V; Ke, Linfeng; Mavrodi, Olga V; Yang, Mingming; Thomashow, Linda S; Zheng, Na; Weller, David M; Zhang, Jibin

    2015-05-01

    The aim of this study was to inventory the types of plant growth-promoting rhizobacteria (PGPR) present in the rhizosphere of plants grown in soils contaminated with heavy metals, recalcitrant organics, petroleum sewage or salinity in China. We screened 1223 isolates for antifungal activity and about 24% inhibited Rhizoctonia solani or Sclerotinia sclerotiorum. Twenty-four strains inhibitory to R. solani, Gaeumannomyces graminis var. tritici and/or S. sclerotiorum and representing the dominant morphotypes were assayed for PGPR activity. Seven strains contained phlD, prnD, pltC or phzF genes and produced the antibiotics 2,4-diacetylphloroglucinol, pyrrolnitrin, pyoluteorin and phenazines respectively. Six strains contained acdS, which encodes 1-aminocyclopropane-1-carboxylic acid deaminase. Phylogenetic analysis of 16S rDNA and phlD, phzF and acdS genes demonstrated that some strains identified as Pseudomonas were similar to model PGPR strains Pseudomonas protegens Pf-5, Pseudomonas chlororaphis subsp. aureofaciens 30-84 and P. brassicacearum Q8r1-96. Pseudomonas protegens- and P. chlororaphis-like strains had the greatest biocontrol activity against Rhizoctonia root rot and take-all of wheat. Pseudomonas protegens and P. brassicacearum-like strains showed the greatest promotion of canola growth. Our results indicate that strains from contaminated soils are similar to well-described PGPR found in agricultural soils worldwide.

  17. Identifying relevant hyperspectral bands using Boruta: a temporal analysis of water hyacinth biocontrol

    NASA Astrophysics Data System (ADS)

    Agjee, Na'eem Hoosen; Ismail, Riyad; Mutanga, Onisimo

    2016-10-01

    Water hyacinth plants (Eichhornia crassipes) are threatening freshwater ecosystems throughout Africa. The Neochetina spp. weevils are seen as an effective solution that can combat the proliferation of the invasive alien plant. We aimed to determine if multitemporal hyperspectral data could be utilized to detect the efficacy of the biocontrol agent. The random forest (RF) algorithm was used to classify variable infestation levels for 6 weeks using: (1) all the hyperspectral bands, (2) bands selected by the recursive feature elimination (RFE) algorithm, and (3) bands selected by the Boruta algorithm. Results showed that the RF model using all the bands successfully produced low-classification errors (12.50% to 32.29%) for all 6 weeks. However, the RF model using Boruta selected bands produced lower classification errors (8.33% to 15.62%) than the RF model using all the bands or bands selected by the RFE algorithm (11.25% to 21.25%) for all 6 weeks, highlighting the utility of Boruta as an all relevant band selection algorithm. All relevant bands selected by Boruta included: 352, 754, 770, 771, 775, 781, 782, 783, 786, and 789 nm. It was concluded that RF coupled with Boruta band-selection algorithm can be utilized to undertake multitemporal monitoring of variable infestation levels on water hyacinth plants.

  18. Novel Lectin-Like Bacteriocins of Biocontrol Strain Pseudomonas fluorescens Pf-5

    PubMed Central

    Parret, Annabel H. A.; Temmerman, Koen; De Mot, René

    2005-01-01

    Bacteriocin LlpA, produced by Pseudomonas sp. strain BW11M1, is a peculiar antibacterial protein due to its homology to mannose-binding lectins mostly found in monocots (A. H. A. Parret, G. Schoofs, P. Proost, and R. De Mot, J. Bacteriol. 185:897-908, 2003). Biocontrol strain Pseudomonas fluorescens Pf-5 contains two llpA-like genes, named llpA1Pf-5 and llpA2Pf-5. Recombinant Escherichia coli cells expressing llpA1Pf-5 or llpA2Pf-5 acquired bacteriocin activity and secreted a 31-kDa protein cross-reacting with LlpABW11M1 antibodies. Antibacterial activity of the recombinant proteins was evidenced by gel overlay assays. Analysis of the antimicrobial spectrum indicated that LlpA1Pf-5 and LlpA2Pf-5 are able to inhibit P. fluorescens strains, as well as the related mushroom pathogen Pseudomonas tolaasii. LlpA-type bacteriocins are characterized by a domain structure consisting of tandem monocot mannose-binding lectin (MMBL) domains. Molecular phylogeny of these MMBL domains suggests that the individual MMBL domains within an LlpA protein have evolved separately toward a specific, as yet unknown, function or, alternatively, were acquired from different ancestral sources. Our observations are consistent with earlier observations, which hinted that MMBL-like bacteriocins represent a new family of antibacterial proteins, probably with a novel mode of action. PMID:16151105

  19. Transcriptomic response of Arabidopsis thaliana after 24 h incubation with the biocontrol fungus Trichoderma harzianum.

    PubMed

    Morán-Diez, Eugenia; Rubio, Belén; Domínguez, Sara; Hermosa, Rosa; Monte, Enrique; Nicolás, Carlos

    2012-04-15

    Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities against phytopathogenic fungi, although it has also direct effects on plants, increasing or accelerating their growth and resistance to diseases and the tolerance to abiotic stresses. We analyzed Arabidopsis thaliana gene expression changes after 24 h of incubation in the presence of T. harzianum T34 using the Affymetrix GeneChip Arabidopsis ATH1. Because this microarray contains more than 22,500 probe sets representing approximately 24,000 genes, we were able to construct a global picture of the molecular physiology of the plant at 24 h of T. harzianum-Arabidopsis interaction. We identified several differentially expressed genes that are involved in plant responses to stress, regulation of transcription, signal transduction or plant metabolism. Our data support the hypothesis that salicylic acid- and jasmonic acid-related genes were down-regulated in A. thaliana after 24 h of incubation in the presence of T. harzianum T34, while several genes related to abiotic stress responses were up-regulated. These systemic changes elicited by T. harzianum in Arabidopsis are discussed.

  20. Biosurfactants in plant-Pseudomonas interactions and their importance to biocontrol.

    PubMed

    D'aes, Jolien; De Maeyer, Katrien; Pauwelyn, Ellen; Höfte, Monica

    2010-06-01

    Production of biosurfactants is a common feature in bacteria, and in particular in plant-associated species. These bacteria include many plant beneficial and plant pathogenic Pseudomonas spp., which produce primarily cyclic lipopeptide and rhamnolipid type biosurfactants. Pseudomonas-derived biosurfactants are involved in many important bacterial functions. By modifying surface properties, biosurfactants can influence common traits such as surface motility, biofilm formation and colonization. Biosurfactants can alter the bio-availability of exogenous compounds, such as nutrients, to promote their uptake, and of endogenous metabolites, including phenazine antibiotics, resulting in an enhanced biological activity. Antibiotic activity of biosurfactants towards microbes could play a role in intraspecific competition, self-defence and pathogenesis. In addition, bacterial surfactants can affect plants in different ways, either protecting them from disease, or acting as a toxin in a plant-pathogen interaction. Biosurfactants are involved in the biocontrol activity of an increasing number of Pseudomonas strains. Consequently, further insight into the roles and activities of surfactants produced by bacteria could provide means to optimize the use of biological control as an alternative crop protection strategy.

  1. Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew

    PubMed Central

    Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

    2015-01-01

    Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway. PMID:26379654

  2. Selection rhizosphere-competent microbes for development of microbial products as biocontrol agents

    NASA Astrophysics Data System (ADS)

    Mashinistova, A. V.; Elchin, A. A.; Gorbunova, N. V.; Muratov, V. S.; Kydralieva, K. A.; Khudaibergenova, B. M.; Shabaev, V. P.; Jorobekova, Sh. J.

    2009-04-01

    Rhizosphere-borne microorganisms reintroduced to the soil-root interface can establish without inducing permanent disturbance in the microbial balance and effectively colonise the rhizosphere due to carbon sources of plant root exudates. A challenge for future development of microbial products for use in agriculture will be selection of rhizosphere-competent microbes that both protect the plant from pathogens and improve crop establishment and persistence. In this study screening, collection, identification and expression of stable and technological microbial strains living in soils and in the rhizosphere of abundant weed - couch-grass Elytrigia repens L. Nevski were conducted. A total of 98 bacteria isolated from the rhizosphere were assessed for biocontrol activity in vitro against phytopathogenic fungi including Fusarium culmorum, Fusarium heterosporum, Fusarium oxysporum, Drechslera teres, Bipolaris sorokiniana, Piricularia oryzae, Botrytis cinerea, Colletothrichum atramentarium and Cladosporium sp., Stagonospora nodorum. Biocontrol activity were performed by the following methods: radial and parallel streaks, "host - pathogen" on the cuts of wheat leaves. A culture collection comprising 64 potential biocontrol agents (BCA) against wheat and barley root diseases has been established. Of these, the most effective were 8 isolates inhibitory to at least 4 out of 5 phytopathogenic fungi tested. The remaining isolates inhibited at least 1 of 5 fungi tested. Growth stimulating activity of proposed rhizobacteria-based preparations was estimated using seedling and vegetative pot techniques. Seeds-inoculation and the tests in laboratory and field conditions were conducted for different agricultural crops - wheat and barley. Intact cells, liquid culture filtrates and crude extracts of the four beneficial bacterial strains isolated from the rhizosphere of weed were studied to stimulate plant growth. As a result, four bacterial strains selected from rhizosphere of weed

  3. Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew.

    PubMed

    Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

    2015-01-01

    Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway.

  4. Biocontrol Efficacy Among Strains of Pochonia chlamydosporia Obtained from a Root-Knot Nematode Suppressive Soil

    PubMed Central

    Yang, Jiue-in; Loffredo, Angelo; Borneman, James; Becker, J. Ole

    2012-01-01

    Three Pochonia chlamydosporia var. chlamydosporia strains were isolated from a Meloidogyne incognita-suppressive soil, and then genetically characterized with multiple Pochonia-selective typing methods based on analysis of ß-tubulin, rRNA internal transcribed spacer (ITS), rRNA small subunit (SSU), and enterobacterial repetitive intergenic consensus (ERIC) PCR. All strains exhibited different patterns with the ERIC analysis. Strains 1 and 4 were similar with PCR analysis of ß-tubulin and ITS. The strains' potential as biological control agents against root-knot nematodes were examined in greenhouse trials. All three P. chlamydosporia strains significantly reduced the numbers of nematode egg masses. When chlamydospores were used as inoculum, strain 4 reduced egg numbers on tomato roots by almost 50%, and showed effects on the numbers of J2 and on nematode-caused root-galling. A newly developed SSU-based PCR analysis differentiated strain 4 from the others, and could therefore potentially be used as a screening tool for identifying other effective biocontrol strains of P. chlamydosporia var. chlamydosporia. PMID:23483846

  5. Plot- and landscape-level changes in climate and vegetation following defoliation of exotic saltcedar (Tamarix sp.) from the biocontrol agent Diorhabda carinulata along a stream in the Mojave Desert (USA)

    USGS Publications Warehouse

    Bateman, H.L.; Nagler, P.L.; Glenn, E.P.

    2013-01-01

    The biocontrol agent, northern tamarisk beetle (Diorhabda carinulata), has been used to defoliate non-native saltcedar (Tamarix spp.) in USA western riparian systems since 2001. Biocontrol has the potential to impact biotic communities and climatic conditions in affected riparian areas. To determine the relationships between biocontrol establishment and effects on vegetation and climate at the plot and landscape scales, we measured temperature, relative humidity, foliage canopy, solar radiation, and used satellite imagery to assess saltcedar defoliation and evapotranspiration (ET) along the Virgin River in the Mojave Desert. Following defoliation solar radiation increased, daily humidity decreased, and maximum daily temperatures tended to increase. MODIS and Landsat satellite imagery showed defoliation was widespread, resulting in reductions in ET and vegetation indices. Because biocontrol beetles are spreading into new saltcedar habitats on arid western rivers, and the eventual equilibrium between beetles and saltcedar is unknown, it is necessary to monitor trends for ecosystem functions and higher trophic-level responses in habitats impacted by biocontrol.

  6. Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus × domestica).

    PubMed

    Vero, Silvana; Garmendia, Gabriela; González, M Belén; Bentancur, Oscar; Wisniewski, Michael

    2013-03-01

    Psychrotrophic yeasts were isolated from Antarctic soils, selected based on their ability to grow in apple juice at low temperatures, and were evaluated as potential biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, an isolate of Leucosporidium scottii, designated At17, was identified as a good biocontrol agent for blue and gray mold of two apple cultivars. The selected isolate produced soluble and volatile antifungal substances that were inhibitory to apple pathogens. Siderophore production was also demonstrated, but it did not appear to play a role in pathogen inhibition. The selected yeast had the capacity to form a biofilm when grown in apple juice, which is considered an important attribute of postharvest antagonists to successfully colonize wounds and intact fruit surfaces. At17 was resistant to commonly used postharvest fungicides, so application of a combination of low-dose fungicide along with the biocontrol agent could be used as an integrated management practice.

  7. Characterization of antagonistic-potential of two Bacillus strains and their biocontrol activity against Rhizoctonia solani in tomato.

    PubMed

    Solanki, Manoj Kumar; Singh, Rajesh Kumar; Srivastava, Supriya; Kumar, Sudheer; Kashyap, Prem Lal; Srivastava, Alok K

    2015-01-01

    To investigate the biocontrol mechanism of two antagonistic Bacillus strains (Bacillus subtilis MB14 and Bacillus amyloliquefaciens MB101), three in vitro antagonism assays were screened and the results were concluded that both strains inhibited Rhizoctonia solani growth in a similar manner by dual culture assay, but the maximum percent of inhibition only resulted with MB101 by volatile and diffusible metabolite assays. Moreover, cell free supernatant (CFS) of MB101 also showed significant (p > 0.05) growth inhibition as compared to MB14, when 10 and 20% CFS mix with the growth medium of R. solani. After in vitro-validation, both strains were evaluated under greenhouse and the results concluded that strain MB101 had significant biocontrol potential as compared to MB14. Strain MB101 was enhanced the plant height, biomass and chlorophyll content of tomato plant through a higher degree of root colonization. In field trials, strain MB101 showed higher lessening in root rot symptoms with significant fruit yield as compare to strain MB14 and infected control. Next to the field study, the presence of four antibiotic genes (srfAA, fenD, ituC, and bmyB) also concluded the antifungal nature of both Bacillus strains. Phylogenetic analysis of protein sequences revealed a close relatedness of three genes (srfAA, fenD, and ituC) with earlier reported sequences of B. subtilis and B. amyloliquefaciens. However, bmyB showed heterogeneity in among both strains (MB14 and MB101) and it may be concluded that higher degree of antagonism, root colonization and different antibiotic producing genes may play an important role in biocontrol mechanism of strain MB101.

  8. Phytohormone profiles induced by trichoderma isolates correspond with their biocontrol and plant growth-promoting activity on melon plants.

    PubMed

    Martínez-Medina, Ainhoa; Del Mar Alguacil, Maria; Pascual, Jose A; Van Wees, Saskia C M

    2014-07-01

    The application of Trichoderma strains with biocontrol and plant growth-promoting capacities to plant substrates can help reduce the input of chemical pesticides and fertilizers in agriculture. Some Trichoderma isolates can directly affect plant pathogens, but they also are known to influence the phytohormonal network of their host plant, thus leading to an improvement of plant growth and stress tolerance. In this study, we tested whether alterations in the phytohormone signature induced by different Trichoderma isolates correspond with their ability for biocontrol and growth promotion. Four Trichoderma isolates were collected from agricultural soils and were identified as the species Trichoderma harzianum (two isolates), Trichoderma ghanense, and Trichoderma hamatum. Their antagonistic activity against the plant pathogen Fusarium oxysporum f. sp. melonis was tested in vitro, and their plant growth-promoting and biocontrol activity against Fusarium wilt on melon plants was examined in vivo, and compared to that of the commercial strain T. harzianum T-22. Several growth- and defense-related phytohormones were analyzed in the shoots of plants that were root-colonized by the different Trichoderma isolates. An increase in auxin and a decrease in cytokinins and abscisic acid content were induced by the isolates that promoted the plant growth. Principal component analysis (PCA) was used to evaluate the relationship between the plant phenotypic and hormonal variables. PCA pointed to a strong association of auxin induction with plant growth stimulation by Trichoderma. Furthermore, the disease-protectant ability of the Trichoderma strains against F. oxysporum infection seems to be more related to their induced alterations in the content of the hormones abscisic acid, ethylene, and the cytokinin trans-zeatin riboside than to the in vitro antagonism activity against F. oxysporum.

  9. Selection and characterization of Argentine isolates of Trichoderma harzianum for effective biocontrol of Septoria leaf blotch of wheat.

    PubMed

    Stocco, Marina C; Mónaco, Cecilia I; Abramoff, Cecilia; Lampugnani, Gladys; Salerno, Graciela; Kripelz, Natalia; Cordo, Cristina A; Consolo, Verónica F

    2016-03-01

    Species of the genus Trichoderma are economically important as biocontrol agents, serving as a potential alternative to chemical control. The applicability of Trichoderma isolates to different ecozones will depend on the behavior of the strains selected from each zone. The present study was undertaken to isolate biocontrol populations of Trichoderma spp. from the Argentine wheat regions and to select and characterize the best strains of Trichoderma harzianum by means of molecular techniques. A total of 84 out of the 240 strains of Trichoderma were able to reduce the disease severity of the leaf blotch of wheat. Thirty-seven strains were selected for the reduction equal to or greater than 50% of the severity, compared with the control. The percentage values of reduction of the pycnidial coverage ranged between 45 and 80%. The same last strains were confirmed as T. harzianum by polymerase chain reaction amplification of internal transcribed spacers, followed by sequencing. Inter-simple sequence repeat was used to examine the genetic variability among isolates. This resulted in a total of 132 bands. Further numerical analysis revealed 19 haplotypes, grouped in three clusters (I, II, III). Shared strains, with different geographical origins and isolated in different years, were observed within each cluster. The origin of the isolates and the genetic group were partially related. All isolates from Paraná were in cluster I, all isolates from Lobería were in cluster II, and all isolates from Pergamino and Santa Fe were in cluster III. Our results suggest that the 37 native strains of T. harzianum are important in biocontrol programs and could be advantageous for the preparation of biopesticides adapted to the agroecological conditions of wheat culture.

  10. PtrA Is Functionally Intertwined with GacS in Regulating the Biocontrol Activity of Pseudomonas chlororaphis PA23

    PubMed Central

    Shah, Nidhi; Klaponski, Natasha; Selin, Carrie; Rudney, Rachel; Fernando, W. G. Dilantha; Belmonte, Mark F.; de Kievit, Teresa R.

    2016-01-01

    In vitro inhibition of the fungal pathogen Sclerotinia sclerotiorum by Pseudomonas chlororaphis PA23 is reliant upon a LysR-type transcriptional regulator (LTTR) called PtrA. In the current study, we show that Sclerotinia stem rot and leaf infection are significantly increased in canola plants inoculated with the ptrA-mutant compared to the wild type, establishing PtrA as an essential regulator of PA23 biocontrol. LTTRs typically regulate targets that are upstream of and divergently transcribed from the LTTR locus. We identified a short chain dehydrogenase (scd) gene immediately upstream of ptrA. Characterization of a scd mutant revealed that it is phenotypically identical to the wild type. Moreover, scd transcript abundance was unchanged in the ptrA mutant. These findings indicate that PtrA regulation does not involve scd, rather this LTTR controls genes located elsewhere on the chromosome. Employing a combination of complementation and transcriptional analysis we investigated whether connections exist between PtrA and other regulators of biocontrol. Besides ptrA, gacS was the only gene able to partially rescue the wild-type phenotype, establishing a connection between PtrA and the sensor kinase GacS. Transcriptomic analysis revealed decreased expression of biosynthetic (phzA, prnA) and regulatory genes (phzI, phzR, rpoS, gacA, rsmX, rsmZ, retS) in the ptrA mutant; conversely, rsmE, and rsmY were markedly upregulated. The transcript abundance of ptrA was nine-fold higher in the mutant background indicating that this LTTR negatively autoregulates itself. In summary, PtrA is an essential regulator of genes required for PA23 biocontrol that is functionally intertwined with GacS. PMID:27713742

  11. Draft Genome Sequence of a Natural Root Isolate, Bacillus subtilis UD1022, a Potential Plant Growth-Promoting Biocontrol Agent

    PubMed Central

    Bishnoi, Usha

    2015-01-01

    Bacillus subtilis, which belongs to the phylum Firmicutes, is the most widely studied Gram-positive model organism. It is found in a wide variety of environments and is particularly abundant in soils and in the gastrointestinal tracts of ruminants and humans. Here, we present the complete genome sequence of the newly described B. subtilis strain UD1022. The UD1022 genome consists of a 4.025-Mbp chromosome, and other major findings from our analysis will provide insights into the genomic basis of it being a plant growth-promoting rhizobacterium (PGPR) with biocontrol potential. PMID:26159522

  12. Survival and ecological fitness of Pseudomonas fluorescens genetically engineered with dual biocontrol mechanisms.

    PubMed

    Bainton, N J; Lynch, J M; Naseby, D; Way, J A

    2004-10-01

    competitiveness around the root systems of plants even with the introduction of the Phl locus. Thus, strain Pa21 possesses the qualities necessary to provide effective integrated biocontrol, through maintaining both its wt trait of competitive exclusion on the plant roots, while also expressing the genes from the F113 biocontrol strain for Phl production. Interestingly, however, an additional beneficial trait appears to emerge with the strain Pa21's lowered survival competence compared with SBW25 EeZY6KX in the rhizosphere soil. With fears of the spread of genetically modified organisms and persistence in the soil, this trait may be of some ecological and commercial benefit and becomes a candidate for further investigation and possible exploitation.

  13. Biocontrol treatments confer protection against Verticillium dahliae infection of potato by inducing antimicrobial metabolites.

    PubMed

    El Hadrami, A; Adam, L R; Daayf, F

    2011-03-01

    Verticillium wilt, caused by Verticillium dahliae Kleb., is a serious potato (Solanum tuberosum L.) disease worldwide, and biocontrol represents a promising eco-friendly strategy to reduce its impact. We used extracts from Canada milk vetch (CMV) and a set of four V. dahliae-antagonistic bacterial strains to coat potato seeds at planting and examined the degree of protection provided against V. dahliae as well as accumulation of soluble phenolics as markers for induced resistance. All tested treatments were effective in reducing disease severity, and CMV showed the highest level of protection. In this treatment, flavonol-glycoside rutin was a highly abundant compound induced in potato tissues, with levels two to three times higher than those detected in noninoculated controls and V. dahliae-inoculated plants. We investigated dose-dependent effects of rutin on V. dahliae growth and sporulation in vitro and in planta. The effect of rutin on mycelial growth was inconsistent between disk assay and amended medium experiments. On the other hand, significant reduction of V. dahliae sporulation in vitro was consistently observed starting at 300 and 100 μM for isolates Vd-9 and Vd-21, respectively. We successfully detected 2-protocatechuoylphloroglucinolcarboxylic acid (2-PCPGCA) using ultra-performance liquid chromatography tandem mass spectrometry, indicating that V. dahliae dioxygenally oxidizes quercetin. Quercetin, as an aglycone, is freed from the sugar moiety by glucosidases and rhamnosidases produced by the fungus and is a substrate for quercetinases. The occurrence of quercetinases in V. dahliae provides a background to formulate a hypothesis about how by-product 2-PCPGCA may be interfering with potato defenses.

  14. Bacteriophage biocontrol of Listeria monocytogenes on soft ripened white mold and red-smear cheeses

    PubMed Central

    Guenther, Susanne

    2011-01-01

    Soft-ripened cheeses belong to the type of food most often contaminated with Listeria monocytogenes, and they have been implicated in several outbreaks of listeriosis. Bacteriophages represent an attractive way to combat foodborne pathogens without affecting other properties of the food. We used the broad host range, virulent Listeria phage A511 for control of L. monocytogenes during the production and ripening phases of both types of soft-ripened cheeses, white mold (Camembert-type) cheese, as well as washed-rind cheese with a red-smear surface (Limburger-type). The surfaces of young, unripened cheese were inoculated with 101–103 cfu/cm2 L. monocytogenes strains Scott A (serovar 4b) or CNL 103/2005 (serovar 1/2a). Phage was applied at defined time points thereafter, in single or repeated treatments, at 3 × 108 or 1 × 109 pfu/cm2. With Scott A (103 cfu/cm2) and a single dose of A511 (3 × 108 pfu/cm2) on camembert-type cheese, viable counts dropped 2.5 logs at the end of the 21 day ripening period. Repeated phage application did not further inhibit the bacteria, whereas a single higher dose (1 × 109 pfu/cm2) was found to be more effective. On red-smear cheese ripened for 22 days, Listeria counts were down by more than 3 logs. Repeated application of A511 further delayed re-growth of Listeria, but did not affect bacterial counts after 22 days. With lower initial Listeria contamination (101–102 cfu/cm2), viable counts dropped below the limit of detection, corresponding to more than 6 logs reduction compared to the control. Our data clearly demonstrate the potential of bacteriophage for biocontrol of L. monocytogenes in soft cheese. PMID:22334865

  15. Biocontrol Characteristics of Bacillus Species in Suppressing Stem Rot of Grafted Cactus Caused by Bipolaris cactivora.

    PubMed

    Bae, Sooil; Kim, Sang Gyu; Kim, Young Ho

    2013-03-01

    One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4) selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

  16. Three New Pierce's Disease Pathogenicity Effectors Identified Using Xylella fastidiosa Biocontrol Strain EB92-1

    PubMed Central

    Zhang, Shujian; Chakrabarty, Pranjib K.; Fleites, Laura A.; Rayside, Patricia A.; Hopkins, Donald L.; Gabriel, Dean W.

    2015-01-01

    Xylella fastidiosa (X. fastidiosa) infects a wide range of plant hosts and causes economically serious diseases, including Pierce's Disease (PD) of grapevines. X. fastidiosa biocontrol strain EB92-1 was isolated from elderberry and is infectious and persistent in grapevines but causes only very slight symptoms under ideal conditions. The draft genome of EB92-1 revealed that it appeared to be missing genes encoding 10 potential PD pathogenicity effectors found in Temecula1. Subsequent PCR and sequencing analyses confirmed that EB92-1 was missing the following predicted effectors found in Temecula1: two type II secreted enzymes, including a lipase (LipA; PD1703) and a serine protease (PD0956); two identical genes encoding proteins similar to Zonula occludens toxins (Zot; PD0915 and PD0928), and at least one relatively short, hemagglutinin-like protein (PD0986). Leaves of tobacco and citrus inoculated with cell-free, crude protein extracts of E. coli BL21(DE3) overexpressing PD1703 exhibited a hypersensitive response (HR) in less than 24 hours. When cloned into shuttle vector pBBR1MCS-5, PD1703 conferred strong secreted lipase activity to Xanthomonas citri, E. coli and X. fastidiosa EB92-1 in plate assays. EB92-1/PD1703 transformants also showed significantly increased disease symptoms on grapevines, characteristic of PD. Genes predicted to encode PD0928 (Zot) and a PD0986 (hemagglutinin) were also cloned into pBBR1MCS-5 and moved into EB92-1; both transformants also showed significantly increased symptoms on V. vinifera vines, characteristic of PD. Together, these results reveal that PD effectors include at least a lipase, two Zot-like toxins and a possibly redundant hemagglutinin, none of which are necessary for parasitic survival of X. fastidiosa populations in grapevines or elderberry. PMID:26218423

  17. Amblyseius swirskii: what made this predatory mite such a successful biocontrol agent?

    PubMed

    Calvo, F Javier; Knapp, Markus; van Houten, Yvonne M; Hoogerbrugge, Hans; Belda, José E

    2015-04-01

    The predatory mite Amblyseius swirskii quickly became one of the most successful biocontrol agents in protected cultivation after its introduction into the market in 2005 and is now released in more than 50 countries. There are several key factors contributing to this success: (1) it can control several major pests including the western flower thrips, Frankliniella occidentalis, the whiteflies Bemisia tabaci and Trialeurodes vaporariorum and the broad mite, Polyphagotarsonemus latus, simultaneously in vegetables and ornamental crops; (2) it can develop and reproduce feeding on non-prey food sources such as pollen, which allows populations of the predator to build up on plants before the pests are present and to persist in the crop during periods when prey is scarce or absent; and (3) it can be easily reared on factitious prey, which allows economic mass production. However, despite the fact that A. swirskii provides growers with a robust control method, external demands were initially a key factor in promoting the use of this predator, particularly in Spain. In 2006, when exports of fresh vegetables from Spain were stopped due to the presence of pesticide residues, growers were forced to look for alternatives to chemical control. This resulted in the massive adoption of biological control-based integrated pest management programmes based on the use of A. swirskii in sweet pepper. Biological control increased from 5 % in 2005, 1 year before A. swirskii was commercially released, to almost 100 % of a total 6,000 ha of protected sweet pepper in Spain within 3 years. Later, it was demonstrated that A. swirskii was equally effective in other crops and countries, resulting in extensive worldwide use of A. swirskii in greenhouses.

  18. What magnitude are observed non-target impacts from weed biocontrol?

    PubMed

    Suckling, David Maxwell; Sforza, René François Henri

    2014-01-01

    A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no

  19. Assessment of Virally Vectored Autoimmunity as a Biocontrol Strategy for Cane Toads

    PubMed Central

    Robinson, Anthony J.; Venables, Daryl; Voysey, Rhonda D.; Boyle, Donna G.; Shanmuganathan, Thayalini; Hardy, Christopher M.; Siddon, Nicole A.; Hyatt, Alex D.

    2011-01-01

    Background The cane toad, Bufo (Chaunus) marinus, is one of the most notorious vertebrate pests introduced into Australia over the last 200 years and, so far, efforts to identify a naturally occurring B. marinus-specific pathogen for use as a biological control agent have been unsuccessful. We explored an alternative approach that entailed genetically modifying a pathogen with broad host specificity so that it no longer caused disease, but carried a gene to disrupt the cane toad life cycle in a species specific manner. Methodology/Principal Findings The adult beta globin gene was selected as the model gene for proof of concept of autoimmunity as a biocontrol method for cane toads. A previous report showed injection of bullfrog tadpoles with adult beta globin resulted in an alteration in the form of beta globin expressed in metamorphs as well as reduced survival. In B. marinus we established for the first time that the switch from tadpole to adult globin exists. The effect of injecting B. marinus tadpoles with purified recombinant adult globin protein was then assessed using behavioural (swim speed in tadpoles and jump length in metamorphs), developmental (time to metamorphosis, weight and length at various developmental stages, protein profile of adult globin) and genetic (adult globin mRNA levels) measures. However, we were unable to detect any differences between treated and control animals. Further, globin delivery using Bohle iridovirus, an Australian ranavirus isolate belonging to the Iridovirus family, did not reduce the survival of metamorphs or alter the form of beta globin expressed in metamorphs. Conclusions/Significance While we were able to show for the first time that the switch from tadpole to adult globin does occur in B. marinus, we were not able to induce autoimmunity and disrupt metamorphosis. The short development time of B. marinus tadpoles may preclude this approach. PMID:21283623

  20. Three New Pierce's Disease Pathogenicity Effectors Identified Using Xylella fastidiosa Biocontrol Strain EB92-1.

    PubMed

    Zhang, Shujian; Chakrabarty, Pranjib K; Fleites, Laura A; Rayside, Patricia A; Hopkins, Donald L; Gabriel, Dean W

    2015-01-01

    Xylella fastidiosa (X. fastidiosa) infects a wide range of plant hosts and causes economically serious diseases, including Pierce's Disease (PD) of grapevines. X. fastidiosa biocontrol strain EB92-1 was isolated from elderberry and is infectious and persistent in grapevines but causes only very slight symptoms under ideal conditions. The draft genome of EB92-1 revealed that it appeared to be missing genes encoding 10 potential PD pathogenicity effectors found in Temecula1. Subsequent PCR and sequencing analyses confirmed that EB92-1 was missing the following predicted effectors found in Temecula1: two type II secreted enzymes, including a lipase (LipA; PD1703) and a serine protease (PD0956); two identical genes encoding proteins similar to Zonula occludens toxins (Zot; PD0915 and PD0928), and at least one relatively short, hemagglutinin-like protein (PD0986). Leaves of tobacco and citrus inoculated with cell-free, crude protein extracts of E. coli BL21(DE3) overexpressing PD1703 exhibited a hypersensitive response (HR) in less than 24 hours. When cloned into shuttle vector pBBR1MCS-5, PD1703 conferred strong secreted lipase activity to Xanthomonas citri, E. coli and X. fastidiosa EB92-1 in plate assays. EB92-1/PD1703 transformants also showed significantly increased disease symptoms on grapevines, characteristic of PD. Genes predicted to encode PD0928 (Zot) and a PD0986 (hemagglutinin) were also cloned into pBBR1MCS-5 and moved into EB92-1; both transformants also showed significantly increased symptoms on V. vinifera vines, characteristic of PD. Together, these results reveal that PD effectors include at least a lipase, two Zot-like toxins and a possibly redundant hemagglutinin, none of which are necessary for parasitic survival of X. fastidiosa populations in grapevines or elderberry.

  1. Biocontrol and Rapid Detection of Food-Borne Pathogens Using Bacteriophages and Endolysins

    PubMed Central

    Bai, Jaewoo; Kim, You-Tae; Ryu, Sangryeol; Lee, Ju-Hoon

    2016-01-01

    Bacteriophages have been suggested as natural food preservatives as well as rapid detection materials for food-borne pathogens in various foods. Since Listeria monocytogenes-targeting phage cocktail (ListShield) was approved for applications in foods, numerous phages have been screened and experimentally characterized for phage applications in foods. A single phage and phage cocktail treatments to various foods contaminated with food-borne pathogens including E. coli O157:H7, Salmonella enterica, Campylobacter jejuni, Listeria monocytogenes, Staphylococcus aureus, Cronobacter sakazakii, and Vibrio spp. revealed that they have great potential to control various food-borne pathogens and may be alternative for conventional food preservatives. In addition, phage-derived endolysins with high host specificity and host lysis activities may be preferred to food applications rather than phages. For rapid detection of food-borne pathogens, cell-wall binding domains (CBDs) from endolysins have been suggested due to their high host-specific binding. Fluorescence-tagged CBDs have been successfully evaluated and suggested to be alternative materials of expensive antibodies for various detection applications. Most recently, reporter phage systems have been developed and tested to confirm their usability and accuracy for specific detection. These systems revealed some advantages like rapid detection of only viable pathogenic cells without interference by food components in a very short reaction time, suggesting that these systems may be suitable for monitoring of pathogens in foods. Consequently, phage is the next-generation biocontrol agent as well as rapid detection tool to confirm and even identify the food-borne pathogens present in various foods. PMID:27092128

  2. Leuconostoc citreum MB1 as biocontrol agent of Listeria monocytogenes in milk.

    PubMed

    Pujato, Silvina A; del L Quiberoni, Andrea; Candioti, Mario C; Reinheimer, Jorge A; Guglielmotti, Daniela M

    2014-05-01

    Cell-free supernatant from Leuconostoc citreum MB1 revealed specific antilisterial activity. Preliminary studies demonstrated the proteinaceous, heat-stable, bacteriocin-like trait of the antimicrobial components present in the supernatant. Determination of the genes encoding bacteriocins by PCR and DNA sequencing led to amplification products highly homologous with leucocin A (found in diverse Leuconostoc species) and UviB (found in Leuc. citreum KM20) sequences. Additionally, antimicrobial activity of cell-free supernatant from Leuc. citreum MB1 was revealed by an inhibition halo of the SDS-PAGE gel subjected to a direct detection using Listeria monocytogenes as indicator strain. Different assays were carried out to assess the capacity of Leuc.citreum MB1 to control List. monocytogenes growth: (i) inactivation kinetics of the pathogen by antilisterial compounds present in concentrated cell-free supernatant from Leuc. citreum MB1, (ii) evaluation of optimal Leuc. citreum MB1 initial concentration to obtain maximum List. monocytogenes ATCC 15313 inhibition, and (iii) biocontrol of List. monocytogenes ATCC 15313 with Leuc. citreum MB1 during growth in milk at refrigeration temperature. According to our results, it is unquestionable that at least one bacteriocin is active in Leuc. citreum MB1, since important antilisterial activity was verified either in its cell-free supernatant or in co-culture experiments. Co-culture tests showed that ∼107 CFU/ml Leuc. citreum MB1 was the optimal initial concentration to obtain maximum pathogen inhibition. Moreover, Leuc. citreum MB1 was able to delay List. monocytogenes growth at refrigerated temperature.

  3. Biocontrol Characteristics of Bacillus Species in Suppressing Stem Rot of Grafted Cactus Caused by Bipolaris cactivora

    PubMed Central

    Bae, Sooil; Kim, Sang Gyu; Kim, Young Ho

    2013-01-01

    One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4) selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus. PMID:25288927

  4. Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast, Pichia anomala, for aflatoxin reduction.

    PubMed

    Hua, Sui Sheng T; Hernlem, Bradley J; Yokoyama, Wallace; Sarreal, Siov Bouy L

    2015-05-01

    Pichia anomala (Wickerhamomyces anomalus) WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of aflatoxin in the food chain. Maintaining the viability of biocontrol agents in formulated products is a great challenge for commercial applications. Four media, NYG, NYGS, NYGT and NYGST are described which support good growth of yeast cells and were tested as storage formulations. Post growth supplement of 5 % trehalose to NYGST resulted in 83 % viable yeast cells after 12 months in cold storage. Intracellular sorbitol and trehalose concentrations were determined by HPLC analysis at the beginning of the storage and at the end of 12 month. Correlation of cell viability to both trehalose and sorbitol suggested a synergistic effect. Bonferroni (Dunn) t Test, Tukey's Studentized Range (HSD) Test and Duncan's Multiple Range Test, all showed that yeast cell viability in samples with both intracellular trehalose and sorbitol were significantly higher than those with either or none, at a 95 % confidence level. DiBAC4(5) and CFDA-AM were used as the membrane integrity fluorescent stains to create a two-color vital staining scheme with red and green fluorescence, respectively. Yeast cells stored in formulations NYG and NYGS with no detectable trehalose, displayed mostly red fluorescence. Yeast cells in NYGST+5T showed mostly green fluorescence.

  5. The type III secretion system of biocontrol Pseudomonas fluorescens KD targets the phytopathogenic Chromista Pythium ultimum and promotes cucumber protection.

    PubMed

    Rezzonico, Fabio; Binder, Christian; Défago, Geneviève; Moënne-Loccoz, Yvan

    2005-09-01

    The type III secretion system (TTSS) is used by Proteobacteria for pathogenic or symbiotic interaction with plant and animal hosts. Recently, TTSS genes thought to originate from the phytopathogen Pseudomonas syringae were evidenced in Pseudomonas fluorescens KD, which protects cucumber from the oomycete Pythium ultimum (kingdom Chromista/Stramenopila). However, it is not known whether the TTSS contributes to plant protection by the bacterium and, if so, whether it targets the plant or the phytopathogen. Inactivation of TTSS gene hrcV following the insertion of an omega cassette strongly reduced the biocontrol activity of the pseudomonad against P. ultimum on cucumber when compared with the wild type, but had no effect on its root-colonization ability. Analysis of a plasmid-based transcriptional hrpJ'-inaZ reporter fusion revealed that expression in strain KD of the operon containing hrcV was strongly stimulated in vitro and in situ by the oomycete and not by the plant. In vitro, both strain KD and its hrcV mutant reduced the activity level of the pectinase polygalacturonase (a key pathogenicity factor) from P. ultimum, but the reduction was much stronger with the wild type. Together, these results show that the target range of bacterial TTSS is not restricted to plants and animals but also can include members of Chromista/Stramenopila, and suggest that virulence genes acquired horizontally from phytopathogenic bacteria were functionally recycled in biocontrol saprophytic Pseudomonas spp., resulting in enhanced plant protection by the latter.

  6. Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation

    PubMed Central

    Liu, Hongxia; Kolter, Roberto; Losick, Richard; Guo, Jian-hua

    2014-01-01

    Summary Bacillus subtilis and other Bacilli have long been used as biological control agents against plant bacterial diseases but the mechanisms by which the bacteria confer protection are not well understood. Our goal in this study was to isolate strains of B. subtilis that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. We screened a total of sixty isolates collected from various locations across China and obtained six strains that exhibited above 50% biocontrol efficacy on tomato plants against the plant pathogen Ralstonia solanacearum under greenhouse conditions. These wild strains were able to form robust biofilms both in defined medium and on tomato plant roots and exhibited strong antagonistic activities against various plant pathogens in plate assays. We show that plant protection by those strains depended on widely conserved genes required for biofilm formation, including regulatory genes and genes for matrix production. We provide evidence suggesting that matrix production is critical for bacterial colonization on plant root surfaces. Finally, we have established a model system for studies of B. subtilis-tomato plant interactions in protection against a plant pathogen. PMID:22934631

  7. Endospore production allows using spray-drying as a possible formulation system of the biocontrol agent Bacillus subtilis CPA-8.

    PubMed

    Yánez-Mendizabal, V; Viñas, I; Usall, J; Cañamás, T; Teixidó, N

    2012-04-01

    The role of endospore production by Bacillus subtilis CPA-8 on survival during spray-drying was investigated by comparison with a non-spore-forming biocontrol agent Pantoea agglomerans CPA-2. Endospore formation promoted heat resistance in CPA-8 depending on growth time (72 h cultures were more resistant than 24 h ones). The survival of CPA-8 and CPA-2 after spray-drying was determined after being grown in optimised media for 24 and 72 h. Spray-dried 72 h CPA-8 had the best survival (32%), while CPA-2 viability was less than 2%. CPA-8 survival directly related with its ability to produce endospores. Spray-dried CPA-8 reduced Monilinia fructicola conidia germination similarly to fresh cells, demonstrating that spray-drying did not adversely affect biocontrol efficacy. Endospore production thus improves CPA-8 resistance to spray-drying. These results can provide a reliable basis for optimising of the spray-drying formulation process for CPA-8 and other microorganisms.

  8. Phytic Acid Enhances Biocontrol Activity of Rhodotorula mucilaginosa against Penicillium expansum Contamination and Patulin Production in Apples.

    PubMed

    Yang, Qiya; Zhang, Hongyin; Zhang, Xiaoyun; Zheng, Xiangfeng; Qian, Jingya

    2015-01-01

    The effect of Rhodotorula mucilaginosa in combination with phytic acid (PA) on blue mold decay and patulin contamination of apples was investigated. Results from this study show that different concentrations of PA were effective in reducing the disease incidence of apples and that PA at concentration of 4 μmol/mL, decreased the incidence of blue mold decay in apples from 86.1 to 62.5%, and showed higher control efficacy compared to untreated, control fruit during storage at 20°C. However, R. mucilaginosa combined with PA (4 μmol/mL) showed better control efficacy of blue mold decay than R. mucilaginosa used as single treatment, the disease incidence was reduced to 62.5% and lesion diameter on apples was reduced to 16.59 cm. In in vitro experiments, the addition of PA enhanced the biocontrol effect of R. mucilaginosa against the growth of Penicillium expansum and reduced patulin level when compared with either R. mucilaginosa or PA used separately. R. mucilaginosa together with PA, improved the inhibition of patulin production in wounded apples, decreasing the content of patulin by 89.6% compared to the control, under experimental conditions. Both R. mucilaginosa and R. mucilaginosa in combination with PA degraded patulin in vitro. In conclusion, the appropriate combination of R. mucilaginosa and PA may provide an effective biocontrol method for reducing postharvest decay of apples.

  9. Effects of rhizobacteria Paenibacillus polymyxa APEC136 and Bacillus subtilis APEC170 on biocontrol of postharvest pathogens of apple fruits*

    PubMed Central

    Kim, Young Soo; Balaraju, Kotnala; Jeon, Yongho

    2016-01-01

    In this study, plant growth-promoting rhizobacteria (PGPR) were evaluated as potential biocontrol agents against postharvest pathogens of apple fruits. In vitro bioassays revealed that, out of 30 isolates screened, isolates APEC136 and APEC170 had the most significant inhibitory effects against the mycelial growth of several fungal pathogens. Analysis of 16S ribosomal RNA (rRNA) sequences identified the two effective isolates as Paenibacillus polymyxa and Bacillus subtilis, respectively. The two strains showed greater growth in brain-heart infusion broth than in other growth media. Treatment of harvested apples with suspensions of either strain reduced the symptoms of anthracnose disease caused by two fungal pathogens, Colletotrichum gloeosporioides and Colletotrichum acutatum, and white rot disease caused by Botryosphaeria dothidea. Increased productions of amylase and protease by APEC136, and increased productions of chitinase, amylase, and protease by APEC170 might have been responsible for inhibiting mycelial growth. The isolates caused a greater reduction in the growth of white rot than of anthracnose. These results indicate that the isolates APEC136 and APEC170 are promising agents for the biocontrol of anthracnose and white rot diseases in apples after harvest, and suggest that these isolates may be useful in controlling these diseases under field conditions. PMID:27921398

  10. Antifungal modes of action of Saccharomyces and other biocontrol yeasts against fungi isolated from sour and grey rots.

    PubMed

    Nally, M C; Pesce, V M; Maturano, Y P; Rodriguez Assaf, L A; Toro, M E; Castellanos de Figueroa, L I; Vazquez, F

    2015-07-02

    The aim of this study was to determine the putative modes of action of 59 viticultural yeasts (31 Saccharomyces and 28 non-Saccharomyces) that inhibited fungi isolated from sour and grey rot in grapes. Inhibition of fungal mycelial growth by metabolites, enzyme activities (laminarinases, chitinases), antifungal volatiles, competition for nutrients (siderophores, Niche Overlap Index (NOI)), inhibition of fungal spore germination and decreased germinal tube length and induction of resistance were assayed. Biofungicide yeasts were classified into "antifungal patterns", according to their mechanisms of action. Thirty isolates presented at least two of the mechanisms assayed. We propose that inhibition of fungal mycelial growth by metabolites, laminarinases, competition for nutrients, inhibition of fungal spore germination and decreased germinal tube length, and antifungal volatiles by Saccharomyces and non-Saccharomyces viticultural yeasts is used as putative biocontrol mechanisms against phytopathogenic fungi. Twenty-four different antifungal patterns were identified. Siderophore production (N)and a combination of siderophore production and NOI>0.92 (M)were the most frequent antifungal patterns observed in the biofungicide yeasts assayed. Elucidation of these mechanisms could be useful for optimization of an inoculum formulation, resulting in a more consistent control of grey and sour rot with Saccharomyces and non-Saccharomyces biocontrol yeasts.

  11. Statistical test for tolerability of effects of an antifungal biocontrol strain on fungal communities in three arable soils.

    PubMed

    Antweiler, Kai; Schreiter, Susanne; Keilwagen, Jens; Baldrian, Petr; Kropf, Siegfried; Smalla, Kornelia; Grosch, Rita; Heuer, Holger

    2017-03-01

    A statistical method was developed to test for equivalence of microbial communities analysed by next-generation sequencing of amplicons. The test uses Bray-Curtis distances between the microbial community structures and is based on a two-sample jackknife procedure. This approach was applied to investigate putative effects of the antifungal biocontrol strain RU47 on fungal communities in three arable soils which were analysed by high-throughput ITS amplicon sequencing. Two contrasting workflows to produce abundance tables of operational taxonomic units from sequence data were applied. For both, the developed test indicated highly significant equivalence of the fungal communities with or without previous exposure to RU47 for all soil types, with reference to fungal community differences in conjunction with field site or cropping history. However, minor effects of RU47 on fungal communities were statistically significant using highly sensitive multivariate tests. Nearly all fungal taxa responding to RU47 increased in relative abundance indicating the absence of ecotoxicological effects. Use of the developed equivalence test is not restricted to evaluate effects on soil microbial communities by inoculants for biocontrol, bioremediation or other purposes, but could also be applied for biosafety assessment of compounds like pesticides, or genetically engineered plants.

  12. Short-chain fatty acids and poly-beta-hydroxyalkanoates: (New) Biocontrol agents for a sustainable animal production.

    PubMed

    Defoirdt, Tom; Boon, Nico; Sorgeloos, Patrick; Verstraete, Willy; Bossier, Peter

    2009-01-01

    Because of the risk of antibiotic resistance development, there is a growing awareness that antibiotics should be used more carefully in animal production. However, a decreased use of antibiotics could result in a higher frequency of pathogenic bacteria, which in its turn could lead to a higher incidence of infections. Short-chain fatty acids (SCFAs) have long been known to exhibit bacteriostatic activity. These compounds also specifically downregulate virulence factor expression and positively influence the gastrointestinal health of the host. As a consequence, there is currently considerable interest in SCFAs as biocontrol agents in animal production. Polyhydroxyalkanoates (PHAs) are polymers of beta-hydroxy short-chain fatty acids. Currently, PHAs are applied as replacements for synthetic polymers. These biopolymers can be depolymerised by many different microorganisms that produce extracellular PHA depolymerases. Interestingly, different studies provided some evidence that PHAs can also be degraded upon passage through the gastrointestinal tract of animals and consequently, adding these compounds to the feed might result in biocontrol effects similar to those described for SCFAs.

  13. Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent

    PubMed Central

    Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

    2016-01-01

    Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China’s Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent. PMID:27832162

  14. Effects of rhizobacteria Paenibacillus polymyxa APEC136 and >Bacillus subtilis APEC170 on biocontrol of postharvest pathogens of apple fruits.

    PubMed

    Kim, Young Soo; Balaraju, Kotnala; Jeon, Yongho

    In this study, plant growth-promoting rhizobacteria (PGPR) were evaluated as potential biocontrol agents against postharvest pathogens of apple fruits. In vitro bioassays revealed that, out of 30 isolates screened, isolates APEC136 and APEC170 had the most significant inhibitory effects against the mycelial growth of several fungal pathogens. Analysis of 16S ribosomal RNA (rRNA) sequences identified the two effective isolates as Paenibacillus polymyxa and Bacillus subtilis, respectively. The two strains showed greater growth in brain-heart infusion broth than in other growth media. Treatment of harvested apples with suspensions of either strain reduced the symptoms of anthracnose disease caused by two fungal pathogens, Colletotrichum gloeosporioides and Colletotrichum acutatum, and white rot disease caused by Botryosphaeria dothidea. Increased productions of amylase and protease by APEC136, and increased productions of chitinase, amylase, and protease by APEC170 might have been responsible for inhibiting mycelial growth. The isolates caused a greater reduction in the growth of white rot than of anthracnose. These results indicate that the isolates APEC136 and APEC170 are promising agents for the biocontrol of anthracnose and white rot diseases in apples after harvest, and suggest that these isolates may be useful in controlling these diseases under field conditions.

  15. Wheat seeds harbour bacterial endophytes with potential as plant growth promoters and biocontrol agents of Fusarium graminearum.

    PubMed

    Díaz Herrera, Silvana; Grossi, Cecilia; Zawoznik, Myriam; Groppa, María Daniela

    2016-01-01

    The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community.

  16. Rhizocompetence and antagonistic activity towards genetically diverse Ralstonia solanacearum strains--an improved strategy for selecting biocontrol agents.

    PubMed

    Xue, Qing-Yun; Ding, Guo-Chun; Li, Shi-Mo; Yang, Yang; Lan, Cheng-Zhong; Guo, Jian-Hua; Smalla, Kornelia

    2013-02-01

    Bacterial wilt caused by Ralstonia solanacearum is a serious threat for agricultural production in China. Eight soil bacterial isolates with activity against R. solanacearum TM15 (biovar 3) were tested in this study for their in vitro activity towards ten genetically diverse R. solanacearum isolates from China. The results indicated that each antagonist showed remarkable differences in its ability to in vitro antagonize the ten different R. solanacearum strains. Strain XY21 (based on 16S rRNA gene sequencing affiliated to Serratia) was selected for further studies based on its in vitro antagonistic activity and its excellent rhizocompetence on tomato plants. Under greenhouse conditions XY21 mediated biocontrol of tomato wilt caused by seven different R. solanacearum strains ranged from 19 to 70 %. The establishment of XY21 and its effects on the bacterial community in the tomato rhizosphere were monitored by denaturing gradient gel electrophoresis of 16S rRNA gene fragments PCR-amplified from total community DNA. A positive correlation of the in vitro antagonistic activities of XY21 and the actual biocontrol efficacies towards seven genetically different R. solanacearum strains was found and further confirmed by the efficacy of XY21 in controlling bacterial wilt under field conditions.

  17. Effect of bacterial antagonists on lettuce: active biocontrol of Rhizoctonia solani and negligible, short-term effects on nontarget microorganisms.

    PubMed

    Scherwinski, Katja; Grosch, Rita; Berg, Gabriele

    2008-04-01

    The aim of this study was to assess the biocontrol efficacy against Rhizoctonia solani of three bacterial antagonists introduced into naturally Rhizoctonia-infested lettuce fields and to analyse their impact on the indigenous plant-associated bacteria and fungi. Lettuce seedlings were inoculated with bacterial suspensions of two endophytic strains, Serratia plymuthica 3Re4-18 and Pseudomonas trivialis 3Re2-7, and with the rhizobacterium Pseudomonas fluorescens L13-6-12 7 days before and 5 days after planting in the field. Similar statistically significant biocontrol effects were observed for all applied bacterial antagonists compared with the uninoculated control. Single-strand conformation polymorphism analysis of 16S rRNA gene or ITS1 fragments revealed a highly diverse rhizosphere and a less diverse endophytic microbial community for lettuce. Representatives of several bacterial (Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Bacteriodetes), fungal (Ascomycetes, Basidiomycetes) and protist (Oomycetes) groups were present inside or on lettuce plants. Surprisingly, given that lettuce is a vegetable that is eaten raw, species of genera such as Flavobacterium, Burkholderia, Staphylococcus, Cladosporium and Aspergillus, which contain potentially human pathogenic strains, were identified. Analysis of the indigenous bacterial and endophytic fungal populations revealed only negligible, short-term effects resulting from the bacterial treatments, and that they were more influenced by field site, plant growth stage and microenvironment.

  18. Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases.

    PubMed

    Calvo, H; Marco, P; Blanco, D; Oria, R; Venturini, M E

    2017-05-01

    The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 10(7) CFU mL(-1) as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products.

  19. Novel approach of using a cocktail of designed bacteriophages against gut pathogenic E. coli for bacterial load biocontrol

    PubMed Central

    2014-01-01

    Background This study was conducted to explore new approaches of animal biocontrol via biological control feed. Method White rats were subjected to 140 highly lytic designed phages specific against E. coli. Phages were fed via drinking water, oral injection, and vegetable capsules. Phage feeding was applied by 24 h feeding with 11d monitoring and 20d phage feeding and monitoring. Group of rats received external pathogenic E. coli and another group did not, namely groups A and B. Results Phage feeding for 20d via vegetable capsules yielded the highest reduction of fecal E. coli, 3.02 and 4.62 log, in rats group A and B respectively. Second best, feeding for 20d via drinking water with alkali yielded 2.78 and 4.08 log in rats groups A and B respectively. The peak reduction in E. coli output was 5–10 d after phage feeding. Phage control declined after 10th day of feeding. Conclusions The use of cocktail of designed phages succeeded in suppressing flora or external E. coli. The phage feed biocontrol is efficient in controlling E. coli at the pre-harvest period, precisely at the 6th-8th day of phage feeding when the lowest E. coli output found. PMID:25062829

  20. Evidence for biotrophic lifestyle and biocontrol potential of dark septate endophyte Harpophora oryzae to rice blast disease.

    PubMed

    Su, Zhen-Zhu; Mao, Li-Juan; Li, Na; Feng, Xiao-Xiao; Yuan, Zhi-Lin; Wang, Li-Wei; Lin, Fu-Cheng; Zhang, Chu-Long

    2013-01-01

    The mutualism pattern of the dark septate endophyte (DSE) Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA) signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS) and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast.

  1. Killer activity of Saccharomyces cerevisiae strains: partial characterization and strategies to improve the biocontrol efficacy in winemaking.

    PubMed

    de Ullivarri, Miguel Fernández; Mendoza, Lucía M; Raya, Raúl R

    2014-11-01

    Killer yeasts are considered potential biocontrol agents to avoid or reduce wine spoilage by undesirable species. In this study two Saccharomyces cerevisiae strains (Cf8 and M12) producing killer toxin were partially characterized and new strategies to improve their activity in winemaking were evaluated. Killer toxins were characterized by biochemical tests and growth inhibition of sensitive yeasts. Also genes encoding killer toxin were detected in the chromosomes of both strains by PCR. Both toxins showed optimal activity and production at conditions used during the wine-making process (pH 3.5 and temperatures of 15-25 °C). In addition, production of both toxins was higher when a nitrogen source was added. To improve killer activity different strategies of inoculation were studied, with the sequential inoculation of killer strains the best combination to control the growth of undesired yeasts. Sequential inoculation of Cf8-M12 showed a 45 % increase of killer activity on sensitive S. cerevisiae and spoilage yeasts. In the presence of ethanol (5-12 %) and SO2 (50 mg/L) the killer activity of both toxins was increased, especially for toxin Cf8. Characteristics of both killer strains support their future application as starter cultures and biocontrol agents to produce wines of controlled quality.

  2. Phytic Acid Enhances Biocontrol Activity of Rhodotorula mucilaginosa against Penicillium expansum Contamination and Patulin Production in Apples

    PubMed Central

    Yang, Qiya; Zhang, Hongyin; Zhang, Xiaoyun; Zheng, Xiangfeng; Qian, Jingya

    2015-01-01

    The effect of Rhodotorula mucilaginosa in combination with phytic acid (PA) on blue mold decay and patulin contamination of apples was investigated. Results from this study show that different concentrations of PA were effective in reducing the disease incidence of apples and that PA at concentration of 4 μmol/mL, decreased the incidence of blue mold decay in apples from 86.1 to 62.5%, and showed higher control efficacy compared to untreated, control fruit during storage at 20°C. However, R. mucilaginosa combined with PA (4 μmol/mL) showed better control efficacy of blue mold decay than R. mucilaginosa used as single treatment, the disease incidence was reduced to 62.5% and lesion diameter on apples was reduced to 16.59 cm. In in vitro experiments, the addition of PA enhanced the biocontrol effect of R. mucilaginosa against the growth of Penicillium expansum and reduced patulin level when compared with either R. mucilaginosa or PA used separately. R. mucilaginosa together with PA, improved the inhibition of patulin production in wounded apples, decreasing the content of patulin by 89.6% compared to the control, under experimental conditions. Both R. mucilaginosa and R. mucilaginosa in combination with PA degraded patulin in vitro. In conclusion, the appropriate combination of R. mucilaginosa and PA may provide an effective biocontrol method for reducing postharvest decay of apples. PMID:26635764

  3. Evaluation of yeasts from Tibetan fermented products as agents for biocontrol of blue mold of Nashi pear fruits*

    PubMed Central

    Hu, Hao; Xu, Yang; Lu, Huang-ping; Xiao, Rui; Zheng, Xiao-dong; Yu, Ting

    2015-01-01

    A total of 20 strains of yeast isolated from Tibetan fermented products were screened for antagonism against blue mold of pear caused by Penicillium expansum. Six isolates that inhibited incidence of postharvest decay by 35% or more were selected for further screening. Among them, the most effective was Rhodotorula mucilaginosa. The results showed that washed cell suspensions of R. mucilaginosa yielded better antagonistic efficacy than unwashed cell-culture mixtures, cell-free culture filtrates, and autoclaved cell cultures. Biocontrol activity improved with increasing concentrations of incubated cells. The best concentration was 1×108 cells/ml, at which the incidence of decay was only 16.7% after 6 d of incubation. The germination of conidia of P. expansum in vitro was significantly inhibited by both washed cell-suspensions and unwashed cell-culture mixtures. Rapid colonization by yeast at different concentrations showed a relationship between yeast-cell concentration and biocontrol activity. Although the titratable acidity of pear fruits increased after treatment, R. mucilaginosa did not affect the total soluble solids or ascorbic acid content. This is the first study to report that the yeast R. mucilaginosa from Tibet Autonomous Region of China may have potential as an antagonist to control the postharvest decay of pear fruits. PMID:25845361

  4. Genetic diversity and biocontrol potential of fluorescent pseudomonads producing phloroglucinols and hydrogen cyanide from Swiss soils naturally suppressive or conducive to Thielaviopsis basicola-mediated black root rot of tobacco.

    PubMed

    Ramette, Alban; Moënne-Loccoz, Yvan; Défago, Geneviève

    2006-03-01

    Pseudomonas populations producing the biocontrol compounds 2,4-diacetylphloroglucinol (Phl) and hydrogen cyanide (HCN) were found in the rhizosphere of tobacco both in Swiss soils suppressive to Thielaviopsis basicola and in their conducive counterparts. In this study, a collection of Phl+ HCN+Pseudomonas isolates from two suppressive and two conducive soils were used to assess whether suppressiveness could be linked to soil-specific properties of individual pseudomonads. The isolates were compared based on restriction analysis of the biocontrol genes phlD and hcnBC, enterobacterial repetitive intergenic consensus (ERIC)-PCR profiling and their biocontrol ability. Restriction analyses of phlD and hcnBC yielded very concordant relationships between the strains, and suggested significant population differentiation occurring at the soil level, regardless of soil suppressiveness status. This was corroborated by high strain diversity (ERIC-PCR) within each of the four soils and among isolates harboring the same phlD or hcnBC alleles. No correlation was found between the origin of the isolates and their biocontrol activity in vitro and in planta. Significant differences in T. basicola inhibition were however evidenced between the isolates when they were grouped according to their biocontrol alleles. Moreover, two main Pseudomonas lineages differing by the capacity to produce pyoluteorin were evidenced in the collection. Thus, Phl+ HCN+ pseudomonads from suppressive soils were not markedly different from those from nearby conducive soils. Therefore, as far as biocontrol pseudomonads are concerned, this work yields the hypothesis that the suppressiveness of Swiss soils may rely on the differential effects of environmental factors on the expression of key biocontrol genes in pseudomonads rather than differences in population structure of biocontrol Pseudomonas subcommunities or the biocontrol potential of individual Phl+ HCN+ pseudomonad strains.

  5. Draft Genome Sequences of Pseudomonas fluorescens Strains SF39a and SF4c, Potential Plant Growth Promotion and Biocontrol Agents

    PubMed Central

    Ly, Lindsey K.; Underwood, Grace E.; McCully, Lucy M.; Bitzer, Adam S.; Godino, Agustina; Bucci, Vanni; Brigham, Christopher J.; Príncipe, Analía; Fischer, Sonia E.

    2015-01-01

    Pseudomonas fluorescens SF4c and SF39a, strains isolated from wheat rhizosphere, have potential applications in plant growth promotion and biocontrol of fungal diseases of crop plants. We report the draft genome sequences of SF4c and SF39a with estimated sizes of 6.5 Mb and 5.9 Mb, respectively. PMID:25814613

  6. Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus x domestica)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Psychrotrophic yeasts isolated from soils collected in Antarctica and selected by its capacity of growing in apple juice at low temperatures were evaluated for their potential as biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, ...

  7. Regulation of aflatoxin biosynthesis and branched-chain amino acids metabolism in Aspergillus flavus by 2-phenylethanol reveal biocontrol mechanism of Pichia anomala

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pichia anomala WRL-076 is a biocontrol yeast which has been shown to inhibit growth and aflatoxin production of A. flavus. Using the SPME-GC/MS analysis we identified that the volatile, 2-phenylethanol (2-PE) produced by this yeast and demonstrated that the compound inhibited aflatoxin production. W...

  8. The phosphotransferase system gene ptsI in the endophytic bacterium Bacillus cereus is required for biofilm formation, colonization, and biocontrol against wheat sharp eyespot.

    PubMed

    Xu, Yu-Bin; Chen, Mai; Zhang, Ying; Wang, Miao; Wang, Ying; Huang, Qiu-bin; Wang, Xue; Wang, Gang

    2014-05-01

    Natural resistance of wheat plants to wheat sharp eyespot is inadequate, and new strategies for controlling the disease are required. Biological control is an alternative and attractive way of reducing the use of chemicals in agriculture. In this study, we investigated the biocontrol properties of endophytic bacterium Bacillus cereus strain 0-9, which was isolated from the root systems of healthy wheat varieties. The phosphotransferase system is a major regulator of carbohydrate metabolism in bacteria. Enzyme I is one of the protein components of this system. Specific disruption and complementation of the enzyme I-coding gene ptsI from B. cereus was achieved through homologous recombination. Disruption of ptsI in B. cereus caused a 70% reduction in biofilm formation, a 30.4% decrease in biocontrol efficacy, and a 1000-fold reduction in colonization. The growth of ΔptsI mutant strain on G-tris synthetic medium containing glucose as the exclusive carbon source was also reduced. Wild-type properties could be restored to the ΔptsI mutant strain by ptsI complementation. These results suggested that ptsI may be one of the key genes involved in biofilm formation, colonization, and biocontrol of B. cereus and that B. cereus wild-type strain 0-9 may be an ideal biocontrol agent for controlling wheat sharp eyespot.

  9. Selection of a biocontrol agent based on a potential mechanism of action: degradation of nicotinic acid, a growth factor essential for Erwinia amylovora.

    PubMed

    Paternoster, Thomas; Défago, Geneviève; Duffy, Brion; Gessler, Cesare; Pertot, Ilaria

    2010-12-01

    This work describes a medium-based screening method for selecting microbial biocontrol agents against Erwinia amylovora based on the degradation of a specific growth factor. Erwinia amylovora, the causal agent of the devastating fire blight disease, requires nicotinic acid or nicotinamide as an essential growth factor. Potential biocontrol agents are either selected for antimicrobial production in plate or directly on immature pears or apple blossoms. In this work, we have attempted to streamline the selection of a new potential biocontrol agent with a lower risk of non-target effects by isolation based on the ability to degrade nicotinic acid in vitro, using therefore few plant materials. A total of 735 bacteria and 1237 yeast were isolated from apple blossoms and pre-screened for nicotinic acid-degradation. Pseudomonas rhizosphaerae strain JAN was able to degrade both nicotinic acid and nicotinamide. Mutants deficient in this ability were constructed. JAN, but not the mutants, controlled E. amylovora on pear slices. On detached apple blossoms, JAN colonized apple hypanthia and strongly suppressed E. amylovora growth. Under greenhouse conditions, JAN was more effective in controlling blossom blight than P. fluorescens A506, a commercial biocontrol agent of fire blight unable to degrade nicotinic acid and nicotinamide.

  10. Role of 2-hexyl, 5-propyl resorcinol production by Pseudomonas chlororaphis PCL1606 in the multitrophic interactions in the avocado rhizosphere during the biocontrol process.

    PubMed

    Calderón, Claudia E; de Vicente, Antonio; Cazorla, Francisco M

    2014-07-01

    Different bacterial traits can contribute to the biocontrol of soilborne phytopathogenic fungus. Among others, (1) antagonism, (2) competition for nutrients and niches, (3) induction of systemic resistance of the plants and (4) predation and parasitism are the most studied. Pseudomonas chlororaphis PCL1606 is an antagonistic rhizobacterium that produces the antifungal metabolite 2-hexyl, 5-propyl resorcinol (HPR). This bacterium can biologically control the avocado white root rot caused by Rosellinia necatrix. Confocal laser scanning microscopy of the avocado rhizosphere revealed that this biocontrol bacterium and the fungal pathogen compete for the same niche and presumably also for root exudate nutrients. The use of derivative mutants in the geners related to HPR biosynthesis (dar genes) revealed that the lack of HPR production by P. chlororaphis PCL1606 negatively influences the bacterial colonisation of the avocado root surface. Microscopical analysis showed that P. chlororaphis PCL1606 closely interacts and colonises the fungal hyphae, which may represent a novel biocontrol mechanism in this pseudomonad. Additionally, the presence of HPR-producing biocontrol bacteria negatively affects the ability of the fungi to infect the avocado root. HPR production negatively affects hyphal growth, leading to alterations in the R. necatrix physiology visible under microscopy, including the curling, vacuolisation and branching of hyphae, which presumably affects the colonisation and infection abilities of the fungus. This study provides the first report of multitrophic interactions in the avocado rhizosphere, advancing our understanding of the role of HPR production in those interactions.

  11. Construction of a Streptomyces lydicus A01 transformant with a chit42 gene from Trichoderma harzianum P1 and evaluation of its biocontrol activity against Botrytis cinerea.

    PubMed

    Wu, Qiong; Bai, Linquan; Liu, Weicheng; Li, Yingying; Lu, Caige; Li, Yaqian; Fu, Kehe; Yu, Chuanjin; Chen, Jie

    2013-04-01

    Streptomyces lydicus A01 and Trichoderma harzianum P1 are potential biocontrol agents of fungal diseases in plants. S. lydicus A01 produces natamycin to bind the ergosterol of the fungal cell membrane and inhibits the growth of Botrytis cinerea. T. harzianum P1, on the other hand, features high chitinase activity and decomposes the chitin in the cell wall of B. cinerea. To obtain the synergistic biocontrol effects of chitinase and natamycin on Botrytis cinerea, this study transformed the chit42 gene from T. harzianum P1 to S. lydicus A01. The conjugal transformant (CT) of S. lydicus A01 with the chit42 gene was detected using polymerase chain reaction (PCR). Associated chitinase activity and natamycin production were examined using the 3, 5-dinitrosalicylic acid (DNS) method and ultraviolet spectrophotometry, respectively. The S. lydicus A01-chit42 CT showed substantially higher chitinase activity and natamycin production than its wild type strain (WT). Consequently, the biocontrol effects of S. lydicus A01-chit42 CT on B. cinerea, including inhibition to spore germination and mycelial growth, were highly improved compared with those of the WT. Our research indicates that the biocontrol effect of Streptomyces can be highly improved by transforming the exogenous resistance gene, i.e. chit42 from Trichoderma, which not only enhances the production of antibiotics, but also provides a supplementary function by degrading the cell walls of the pathogens.

  12. Superoxide anion and hydrogen peroxide in the yeast antagonist-fruit interaction: a new role for reactive oxygen species in postharvest biocontrol?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of reactive oxygen species (ROS) in plant defense responses against certain pathogens is well documented. There is some evidence that microbial biocontrol agents also induce a transient production of ROS in a host plant which triggers local and systemic defense responses to pathogens....

  13. Response of tomato wilt pathogen Ralstonia solanacearum to the volatile organic compounds produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9

    PubMed Central

    Raza, Waseem; Ling, Ning; Yang, Liudong; Huang, Qiwei; Shen, Qirong

    2016-01-01

    It is important to study the response of plant pathogens to the antibiosis traits of biocontrol microbes to design the efficient biocontrol strategies. In this study, we evaluated the role of volatile organic compounds (VOCs) produced by a biocontrol strain Bacillus amyloliquefaciens SQR-9 on the growth and virulence traits of tomato wilt pathogen Ralstonia solanacearum (RS). The VOCs of SQR-9 significantly inhibited the growth of RS on agar medium and in soil. In addition, the VOCs significantly inhibited the motility traits, production of antioxidant enzymes and exopolysaccharides, biofilm formation and tomato root colonization by RS. The strain SQR-9 produced 22 VOCs, but only nine VOCs showed 1–11% antibacterial activity against RS in their corresponding amounts; however, the consortium of all VOCs showed 70% growth inhibition of RS. The proteomics analysis showed that the VOCs of SQR-9 downregulated RS proteins related to the antioxidant activity, virulence, carbohydrate and amino acid metabolism, protein folding and translation, while the proteins involved in the ABC transporter system, amino acid synthesis, detoxification of aldehydes and ketones, methylation, protein translation and folding, and energy transfer were upregulated. This study describes the significance and effectiveness of VOCs produced by a biocontrol strain against tomato wilt pathogen. PMID:27103342

  14. What Magnitude Are Observed Non-Target Impacts from Weed Biocontrol?

    PubMed Central

    Suckling, David Maxwell; Sforza, René François Henri

    2014-01-01

    A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no

  15. Transcriptional reprogramming underpins enhanced plant growth promotion by the biocontrol fungus Trichoderma hamatum GD12 during antagonistic interactions with Sclerotinia sclerotiorum in soil.

    PubMed

    Shaw, Sophie; Le Cocq, Kate; Paszkiewicz, Konrad; Moore, Karen; Winsbury, Rebecca; de Torres Zabala, Marta; Studholme, David J; Salmon, Deborah; Thornton, Christopher R; Grant, Murray R

    2016-12-01

    The free-living soil fungus Trichoderma hamatum strain GD12 is notable amongst Trichoderma strains in both controlling plant diseases and stimulating plant growth, a property enhanced during its antagonistic interactions with pathogens in soil. These attributes, alongside its markedly expanded genome and proteome compared with other biocontrol and plant growth-promoting Trichoderma strains, imply a rich potential for sustainable alternatives to synthetic pesticides and fertilizers for the control of plant disease and for increasing yields. The purpose of this study was to investigate the transcriptional responses of GD12 underpinning its biocontrol and plant growth promotion capabilities during antagonistic interactions with the pathogen Sclerotinia sclerotiorum in soil. Using an extensive mRNA-seq study capturing different time points during the pathogen-antagonist interaction in soil, we show that dynamic and biphasic signatures in the GD12 transcriptome underpin its biocontrol and plant (lettuce) growth-promoting activities. Functional predictions of differentially expressed genes demonstrate the enrichment of transcripts encoding proteins involved in transportation and oxidation-reduction reactions during both processes and an over-representation of siderophores. We identify a biphasic response during biocontrol characterized by a significant induction of transcripts encoding small-secreted cysteine-rich proteins, secondary metabolite-producing gene clusters and genes unique to GD12. These data support the hypothesis that Sclerotinia biocontrol is mediated by the synthesis and secretion of antifungal compounds and that GD12's unique reservoir of uncharacterized genes is actively recruited during the effective biological control of a plurivorous plant pathogen.

  16. Complete genome sequence of Bacillus velezensis M75, a biocontrol agent against fungal plant pathogens, isolated from cotton waste.

    PubMed

    Kim, Sang Yoon; Lee, Sang Yeob; Weon, Hang-Yeon; Sang, Mee Kyung; Song, Jaekyeong

    2017-01-10

    Bacillus species have been widely used as biological control agents in agricultural fields due to their ability to suppress plant pathogens. Bacillus velezensis M75 was isolated from cotton waste used for mushroom cultivation in Korea, and was found to be antagonistic to fungal plant pathogens. Here, we report the complete genome sequence of the M75 strain, which has a 4,007,450-bp single circular chromosome with 3921 genes and a G+C content of 46.60%. The genome contained operons encoding various non-ribosomal peptide synthetases and polyketide synthases, which are responsible for the biosynthesis of secondary metabolites. Our results will provide a better understanding of the genome of B. velezensis strains for their application as biocontrol agents against fungal plant pathogens in agricultural fields.

  17. Antagonistic and Biocontrol Potential of Trichoderma asperellum ZJSX5003 Against the Maize Stalk Rot Pathogen Fusarium graminearum.

    PubMed

    Li, Yaqian; Sun, Ruiyan; Yu, Jia; Saravanakumar, Kandasamy; Chen, Jie

    2016-09-01

    The efficacy of seven strains of Trichoderma asperellum collected from the fields in Southern China was assessed against Fusarium graminearum (FG) the causal agent of corn stalk rot of maize were in vitro for their antagonistic properties followed by statistical model of principal compound analysis to identify the beneficial antagonist T. asperellum strain. The key factors of antagonist activity were attributed to a total of 13 factors including cell wall degrading enzymes (chitnase, protease and β-glucanases), secondary metabolites and peptaibols and these were analyzed from eight strains of Trichoderma. A linear regression model demonstrated that interaction of enzymes and secondary metabolites of T. asperellum strain ZJSX5003 enhanced the antagonist activity against FG. Further, this strain displayed a disease reduction of 71 % in maize plants inoculated with FG compared to negative control. Pointing out that the T. asperellum strain ZJSX5003 is a potential source for the development of a biocontrol agent against corn stalk rot.

  18. Biocontrol of tomato plant diseases caused by Fusarium solani using a new isolated Aspergillus tubingensis CTM 507 glucose oxidase.

    PubMed

    Kriaa, Mouna; Hammami, Inès; Sahnoun, Mouna; Azebou, Manel Cheffi; Triki, Mohamed Ali; Kammoun, Radhouane

    2015-10-01

    The present study focuses on the potential of glucose oxidase (GOD) as a promising biocontrol agent for fungal plant pathogens. In fact, a new GOD producing fungus was isolated and identified as an Aspergillus tubingensis. GOD (125 AU) has been found to inhibit Fusarium solani growth and spore production. Indeed, GOD caused the reduction of spores, the formation of chlamydospores, the induction of mycelial cords and the vacuolization of mycelium. In vivo assays, GOD acted as a curative treatment capable of protecting the tomato plants against F. solani diseases. In fact, the incidence was null in the curative treatment with GOD and it is around 45% for the preventive treatment. The optimization of media composition and culture conditions led to a 2.6-fold enhancement in enzyme activity, reaching 81.48U/mL. This study has demonstrated that GOD is a potent antifungal agent that could be used as a new biofungicide to protect plants from diseases.

  19. Yeasts from native Brazilian Cerrado plants: Occurrence, diversity and use in the biocontrol of citrus green mould.

    PubMed

    Sperandio, Eugenio Miranda; do Vale, Helson Mario Martins; Moreira, Geisianny Augusta Monteiro

    2015-11-01

    Yeasts are some of the most important postharvest biocontrol agents. Postharvest oranges frequently deteriorate due to green mould (Penicillium digitatum), which causes significant losses. The aims of this study were to determine the composition and diversity of yeasts on plants of the Brazilian Cerrado and to explore their potential for inhibiting citrus green mould. Leaves and fruit of Byrsonima crassifolia and Eugenia dysenterica were collected from Cerrado conservation areas, and thirty-five yeasts were isolated and identified by sequencing the D1-D2 domain of the rDNA large subunit (26S). The isolates represented the Aureobasidium, Meyerozyma, Candida, and Pichia genera. Three isolates identified as Aureobasidium pullulans exhibited potential for the control of P. digitatum in both in vitro and in vivo tests; these isolates reduced the incidence of disease and increased the storage time of fruit. Aureobasidium. pullulans has immense potential for the biological control of filamentous fungi.

  20. Quaternary chitosan oligomers enhance resistance and biocontrol efficacy of Rhodosporidium paludigenum to green mold in satsuma orange.

    PubMed

    Lu, Laifeng; Liu, Yan; Yang, Jiali; Azat, Ramila; Yu, Ting; Zheng, Xiaodong

    2014-11-26

    This study investigated the capacity of chitosan oligomers (COS), applied before harvest singly or in combination with antagonists, in controlling postharvest green mold caused by Penicillium digitatum in satsuma orange. Oranges treated with COS or Rhodosporidium paludigenum were observed having a delay in onset and progression of disease symptoms relative to wounded controls. Preharvest application of COS at different concentrations achieved similar biocontrol efficiency rates in green mold control after 4 days storage. However, the combination of pre-COS (1%, w/v) and R. paludigenum showed a more effective decay control than any other treatments. COS (1%, w/v) alone did not negatively affect R. paludigenum growth in wounds, but severely inhibited P. digitatum spore germination than lower dose treatments in vitro. The expression levels of the defense-related genes chitinase and phenylalanine ammonia lyase increased with decreased disease symptoms. Moreover, this phenomenon was more prominent in the integrated treatments than in the individual ones.

  1. Effect of pyrimethanil on Cryptococcus laurentii, Rhodosporidium paludigenum, and Rhodotorula glutinis biocontrol of Penicillium expansum infection in pear fruit.

    PubMed

    Yu, Chen; Zhou, Tao; Sheng, Kuang; Zeng, Lizhen; Ye, Changzhou; Yu, Ting; Zheng, Xiaodong

    2013-06-17

    The effect of biocontrol yeasts and pyrimethanil at low concentration on inhibition of blue mold rot caused by Penicillium expansum in pear fruit was investigated. Pyrimethanil at low concentration (40μg/mL) alone had little inhibitory activity against the P. expansum infection in pear fruit wounds although it was effective in inhibiting the survival of P. expansum on Asp-agar medium. Pyrimethanil at this low concentration significantly enhanced the efficacy of Cryptococcus laurentii at 1×10(7)CFU/mL in reducing blue mold rot in vivo compared with C. laurentii at 1×10(7)CFU/mL alone. However, there was no additive inhibitory activity when pyrimethanil was combined for application with biocontrol yeasts Rhodosporidium paludigenum or Rhodotorula glutinis. Combination of pyrimethanil and C. laurentii at low concentration also inhibited blue mold rot when P. expansum was inoculated into fruit wounds 12h before treatment and fruit was stored at low temperature (4°C). Pyrimethanil at 0.04 to 400μg/mL did not influence the survival of C. laurentii in vitro, and it only slightly reduced the population growth of C. laurentii after 48h of incubation in the pear fruit wounds. There was no significant difference in quality parameters including total soluble solids, titratable acidity and ascorbic acid of pear fruit wounds among all treatments after 5days of treatment at 25°C. Integration of C. laurentii and pyrimethanil at low concentration might be an effective and safe strategy to control P. expansum infection in pear fruit, especially in an integrated postharvest disease management strategy.

  2. A mutant of the nematophagous fungus Paecilomyces lilacinus (Thom) is a novel biocontrol agent for Sclerotinia sclerotiorum.

    PubMed

    Yang, Fan; Abdelnabby, Hazem; Xiao, Yannong

    2015-12-01

    Sclerotinia sclerotiorum causes severe stem rot and yield loss in oilseed rape (Brassica napus L.) and other crops worldwide. Extensive studies have been conducted on Paecilomyces lilacinus as a nematophagous bioagent. However, no reports stated the effect of P. lilacinus as a biocontrol agent against oilseed rape rot S. sclerotiorum. This study describes such effect in lab and field trials using the new transformant pt361 derived from the wild strain P. lilacinus 36-1. Unlike the wild-type strain, the mutant pt361 showed high antagonistic effect against S. Sclerotiorum A. Under lab conditions, the pt361 inhibited (65%) radial mycelial growth of S. sclerotiorum in dual culture test producing 5.9 mm inhibition zone IZ in front of the S. sclerotiorum colony. Moreover, the cell-free filtrate of pt361 culture showed strong inhibitory effects (60.3-100%) on mycelial growth of S. sclerotiorum. In leaf detached assay, pt361 significantly (p < 0.05) inhibited (40.4-97.9%) the extension of the leaf spots caused by S. sclerotiorum A at all tested concentrations. The genomic DNA sequences of the inserted T-DNA flanking obtained from pt361 strain was cloned, verified as a glycoside hydrolase 31 family by homologous analysis with other fungal strains, and named PGH31 (2556bp). Secondary structure prediction showed a domain (Glycoside hydrolase31). Three years field trial confirmed that the cell-free filtrates or spores suspension of pt361 achieved significant (p < 0.05) suppression of oilseed rape stem rot, promoted growth and increased yield compared to the control and exceeded, at dose 100%, the action of the fungicide procymidone(®). In conclusion, the mutant pt361 of P. lilacinus is a novel and promising biocontrol agent against oilseed rape Sclerotinia stem rot.

  3. Effects of community versus single strain inoculants on the biocontrol of Salmonella and microbial community dynamics in alfalfa sprouts.

    PubMed

    Matos, Anabelle; Garland, Jay L

    2005-01-01

    Potential biological control inoculants, Pseudomonas fluorescens 2-79 and microbial communities derived from market sprouts or laboratory-grown alfalfa sprouts, were introduced into alfalfa seeds with and without a Salmonella inoculum. We examined their ability to inhibit the growth of this foodborne pathogen and assess the relative effects of the inoculants on the alfalfa microbial community structure and function. Alfalfa seeds contaminated with a Salmonella cocktail were soaked for 2 h in bacterial suspensions from each inoculant tested. Inoculated alfalfa seeds were grown for 7 days and sampled during days 1, 3, and 7. At each sampling, alfalfa sprouts were sonicated for 7 min to recover microflora from the surface, and the resulting suspensions were diluted and plated on selective and nonselective media. Total bacterial counts were obtained using acridine orange staining, and the percentage culturability was calculated. Phenotypic potential of sprout-associated microbial communities inoculated with biocontrol treatments was assessed using community-level physiological profiles based on patterns of use of 95 separate carbon sources in Biolog plates. Community-level physiological profiles were also determined using oxygen-sensitive fluorophore in BD microtiter plates to examine functional patterns in these communities. No significant differences in total and mesophilic aerobe microbial cell density or microbial richness resulting from the introduction of inoculants on alfalfa seeds with and without Salmonella were observed. P. fluorescens 2-79 exhibited the greatest reduction in the growth of Salmonella early during alfalfa growth (4.22 log at day 1), while the market sprout inoculum had the reverse effect, resulting in a maximum log reduction (5.48) of Salmonella on day 7. Community-level physiological profiles analyses revealed that market sprout communities peaked higher and faster compared with the other inoculants tested. These results suggest that

  4. Colonization Pattern of the Biocontrol Strain Pseudomonas chlororaphis MA 342 on Barley Seeds Visualized by Using Green Fluorescent Protein

    PubMed Central

    Tombolini, Riccardo; van der Gaag, Dirk Jan; Gerhardson, Berndt; Jansson, Janet K.

    1999-01-01

    Pseudomonas chlororaphis MA 342 is a potent biocontrol agent that can be used against several seed-borne diseases of cereal crops, including net blotch of barley caused by the fungus Drechslera teres. In this study, strain MA 342 was tagged with the gfp gene (encoding the green fluorescent protein) in order to study the fate of cells after seed inoculation. The gfp-tagged strain, MA 342G2, had the same biocontrol efficacy as the wild type when it was applied at high cell concentrations to seeds but was less effective at lower cell concentrations. By comparing cell counts determined by microscopy to the number of CFU, we found that the number of culturable cells was significantly lower than the total number of bacteria on seeds which were inoculated and dried for 20 h. Confocal microscopy and epifluorescence stereomicroscopy were used to determine the pattern of MA 342G2 colonization and cell aggregation on barley seeds. Immediately after inoculation of seeds, bacteria were found mainly under the seed glume, and there was no particular aggregation pattern. However, after the seeds were sown, irregularly distributed areas of bacterial aggregation were found, which reflected epiphytic colonization of glume cells. There was a trend towards bacterial aggregation near the embryo but never within the embryo. Bacterial aggregates were regularly found in the groove of each seed formed by the base of the coleoptile and the scutellum. Based on these results, we suggest that MA 342 colocalizes with the pathogen D. teres, which facilitates the action of the fungistatic compound(s) produced by this strain. PMID:10427065

  5. Biocontrol of Aspergillus species on peanut kernels by antifungal diketopiperazine producing Bacillus cereus associated with entomopathogenic nematode.

    PubMed

    Kumar, Sasidharan Nishanth; Sreekala, Sreerag Ravikumar; Chandrasekaran, Dileep; Nambisan, Bala; Anto, Ruby John

    2014-01-01

    The rhabditid entomopathogenic nematode associated Bacillus cereus and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by Aspergillus species in in vitro and in vivo tests. The results showed that B. cereus had a significant effect on biocontrol effectiveness in in vitro and in vivo conditions. The antifungal compounds produced by the B. cereus were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs) [cyclo-(L-Pro-Gly), cyclo(L-Tyr-L-Tyr), cyclo-(L-Phe-Gly) and cyclo(4-hydroxy-L-Pro-L-Trp)]. The antifungal activities of diketopiperazines were studied against five Aspergillus species and best MIC of 2 µg/ml was recorded against A. flavus by cyclo(4-hydroxy-L-Pro-L-Trp). To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp) to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of Aspergillus species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp). The cyclo(4-hydroxy-L-Pro-L-Trp) was nontoxic to two normal cell lines [fore skin (FS) normal fibroblast and African green monkey kidney (VERO)] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp) identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated B. cereus and cyclo(4-hydroxy-L-Pro-L-Trp) could be used as a biocontrol agents against postharvest fungal disease caused by Aspergillus species.

  6. The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots.

    PubMed

    Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

    2014-01-01

    Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the "non-hostile" colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

  7. Biocontrol of Postharvest Anthracnose of Mango Fruit with Debaryomyces Nepalensis and Effects on Storage Quality and Postharvest Physiology.

    PubMed

    Luo, Shanshan; Wan, Bin; Feng, Shuhan; Shao, Yuanzhi

    2015-11-01

    Anthracnose is presently recognized as one of the most important postharvest disease of mango worldwide. To control the disease, chemical fungicides for a long time was widely used among fruit farmers, but recently found that pathogen had developed increasingly resistance to it. With people's growing desire of healthy and green food, finding new and environmentally friendly biological control approach was very necessary. In this paper, we provided a kind of new antagonistic yeast which enriched the strain resources and the efficacy of Debaryomyces nepalensis against postharvest anthracnose of mango fruit and the influence on quality parameters were investigated. The results showed that the decay incidence and lesion diameter of postharvest anthracnose of mango treated by D. nepalensis were significantly reduced compared with the control fruit stored at 25 °C for 30 d or at 15 °C for 40 d, and the higher concentration of D. nepalensis was, the better the efficacy of the biocontrol was. Study also found that 1 h was the best treatment duration and antagonistic yeast inoculated earlier had good biocontrol effect on anthracnose. Meanwhile, treatment by D. nepalensis could significantly reduce postharvest anthracnose of mango, delay the decrease in firmness, TSS, TA, and ascorbic acid value, and do not impair surface color during postharvest storage. Moreover, the increase in MDA (malondialdehyde) content and increase in cell membrane permeability of fruit treated by D. nepalensis was highly inhibited. The results suggested D. nepalensis treatment could not only maintain storage quality of mango fruit, but also decrease the decay incidence to anthracnose disease. All these results indicated that D. nepalensis has great potential for development of commercial formulations to control postharvest pathogens of mango fruit.

  8. Comparative pathogenicity, biocontrol efficacy, and multilocus sequence typing of Verticillium nonalfalfae from the invasive Ailanthus altissima and other hosts.

    PubMed

    Kasson, M T; Short, D P G; O'Neal, E S; Subbarao, K V; Davis, D D

    2014-03-01

    Verticillium wilt, caused by Verticillium nonalfalfae, is currently killing tens of thousands of highly invasive Ailanthus altissima trees within the forests in Pennsylvania, Ohio, and Virginia and is being considered as a biological control agent of Ailanthus. However, little is known about the pathogenicity and virulence of V. nonalfalfae isolates from other hosts on Ailanthus, or the genetic diversity among V. nonalfalfae from confirmed Ailanthus wilt epicenters and from locations and hosts not associated with Ailanthus wilt. Here, we compared the pathogenicity and virulence of several V. nonalfalfae and V. alfalfae isolates, evaluated the efficacy of the virulent V. nonalfalfae isolate VnAa140 as a biocontrol agent of Ailanthus in Pennsylvania, and performed multilocus sequence typing of V. nonalfalfae and V. alfalfae. Inoculations of seven V. nonalfalfae and V. alfalfae isolates from six plant hosts on healthy Ailanthus seedlings revealed that V. nonalfalfae isolates from hosts other than Ailanthus were not pathogenic on Ailanthus. In the field, 100 canopy Ailanthus trees were inoculated across 12 stands with VnAa140 from 2006 to 2009. By 2011, natural spread of the fungus had resulted in the mortality of >14,000 additional canopy Ailanthus trees, 10,000 to 15,000 Ailanthus sprouts, and nearly complete eradication of Ailanthus from several smaller inoculated stands, with the exception of a few scattered vegetative sprouts that persisted in the understory for several years before succumbing. All V. nonalfalfae isolates associated with the lethal wilt of Ailanthus, along with 18 additional isolates from 10 hosts, shared the same multilocus sequence type (MLST), MLST 1, whereas three V. nonalfalfae isolates from kiwifruit shared a second sequence type, MLST 2. All V. alfalfae isolates included in the study shared the same MLST and included the first example of V. alfalfae infecting a non-lucerne host. Our results indicate that V. nonalfalfae is host adapted and

  9. Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

    PubMed Central

    2009-01-01

    Background Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management. Results The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42. Conclusion The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as a good candidate for the

  10. The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

    PubMed Central

    Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

    2014-01-01

    Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the “non-hostile” colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7. PMID:25250017

  11. Complete genome sequence of Pseudomonas fluorescens strain PICF7, an indigenous root endophyte from olive (Olea europaea L.) and effective biocontrol agent against Verticillium dahliae

    PubMed Central

    2015-01-01

    Pseudomonas fluorescens strain PICF7 is a native endophyte of olive roots. Previous studies have shown this motile, Gram-negative, non-sporulating bacterium is an effective biocontrol agent against the soil-borne fungus Verticillium dahliae, the causal agent of one of the most devastating diseases for olive (Olea europaea L.) cultivation. Here, we announce and describe the complete genome sequence of Pseudomonas fluorescens strain PICF7 consisting of a circular chromosome of 6,136,735 bp that encodes 5,567 protein-coding genes and 88 RNA-only encoding genes. Genome analysis revealed genes predicting factors such as secretion systems, siderophores, detoxifying compounds or volatile components. Further analysis of the genome sequence of PICF7 will help in gaining insights into biocontrol and endophytism. PMID:25685259

  12. The Potential Application and Risks Associated With the Use of Predatory Bacteria as a Bio-control Agent Against Wound Infections

    DTIC Science & Technology

    2015-10-01

    inhibition reduces innate immunity and improves isoniazid clearance of Mycobacterium tuberculosis in the lungs of infected mice. PLoS One 6, e17091, doi...Against Wound Infections PRINCIPAL INVESTIGATOR: Daniel E Kadouri, Ph.D CONTRACTING ORGANIZATION: Rutgers, The State University of New Jersey...SUBTITLE The Potential Application and Risks Associated With the Use of Predatory Bacteria as a Bio-control Agent Against Wound Infections 5c. PROGRAM

  13. Multicellular behaviour and production of a wide variety of toxic substances support usage of Bacillus subtilis as a powerful biocontrol agent.

    PubMed

    Nagórska, Krzysztofa; Bikowski, Mariusz; Obuchowski, Michał

    2007-01-01

    Intensive cultivation of plants in the monoculture field system in order to feed the continuously growing human population creates a need for their protection from the variety of natural competitors such as: bacteria, fungi, insects as well as other plants. The increase in the use of chemical substances in the 20th century has brought many effective solutions for the agriculture. However, it was extremely difficult to obtain a substance, which would be directed solely against a specific plant pathogen and would not be harmful for the environment. In the late 1900's scientists began trying to use natural antagonisms between resident soil organism to protect plants. This phenomenon was named biocontrol. Biological control of plants by microorganisms is a very promising alternative to an extended use of pesticides, which are often expensive and accumulate in plants or soil, having adverse effects on humans. Nonpathogenic soil bacteria living in association with roots of higher plants enhance their adaptive potential and, moreover, they can be beneficial for their growth. Here, we present the current status of the use of Bacillus subtilis in biocontrol. This prevalent inhabitant of soil is widely recognized as a powerful biocontrol agent. Naturally present in the immediate vicinity of plant roots, B. subtilis is able to maintain stable contact with higher plants and promote their growth. In addition, due to its broad host range, its ability to form endospores and produce different biologically active compounds with a broad spectrum of activity, B. subtilis as well as other Bacilli are potentially useful as biocontrol agents.

  14. Loss of GltB Inhibits Biofilm Formation and Biocontrol Efficiency of Bacillus subtilis Bs916 by Altering the Production of γ-Polyglutamate and Three Lipopeptides

    PubMed Central

    Luo, Chuping; Fang, Xianwen; Xiang, Yaping; Wang, Xiaoyu; Zhang, Rongsheng; Chen, Zhiyi

    2016-01-01

    Aims This study examined the contribution of GltB on biofilm formation and biocontrol efficiency of B. subtilis Bs916. Methods and Results The gltB gene was identified through a biofilm phenotype screen and a bioinformatics analysis of serious biofilm formation defects, and then a gltB single knockout mutant was constructed using homologous recombination. This mutant demonstrated severe deficits in biofilm formation and colonisation along with significantly altered production ofγ-polyglutamate (γ-PGA) and three lipopeptide antibiotics (LPs) as measured by a transcriptional analysis of both the wild type B. subtilis Bs916 and the gltB mutant. Consequently, the mutant strain retained almost no antifungal activity against Rhizoctonia solani and exhibited decreased biocontrol efficiency against rice sheath blight. Very few gltB mutant cells colonised the rice stem, and they exhibited no significant nutrient chemotaxis compared to the wild type B. subtilis Bs916. The mechanism underlying these deficits in the gltB mutant appears to be decreased significantly in production of γ-PGA and a reduction in the production of both bacillomycin L and fengycin. Biofilm restoration of gltB mutant by additionγ-PGA in the EM medium demonstrated that biofilm formation was able to restore significantly at 20 g/L. Conclusions GltB regulates biofilm formation by altering the production ofγ-PGA, the LPs bacillomycin L and fengcin and influences bacterial colonisation on the rice stem, which consequently leads to poor biocontrol efficiency against rice sheath blight. Significance and Impact of Study This is the first report of a key regulatory protein (GltB) that is involved in biofilm regulation and its regulation mechanism and biocontrol efficiency by B. subtilis. PMID:27223617

  15. Saprotrophic competitiveness and biocontrol fitness of a genetically modified strain of the plant-growth-promoting fungus Trichoderma hamatum GD12.

    PubMed

    Ryder, Lauren S; Harris, Beverley D; Soanes, Darren M; Kershaw, Michael J; Talbot, Nicholas J; Thornton, Christopher R

    2012-01-01

    Trichoderma species are ubiquitous soil fungi that hold enormous potential for the development of credible alternatives to agrochemicals and synthetic fertilizers in sustainable crop production. In this paper, we show that substantial improvements in plant productivity can be met by genetic modification of a plant-growth-promoting and biocontrol strain of Trichoderma hamatum, but that these improvements are obtained in the absence of disease pressure only. Using a quantitative monoclonal antibody-based ELISA, we show that an N-acetyl-β-d-glucosaminidase-deficient mutant of T. hamatum, generated by insertional mutagenesis of the corresponding gene, has impaired saprotrophic competitiveness during antagonistic interactions with Rhizoctonia solani in soil. Furthermore, its fitness as a biocontrol agent of the pre-emergence damping-off pathogen Sclerotinia sclerotiorum is significantly reduced, and its ability to promote plant growth is constrained by the presence of both pathogens. This work shows that while gains in T. hamatum-mediated plant-growth-promotion can be met through genetic manipulation of a single beneficial trait, such a modification has negative impacts on other aspects of its biology and ecology that contribute to its success as a saprotrophic competitor and antagonist of soil-borne pathogens. The work has important implications for fungal morphogenesis, demonstrating a clear link between hyphal architecture and secretory potential. Furthermore, it highlights the need for a holistic approach to the development of genetically modified Trichoderma strains for use as crop stimulants and biocontrol agents in plant agriculture.

  16. Potential of Microbispora sp. V2 as biocontrol agent against Sclerotium rolfsii, the causative agent of southern blight of Zea mays L (Baby corn)--in vitro studies.

    PubMed

    Patil, N N; Waghmode, M S; Gaikwad, P S; Gajbhiye, M H; Gunjal, A B; Nawani, N N; Kapadnis, B P

    2014-11-01

    The study was undertaken with the aim of exploring novel and beneficial agro activities of rare actinomycetes like Microbispora sp. V2. The antagonistic activity of Microbispora sp. V2 was evaluated as a biocontrol agents against Sclerotium rolfsii, a soil-borne fungal plant pathogen. The methodology performed for evaluation of biocontrol agent was in vitro evaluation assay which comprised of three tests viz., cellophane overlay technique, seed germination test and Thiram (fungicide) tolerance of Microbispora sp. V2. The isolate was found to inhibit the fungal pathogen Sclerotium rolfsii to 91.43% in cellophane assay. In seed germination assay, Microbispora sp. V2 treated seeds resulted in 25.75% increased germination efficiency, as compared to seeds infected by Sclerotium rolfsii. The isolate Microbispora sp. V2 could tolerate 1000 microg mL(-1) of Thiram (fungicide). The in vitro assay studies proved that Microbispora sp. V2 can be used as antifungal antagonist and thus posses' great potential as biocontrol agent against southern blight caused by Sclerotium rolfsii in Zea mays L (Baby corn) which causes large economical losses.

  17. Persistence and cell culturability of biocontrol strain Pseudomonas fluorescens CHA0 under plough pan conditions in soil and influence of the anaerobic regulator gene anr.

    PubMed

    Mascher, Fabio; Schnider-Keel, Ursula; Haas, Dieter; Défago, Geneviève; Moënne-Loccoz, Yvan

    2003-02-01

    Certain fluorescent pseudomonads can protect plants from soil-borne pathogens, and it is important to understand how these biocontrol agents survive in soil. The persistence of the biocontrol strain Pseudomonas fluorescens CHA0-Rif under plough pan conditions was assessed in non-sterile soil microcosms by counting total cells (immunofluorescence microscopy), intact cells (BacLight membrane permeability test), viable cells (Kogure's substrate-responsiveness test) and culturable cells (colony counts on selective plates) of the inoculant. Viable but non-culturable cells of CHA0-Rif (106 cells g-1 soil) were found in flooded microcosms amended with fermentable organic matter, in which the soil redox potential was low (plough pan conditions), in agreement with previous observations of plough pan samples from a field inoculated with CHA0-Rif. However, viable but non-culturable cells were not found in unamended flooded, amended unflooded or unamended unflooded (i.e. control) microcosms, suggesting that such cells resulted from exposure of CHA0-Rif to a combination of low redox potential and oxygen limitation in soil. CHA0-Rif is strictly aerobic. Its anaerobic regulator ANR is activated by low oxygen concentrations and it controls production of the biocontrol metabolite hydrogen cyanide under microaerophilic conditions. Under plough pan conditions, an anr-deficient mutant of CHA0-Rif and its complemented derivative displayed the same persistence pattern as CHA0-Rif, indicating that anr was not implicated in the formation of viable but non-culturable cells of this strain at the plough pan.

  18. Application of terminal restriction fragment length polymorphism (T-RFLP) analysis to monitor effect of biocontrol agents on rhizosphere microbial community of hot pepper (Capsicum annuum L.).

    PubMed

    Kim, Young Tae; Cho, Myoungho; Jeong, Je Yong; Lee, Hyang Burm; Kim, Seung Bum

    2010-10-01

    Microbial communities in hot pepper (Capsicum annuum L.) cultivation fields under different cultivation methods were investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis. Rhizosphere soil and leaf samples were collected from control, conventional and nature-friendly cultivation fields between May and July, 2009. Two Bacillus subtilis strains were applied to nature-friendly cultivation fields as biocontrol agents during the sampling period. Relative abundances of bacteria and plant pathogenic fungi related T-RFs were also measured to monitor the effect of biocontrol agents on potential plant pathogenic fungi. In the principal component analysis (PCA) based on T-RFLP profiles, the microbial communities from rhizosphere soil samples in July, including bacteria and fungi, showed distinct difference between nature-friendly cultivation fields and other cultivation fields. However, there was no correlation between cultivation methods and leaf microbial communities at any sampling period. Changes in the abundance of bacteria related T-RF in the rhizosphere of nature-friendly cultivation fields were observed clearly two months after application of biocontrol agent, while the abundance of plant pathogenic fungi related T-RFs significantly decreased.

  19. In Planta Biocontrol of Pectobacterium atrosepticum by Rhodococcus erythropolis Involves Silencing of Pathogen Communication by the Rhodococcal Gamma-Lactone Catabolic Pathway.

    PubMed

    Barbey, Corinne; Crépin, Alexandre; Bergeau, Dorian; Ouchiha, Asma; Mijouin, Lily; Taupin, Laure; Orange, Nicole; Feuilloley, Marc; Dufour, Alain; Burini, Jean-François; Latour, Xavier

    2013-01-01

    The virulence of numerous Gram-negative bacteria is under the control of a quorum sensing process based on synthesis and perception of N-acyl homoserine lactones. Rhodococcus erythropolis, a Gram-positive bacterium, has recently been proposed as a biocontrol agent for plant protection against soft-rot bacteria, including Pectobacterium. Here, we show that the γ-lactone catabolic pathway of R. erythropolis disrupts Pectobacterium communication and prevents plant soft-rot. We report the first characterization and demonstration of N-acyl homoserine lactone quenching in planta. In particular, we describe the transcription of the R. erythropolis lactonase gene, encoding the key enzyme of this pathway, and the subsequent lactone breakdown. The role of this catabolic pathway in biocontrol activity was confirmed by deletion of the lactonase gene from R. erythropolis and also its heterologous expression in Escherichia coli. The γ-lactone catabolic pathway is induced by pathogen communication rather than by pathogen invasion. This is thus a novel and unusual biocontrol pathway, differing from those previously described as protecting plants from phytopathogens. These findings also suggest the existence of an additional pathway contributing to plant protection.

  20. Optimization of storage condition for maintaining long-term viability of nematophagous fungus Esteya vermicola as biocontrol agent against pinewood nematode.

    PubMed

    Xue, Jian Jie; Hou, Jin Gang; Zhang, Yong An; Wang, Chun Yan; Wang, Zhen; Yu, Jiao Jiao; Wang, Yun Bo; Wang, Yu Zhu; Wang, Qing Hua; Sung, Chang Keun

    2014-11-01

    The fungus, Esteya vermicola has been proposed as biocontrol agent against pine wilting disease caused by Bursaphelenchus xylophilus. In this study, we reported the effects of temperature and different additives on the viability and biocontrol efficacy of E. vermicola formulated by alginate-clay. The viability of the E. vermicola formulation was determined for six consecutive months at temperature ranged from -70 to 25 °C. The fresh conidia without any treatment were used as control. Under the optimal storage conditions with E. vermicola alginate-clay formulation, the results suggested that E. vermicola alginate-clay formulation with a long shelf life could be a non-vacuum-packed formulation that contains 2 % sodium alginate and 5 % clay at 4 °C. Three conidial formulations prepared with additives of 15 % glycerol, 0.5 % yeast extract and 0.5 % herbal extraction, respectively significantly improved the shelf life. In addition, these tested formulations retained the same biocontrol efficacy as the fresh conidial against pinewood nematode. This study provided a tractable and low-cost method to preserve the shelf life of E. vermicola.

  1. Endophytic colonization and biocontrol performance of Pseudomonas fluorescens PICF7 in olive (Olea europaea L.) are determined neither by pyoverdine production nor swimming motility.

    PubMed

    Maldonado-González, M Mercedes; Schilirò, Elisabetta; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-09-01

    Pseudomonas fluorescens PICF7 is an indigenous inhabitant of olive (Olea europaea L.) rhizosphere, able to display endophytic lifestyle in roots, to induce a wide range of defence responses upon colonization of this organ and to exert effective biological control against Verticillium wilt of olive (VWO) (Verticillium dahliae). We aimed to evaluate the involvement of specific PICF7 phenotypes in olive root colonization and VWO biocontrol effectiveness by generating mutants impaired in swimming motility (fliI) or siderophore pyoverdine production (pvdI). Besides, the performance of mutants with diminished in vitro growth in potato dextrose agar medium (gltA) and cysteine (Cys) auxotrophy was also assessed. Results showed that olive root colonization and VWO biocontrol ability of the fliI, pvdI and gltA mutants did not significantly differ from that displayed by the parental strain PICF7. Consequently, altered in vitro growth, swimming motility and pyoverdine production contribute neither to PICF7 VWO suppressive effect nor to its colonization ability. In contrast, the Cys auxotroph mutant showed reduced olive root colonization capacity and lost full biocontrol efficacy. Moreover, confocal laser scanning microscopy revealed that all mutants tested were able to endophytically colonize root tissue to the same extent as wild-type PICF7, discarding these traits as relevant for its endophytic lifestyle.

  2. Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

    PubMed

    Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

    2012-08-01

    Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage.

  3. Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

    PubMed Central

    Kamber, Tim; Lansdell, Theresa A.; Stockwell, Virginia O.; Ishimaru, Carol A.; Smits, Theo H. M.

    2012-01-01

    Pantoea vagans C9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth of Erwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates of P. vagans C9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known as Nß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster in P. vagans C9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters in Pantoea agglomerans CU0119 and Serratia proteamaculans 568. A low incidence of detection of the biosynthetic cluster in a collection of 45 Pantoea spp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains. PMID:22504810

  4. Pea Broth Enhances the Biocontrol Efficacy of Lysobacter capsici AZ78 by Triggering Cell Motility Associated with Biogenesis of Type IV Pilus

    PubMed Central

    Tomada, Selena; Puopolo, Gerardo; Perazzolli, Michele; Musetti, Rita; Loi, Nazia; Pertot, Ilaria

    2016-01-01

    Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components and regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78. PMID:27507963

  5. Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape.

    PubMed

    Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

    2015-05-01

    Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape.

  6. Improvement of Biocontrol of Damping-off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide.

    PubMed

    Abdel-Monaim, Montaser Fawzy

    2013-03-01

    Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seeds soaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the

  7. Improvement of Biocontrol of Damping-off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide

    PubMed Central

    2013-01-01

    Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seeds soaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the

  8. A river system to watch: documenting the effects of saltcedar (Tamarix spp.) biocontrol in the Virgin River valley

    USGS Publications Warehouse

    Bateman, Heather L.; Dudley, Tom L.; Bean, Dan W.; Ostoja, Steven M.; Hultine, Kevin R.; Kuehn, Michael J.

    2010-01-01

    Throughout riparian areas of the southwestern United States, non-native saltcedar (also known as tamarisk; Tamarix spp.) can form dense, monotypic stands and is often reported to have detrimental effects on native plants and habitat quality (Everitt 1980; Shafroth et al. 2005). Natural resource managers of these riparian areas spend considerable time and resources controlling saltcedar using a variety of techniques, including chemical (Duncan and McDaniel 1998), mechanical, and burning methods (Shafroth et al. 2005). Approximately one billion dollars are spent each year on river restoration projects nationally (Bernhardt et al. 2005), and a majority of these projects focus on invasive species control in the Southwest (Follstad Shah et al. 2007). A technique that has drawn much attention is the use of the saltcedar leaf beetle (Diorhabda spp.), a specialist herbivore, as biological control of saltcedar (Lewis et al. 2003). Research testing was conducted with beetles housed in secure enclosures in six states in 1998 and 1999 (Dudley et al. 2001), followed by open release at some of those sites starting in 2001 (DeLoach et al. 2004). By 2005, full-scale saltcedar biocontrol was implemented in 13 states, led by the USDA Animal and Plant Health Inspection Service (APHIS), the agency that oversees biological control programs, and with the participation and support of the U.S. Fish and Wildlife Service (USFWS). Despite the widespread application of Diorhabda, however, only limited research has quantified the consequences (benefits and costs) on biotic communities and ecosystem services. Alterations to riparian areas caused by various non-native species control activities have the potential to affect a variety of habitat types used by wildlife (Bateman et al. 2008a); processes like water availability, fluvial deposition, and erosion; and the establishment of other non-native species (Carruthers and D'Antonio 2005, Shafroth et al. 2005, DeLoach et al. 2006). Similarly

  9. Hydrophobins are required for conidial hydrophobicity and plant root colonization in the fungal biocontrol agent Clonostachys rosea

    PubMed Central

    2014-01-01

    Background Filamentous fungi produce small cysteine rich surface active amphiphilic hydrophobins on the outer surface of cell walls that mediate interactions between the fungus and the environment. The role of hydrophobins in surface hydrophobicity, sporulation, fruit body formation, recognition and adhesion to host surface and virulence have been reported. The aim of the present study was to characterize the biological function of hydrophobins in the fungal biocontrol agent Clonostachys rosea in order to understand their potential roles in biocontrol mechanisms. Results Based on the presence of hydrophobin domains, cysteine spacing patterns and hydropathy plots, we identified three class II hydrophobin genes in C. rosea. Gene expression analysis showed basal expression of Hyd1, Hyd2 and Hyd3 in all conditions tested with the exception of induced Hyd1 expression in conidiating mycelium. Interestingly, up-regulation of Hyd1, Hyd2 and Hyd3 was found during C. rosea self interaction compared to interactions with the fungal plant pathogens Botrytis cinerea or Fusarium graminearum in dual culture assays. Phenotypic analysis of C. rosea deletion and complementation strains showed that Hyd1 and Hyd3 are jointly required for conidial hydrophobicity, although no difference in mycelia hydrophobicity was found between wild type (WT) and mutant strains. Interestingly, mutant strains showed increased growth rates, conidiation and enhanced tolerances of conidia to abiotic stresses. Antagonism tests using in vitro dual culture and detached leaf assays showed that the mutant strains were more aggressive towards B. cinerea, F. graminearum or Rhizoctonia solani, and that aggression was partly related to earlier conidial germination and enhanced tolerance of mutant strains to secreted fungal metabolites. Furthermore, in vitro Arabidopsis thaliana root colonization assays revealed reduced root colonization ability of the ΔHyd3 strain, but not for the ΔHyd1 strain. Furthermore

  10. Biocontrol of Aspergillus Species on Peanut Kernels by Antifungal Diketopiperazine Producing Bacillus cereus Associated with Entomopathogenic Nematode

    PubMed Central

    Kumar, Sasidharan Nishanth; Sreekala, Sreerag Ravikumar; Chandrasekaran, Dileep; Nambisan, Bala; Anto, Ruby John

    2014-01-01

    The rhabditid entomopathogenic nematode associated Bacillus cereus and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by Aspergillus species in in vitro and in vivo tests. The results showed that B. cereus had a significant effect on biocontrol effectiveness in in vitro and in vivo conditions. The antifungal compounds produced by the B. cereus were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs) [cyclo-(L-Pro-Gly), cyclo(L-Tyr-L-Tyr), cyclo-(L-Phe-Gly) and cyclo(4-hydroxy-L-Pro-L-Trp)]. The antifungal activities of diketopiperazines were studied against five Aspergillus species and best MIC of 2 µg/ml was recorded against A. flavus by cyclo(4-hydroxy-L-Pro-L-Trp). To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp) to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of Aspergillus species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp). The cyclo(4-hydroxy-L-Pro-L-Trp) was nontoxic to two normal cell lines [fore skin (FS) normal fibroblast and African green monkey kidney (VERO)] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp) identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated B. cereus and cyclo(4-hydroxy-L-Pro-L-Trp) could be used as a biocontrol agents against postharvest fungal disease caused by Aspergillus species. PMID:25157831

  11. Biocontrol of postharvest gray and blue mold decay of apples with Rhodotorula mucilaginosa and possible mechanisms of action.

    PubMed

    Li, Renping; Zhang, Hongyin; Liu, Weimin; Zheng, Xiaodong

    2011-03-30

    The efficacy of Rhodotorula mucilaginosa against postharvest gray mold, blue mold and natural decay development of apples and the possible mechanisms involved were investigated. The decay incidence and lesion diameter of gray mold and blue mold of apples treated by R. mucilaginosa were significantly reduced compared with the control fruits, and the higher concentration of R. mucilaginosa, the better the efficacy of the biocontrol. R. mucilaginosa also significantly reduced the natural decay development of apples following storage at 20°C for 35 days or at 4°C for 45 days followed by 20°C for 15 days. Germination and survival of spores of Penicillium expansum and Botrytis cinerea were markedly inhibited by R. mucilaginosa in an in vitro test. Rapid colonization of the yeast in apple wounds was observed whether stored at 20°C or 4°C. In apples, the activities of peroxidase (POD) and polyphenoloxidase (PPO) were significantly induced and lipid peroxidation (malondialdehyde (MDA) content) was highly inhibited by R. mucilaginosa treatment compared with those of the control fruits. All these results indicated that R. mucilaginosa has great potential for development of commercial formulations to control postharvest pathogens on fruits. Its modes of action were based on competition for space and nutrients with pathogens, inducement of activities of defense-related enzymes such as POD, PPO and inhibition of lipid peroxidation (MDA content) of apples, so as to enhance the resistance and delay the ripening and senescence of apples.

  12. Biocontrol of Late Blight (Phytophthora capsici) Disease and Growth Promotion of Pepper by Burkholderia cepacia MPC-7

    PubMed Central

    Sopheareth, Mao; Chan, Sarun; Naing, Kyaw Wai; Lee, Yong Seong; Hyun, Hae Nam; Kim, Young Cheol; Kim, Kil Yong

    2013-01-01

    A chitinolytic bacterial strain having strong antifungal activity was isolated and identified as Burkholderia cepacia MPC-7 based on 16S rRNA gene analysis. MPC-7 solubilized insoluble phosphorous in hydroxyapatite agar media. It produced gluconic acid and 2-ketogluconic acid related to the decrease in pH of broth culture. The antagonist produced benzoic acid (BA) and phenylacetic acid (PA). The authentic compounds, BA and PA, showed a broad spectrum of antimicrobial activity against yeast, several bacterial and fungal pathogens in vitro. To demonstrate the biocontrol efficiency of MPC-7 on late blight disease caused by Phytophthora capsici, pepper plants in pot trials were treated with modified medium only (M), M plus zoospore inoculation (MP), MPC-7 cultured broth (B) and B plus zoospore inoculation (BP). With the sudden increase in root mortality, plants in MP wilted as early as five days after pathogen inoculation. However, plant in BP did not show any symptom of wilting until five days. Root mortality in BP was markedly reduced for as much as 50%. Plants in B had higher dry weight, P concentration in root, and larger leaf area compared to those in M and MP. These results suggested that B. cepacia MPC-7 should be considered as a candidate for the biological fertilizer as well as antimicrobial agent for pepper plants. PMID:25288930

  13. Effect of biocontrol agents Candida sake and Pantoea agglomerans on Penicillium expansum growth and patulin accumulation in apples.

    PubMed

    Morales, Hector; Sanchis, Vicente; Usall, Josep; Ramos, Antonio J; Marín, Sonia

    2008-02-29

    Penicillium expansum is the major responsible of fruit pome decaying in cold storage. Apples spoiled by P. expansum are expected to contain patulin, a mycotoxin which is proven to affect human health. The use of chemicals is the most common procedure to prevent rots in postharvest but legislation is becoming more and more restrictive. The use of biocontrol agents (BCA) as an alternative tool is currently being proposed. The aim of this study was to evaluate the effect of two BCA (Candida sake CPA-2 and Pantoea agglomerans CPA-1) on P. expansum growth and patulin accumulation in cold storage and further deck (ambient) storage. Wounded apples were inoculated with a cell suspension of either C. sake or P. agglomerans and with a P. expansum conidial suspension. Apples were cold stored at 1 degrees C until lesion diameter reached 2 or 4 cm. Half the apples of each treatment were further stored at 20 degrees C for three days before patulin analyses. Both BCA tested controlled blue rot and patulin accumulation during cold storage. The control of P. expansum growth was enhanced in C. sake treated apples. On the other side, control of patulin accumulation in P. agglomerans treated apples seemed to be more efficient. BCA treatment could not control blue rot and patulin accumulation during further storage at room temperature and in some cases, an increase in P. expansum aggressiveness was observed.

  14. Tomato progeny inherit resistance to the nematode Meloidogyne javanica linked to plant growth induced by the biocontrol fungus Trichoderma atroviride

    PubMed Central

    Medeiros, Hugo Agripino de; Araújo Filho, Jerônimo Vieira de; Freitas, Leandro Grassi de; Castillo, Pablo; Rubio, María Belén; Hermosa, Rosa; Monte, Enrique

    2017-01-01

    Root-knot nematodes (RKN) are major crop pathogens worldwide. Trichoderma genus fungi are recognized biocontrol agents and a direct activity of Trichoderma atroviride (Ta) against the RKN Meloidogyne javanica (Mj), in terms of 42% reduction of number of galls (NG), 60% of number of egg masses and 90% of number of adult nematodes inside the roots, has been observed in tomato grown under greenhouse conditions. An in vivo split-root designed experiment served to demonstrate that Ta induces systemic resistance towards Mj, without the need for the organisms to be in direct contact, and significantly reduces NG (20%) and adult nematodes inside tomato roots (87%). The first generation (F1) of Ta-primed tomato plants inherited resistance to RKN; although, the induction of defenses occurred through different mechanisms, and in varying degrees, depending on the Ta-Mj interaction. Plant growth promotion induced by Ta was inherited without compromising the level of resistance to Mj, as the progeny of Ta-primed plants displayed increased size and resistance to Mj without fitness costs. Gene expression results from the defense inductions in the offspring of Ta-primed plants, suggested that an auxin-induced reactive oxygen species production promoted by Ta may act as a major defense strategy during plant growth. PMID:28071749

  15. Exploring ComQXPA quorum-sensing diversity and biocontrol potential of Bacillus spp. isolates from tomato rhizoplane.

    PubMed

    Oslizlo, A; Stefanic, P; Vatovec, S; Beigot Glaser, S; Rupnik, M; Mandic-Mulec, I

    2015-05-01

    Bacillus subtilis is a widespread and diverse bacterium t exhibits a remarkable intraspecific diversity of the ComQXPA quorum-sensing (QS) system. This manifests in the existence of distinct communication groups (pherotypes) that can efficiently communicate within a group, but not between groups. Similar QS diversity was also found in other bacterial species, and its ecological and evolutionary meaning is still being explored. Here we further address the ComQXPA QS diversity among isolates from the tomato rhizoplane, a natural habitat of B. subtilis, where these bacteria likely exist in their vegetative form. Because this QS system regulates production of anti-pathogenic and biofilm-inducing substances such as surfactins, knowledge on cell-cell communication of this bacterium within rhizoplane is also important from the biocontrol perspective. We confirm the presence of pherotype diversity within B. subtilis strains isolated from a rhizoplane of a single plant. We also show that B. subtilis rhizoplane isolates show a remarkable diversity of surfactin production and potential plant growth promoting traits. Finally, we discover that effects of surfactin deletion on biofilm formation can be strain specific and unexpected in the light of current knowledge on its role it this process.

  16. Exploring ComQXPA quorum-sensing diversity and biocontrol potential of Bacillus spp. isolates from tomato rhizoplane

    PubMed Central

    Oslizlo, A; Stefanic, P; Vatovec, S; Beigot Glaser, S; Rupnik, M; Mandic-Mulec, I

    2015-01-01

    Bacillus subtilis is a widespread and diverse bacterium t exhibits a remarkable intraspecific diversity of the ComQXPA quorum-sensing (QS) system. This manifests in the existence of distinct communication groups (pherotypes) that can efficiently communicate within a group, but not between groups. Similar QS diversity was also found in other bacterial species, and its ecological and evolutionary meaning is still being explored. Here we further address the ComQXPA QS diversity among isolates from the tomato rhizoplane, a natural habitat of B. subtilis, where these bacteria likely exist in their vegetative form. Because this QS system regulates production of anti-pathogenic and biofilm-inducing substances such as surfactins, knowledge on cell–cell communication of this bacterium within rhizoplane is also important from the biocontrol perspective. We confirm the presence of pherotype diversity within B. subtilis strains isolated from a rhizoplane of a single plant. We also show that B. subtilis rhizoplane isolates show a remarkable diversity of surfactin production and potential plant growth promoting traits. Finally, we discover that effects of surfactin deletion on biofilm formation can be strain specific and unexpected in the light of current knowledge on its role it this process. PMID:25757097

  17. Biocontrol agents-mediated suppression of oxalic acid induced cell death during Sclerotinia sclerotiorum-pea interaction.

    PubMed

    Jain, Akansha; Singh, Akanksha; Singh, Surendra; Sarma, Birinchi Kumar; Singh, Harikesh Bahadur

    2015-05-01

    Oxalic acid (OA) is an important pathogenic factor during early Sclerotinia sclerotiorum-host interaction and might work by reducing hydrogen peroxide production (H2 O2 ). In the present investigation, oxalic acid-induced cell death in pea was studied. Pea plants treated with biocontrol agents (BCAs) viz., Pseudomonas aeruginosa PJHU15, Bacillus subtilis BHHU100, and Trichoderma harzianum TNHU27 either singly and/or in consortium acted on S. sclerotiorum indirectly by enabling plants to inhibit the OA-mediated suppression of oxidative burst via induction of H2 O2 . Our results showed that BCA treated plants upon treatment with culture filtrate of the pathogen, conferred the resistance via. significantly decreasing relative cell death of pea against S. sclerotiorum compared to control plants without BCA treatment but treated with the culture filtrate of the pathogen. The results obtained from the present study indicate that the microbes especially in consortia play significant role in protection against S. sclerotiorum by modulating oxidative burst and partially enhancing tolerance by increasing the H2 O2 generation, which is otherwise suppressed by OA produced by the pathogen.

  18. Heterologous expression of VHb can improve the yield and quality of biocontrol fungus Paecilomyces lilacinus, during submerged fermentation.

    PubMed

    Zhang, Shumeng; Wang, Jieping; Wei, Yale; Tang, Qing; Ali, Maria Kanwal; He, Jin

    2014-10-10

    Paecilomyces lilacinus is an egg-parasitic fungus which is effective against plant-parasitic nematodes and it has been successfully commercialized for the control of many plant-parasitic nematodes. However, during the large-scale industrial fermentation process of the filamentous fungus, the dissolved oxygen supply is a limiting factor, which influences yield, product quality and production cost. To solve this problem, we intended to heterologously express VHb in P. lilacinus ACSS. After optimizing the vgb gene, we fused it with a selection marker gene nptII, a promoter PgpdA and a terminator TtrpC. The complete expression cassette PgpdA-nptII-vgb-TtrpC was transferred into P. lilacinus ACSS by Agrobacterium tumefaciens-mediated transformation. Consequently, we successfully screened an applicable fungus strain PNVT8 which efficiently expressed VHb. The submerged fermentation experiments demonstrated that the expression of VHb not only increased the production traits of P. lilacinus such as biomass and spore production, but also improved the beneficial product quality and application value, due to the secretion of more protease and chitinase. It can be speculated that the recombinant strain harboring vgb gene will have a growth advantage over the original strain under anaerobic conditions in soil and therefore will possess higher biocontrol efficiency against plant-parasitic nematodes.

  19. Warming benefits a native species competing with an invasive congener in the presence of a biocontrol beetle.

    PubMed

    Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, Jianqing

    2016-09-01

    Climate warming may affect biological invasions by altering competition between native and non-native species, but these effects may depend on biotic interactions. In field surveys at 33 sites in China along a latitudinal and temperature gradient from 21°N to 30.5°N and a 2-yr field experiment at 30.5°N, we tested the role of the biocontrol beetle Agasicles hygrophila in mediating warming effects on competition between the invasive plant Alternanthera philoxeroides and the native plant Alternanthera sessilis. In surveys, native populations were perennial below 25.8°N but only annual populations were found above 26.5°N where the invader dominated the community. Beetles were present throughout the gradient. Experimental warming (+ 1.8°C) increased native plant performance directly by shifting its lifecycle from annual to perennial, and indirectly by releasing the native from competition via disproportionate increases in herbivory on the invader. Consequently, warming shifted the plant community from invader-dominated to native-dominated but only in the presence of the beetle. Our results show that herbivores can play a critical role in determining warming effects on plant communities and species invasions. Understanding how biotic interactions shape responses of communities to climate change is crucial for predicting the risk of plant invasions.

  20. Sm1, a proteinaceous elicitor secreted by the biocontrol fungus Trichoderma virens induces plant defense responses and systemic resistance.

    PubMed

    Djonović, Slavica; Pozo, Maria J; Dangott, Lawrence J; Howell, Charles R; Kenerley, Charles M

    2006-08-01

    The soilborne filamentous fungus Trichoderma virens is a biocontrol agent with a well-known ability to produce antibiotics, parasitize pathogenic fungi, and induce systemic resistance in plants. Even though a plant-mediated response has been confirmed as a component of bioprotection by Trichoderma spp., the molecular mechanisms involved remain largely unknown. Here, we report the identification, purification, and characterization of an elicitor secreted by T. virens, a small protein designated Sm1 (small protein 1). Sm1 lacks toxic activity against plants and microbes. Instead, native, purified Sm1 triggers production of reactive oxygen species in monocot and dicot seedlings, rice, and cotton, and induces the expression of defense-related genes both locally and systemically in cotton. Gene expression analysis revealed that SM1 is expressed throughout fungal development under different nutrient conditions and in the presence of a host plant. Using an axenic hydroponic system, we show that SM1 expression and secretion of the protein is significantly higher in the presence of the plant. Pretreatment of cotton cotyledons with Sm1 provided high levels of protection to the foliar pathogen Colletotrichum sp. These results indicate that Sm1 is involved in the induction of resistance by Trichoderma spp. through the activation of plant defense mechanisms.

  1. Putative use of a Bacillus subtilis L194 strain for biocontrol of Phoma medicaginis in Medicago truncatula seedlings.

    PubMed

    Ben Slimene, Imen; Tabbene, Olfa; Djebali, Naceur; Cosette, Pascal; Schmitter, Jean Marie; Jouenne, Thierry; Urdaci, Maria-Camino; Limam, Ferid

    2012-06-01

    An antagonist L194 strain against Phoma medicaginis pathogenic fungi was isolated from Tunisian soil (vicinity of Tunis) and identified as Bacillus subtilis based on biochemical characteristics and partial 16S rDNA sequence. When cells were grown in a minimal medium for 24 h, spore culture supernatant exhibited 2-fold higher antifungal activity than vegetative cells. MALDI-TOF mass spectrometry analysis showed that L194 spores produced mainly iturins, surfactins and fengycins with long-chain fatty acids, and other not yet identified compounds. Both vegetative cells and spores of L194 efficiently reduced germination of P. medicaginis conidia. As revealed by atomic force microscopy, L194 spores modified conidia morphology from a regular to a deflated shape. Data suggest that lipopeptides interacted with the cytoplasmic membrane, causing pore formation. In vivo, L194 spores were highly protective against P. medicaginis by reducing disease symptoms and alleviating growth disturbance of Medicago truncatula seedlings. As a whole, the lipopeptide-producing L194 strain may be successfully used in biocontrol of plant diseases induced by phytopathogenic fungi such as P. medicaginis.

  2. The crown-of-thorns starfish genome as a guide for biocontrol of this coral reef pest.

    PubMed

    Hall, Michael R; Kocot, Kevin M; Baughman, Kenneth W; Fernandez-Valverde, Selene L; Gauthier, Marie E A; Hatleberg, William L; Krishnan, Arunkumar; McDougall, Carmel; Motti, Cherie A; Shoguchi, Eiichi; Wang, Tianfang; Xiang, Xueyan; Zhao, Min; Bose, Utpal; Shinzato, Chuya; Hisata, Kanako; Fujie, Manabu; Kanda, Miyuki; Cummins, Scott F; Satoh, Noriyuki; Degnan, Sandie M; Degnan, Bernard M

    2017-04-05

    The crown-of-thorns starfish (COTS, the Acanthaster planci species group) is a highly fecund predator of reef-building corals throughout the Indo-Pacific region. COTS population outbreaks cause substantial loss of coral cover, diminishing the integrity and resilience of reef ecosystems. Here we sequenced genomes of COTS from the Great Barrier Reef, Australia and Okinawa, Japan to identify gene products that underlie species-specific communication and could potentially be used in biocontrol strategies. We focused on water-borne chemical plumes released from aggregating COTS, which make the normally sedentary starfish become highly active. Peptide sequences detected in these plumes by mass spectrometry are encoded in the COTS genome and expressed in external tissues. The exoproteome released by aggregating COTS consists largely of signalling factors and hydrolytic enzymes, and includes an expanded and rapidly evolving set of starfish-specific ependymin-related proteins. These secreted proteins may be detected by members of a large family of olfactory-receptor-like G-protein-coupled receptors that are expressed externally, sometimes in a sex-specific manner. This study provides insights into COTS-specific communication that may guide the generation of peptide mimetics for use on reefs with COTS outbreaks.

  3. Potential of Epicoccum purpurascens Strain 5615 AUMC as a Biocontrol Agent of Pythium irregulare Root Rot in Three Leguminous Plants

    PubMed Central

    Koutb, Mostafa

    2010-01-01

    Epicoccum purpurascens stain 5615 AUMC was investigated for its biocontrol activity against root rot disease caused by Pythium irregulare. E. purpurascens greenhouse pathogenicity tests using three leguminous plants indicated that the fungus was nonpathogenic under the test conditions. The germination rate of the three species of legume seeds treated with a E. purpurascens homogenate increased significantly compared with the seeds infested with P. irregulare. No root rot symptoms were observed on seeds treated with E. purpurascens, and seedlings appeared more vigorous when compared with the non-treated control. A significant increase in seedling growth parameters (seedling length and fresh and dry weights) was observed in seedlings treated with E. purpurascens compared to pathogen-treated seedlings. Pre-treating the seeds with the bioagent fungus was more efficient for protecting seeds against the root rot disease caused by P. irregulare than waiting for disease dispersal before intervention. To determine whether E. purpurascens produced known anti-fungal compounds, an acetone extract of the fungus was analyzed by gas chromatography mass spectrometry. The extract revealed a high percentage of the cinnamic acid derivative (trimethylsiloxy) cinnamic acid methyl ester. The E. purpurascens isolate grew more rapidly than the P. irregulare pathogen in a dual culture on potato dextrose agar nutrient medium, although the two fungi grew similarly when cultured separately. This result may indicate antagonism via antibiosis or competition. PMID:23956668

  4. Impact of osmotic/matric stress and heat shock on environmental tolerance induction of bacterial biocontrol agents against Fusarium verticillioides.

    PubMed

    Sartori, Melina; Nesci, Andrea; Etcheverry, Miriam

    2010-10-01

    Bacillus amyloliquefaciens and Microbacterium oleovorans reduced the Fusarium verticillioides count and significantly decreased fumonisin B(1) and B(2) levels in maize grains. The aim of this study was to determine the effect of water stress tolerance and heat shock survival upon cells of the biocontrol agents B. amyloliquefaciens and M. oleovorans. The a(w) of solid and liquid media and tryptic soy medium was modified to 0.99, 0.98, 0.97 and 0.96 by addition of ionic solute NaCl and non-ionic solutes such as glycerol and glucose. The non-ionic solute polyethylene glycol 600 (PEG 600) was used to modify matrically solid media. Bacterial incubation was at 30 °C. After 24, 48 and 72 h of incubation, samples from liquid media were spread-plate on nutrient agar medium and incubated for 24 h to determine the number of viable cells. The bacterial cells were harvested by centrifugation and heat treatment carried out in a water bath at 45 °C for 30 min. The viability of cells from different incubation times in liquid media showed statistically significant differences. Cells of B. amyloliquefaciens grown in liquid media amended with glycerol showed better tolerance at low a(w) and high survival under heat stress. These results could have important implications for optimizing and improving formulations.

  5. Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome

    PubMed Central

    Zhang, Tao; Chaturvedi, Vishnu; Chaturvedi, Sudha

    2015-01-01

    White-nose syndrome (WNS), an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd), the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp) from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1) Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C), (2) Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3) Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4) Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp), (5) Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6) Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites. PMID:26509269

  6. In vitro evaluation of Pseudomonas bacterial isolates from rice phylloplane for biocontrol of Rhizoctonia solani and plant growth promoting traits.

    PubMed

    Akter, Shamima; Kadir, Jugah; Juraimi, Abdul Shukor; Saud, Halimi Mohd

    2016-07-01

    The ability for biocontrol and plant growth promotion of three Pseudomonas bacterial isolates namely Pseudomonas fluorescens (UMB20), Pseudomonas aeruginosa (KMB25) and Pseudomonas asplenii (BMB42) obtained from rice plants was investigated. Fungal growth inhibition by the isolates ranged from 86.85 to 93.15% in volatile and 100% in diffusible metabolites test. Among the isolates, BMB42 showed fungal growth inhibition significantly in the volatile metabolite test. Isolates UMB20 and BMB42 were able to synthesis chitinase with chitinolytic indices of 13.66 and 13.50, respectively. In case of -1,3-glucanase, all the isolates showed activity to produce this enzyme at varied levels and isolate KMB25 showed significantly highest activity (53.53 ppm). Among the three isolates, KMB25 showed positive response to protease production and all of them were negative to pectinase and lipase and positive to the production of siderophore, and HCN, and were able to solubilize tricalcium phosphate. All the three bacterial isolates were capable of forming biofilm at different levels. Above results suggest that phylloplane Pseudomonas bacterial isolates have potential for antifungal activities and plant growth promotion.

  7. Production of trichodiene by Trichoderma harzianum alters the perception of this biocontrol strain by plants and antagonized fungi.

    PubMed

    Malmierca, Mónica G; McCormick, Susan P; Cardoza, Rosa E; Alexander, Nancy J; Monte, Enrique; Gutiérrez, Santiago

    2015-08-01

    Trichothecenes are phytotoxic sesquiterpenic mycotoxins that can act as virulence factors in plant diseases. Harzianum A (HA) is a non-phytotoxic trichothecene produced by Trichoderma arundinaceum. The first step in HA biosynthesis is the conversion of farnesyl diphosphate to trichodiene (TD), a volatile organic compound (VOC), catalysed by a sesquiterpene synthase encoded by the tri5 gene. Expression of tri5 in the biocontrol strain Trichoderma harzianum CECT 2413 resulted in production of TD in parallel with a reduction of ergosterol biosynthesis and an unexpected increase in the level of squalene. Transformants expressing tri5 displayed low chitinase activity and induced expression of Botrytis cinerea BOT genes, although their total antagonistic potential against phytopathogenic fungi was not reduced. VOCs released by the tri5-transformant induced expression of tomato defence genes related to salicylic acid (SA), and TD itself strongly induced the expression of SA-responsive genes and reduced the development of lateral roots. Together, these results suggest that TD acts as a signalling VOC in the interactions of Trichoderma with plants and other microorganisms by modulating the perception of this fungus to a given environment. Moreover, the TD ability to induce systemic defences indicates that complex trichothecene structures may not be necessary for inducing such responses.

  8. Lipopeptides, a novel protein, and volatile compounds contribute to the antifungal activity of the biocontrol agent Bacillus atrophaeus CAB-1.

    PubMed

    Zhang, Xiaoyun; Li, Baoqing; Wang, Ye; Guo, Qinggang; Lu, Xiuyun; Li, Shezeng; Ma, Ping

    2013-11-01

    Bacillus atrophaeus CAB-1 displays a high inhibitory activity against various fungal pathogens and suppresses cucumber powdery mildew and tomato gray mold. We extracted and identified lipopeptides and secreted proteins and volatile compounds produced by strain CAB-1 to investigate the mechanisms involved in its biocontrol performance. In vitro assays indicated all three types of products contributed to the antagonistic activity against the fungal pathogen Botrytis cinerea. Each of these components also effectively prevented the occurrence of the cucumber powdery mildew caused by Sphaerotheca fuliginea under greenhouse conditions. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry revealed that the major bioactive lipopeptide was fengycin A (C15-C17). We isolated the crude-secreted proteins of CAB-1 and purified a fraction with antifungal activity. This protein sequence shared a high identity with a putative phage-related pre-neck appendage protein, which has not been reported as an antifungal factor. The volatile compounds produced by CAB-1 were complex, including a range of alcohols, phenols, amines, and alkane amides. O-anisaldehyde represented one of the most abundant volatiles with the highest inhibition on the mycelial growth of B. cinerea. To our knowledge, this is the first report on profiling three types of antifungal substances in Bacilli and demonstrating their contributions to plant disease control.

  9. Behaviorally active green leaf volatiles for monitoring the leaf beetle, Diorhabda elongata, a biocontrol agent of saltcedar, Tamarix spp.

    PubMed

    Cossé, Allard A; Bartelt, Robert J; Zilkowski, Bruce W; Bean, Daniel W; Andress, Earl R

    2006-12-01

    Biological activity and chemistry of host plant volatiles were investigated for Diorhabda elongata, Brullé (Coleoptera: Chrysomelidae), a biological control agent for the invasive tree, saltcedar (Tamarix spp., Tamaricaceae). Gas chromatographic-electroantennographic detection (GC-EAD) analysis of volatiles collected from adult D. elongata feeding on saltcedar foliage or from saltcedar foliage alone showed 15 antennally active compounds. These compounds were more abundant in collections from beetle-infested foliage. Antennally active compounds were identified by GC-mass spectrometry (MS) and confirmed with authentic standards. The emissions of the most abundant GC-EAD-active compounds, green leaf volatiles (GLV), were quantitated by GC-MS. A blend of four GLV compounds, mimicking the natural blend ratio, was highly attractive to male and female D. elongata in the field, and a combination of GLV and male-produced aggregation pheromone attracted significantly greater numbers of D. elongata than did either bait alone. A preliminary experiment with a blend of seven additional GC-EAD-active saltcedar volatiles did not show any behavioral activity. The combination of the pheromone and the green leaf odor blend could be a useful attractant in detecting the presence of the biocontrol agent, D. elongata, in stands of saltcedar newly colonized by the beetle.

  10. [Discussion on applications and mechanisms of biocontrol microoganisms used for controlling medicinal plant soil-borne diseases].

    PubMed

    Yang, Li; Chen, Mei-Lan; Shao, Ai-Juan; Yang, Guang

    2012-11-01

    In recent years, the soil borne disease of medicinal plants becomes severely during the process of cultivation and directly endangered the production and quality of raw materials used in traditional Chinese medicine (TCM). The chemical pesticides have been constantly used to prevent and control the soil borne disease, but only a few are effective. Meanwhile, the excessive uses of chemical pesticides also lead pesticide residues in TCM, which often exceed limit of the standard, and harm the human health and cause environmental pollution. Therefore, biological control has become a hot research point for its environmental advantages. This paper mainly discussed the mechanisms of different species of microorganisms, which could control the soil borne disease of medicinal plants, from the following aspects: improving host plants' nutrient absorption, the nutrient and space competition with the pathogenic bacteria, changing the morphology and anatomical structure of roots, adjusting the host plants' endogenous hormones, restoring the balance of host rhizosphere soil microecology and activating the host plants' defense system etc. Then put forward the prospect of biocontrol agents in the future.

  11. Soil type dependent rhizosphere competence and biocontrol of two bacterial inoculant strains and their effects on the rhizosphere microbial community of field-grown lettuce.

    PubMed

    Schreiter, Susanne; Sandmann, Martin; Smalla, Kornelia; Grosch, Rita

    2014-01-01

    Rhizosphere competence of bacterial inoculants is assumed to be important for successful biocontrol. Knowledge of factors influencing rhizosphere competence under field conditions is largely lacking. The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica 3Re4-18 in field-grown lettuce in soils inoculated with Rhizoctonia solani AG1-IB or not. Two independent experiments were carried out in 2011 on an experimental plot system with three soil types sharing the same cropping history and weather conditions for more than 10 years. Rifampicin resistant mutants of the inoculants were used to evaluate their colonization in the rhizosphere of lettuce. The rhizosphere bacterial community structure was analyzed by denaturing gradient gel electrophoresis of 16S rRNA gene fragments amplified from total community DNA to get insights into the effects of the inoculants and R. solani on the indigenous rhizosphere bacterial communities. Both inoculants showed a good colonization ability of the rhizosphere of lettuce with more than 10(6) colony forming units per g root dry mass two weeks after planting. An effect of the soil type on rhizosphere competence was observed for 3Re4-18 but not for RU47. In both experiments a comparable rhizosphere competence was observed and in the presence of the inoculants disease symptoms were either significantly reduced, or at least a non-significant trend was shown. Disease severity was highest in diluvial sand followed by alluvial loam and loess loam suggesting that the soil types differed in their conduciveness for bottom rot disease. Compared to effect of the soil type of the rhizosphere bacterial communities, the effects of the pathogen and the inoculants were less pronounced. The soil types had a surprisingly low influence on rhizosphere competence and biocontrol activity while they significantly affected

  12. Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease.

    PubMed

    Hanada, Rogério Eiji; Pomella, Alan William V; Costa, Heron Salazar; Bezerra, José Luiz; Loguercio, Leandro L; Pereira, José O

    2010-01-01

    The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupuaçu) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupuaçu plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ∼70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies

  13. Impact of Biocontrol Pseudomonas fluorescens CHA0 and a Genetically Modified Derivative on the Diversity of Culturable Fungi in the Cucumber Rhizosphere

    PubMed Central

    Girlanda, M.; Perotto, S.; Moenne-Loccoz, Y.; Bergero, R.; Lazzari, A.; Defago, G.; Bonfante, P.; Luppi, A. M.

    2001-01-01

    Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day

  14. Requirement of simultaneous assessment of crystal- and supernatant-related entomotoxic activities of Bacillus thuringiensis strains for biocontrol-product development.

    PubMed

    Argôlo-Filho, Ronaldo Costa; Costa, Robson Luz; Pinheiro, Daniele Heloisa; Corrêa, Fábio Mathias; Valicente, Fernando Hercos; Pomella, Alan William Vilela; Loguercio, Leandro Lopes

    2014-05-20

    Bioinsecticides with lower concentrations of endospores/crystals and without loss of efficiency are economically advantageous for pest biocontrol. In addition to Cry proteins, other Bacillus thuringiensis (Bt) toxins in culture supernatants (SN) have biocontrol potential (e.g., Vip3A, Cry1I, Sip1), whereas others are unwanted (β-exotoxins), as they display widespread toxicity across taxa. A strain simultaneously providing distinct toxin activities in crystals and SN would be desirable for bioinsecticides development; however, strains secreting β-exotoxins should be discarded, independently of other useful entomotoxins. Entomotoxicity of crystals and SN from a Brazilian Bt tolworthi strain (Btt01) was tested against Spodoptera frugiperda to assess the potential for biocontrol-product development based on more than one type of toxin/activity. Tests showed that 10(7) endospores mL(-1) caused >80% of larvae mortality, suggesting Btt01 may be used in similar concentrations as those of other Bt-based biopesticides. When it was applied to cornfields, a significant 60% reduction of larvae infestation was observed. However, bioassays with Btt01 SN revealed a thermostable toxic activity. Physicochemical characterization strongly suggests the presence of unwanted β-exotoxins, with isolate-specific temporal variation in its secretion. Knowledge of the temporal pattern of secretion/activity in culture for all forms of toxins produced by a single strain is required to both detect useful activities and avoid the potential lack of identification of undesirable toxins. These findings are discussed in the contexts of commercial Bt product development, advantages of multiple-activity strains, and care and handling recommended for large-scale fermentation systems.

  15. Requirement of Simultaneous Assessment of Crystal- and Supernatant-Related Entomotoxic Activities of Bacillus thuringiensis Strains for Biocontrol-Product Development

    PubMed Central

    Argôlo-Filho, Ronaldo Costa; Costa, Robson Luz; Pinheiro, Daniele Heloisa; Corrêa, Fábio Mathias; Valicente, Fernando Hercos; Pomella, Alan William Vilela; Loguercio, Leandro Lopes

    2014-01-01

    Bioinsecticides with lower concentrations of endospores/crystals and without loss of efficiency are economically advantageous for pest biocontrol. In addition to Cry proteins, other Bacillus thuringiensis (Bt) toxins in culture supernatants (SN) have biocontrol potential (e.g., Vip3A, Cry1I, Sip1), whereas others are unwanted (β-exotoxins), as they display widespread toxicity across taxa. A strain simultaneously providing distinct toxin activities in crystals and SN would be desirable for bioinsecticides development; however, strains secreting β-exotoxins should be discarded, independently of other useful entomotoxins. Entomotoxicity of crystals and SN from a Brazilian Bt tolworthi strain (Btt01) was tested against Spodoptera frugiperda to assess the potential for biocontrol-product development based on more than one type of toxin/activity. Tests showed that 107 endospores mL−1 caused >80% of larvae mortality, suggesting Btt01 may be used in similar concentrations as those of other Bt-based biopesticides. When it was applied to cornfields, a significant 60% reduction of larvae infestation was observed. However, bioassays with Btt01 SN revealed a thermostable toxic activity. Physicochemical characterization strongly suggests the presence of unwanted β-exotoxins, with isolate-specific temporal variation in its secretion. Knowledge of the temporal pattern of secretion/activity in culture for all forms of toxins produced by a single strain is required to both detect useful activities and avoid the potential lack of identification of undesirable toxins. These findings are discussed in the contexts of commercial Bt product development, advantages of multiple-activity strains, and care and handling recommended for large-scale fermentation systems. PMID:24854738

  16. Health economic impacts and cost-effectiveness of aflatoxin-reduction strategies in Africa: case studies in biocontrol and post-harvest interventions.

    PubMed

    Wu, F; Khlangwiset, P

    2010-04-01

    Advances in health economics have proven useful in evaluating the cost-effectiveness of interventions, where the benefit usually takes the form of improved health outcomes rather than market outcomes. The paper performs health-based cost-effectiveness analyses of two potential aflatoxin control strategies in Africa: (1) pre-harvest biocontrol, using atoxigenic strains of Aspergillus flavus competitively to exclude toxigenic strains from colonizing maize in Nigeria; and (2) post-harvest interventions in a package to reduce aflatoxin accumulation in groundnuts in Guinea. It is described how health benefits gained from each intervention, in terms of fewer aflatoxin-induced hepatocellular carcinoma cases, can be compared with the costs of implementing the interventions. It is found that both interventions would be extremely cost-effective if applied widely in African agriculture. That is, the monetized value of lives saved and quality of life gained by reducing aflatoxin-induced hepatocellular carcinoma far exceeds the cost of either biocontrol or the post-harvest intervention package to achieve those health benefits. The estimated cost-effectiveness ratio (CER; gross domestic product multiplied by disability-adjusted life years saved per unit cost) for biocontrol in Nigerian maize ranged from 5.10 to 24.8; while the estimated CER for the post-harvest intervention package in Guinean groundnuts ranged from 0.21 to 2.08. Any intervention with a CER > 1 is considered by the World Health Organization (WHO) to be 'very cost-effective', while an intervention with a CER > 0.33 is considered 'cost-effective'. Aside from cost-effectiveness, public health interventions must be readily accepted by the public, and must have financial and infrastructural support to be feasible in the parts of the world where they are most needed.

  17. The SRAP based molecular diversity related to antifungal and antioxidant bioactive constituents for biocontrol potentials of Trichoderma against Sclerotium rolfsii Scc.

    PubMed

    Hirpara, Darshna G; Gajera, H P; Bhimani, R D; Golakiya, B A

    2016-08-01

    The study was performed to examine 11 isolates of Trichoderma for their bio-control potentials against Sclerotium rolfsii Sacc. causing stem rot in groundnut. The antagonists Trichoderma were subjected to sequence related amplified polymorphism (SRAP) based molecular diversity analysis and compared with their hardness to S. rolfsii with respect to secretary antifungal and antioxidant profile. T. virens NBAII Tvs 12 evident highest (87.91 %) growth inhibition of test pathogen followed by T. koningii MTCC 796 (67.03 %) at 7 days after inoculation (DAI). Microscopic study confirmed biocontrol mechanism as mycoparasitism for Tvs 12 and antibiosis for MTCC 796. The growth inhibition of test pathogen was significantly negatively correlated with sclerotia formation and lipid peroxidation during antagonism due to release of secretary bioactive antioxidants by antagonists to terminate oxidative burst generated by S. rolfsii and causing inhibition of sclerotium formation. The GC-MS profile identified antifungal and antioxidant constituents hexadecane, 1,2-benzenedicarboxylic acid, mono (2-ethylhexyl) ester, 1-hexadecanesulfonyl chloride, and octadecane in potent antagonists Tvs 12; and nonacosane and octadecane in MTCC 796 along with two novel compounds 1-pentadecene and 1-heneicosyl formate for biocontrol activity. Molecular diversity of Trichoderma isolates associated with antagonistic activity was assessed by SRAP markers. The 115 primer combinations generate total 1328 amplified products of which, 1095 are shared polymorphic and 199 are unique polymorphic. The 15 SRAP combinations produced 18 bands to diagnose best antagonist Tvs 12 and 13 SRAP combinations generated 19 unique bands for identification of MTCC 796. The mycoparasitic antagonist Tvs 12 would be the best antagonist and released unique antifungal and antioxidant constituents to combat pathogen infection. The SRAP based genetic diversity indicates Tvs12 strain clustered with T. viride NBAII Tv23 and shared

  18. Do Biopesticides Affect the Demographic Traits of a Parasitoid Wasp and Its Biocontrol Services through Sublethal Effects?

    PubMed Central

    Biondi, Antonio; Zappalà, Lucia; Stark, John D.; Desneux, Nicolas

    2013-01-01

    Pesticide risk assessments are usually based on short-term acute toxicity tests, while longer-term population dynamic related traits, critical to the success of biological control and Integrated Pest Management (IPM) programs, are often overlooked. This is increasingly important with respect to new biopesticides that frequently cause no short-term acute effects, but that can induce multiple physiological and behavioral sublethal effects, leading to a decrease in population growth and ecosystem services. In this study we assessed the lethal and sublethal effects of six biopesticides [abamectin, azadirachtin, Bacillus thuringiensis, borax plus citrus oil (Prev-Am®), emamectin benzoate, and spinosad], used in tomato crops to control the invasive pest Tuta absoluta (Lepidoptera: Gelechiidae), on adults and pupae of the parasitoid Bracon nigricans (Hymenoptera: Braconidae). Data on female survival and production of female offspring were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinosad caused 100% and 80% mortality in exposed adults (even 10 d after the treatment) and pupae, respectively. Although most of the biopesticides had low levels of acute toxicity, multiple sublethal effects were observed. The biocontrol activity of both females that survived 1-h and 10-d old residues, and females that emerged from topically treated pupae was significantly affected by the application of the neurotoxic insecticides emamectin benzoate and abamectin. Furthermore, very low B. nigricans demographic growth indices were estimated for these two insecticides, indicating potential local extinction of the wasp populations. Among the tested products, Bt proved to be the safest for B. nigricans adults and pupae. Our findings emphasize that acute toxicity assessment alone cannot fully predict the actual impact of pesticides on non-target parasitoids. Thus, sublethal effects related to the species specific life-history variables

  19. Studies of plant colonisation by closely related Bacillus amyloliquefaciens biocontrol agents using strain specific quantitative PCR assays.

    PubMed

    Johansson, Anna H; Bejai, Sarosh; Niazi, Adnan; Manzoor, Shahid; Bongcam-Rudloff, Erik; Meijer, Johan

    2014-12-01

    Certain strains of Bacillus amyloliquefaciens can colonize plants and improve growth and stress management. In order to study these effects, bacterial growth dynamics on plants and in the rhizosphere are of interest calling for specific analytical tools. For that purpose, quantitative real-time PCR (qPCR) assays were developed in order to differentiate among three closely related B. amyloliquefaciens subsp. plantarum strains (UCMB5033, UCMB5036, UCMB5113) and to determine their levels with high accuracy. Oligonucleotide primers were designed for strain unique gene sequences and used for SYBR green based qPCR analysis. Standard curves covered a wide linear range (10(6)) of DNA amounts with the lowest detection level at 50 fg. Post-reaction melting curve analysis showed only a single product. Accurate threshold cycles were obtained, even in the presence of high excess of related Bacillus strains and total bacterial DNA from soil. Analysis of Bacillus colonisation after seed treatment of two oilseed rape cultivars (Oase and Ritz) grown on agar support showed a time dependent effect but that the bacteria mostly were found on root tissues and little on green tissues. The colonisation on plants grown in soil varied among the Bacillus strains where Oase seemed to house more bacteria than Ritz. Applied as a mixture, all three Bacillus strains co-existed on the roots of plants grown in soil. The qPCR assay in combination with other techniques will be a powerful tool to study plant interactions of these B. amyloliquefaciens biocontrol agents to further understand the requirements for successful interactions and improvement of plant properties.

  20. Can the halophilic ciliate Fabrea salina be used as a bio-control of microalgae blooms in solar salterns?

    NASA Astrophysics Data System (ADS)

    Hong, Hyun Pyo; Choi, Joong Ki

    2015-09-01

    The microlage Dunaliella salina, a major producer in salterns, is a serious problem for salt production. In this study we tried to assess if Fabrea salina can control D. salina. By parameterising numerical and functional response (growth and grazing vs prey abundance, respectively) at 90 psu and 30°C, where the ciliate is abundant and grows well, we developed a predator-prey model. The model is used to explore how change in microalga growth rate affect the dynamics, and the functional response is used in combination with field data to assess the potential impact of F. salina on D. salina. Over the 20 d simulation the ciliate controlled the prey population under all prey growth rates; although once D. salina were exhausted below the threshold level, F. salina died due to starvation, allowing the alga to increase in abundance, resulting in one or two predatorprey cycle, depending on prey growth rate. In general, the model predicted trends observed by others in the field, suggesting that it provided a good prediction of what may occur under the conditions we examined. Likewise we show that the ciliate can have a high impact on microalgal populations in the field. Finally, a literature review indicated that F. salina could be a good competitor with other protozoa and metazoan in salterns, depending on salinity and temperature, which requires further study and attention. In summary, we encourage continued studies on this unique ciliate on solar salterns and suggest that it may be useful in the bio-control of micoalgae.

  1. Biocontrol of Rhizoctonia solani damping-off disease in cucumber with Bacillus pumilus SQR-N43.

    PubMed

    Huang, Xinqi; Zhang, Nan; Yong, Xiaoyu; Yang, Xingming; Shen, Qirong

    2012-03-20

    Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Micrographs were used to investigate the ability of Bacillus pumilus (B. pumilus) SQR-N43 to control Rhizoctonia solani (R. solani) Q1 in cucumbers. The root colonization ability of B. pumilus SQR-N43 was analyzed in vivo with a green fluorescent protein (GFP) tag. A pot experiment was performed to assess the in vivo disease-control efficiency of B. pumilus SQR-N43 and its bio-organic fertilizer. Results indicate that B. pumilus SQR-N43 induced hyphal deformation, enlargement of cytoplasmic vacuoles and cytoplasmic leakage in R. solani Q1 mycelia. A biofilm on the root surface was formed when the roots were inoculated with 10(7)-10(8)cells g(-1) of soil of GFP-tagged B. pumilus SQR-N43. In the pot experiment, the biocontrol reduced the concentration of R. solani. In contrast to applications of only B. pumilus SQR-N43 (N treatment), which produced control efficiencies of 23%, control efficiencies of 68% were obtained with applications of a fermented organic fertilizer inoculated with B. pumilus SQR-N43 (BIO treatment). After twenty days of incubation, significant differences in the number of CFUs and the percentage of spores of B. pumilus SQR-N43 were recorded between the N treatment (2.20×10(7)CFU g(-1) of soil and 79%, respectively) and the BIO treatment (1.67×10(8)CFU g(-1) of soil and 52%, respectively). The results indicate that B. pumilus SQR-N43 is a potent antagonist against R. solani Q1. The BIO treatment was more effective than the N treatment because it stabilized the population and increased the active form of the antagonist.

  2. Influence of container design on predation rate of potential biocontrol agent, Toxorhynchites splendens (Diptera: Culicidae) against dengue vector.

    PubMed

    Mohamad, N; Zuharah, W F

    2014-03-01

    Toxorhynchites splendens larvae are a natural predator of dengue vector mosquito larvae, Aedes albopictus. This study was carried out to evaluate the predation rate of Tx. splendens third instar larvae on Ae. albopictus larvae in 24 h. Each predator was offered prey at a density between 10 to 50 individuals. Predation rate of Tx. splendens were also tested with two manipulated factors; various types of container and different water volumes. The experiment was evaluated in man-made containers (tin cans, plastic drinking glasses and rubber tires) and natural container (bamboo stumps) which were filled with different water volumes (full, half full, 1/4 full, and 1/8 full). The prey density and the characteristics of the container were found as significant factors which influence the predation rate of Tx. splendens. The predator consumed significantly more prey at higher prey densities (40 and 50 preys) compared to the lowest density (10 preys) (F=3.935, df=4, p=0.008). The results showed significantly higher consumption in horizontal shaped container of rubber tire than in vertical shape of bamboo stumps (F=3.100, df=3, p=0.029). However, the water volume had no significant effect on predation rate of Tx. splendens (F=1.736, df=3, p=0.162). We generally suggest that Tx. splendens is best to be released in discarded tires or any other containers with horizontal shape design with wide opening since Tx. splendens can become more effective in searching prey in this type of container design. This predator is also a suitable biocontrol candidates to be introduced either in wet and dry seasons in Malaysia.

  3. Do biopesticides affect the demographic traits of a parasitoid wasp and its biocontrol services through sublethal effects?

    PubMed

    Biondi, Antonio; Zappalà, Lucia; Stark, John D; Desneux, Nicolas

    2013-01-01

    Pesticide risk assessments are usually based on short-term acute toxicity tests, while longer-term population dynamic related traits, critical to the success of biological control and Integrated Pest Management (IPM) programs, are often overlooked. This is increasingly important with respect to new biopesticides that frequently cause no short-term acute effects, but that can induce multiple physiological and behavioral sublethal effects, leading to a decrease in population growth and ecosystem services. In this study we assessed the lethal and sublethal effects of six biopesticides [abamectin, azadirachtin, Bacillus thuringiensis, borax plus citrus oil (Prev-Am®), emamectin benzoate, and spinosad], used in tomato crops to control the invasive pest Tuta absoluta (Lepidoptera: Gelechiidae), on adults and pupae of the parasitoid Bracon nigricans (Hymenoptera: Braconidae). Data on female survival and production of female offspring were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinosad caused 100% and 80% mortality in exposed adults (even 10 d after the treatment) and pupae, respectively. Although most of the biopesticides had low levels of acute toxicity, multiple sublethal effects were observed. The biocontrol activity of both females that survived 1-h and 10-d old residues, and females that emerged from topically treated pupae was significantly affected by the application of the neurotoxic insecticides emamectin benzoate and abamectin. Furthermore, very low B. nigricans demographic growth indices were estimated for these two insecticides, indicating potential local extinction of the wasp populations. Among the tested products, Bt proved to be the safest for B. nigricans adults and pupae. Our findings emphasize that acute toxicity assessment alone cannot fully predict the actual impact of pesticides on non-target parasitoids. Thus, sublethal effects related to the species specific life-history variables

  4. DNA Polymorphisms and Biocontrol of Bacillus Antagonistic to Citrus Bacterial Canker with Indication of the Interference of Phyllosphere Biofilms

    PubMed Central

    Huang, Tzu-Pi; Tzeng, Dean Der-Syh; Wong, Amy C. L.; Chen, Chun-Han; Lu, Kuan-Min; Lee, Ya-Huei; Huang, Wen-Di; Hwang, Bing-Fang; Tzeng, Kuo-Ching

    2012-01-01

    Citrus bacterial canker caused by Xanthomonas axonopodis pv. citri is a devastating disease resulting in significant crop losses in various citrus cultivars worldwide. A biocontrol agent has not been recommended for this disease. To explore the potential of bacilli native to Taiwan to control this disease, Bacillus species with a broad spectrum of antagonistic activity against various phytopathogens were isolated from plant potting mixes, organic compost and the rhizosphere soil. Seven strains TKS1-1, OF3-16, SP4-17, HSP1, WG6-14, TLB7-7, and WP8-12 showing superior antagonistic activity were chosen for biopesticide development. The genetic identity based on 16S rDNA sequences indicated that all seven native strains were close relatives of the B. subtilis group and appeared to be discrete from the B. cereus group. DNA polymorphisms in strains WG6-14, SP4-17, TKS1-1, and WP8-12, as revealed by repetitive sequence-based PCR with the BOXA1R primers were similar to each other, but different from those of the respective Bacillus type strains. However, molecular typing of the strains using either tDNA-intergenic spacer regions or 16S–23S intergenic transcribed spacer regions was unable to differentiate the strains at the species level. Strains TKS1-1 and WG6-14 attenuated symptom development of citrus bacterial canker, which was found to be correlated with a reduction in colonization and biofilm formation by X. axonopodis pv. citri on leaf surfaces. The application of a Bacillus strain TKS1-1 endospore formulation to the leaf surfaces of citrus reduced the incidence of citrus bacterial canker and could prevent development of the disease. PMID:22848728

  5. Peptaibol, secondary-metabolite, and hydrophobin pattern of commercial biocontrol agents formulated with species of the Trichoderma harzianum complex.

    PubMed

    Degenkolb, Thomas; Fog Nielsen, Kristian; Dieckmann, Ralf; Branco-Rocha, Fabiano; Chaverri, Priscila; Samuels, Gary J; Thrane, Ulf; von Döhren, Hans; Vilcinskas, Andreas; Brückner, Hans

    2015-04-01

    The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics in plant-protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna(®) , Trichosan(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary metabolites, were detected, the latter being known for their antifungal, siderophore, or plant-growth-promoting activities. Notably, none of the isolates produced low-molecular weight mycotoxins.

  6. Biosynthesis of Antibiotic Leucinostatins in Bio-control Fungus Purpureocillium lilacinum and Their Inhibition on Phytophthora Revealed by Genome Mining

    PubMed Central

    Li, Erfeng; Mao, Zhenchuan; Ling, Jian; Yang, Yuhong; Yin, Wen-Bing; Xie, Bingyan

    2016-01-01

    Purpureocillium lilacinum of Ophiocordycipitaceae is one of the most promising and commercialized agents for controlling plant parasitic nematodes, as well as other insects and plant pathogens. However, how the fungus functions at the molecular level remains unknown. Here, we sequenced two isolates (PLBJ-1 and PLFJ-1) of P. lilacinum from different places Beijing and Fujian. Genomic analysis showed high synteny of the two isolates, and the phylogenetic analysis indicated they were most related to the insect pathogen Tolypocladium inflatum. A comparison with other species revealed that this fungus was enriched in carbohydrate-active enzymes (CAZymes), proteases and pathogenesis related genes. Whole genome search revealed a rich repertoire of secondary metabolites (SMs) encoding genes. The non-ribosomal peptide synthetase LcsA, which is comprised of ten C-A-PCP modules, was identified as the core biosynthetic gene of lipopeptide leucinostatins, which was specific to P. lilacinum and T. ophioglossoides, as confirmed by phylogenetic analysis. Furthermore, gene expression level was analyzed when PLBJ-1 was grown in leucinostatin-inducing and non-inducing medium, and 20 genes involved in the biosynthesis of leucionostatins were identified. Disruption mutants allowed us to propose a putative biosynthetic pathway of leucinostatin A. Moreover, overexpression of the transcription factor lcsF increased the production (1.5-fold) of leucinostatins A and B compared to wild type. Bioassays explored a new bioactivity of leucinostatins and P. lilacinum: inhibiting the growth of Phytophthora infestans and P. capsici. These results contribute to our understanding of the biosynthetic mechanism of leucinostatins and may allow us to utilize P. lilacinum better as bio-control agent. PMID:27416025

  7. The effect of locust bean gum (LBG)-based edible coatings carrying biocontrol yeasts against Penicillium digitatum and Penicillium italicum causal agents of postharvest decay of mandarin fruit.

    PubMed

    Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

    2016-09-01

    Strains belonging to Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans species were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic molds Penicillium digitatum and Penicillium italicum. Moreover, studies aimed at screening the antifungal activity of selected yeast strains in vivo conditions against P. digitatum and P. italicum, and investigated the efficacy of a polysaccharidic matrix, locust bean gum (LBG), enriched with the tested BCAs, in controlling postharvest decays in artificially inoculated mandarins. The population dynamics of BCAs on wounds and the magnitude of peroxidase (POD) and superoxide dismutase (SOD) in fruit tissues were also investigated after treatments of mandarins with antagonistic yeasts. W. anomalus BS91, M. pulcherrima MPR3 and A. pullulans PI1 provided excellent control of postharvest decays caused by P. digitatum and P. italicum on mandarins, both when the yeasts were used alone and in combination with LBG, which enhanced the yeast cell viability over time. Finally, the increased activity of POD and lower decrease in SOD activity in response to BCAs application in mandarin fruits confirmed their involvement in the biocontrol mechanism.

  8. Multifunctional exopolysaccharides from Pseudomonas aeruginosa PF23 involved in plant growth stimulation, biocontrol and stress amelioration in sunflower under saline conditions.

    PubMed

    Tewari, Sakshi; Arora, Naveen Kumar

    2014-10-01

    Isolate PF23 selected from among 110 fluorescent pseudomonads, identified as Pseudomonas aeruginosa, displayed salinity tolerance and exopolysaccharides (EPS) production up to 2,000 mM NaCl concentration. EPS-defective mutant PF23(EPS-) of the isolate showed 86 % reduction in EPS production in comparison with wild strain. Defect in EPS production brought loss in salt tolerance capability. Purified EPS obtained from PF23 displayed multiple roles. At low concentration EPS functioned as biocontrol agent, at high concentration EPS behaved as osmoprotective or stress ameliorating metabolite and when introduced in saline soil, served as a plant growth promotor along with seed biopriming agent. Both in planta and in vivo studies were performed taking sunflower as a test crop and it was observed that PF23 showed plant growth promotion and significant biocontrol potential against dreadful phytopathogen Macrophomina phaseolina (under saline conditions). The mutant PF23(EPS-) was ineffective under saline conditions both in growth enhancement as well as in disease suppression. The study reports a potent strain, Pseudomonas aeruginosa PF23, capable of enhancing production of sunflower crop in semiarid regions and minimizing the incidence of charcoal rot disease in sunflower.

  9. The major volatile compound 2-phenylethanol from the biocontrol yeast, Pichia anomala, inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus.

    PubMed

    Hua, Sui Sheng T; Beck, John J; Sarreal, Siov Bouy L; Gee, Wai

    2014-05-01

    Aspergillus flavus is a ubiquitous saprophyte that is able to produce the most potent natural carcinogenic compound known as aflatoxin B1 (AFB1). This toxin frequently contaminates crops including corn, cotton, peanuts, and tree nuts causing substantial economic loss worldwide. Consequently, more than 100 countries have strict regulations limiting AFB1 in foodstuffs and feedstuffs. Plants and microbes are able to produce volatile compounds that act as a defense mechanism against other organisms. Pichia anomala strain WRL-076 is a biocontrol yeast currently being tested to reduce AF contamination of tree nuts in California. We used the SPME-GC/MS analysis and identified the major volatile compound produced by this strain to be 2-phenylethanol (2-PE). It inhibited spore germination and AF production of A. flavus. Inhibition of AF formation by 2-PE was correlated with significant down regulation of clustering AF biosynthesis genes as evidenced by several to greater than 10,000-fold decrease in gene expression. In a time-course analysis we found that 2-PE also altered the expression patterns of chromatin modifying genes, MYST1, MYST2, MYST3, gcn5, hdaA and rpdA. The biocontrol capacity of P. anomala can be attributed to the production of 2-PE, which affects spore germination, growth, toxin production, and gene expression in A. flavus.

  10. Study on Interactions between the Major Apple Valsa Canker Pathogen Valsa mali and Its Biocontrol Agent Saccharothrix yanglingensis Hhs.015 Using RT-qPCR

    PubMed Central

    Fan, Dongying; Li, Yanfang; Zhao, Lingyun; Li, Zhengpeng; Huang, Lili; Yan, Xia

    2016-01-01

    The mechanism of biocontrol agent Saccharothrix yanglingensis Hhs.015 action against Valsa mali, a major apple Valsa canker pathogen, was examined using a novel, sensitive (minimum detection limit 100 pg/μL) and reliably RT-qPCR technique. Prior to lesion formation, total concentration of V. mali in the bark showed a significant decrease (p<0.05) after 24 h of Hhs.015 treatment. This was more pronounced at 48 and 96 h post treatment. After lesion formation, levels of V. mali remained constant at the boundary between infected and uninfected bark tissues, although the relative expansion rate of the lesion was significantly reduced (p<0.05). Gene expression levels of endo-polygalacturonase, a marker for fungal pathogenicity, were sharply reduced while host induced resistance callose synthase levels increased significantly (p<0.05) at the boundary bark at 9 d after Hhs.015 treatment. The results showed that biocontrol agent Hhs.015 prevented infection of V. mali by inhibiting pathogen growth, down-regulating pathogenicity factor expression and inducing a high level of host resistance. PMID:27611855

  11. Influence of host plant genotype, presence of a pathogen, and coinoculation with Pseudomonas fluorescens strains on the rhizosphere expression of hydrogen cyanide- and 2,4-diacetylphloroglucinol biosynthetic genes in P. fluorescens biocontrol strain CHA0.

    PubMed

    Jamali, Fatemeh; Sharifi-Tehrani, Abbas; Lutz, Matthias P; Maurhofer, Monika

    2009-02-01

    The production of hydrogen cyanide (HCN) and 2,4-diacetylphloroglucinol (DAPG) is a major factor in the control of soil-borne diseases by Pseudomonas fluorescens CHA0. We investigated the impact of different biotic factors on the expression of HCN-in comparison to DAPG biosynthetic genes in the rhizosphere. To this end, the influence of plant cultivar, pathogen infection, and coinoculation with other biocontrol strains on the expression of hcnA-lacZ and phlA-lacZ fusion in strain CHA0 was monitored on the roots of bean. Interestingly, all the tested factors influenced the expression of the two biocontrol traits in a similar way. For both genes, we observed a several-fold higher expression in the rhizosphere of cv. Derakhshan compared with cvs. Goli and Naz, although bacterial rhizosphere colonization levels were similar on all cultivars tested. Root infection by Rhizoctonia solani stimulated total phlA and hcnA gene expression in the bean rhizosphere. Coinoculation of strain CHA0 with DAPG-producing P. fluorescens biocontrol strains Pf-68 and Pf-100 did neither result in a substantial alteration of hcnA nor of phlA expression in CHA0 on bean roots. To our best knowledge, this is the first study investigating the impact of biotic factors on HCN production by a bacterial biocontrol strain in the rhizosphere.

  12. Wonder world of phages: potential biocontrol agents safeguarding biosphere and health of animals and humans- current scenario and perspectives.

    PubMed

    Tiwari, Ruchi; Chakraborty, Sandip; Dhama, Kuldeep; Wani, Mohd Yaqoob; Kumar, Amit; Kapoor, Sanjay

    2014-02-01

    Darwin's theory of natural selection and concept of survival of fittest of Wallace is a universal truth which derives the force of life among all live entities on this biosphere. Issues regarding food safety along with increased drug resistance and emerging zoonotic infections have proved that multidisciplinary efforts are in demand for human and animal welfare. This has led to development of various novel therapies the list of which remains incomplete without mentioning about phages. Homologous and non-homologous recombination along with point mutation and addition of new genes play role in their evolution. The rapid emergence of the antibiotic resistant strains of bacteria have created keen interest in finding necessary alternatives to check microbial infections and there comes the importance of phages. Phages kill the bacteria either by lysis or by releasing holins. Bacteriophages; the viruses that live on bacteria are nowadays considered as the best biocontrol agents. They are used as replacers of antibiotics; food industry promoter; guard of aquatic life as well as of plants; pre-slaughter treatment agents; Generally Recognized As Safe (GRAS) food additives; Typing agent of bacteria; active tool of super bug therapy; in post harvest crops and food and during post infection and also to combat intracellular pathogens viz. Mycobacteria and Mycoplasma. Cyanophages/phycophages are particularly useful in controlling blooms produced by various genera of algae and cyanobacteria. By performing centrifugation studies and based on electron microscopy certain virus like particles containing ds RNA have been confirmed as mycophages. They are well proven as threat to pathogenic fungi (both fungal hyphae and yeast). Those that infect yeasts are called zymophages. Virophages have exquisite specificity for their viral host, hence can extensively be used for genetic studies and can also act as evolutionary link. After the discovery of very first virophage till now, a total of 3

  13. An endophytic Streptomyces sp. strain DHV3-2 from diseased root as a potential biocontrol agent against Verticillium dahliae and growth elicitor in tomato (Solanum lycopersicum).

    PubMed

    Cao, Peng; Liu, Chongxi; Sun, Pengyu; Fu, Xuepeng; Wang, Shaoxian; Wu, Fengzhi; Wang, Xiangjing

    2016-12-01

    Plant endophytes play important roles in biocontrol of plant diseases. Actinomycetes are used for biocontrol of fungal diseases caused by Verticillium dahliae. Many studies have focused on the endophytic actinomycetes isolated from the roots of healthy plants, but few on those from the roots of diseased plants. In the present research, actinomycetes were isolated from the roots of diseased and healthy tomato plants, respectively. The results showed that, in total, 86 endophytic actinomycetes were isolated for screening of their antimicrobial activities, 8 of which showed antagonism to V. dahliae in vitro. Among the 8 antagonistic strains, 5 (out of 36) were from the roots of diseased plants, with inhibition diameter zones ranging from 11.2 to 18.2 mm, whereas 3 (out of 50) were from the roots of healthy plants, with inhibition diameter zones ranging from 11.5 to 15.5 mm. Endophytic strain DHV3-2 was isolated from the root of a diseased plant and demonstrated a potent effect against V. dahliae and other pathogenic fungi by showing the largest inhibition diameter zones among all the eight antagonistic strains. Thus, strain DHV3-2 was chosen to investigate its biological control efficacies in vivo. Further study showed that the disease incidence and disease severity indices of tomato Verticillium wilt decreased significantly (P < 0.05). We also found that the plant shoot fresh weight and height increased greatly (P < 0.05) upon treatment with strain DHV3-2 compared to the plants uninoculated in greenhouse conditions. Root colonization showed that strain DHV3-2 had the higher root-colonizing capacity in the roots of infected plants compared with the roots of healthy plants. This isolate was identified as Streptomyces sp. based on morphological characteristics and 16S rRNA gene analysis. In conclusion, the roots of diseased tomato plants are a potential reservoir of biological control actinomycetes, and Streptomyces sp. strain DHV3-2 is a potential biocontrol

  14. Effect of temperature and host plant leaf morphology on the efficacy of two entomopathogenic biocontrol agents of Thrips palmi (Thysanoptera: Thripidae).

    PubMed

    Cuthbertson, A G S; North, J P; Walters, K F A

    2005-08-01

    The efficacy of two entomopathogenic biocontrol agents, Steinernema feltiae (Filipjev) and Verticillium lecanii (Zimmerman) Viégas (reclassified now as Lecanicillium muscarium (Petch) Zare & Gams), against Thrips palmi Karny was investigated. Assessments of the effect of temperature on the efficacy of S. feltiae indicated that higher mortality of T. palmi was recorded at 20 degrees C compared to either 15 or 25 degrees C, whereas significantly higher T. palmi mortality followed application of L. muscarium at 25 degrees C. Testing the control agents efficacy on three host plants; chrysanthemum, sweet pepper and cucumber, under constant temperature and high humidity conditions produced no significant difference in the level of T. palmi larval mortality on each host plant. Incorporating the chemical insecticide imidacloprid with both biological agents in a combined control strategy increased T. palmi juvenile mortality. The potential role of S. feltiae and L. muscarium within integrated pest management programmes for the control of T. palmi is discussed.

  15. Genome Sequences and Characterization of the Related Gordonia Phages GTE5 and GRU1 and Their Use as Potential Biocontrol Agents

    PubMed Central

    Tillett, Daniel; Seviour, Robert J.

    2012-01-01

    Activated sludge plants suffer frequently from the operational problem of stable foam formation on aerobic reactor surfaces, which can be difficult to prevent. Many foams are stabilized by mycolic acid-containing Actinobacteria, the mycolata. The in situ biocontrol of foaming using phages is an attractive strategy. We describe two polyvalent phages, GTE5 and GRU1, targeting Gordonia terrae and Gordonia rubrupertincta, respectively, isolated from activated sludge. Phage GRU1 also propagates on Nocardia nova. Both phages belong to the family Siphoviridae and have similar-size icosahedral heads that encapsulate double-stranded DNA genomes (∼65 kb). Their genome sequences are similar to each other but markedly different from those of other sequenced phages. Both are arranged in a modular fashion. These phages can reduce or eliminate foam formation by their host cells under laboratory conditions. PMID:22038604

  16. Typhlodromus pyri and Euseius finlandicus (Acari: Phytoseiidae) as potential biocontrol agents against spider mites (Acari: Tetranychidae) inhabiting willows: laboratory studies on predator development and reproduction on four diets.

    PubMed

    Puchalska, Ewa K; Kozak, Marcin

    2016-01-01

    Typhlodromus pyri Scheuten and Euseius finlandicus (Oudemans) are important predators of phytophagous mites. The present laboratory study aimed to determine whether both species can develop and reach maturity feeding on spider mites occurring on willows, i.e., Schizotetranychus schizopus (Zacher), Schizotetranychus garmani Pritchard & Baker, and Tetranychus urticae Koch, and on Brassica napus L. pollen. The predators' development, reproduction and demographic parameters were significantly affected by diet. The data suggest that rape pollen can be useful in mass rearing of E. finlandicus but is completely unsuitable as alternative food for T. pyri. Short development time and high values of population parameters achieved by T. pyri feeding on larvae and protonymphs of S. schizopus and by E. finlandicus feeding on juvenile stages of S. garmani indicate great suitability of these preys as food for the phytoseiids, and make both predatory species promising biocontrol agents in spider mite control on willows.

  17. Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

    PubMed Central

    Manhas, Rajesh K.; Kaur, Talwinder

    2016-01-01

    Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75–80%) and vigor index (1167–1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers. PMID:28018402

  18. Use of Rhodomyrtus tomentosa ethanolic leaf extract for the bio-control of Listeria monocytogenes post-cooking contamination in cooked chicken meat.

    PubMed

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2016-12-01

    Controlling foodborne pathogen in ready-to-eat food is important in food safety. The present study accessed the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against Listeria monocytogenes in cooked chicken meat model system. The antilisterial activity of the plant extract was better under microwave condition and enhanced as storage temperature increased from 4 to 37 °C. The extract could reduce L. monocytogenes numbers at low (10(4) CFU/g) and high (10(6) CFU/g) inoculum levels in cooked chicken by both rinse and injection application methods. A 5 min rinse in 8% w/v R. tomentosa extract reduced the bacterial number by ≥2-log before storage and ≥3-log after storage at 4 °C for 5 days. Injection with 0.4% w/w R. tomentosa extract resulted in approximately 2-log reduction in the cell numbers both before and after storage at 4 °C for 5 days. Five minutes rinse in the extract bath demonstrated better sensory preferences which were not significantly different from the control. Addition of black pepper powder to the extract rinsed samples improved odour but not appearance, colour, and texture preferences. Rhodomyrtus tomentosa extract was significantly effective for the bio-control of L. monocytogenes contaminations in cooked chicken meat model. The extract was observed as a potent bio-additive agent to control contaminations from L. monocytogenes and ensure safety in ready-to-eat meat.

  19. The requirement for the LysR-type regulator PtrA for Pseudomonas chlororaphis PA23 biocontrol revealed through proteomic and phenotypic analysis

    PubMed Central

    2014-01-01

    Background Pseudomonas chlororaphis strain PA23 is a biocontrol agent capable of suppressing the fungal pathogen Sclerotinia sclerotiorum. This bacterium produces the antibiotics phenazine and pyrrolnitrin together with other metabolites believed to contribute to biocontrol. A mutant no longer capable of inhibiting fungal growth was identified harboring a transposon insertion in a gene encoding a LysR-type transcriptional regulator (LTTR), designated ptrA (Pseudomonas transcriptional regulator). Isobaric tag for relative and absolute quantitation (iTRAQ) based protein analysis was used to reveal changes in protein expression patterns in the ptrA mutant compared to the PA23 wild type. Results Relative abundance profiles showed 59 differentially-expressed proteins in the ptrA mutant, which could be classified into 16 clusters of orthologous groups (COGs) based on their predicted functions. The largest COG category was the unknown function group, suggesting that many yet-to-be identified proteins are involved in the loss of fungal activity. In the secondary metabolite biosynthesis, transport and catabolism COG, seven proteins associated with phenazine biosynthesis and chitinase production were downregulated in the mutant. Phenotypic assays confirmed the loss of phenazines and chitinase activity. Upregulated proteins included a lipoprotein involved in iron transport, a flagellin and hook-associated protein and four proteins categorized into the translation, ribosome structure and biogenesis COG. Phenotypic analysis revealed that the mutant exhibited increased siderophore production and flagellar motility and an altered growth profile, supporting the proteomic findings. Conclusion PtrA is a novel LTTR that is essential for PA23 fungal antagonism. Differential protein expression was observed across 16 COG categories suggesting PtrA is functioning as a global transcriptional regulator. Changes in protein expression were confirmed by phenotypic assays that showed reduced

  20. Bacillomycin L and surfactin contribute synergistically to the phenotypic features of Bacillus subtilis 916 and the biocontrol of rice sheath blight induced by Rhizoctonia solani.

    PubMed

    Luo, Chuping; Zhou, Huafei; Zou, Jincheng; Wang, Xiaoyu; Zhang, Rongsheng; Xiang, Yaping; Chen, Zhiyi

    2015-02-01

    The antagonistic activity of lipopeptides in Bacillus subtilis 916 has been well documented, yet relatively little is known about their mechanism in biofilm formation and environmental colonization. This study sought to examine the interaction of B. subtilis 916 on Rhizoctonia solani-infected rice sheath to elucidate the mechanism of colonization on plant leaves. Results showed that the mutants Δbac, Δsrf, and Δsrf + bac of B. subtilis 916, deficient in bacillomycin L and surfactin production, respectively, not only altered colony morphology but also changed swarming motility, reduced antagonistic activity, and decreased biofilm formation. In particular, biofilm formation in mutant Δbac, not Δsrf or Δsrf + bac, were restored with addition of surfactin and bacillomycin L at 10 and 50 μg/mL, respectively. Moreover, surfactin and bacillomycin L were able to restore or enhance swarming motility in the corresponding mutants at 10 μg/mL, respectively. With the aid of green fluorescent protein tagging, it was demonstrated that B. subtilis 916 formed a robust biofilm on the rice sheath blight lesion and colonized well on R. solani-infected rice sheath, while its corresponding mutants performed poorly. These observations also correlated with the rice cultivar pot experiments, in which B. subtilis 916 exhibited greater biocontrol than its mutants. Our results suggest that surfactin and bacillomycin L contribute differently but synergistically to the biocontrol of rice sheath blight in B. subtilis 916 through its antifungal activity, biofilm formation, and colonization.

  1. Host-pathogen-biocontrol agent interaction as affected by sequential application of Na2CO3 and CaCl2.

    PubMed

    Molinu, G M; Arras, G; Dore, A; Venditti, T; Petretto, A; D'Hallewin, G

    2009-01-01

    Among the alternatives to synthetic postharvest fungicides encouraging results have been reported with biocontrol agents, and on Citrus fruits, their efficacy was improved when co-applied with GRAS compounds or with physical means. Still, the reason for this increased efficacy has not been explained and therefore a study was performed using orange fruit (Citrus sinensis Osbec. cv 'Washington navel') as host, P. digitatum as the pathogen, a yeast (Pichia guiliermondii, isolate 5A) as the biocontrol agent, white 2% Na2CO3 (SC) and 1% CaCl2 were employed as GRAS compounds. When treatments were combined salts were applied sequentially, and SC preceded CaCl2 followed by the yeast. As a result of large scale trait with inoculated and un-inoculated fruit a clear beneficial interaction occurred when treatments were combined. SC exerted a direct fungistatic activity and an indirect one by inducing scoparone in host tissue. Also the isolate A5 induced the phytoalexin accumulation and when combined with SC a greater accumulation occurred within the first 7 days post-treatment. The application of CaCl2 alone had no effect on pathogenesis, while when combined with SC or with the yeast, decay was towered. The yeast growth on an amended medium was negatively affected by the addition of SC; while in vivo this effect was missing. The antagonist growth in vivo was enhanced when applied together with 1% CaCl2 also when applied with SC. The results reported improve our knowledge on the complex interactions among host, pathogen and the antagonist as affected by SC and CaCl2.

  2. Biophysical characterization of Acacia caesia-fabricated silver nanoparticles: effectiveness on mosquito vectors of public health relevance and impact on non-target aquatic biocontrol agents.

    PubMed

    Benelli, Giovanni; Kadaikunnan, Shine; Alharbi, Naiyf S; Govindarajan, Marimuthu

    2017-02-05

    Mosquito-borne diseases lead to serious public health concerns in tropical and sub-tropical countries worldwide, due to development of mosquito resistance to synthetic pesticides, non-target effects of pesticides, and socioeconomic reasons. Currently, green nanotechnology is a promising research field, showing a wide range of potential applications in vector control programs. The employ of natural products as reducing agents to fabricate insecticidal nanocomposites is gaining research attention worldwide, due to low costs and high effectiveness. Interestingly, biophysical features of green-synthesized nanoparticles strongly differ when different botanicals are employed for nanosynthesis. In this study, a cheap Acacia caesia leaf extract was employed to fabricate silver nanoparticles (Ag NPs) with ovicidal, larvicidal, and adulticidal toxicity against three mosquito vectors, Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Ag NPs were analyzed by various biophysical methods, including spectroscopy (UV-visible spectrophotometry, XRD, FTIR, EDX) and microscopy (SEM, TEM, AFM) techniques. High acute larvicidal potential was observed against larvae of An. subpictus (LC50 = 10.33 μg/ml), Ae. albopictus (LC50 = 11.32 μg/ml), and Cx. tritaeniorhynchus (LC50 = 12.35 μg/ml). Ag NPs completely inhibited egg hatchability on three vectors at 60, 75, and 90 μg/ml, respectively. In adulticidal assays, LD50 values were 18.66, 20.94, and 22.63 μg/ml. If compared to mosquito larvae, Ag NPs were safer to three non-target aquatic biocontrol agents, with LC50 ranging from 684 to 2245 μg/ml. Overall, our study highlights the potential of A. caesia as an abundant and cheap bioresource to fabricate biogenic Ag NPs effective against mosquito young instars and adults, with moderate impact on non-target aquatic biocontrol agents.

  3. Antifungal activity of ZnO nanoparticles and their interactive effect with a biocontrol bacterium on growth antagonism of the plant pathogen Fusarium graminearum.

    PubMed

    Dimkpa, Christian O; McLean, Joan E; Britt, David W; Anderson, Anne J

    2013-12-01

    Fungal plant pathogens such as Fusarium graminearum cause severe global economic losses in cereals crops, and current control measures are limited. This work addresses the potential for ZnO nanoparticles (NPs) and biocontrol bacteria to be used in plant fungal control strategies. Growth of F. graminearum was significantly (p = 0.05) inhibited by inclusion of the NPs in a mung bean broth agar and in sand. Suspension in mung bean broth medium modified the surface charge, dissolution, and aggregation state of the ZnO NPs, in comparison to processes occurring in water suspension. The ZnO NPs were significantly more inhibitory to fungal growth than micro-sized particles of ZnO, although both types of particles released similar levels of soluble Zn, indicating size-dependent toxicity of the particles. Zn ions produced dose-dependent inhibition, noticeable at the level of soluble Zn released from NPs after seven-day suspension in medium; inhibitory levels caused acidification of the growth medium. Transfer of fungal inoculum after exposure to the ZnO NPs to fresh medium did not indicate adaptation to the stress because growth was still inhibited by the NPs. The ZnO NPs did not prevent metabolites from a biocontrol bacterium, Pseudomonas chlororaphis O6, from inhibiting Fusarium growth: no synergism was observed in the mung bean agar. Because other studies find that soil amendment with ZnO NPs required high doses for inhibition of plant growth, the findings of pathogen growth control reported in this paper open the possibility of using ZnO NP-based formulations to complement existing strategies for improving crop health in field settings.

  4. Harlequin syndrome: the sudden onset of unilateral flushing and sweating.

    PubMed Central

    Lance, J W; Drummond, P D; Gandevia, S C; Morris, J G

    1988-01-01

    Facial flushing and sweating were investigated in five patients who complained of the sudden onset of unilateral facial flushing in hot weather or when exercising vigorously. One patient probably suffered a brainstem infarct at the time that the unilateral flush was first noticed, and was left with a subtle Horner's syndrome on the side opposite to the flush. The other four had no other neurological symptoms and no ocular signs of Horner's syndrome. Thermal and emotional flushing and sweating were found to be impaired on the non-flushing side of the forehead in all five patients whereas gustatory sweating and flushing were increased on that side in four of the five patients, a combination of signs indicating a deficit of the second sympathetic neuron at the level of the third thoracic segment. CT and MRI of this area failed to disclose a structural lesion but latency from stimulation of the motor cortex and thoracic spinal cord to the third intercostal muscle was delayed on the non-flushing side in one patient. The complaint of unilateral flushing and sweating was abolished in one patient by ipsilateral stellate ganglionectomy. The unilateral facial flushing and sweating induced by heat in all five patients was thus a normal or excessive response by an intact sympathetic pathway, the other side failing to respond because of a sympathetic deficit. The onset in the four cases of peripheral origin followed strenuous exertion, which suggested that an anterior radicular artery may have become occluded at the third thoracic segment during torsion of the thoracic spine. Images PMID:3155385

  5. The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

    PubMed

    Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

    2009-01-01

    In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

  6. Effect of clay mineralogy on iron bioavailability and rhizosphere transcription of 2,4-diacetylphloroglucinol biosynthetic genes in biocontrol Pseudomonas protegens.

    PubMed

    Almario, Juliana; Prigent-Combaret, Claire; Muller, Daniel; Moënne-Loccoz, Yvan

    2013-05-01

    Pseudomonas strains producing 2,4-diacetylphloroglucinol (DAPG) can protect plants from soilborne phytopathogens and are considered the primary reason for suppressiveness of morainic Swiss soils to Thielaviopsis basicola-mediated black root-rot disease of tobacco, even though they also occur nearby in conducive sandstone soils. The underlying molecular mechanisms accounting for this discrepancy are not understood. In this study, we assessed the hypothesis that the presence of iron-rich vermiculite clay (dominant in suppressive soils) instead of illite (dominant in neighboring conducive soils) translates into higher levels of iron bioavailability and transcription of Pseudomonas DAPG synthetic genes in the tobacco rhizosphere. Rhizosphere monitoring of reporter gene systems pvd-inaZ and phlA-gfp in Pseudomonas protegens indicated that the level of iron bioavailability and the number of cells expressing phl genes (DAPG synthesis), respectively, were higher in vermiculitic than in illitic artificial soils. This was in accordance with the effect of iron on phlA-gfp expression in vitro and, indeed, iron addition to the illitic soil increased the number of cells expressing phlA-gfp. Similar findings were made in the presence of the pathogen T. basicola. Altogether, results substantiate the hypothesis that iron-releasing minerals may confer disease suppressiveness by modulating iron bioavailability in the rhizosphere and expression of biocontrol-relevant genes in antagonistic P. protegens.

  7. Biological studies on the snail intermediate hosts of schistosomiasis with a special emphasis on using larval echinostomes as biocontrol agent against larval schistosomes and snails.

    PubMed

    Rashed, A A

    2002-12-01

    The present investigation deals with the infectivity of the two snail intermediate hosts of schistosomiasis, Biomphalaria alexandrina and Bulinus truncatus collected from nine drains in Sharkia Governorate, Egypt. The rate of infection among the snails was general low being 0% in many drains. Regarding B. alexandrina, the rate of infection ranged from 4-16%, and in B. truncatus ranged from 4-8%. Infection with larval echinostomes was dominant over larval schistosomes in the two snail vectors. The distribution of larval schistosomes was restricted to the hepatopancreas of the two snail vectors, while larval echinostomes were distributed in head, foot, kidney, haemocoelic cavity, hepatopancreas...etc. The predation of larval schistosomes by larval echinostomes and the severe histopathological effects induced by larval ecbinostomes strongly enhances using them as biocontrol agent. The physico-chemical parameters and pollution condition in the drains seem to have no effect on the process of snails infectivity. It is concluded that larval echinostomes can resist the polluting conditions in the drain. The two snail vectors exhibit very minimal or rare host response against larval echinostomes. Probably, the toxicants and pollutants in the drain may act as stressor that makes the snails much more susceptible to infection by larval trematodes.

  8. Soil type-dependent effects of a potential biocontrol inoculant on indigenous bacterial communities in the rhizosphere of field-grown lettuce.

    PubMed

    Schreiter, Susanne; Ding, Guo-Chun; Grosch, Rita; Kropf, Siegfried; Antweiler, Kai; Smalla, Kornelia

    2014-12-01

    Bacterial biocontrol strains used as an alternative to chemical fungicides may influence bacterial communities in the rhizosphere and effects might differ depending on the soil type. Here we present baseline data on the effects of Pseudomonas jessenii RU47 on the bacterial community composition in the rhizosphere of lettuce grown in diluvial sand, alluvial loam and loess loam at the same field site. 16S rRNA gene fragments amplified from total community DNA were analyzed by denaturing gradient gel electrophoresis (DGGE) and pyrosequencing. DGGE fingerprints revealed that in three consecutive years (2010-2012) RU47 had a slight but statistically significant effect on the bacterial community composition in one (2010), two (2011) or all the three soils (2012). However, these effects were much less pronounced compared with the influence of soil types. Additional pyrosequence analysis of samples from 2011 showed that significant changes in bacterial community compositions in response to RU47 inoculation occurred only in alluvial loam. Different taxonomic groups responded to the RU47 application depending on the soil type. Most remarkable was the increased relative abundance of OTUs belonging to the genera Bacillus and Paenibacillus in alluvial loam. Pyrosequencing allowed side-effects of the application of bacterial inoculants into the rhizosphere to be identified.

  9. Biocontrol ability of Lysobacter antibioticus HS124 against Phytophthora blight is mediated by the production of 4-hydroxyphenylacetic acid and several lytic enzymes.

    PubMed

    Ko, Hyun-Sun; Jin, Rong-De; Krishnan, Hari B; Lee, Sang-Bog; Kim, Kil-Yong

    2009-12-01

    Several rhizobacteria play a vital role in plant protection, plant growth promotion and the improvement of soil health. In this study, we have isolated a strain of Lysobacter antibioticus HS124 from rhizosphere and demonstrate its antifungal activity against various pathogens including Phytophthora capsici, a destructive pathogen of pepper plants. L. antibioticus HS124 produced lytic enzymes such as chitinase, beta-1,3-glucanase, lipase, protease, and an antibiotic compound. This antibiotic compound was purified by diaion HP-20, silica gel, sephadex LH-20 column chromatography and high performance liquid chromatography. The purified compound was identified as 4-hydroxyphenylacetic acid by gas chromatography-electron ionization (GC-EI) and gas chromatography-chemical ionization (GC-CI) mass spectrometry. This antibiotic exhibited destructive activity toward P. capsici hyphae. In vivo experiments utilizing green house grown pepper plants demonstrated the protective effect of L. antibioticus HS124 against P. capsici. The growth of pepper plants treated with L. antibioticus culture was enhanced, resulting in greater protection from fungal disease. Optimum growth and protection was found when cultures were grown in presence of Fe(III). Additionally, the activities of pathogenesis-related proteins such as chitinase and beta-1,3-glucanase decreased in roots, but increased in leaves with time after treatment compared to controls. Our results demonstrate L. antibioticus HS124 as a promising candidate for biocontrol of P. capsici in pepper plants.

  10. Secretome of the Biocontrol Agent Metarhizium anisopliae Induced by the Cuticle of the Cotton Pest Dysdercus peruvianus Reveals New Insights into Infection

    PubMed Central

    2015-01-01

    Metarhizium anisopliae is an entomopathogenic fungus that has evolved specialized strategies to infect insect hosts. Here we analyzed secreted proteins related to Dysdercus peruvianus infection. Using shotgun proteomics, abundance changes in 71 proteins were identified after exposure to host cuticle. Among these proteins were classical fungal effectors secreted by pathogens to degrade physical barriers and alter host physiology. These include lipolytic enzymes, Pr1A, B, C, I, and J proteases, ROS-related proteins, oxidorreductases, and signaling proteins. Protein interaction networks were generated postulating interesting candidates for further studies, including Pr1C, based on possible functional interactions. On the basis of these results, we propose that M. anisopliae is degrading host components and actively secreting proteins to manage the physiology of the host. Interestingly, the secretion of these factors occurs in the absence of a host response. The findings presented here are an important step in understanding the host–pathogen interaction and developing more efficient biocontrol of D. peruvianus by M. anisopliae. PMID:24702058

  11. Biocontrol potential of Lariophagus distinguendus (Hymenoptera: Pteromalidae) against Sitophilus granarius (Coleoptera: Curculionidae) at low temperatures: reproduction and parasitoid-induced mortality.

    PubMed

    Hansen, Lise Stengård

    2007-06-01

    Lariophagus distinguendus Forster (Hymenoptera: Pteromalidae) has been suggested as a biological control agent against the granary weevil, Sitophilus granarius (L.), in grain stores. Information on the effect of low temperatures prevailing in grain stores is necessary to be able to predict the potential of this parasitoid against S. granarius in temperate regions, where grain is cooled with ambient air to achieve safe storage conditions. The influence of constant temperatures of 16, 18, and 20 degrees C on life table parameters and parasitoid-induced mortality (PIM) was investigated in the laboratory. L. distinguendus is able to develop and reproduce at temperatures as low as 16 degrees C. The intrinsic rate of natural increase, rm, was 0.0182, 0.0222, and 0.0792 d(-1) at 16, 18, and 20 degrees C, respectively. The proportion of hosts killed due to parasitoid-induced mortality was highest at 20 degrees C. At this temperature, it amounted to 70% of the total mortality exerted by the parasitoid; at 18 and 16'C, it was 57 and 42% of the total, respectively. L. distinguendus is a promising biocontrol agent for grain stores in temperate regions because it is able to develop and reproduce at temperatures down to 16 degrees C; its development is quicker than that of its host, estimated from the literature; and it kills many hosts in addition to those used for reproduction.

  12. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    PubMed Central

    Maldonado-González, M. Mercedes; Bakker, Peter A. H. M.; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  13. Reliability of the entomovector technology using Prestop-Mix and Bombus terrestris L. as a fungal disease biocontrol method in open field

    PubMed Central

    Karise, Reet; Dreyersdorff, Gerit; Jahani, Mona; Veromann, Eve; Runno-Paurson, Eve; Kaart, Tanel; Smagghe, Guy; Mänd, Marika

    2016-01-01

    Botrytis cinerea Pers.:Fr. is a major plant pathogen, and a new approach is needed for its control in strawberry to minimise the increasing use of synthetic fungicides. The biofungicide Prestop-Mix, which contains Gliocladium catenulatum, is effective against Botrytis infections; however, the need for frequent applications increases the costs for farmers. Here, we demonstrate that bumble bees, Bombus terrestris L., effectively disseminate the preparation onto flowers in open field conditions. Over the course of three years, we found a highly significant decrease in the rate of Botrytis infection. Pathogen control was achieved with relatively low numbers of G. catenulatum spores per flower, even using flowers that are not highly attractive to bumble bees. An even distribution of spores was detected up to 100 m from the hives, either due to primary inoculation by bumble bees or secondary distribution by other flower visitors such as honey bees and solitary bees. We showed that the application of a biocontrol agent by bumble bees is reliable for the use of environmentally friendly pest control strategies in northern climatic conditions. This low cost technology is especially relevant for organic farming. This study provides valuable information for introducing this method into practice in open strawberry fields. PMID:27530075

  14. Novel components of leaf bacterial communities of field-grown tomato plants and their potential for plant growth promotion and biocontrol of tomato diseases.

    PubMed

    Romero, Fernando M; Marina, María; Pieckenstain, Fernando L

    2016-04-01

    This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth.

  15. Biocontrol Potentials of Antimicrobial Peptide Producing Bacillus Species: Multifaceted Antagonists for the Management of Stem Rot of Carnation Caused by Sclerotinia sclerotiorum

    PubMed Central

    Vinodkumar, S.; Nakkeeran, S.; Renukadevi, P.; Malathi, V. G.

    2017-01-01

    Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the mycelial growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin, and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of bacterial suspension of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7). PMID:28392780

  16. Characterization and evaluation of Bacillus amyloliquefaciens strain WF02 regarding its biocontrol activities and genetic responses against bacterial wilt in two different resistant tomato cultivars.

    PubMed

    Huang, Chu-Ning; Lin, Chan-Pin; Hsieh, Feng-Chia; Lee, Sook-Kuan; Cheng, Kuan-Chen; Liu, Chi-Te

    2016-11-01

    Bacillus amyloliquefaciens strain WF02, isolated from soil collected at Wufeng Mountain, Taiwan, has siderophore-producing ability and in vitro antagonistic activity against bacterial wilt pathogen. To determine the impact of plant genotype on biocontrol effectiveness, we treated soil with this strain before infecting susceptible (L390) and moderately resistant (Micro-Tom) tomato cultivars with Ralstonia solanacearum strain Pss4. We also compared the efficacy of this strain with that of commercial Bacillus subtilis strain Y1336. Strain WF02 provided longer lasting protection against R. solanacearum than did strain Y1336 and controlled the development of wilt in both cultivars. To elucidate the genetic responses in these plants under WF02 treatment, we analyzed the temporal expression of defense-related genes in leaves. The salicylic acid pathway-related genes phenylalanine ammonia-lyase and pathogenesis-related protein 1a were up-regulated in both cultivars, whereas expression of the jasmonic acid pathway-related gene lipoxygenase was only elevated in the susceptible tomato cultivar (L390). These results suggest that WF02 can provide protection against bacterial wilt in tomato cultivars with different levels of disease resistance via direct and indirect modes of action.

  17. Biocontrol of Rhizoctonia solani damping-off and promotion of tomato plant growth by endophytic actinomycetes isolated from native plants of Algerian Sahara.

    PubMed

    Goudjal, Yacine; Toumatia, Omrane; Yekkour, Amine; Sabaou, Nasserdine; Mathieu, Florence; Zitouni, Abdelghani

    2014-01-20

    Thirty-four endophytic actinomycetes were isolated from the roots of native plants of the Algerian Sahara. Morphological and chemical studies showed that twenty-nine isolates belonged to the Streptomyces genus and five were non-Streptomyces. All isolates were screened for their in vitro antifungal activity against Rhizoctonia solani. The six that had the greatest pathogen inhibitory capacities were subsequently tested for their in vivo biocontrol potential on R. solani damping-off in sterilized and non-sterilized soils, and for their plant-growth promoting activities on tomato seedlings. In both soils, coating tomato seeds with antagonistic isolates significantly reduced (P<0.05) the severity of damping-off of tomato seedlings. Among the isolates tested, the strains CA-2 and AA-2 exhibited the same disease incidence reduction as thioperoxydicarbonic diamide, tetramethylthiram (TMTD) and no significant differences (P<0.05) were observed. Furthermore, they resulted in a significant increase in the seedling fresh weight, the seedling length and the root length of the seed-treated seedlings compared to the control. The taxonomic position based on 16S rDNA sequence analysis and phylogenetic studies indicated that the strains CA-2 and AA-2 were related to Streptomyces mutabilis NBRC 12800(T) (100% of similarity) and Streptomyces cyaneofuscatus JCM 4364(T) (100% of similarity), respectively.

  18. Chitinolytic Streptomyces vinaceusdrappus S5MW2 isolated from Chilika lake, India enhances plant growth and biocontrol efficacy through chitin supplementation against Rhizoctonia solani.

    PubMed

    Yandigeri, Mahesh S; Malviya, Nityanand; Solanki, Manoj Kumar; Shrivastava, Pooja; Sivakumar, G

    2015-08-01

    A chitinolytic actinomycete Streptomyces vinaceusdrappus S5MW2 was isolated from water sample of Chilika lake, India and identified using 16S rRNA gene sequencing. It showed in vitro antifungal activity against the sclerotia producing pathogen Rhizoctonia solani in a dual culture assay and by chitinase enzyme production in a chitin supplemented minimal broth. Moreover, isolate S5MW2 was further characterized for biocontrol (BC) and plant growth promoting features in a greenhouse experiment with or without colloidal chitin (CC). Results of greenhouse experiment showed that CC supplementation with S5MW2 showed a significant growth of tomato plants and superior disease reduction as compared to untreated control and without CC treated plants. Moreover, higher accumulation of chitinase also recovered in the CC supplemented plants. Significant effect of CC also concurred with the Analysis of Variance of greenhouse parameters. These results show that the a marine antagonist S5MW2 has BC efficiency against R. solani and chitinase enzyme played important role in plant resistance.

  19. Partial purification, characterization, and kinetic studies of a low-molecular-weight, alkali-tolerant chitinase enzyme from Bacillus subtilis JN032305, A potential biocontrol strain.

    PubMed

    Shivakumar, Srividya; Karmali, Anika Nayak; Ruhimbana, Charles

    2014-01-01

    A new alkalophilic low-molecular-mass chitinase of 14 kD from the potent biocontrol agent Bacillus subtilis JN032305 was partially purified and enzymology of the chitinase was studied. The enzyme showed optimal pH of 9.0 and temperature of 50°C. The enzyme was found stable during the 60-min incubation at 50 °C. The chitinase was inhibited by group specific agents like IAA, DAN, TLCK, and SDS and metal ions Mg(2+), Ca(2+), Fe(2+), Mn(2+), Ba(2+), and Hg(2+), whereas Zn(2+) did not show significant inhibitory effect against the chitinase. PMSF partially inhibited the enzyme. Substrates specificity tests indicated that the enzyme showed 75% of relative activity on glycol chitin, 58% on carboxymethylcellulose (CMC), 33% on chitin flakes, and 166% laminarin compared to that on colloidal chitin. The enzyme also hydrolyzed 4-methylumbelliferyl-N-acetyl-D-glucosaminide, indicating its chitobiase activity. The chitinase of this study has broad specificity, which could hydrolyze not only the glycosidic bond in GlcNAc-GlcNAc but also that of related carbohydrates with glycosidic linkages. The partially purified chitinase not only showed antifungal activity against Rhizoctonia solani and Colletotrichum gloeosporioides, two potent phytopathogens of chilli, but also increased the germination of chilli seeds when infected with the two potent phytopathogenic fungi.

  20. Effect of organic fertilizers prepared from organic waste materials on the production of antibacterial volatile organic compounds by two biocontrol Bacillus amyloliquefaciens strains.

    PubMed

    Raza, Waseem; Wei, Zhong; Ling, Ning; Huang, Qiwei; Shen, Qirong

    2016-06-10

    Three organic fertilizers made of different animal and plant waste materials (BOFs) were evaluated for their effects on the production of antibacterial volatile organic compounds (VOCs) by two Bacillus amyloliquefaciens strains SQR-9 and T-5 against the tomato wilt pathogen Ralstonia solanacearum (RS). Both strains could produce VOCs that inhibited the growth and virulence traits of RS; however, in the presence of BOFs, the production of antibacterial VOCs was significantly increased. The maximum inhibition of growth and virulence traits of RS by VOCs of T-5 and SQR-9 was determined at 1.5% BOF2 and 2% BOF3, respectively. In case of strain T-5, 2-nonanone, nonanal, xylene, benzothiazole, and butylated hydroxy toluene and in case of strain SQR-9, 2-nonanone, nonanal, xylene and 2-undecanone were the main antibacterial VOCs whose production was increased in the presence of BOFs. The results of this study reveal another significance of using organic fertilizers to improve the antagonistic activity of biocontrol agents against phytopathogens.

  1. Selection of the N-Acylhomoserine Lactone-Degrading Bacterium Alteromonas stellipolaris PQQ-42 and of Its Potential for Biocontrol in Aquaculture.

    PubMed

    Torres, Marta; Rubio-Portillo, Esther; Antón, Josefa; Ramos-Esplá, Alfonso A; Quesada, Emilia; Llamas, Inmaculada

    2016-01-01

    The production of virulence factors by many pathogenic microorganisms depends on the intercellular communication system called quorum sensing, which involves the production and release of signal molecules known as autoinducers. Based on this, new-therapeutic strategies have emerged for the treatment of a variety of infections, such as the enzymatic degradation of signaling molecules, known as quorum quenching (QQ). In this study, we present the screening of QQ activity amongst 450 strains isolated from a bivalve hatchery in Granada (Spain), and the selection of the strain PQQ-42, which degrades a wide range of N-acylhomoserine lactones (AHLs). The selected strain, identified as Alteromonas stellipolaris, degraded the accumulation of AHLs and reduced the production of protease and chitinase and swimming motility of a Vibrio species in co-cultivation experiments in vitro. In the bio-control experiment, strain PQQ-42 significantly reduced the pathogenicity of Vibrio mediterranei VibC-Oc-097 upon the coral Oculina patagonica showing a lower degree of tissue damage (29.25 ± 14.63%) in its presence, compared to when the coral was infected with V. mediterranei VibC-Oc-097 alone (77.53 ± 13.22%). Our results suggest that this AHL-degrading bacterium may have biotechnological applications in aquaculture.

  2. Streptomyces rochei ACTA1551, an Indigenous Greek Isolate Studied as a Potential Biocontrol Agent against Fusarium oxysporum f.sp. lycopersici

    PubMed Central

    Kanini, Grammatiki S.; Katsifas, Efstathios A.; Savvides, Alexandros L.; Karagouni, Amalia D.

    2013-01-01

    Many studies have shown that several Greek ecosystems inhabit very interesting bacteria with biotechnological properties. Therefore Streptomyces isolates from diverse Greek habitats were selected for their antifungal activity against the common phytopathogenic fungus Fusarium oxysporum. The isolate encoded ACTA1551, member of Streptomyces genus, could strongly suppress the fungal growth when examined in antagonistic bioassays in vitro. The isolate was found phylogenetically relative to Streptomyces rochei after analyzing its 16S rDNA sequence. The influence of different environmental conditions, such as medium composition, temperature, and pH on the expression of the antifungal activity was thoroughly examined. Streptomyces rochei ACTA1551 was able to protect tomato seeds from F. oxysporum infection in vivo while it was shown to promote the growth of tomato plants when the pathogen was absent. In an initial effort towards the elucidation of the biochemical and physiological nature of ACTA1551 antifungal activity, extracts from solid streptomycete cultures under antagonistic or/and not antagonistic conditions were concentrated and fractionated. The metabolites involved in the antagonistic action of the isolate showed to be more than one and produced independently of the presence of the pathogen. The above observations could support the application of Streptomyces rochei ACTA1551 as biocontrol agent against F. oxysporum. PMID:23762841

  3. The development of genetic and molecular markers to register and commercialize Penicillium rubens (formerly Penicillium oxalicum) strain 212 as a biocontrol agent.

    PubMed

    Villarino, Maria; De Cal, Antonieta; Melgarejo, Paloma; Larena, Inmaculada; Espeso, Eduardo A

    2016-01-01

    Penicillium oxalicum strain 212 (PO212) is an effective biocontrol agent (BCA) against a large number of economically important fungal plant pathogens. For successful registration as a BCA in Europe, PO212 must be accurately identified. In this report, we describe the use of classical genetic and molecular markers to characterize and identify PO212 in order to understand its ecological role in the environment or host. We successfully generated pyrimidine (pyr-) auxotrophic mutants. In addition we also designed specific oligonucleotides for the pyrF gene at their untranslated regions for rapid and reliable identification and classification of strains of P. oxalicum and P. rubens, formerly P. chrysogenum. Using these DNA-based technologies, we found that PO212 is a strain of P. rubens, and is not a strain of P. oxalicum. This work presents PO212 as the unique P. rubens strain to be described as a BCA and the information contained here serves for its registration and commercialization in Europe.

  4. Selection of the N-Acylhomoserine Lactone-Degrading Bacterium Alteromonas stellipolaris PQQ-42 and of Its Potential for Biocontrol in Aquaculture

    PubMed Central

    Torres, Marta; Rubio-Portillo, Esther; Antón, Josefa; Ramos-Esplá, Alfonso A.; Quesada, Emilia; Llamas, Inmaculada

    2016-01-01

    The production of virulence factors by many pathogenic microorganisms depends on the intercellular communication system called quorum sensing, which involves the production and release of signal molecules known as autoinducers. Based on this, new-therapeutic strategies have emerged for the treatment of a variety of infections, such as the enzymatic degradation of signaling molecules, known as quorum quenching (QQ). In this study, we present the screening of QQ activity amongst 450 strains isolated from a bivalve hatchery in Granada (Spain), and the selection of the strain PQQ-42, which degrades a wide range of N-acylhomoserine lactones (AHLs). The selected strain, identified as Alteromonas stellipolaris, degraded the accumulation of AHLs and reduced the production of protease and chitinase and swimming motility of a Vibrio species in co-cultivation experiments in vitro. In the bio-control experiment, strain PQQ-42 significantly reduced the pathogenicity of Vibrio mediterranei VibC-Oc-097 upon the coral Oculina patagonica showing a lower degree of tissue damage (29.25 ± 14.63%) in its presence, compared to when the coral was infected with V. mediterranei VibC-Oc-097 alone (77.53 ± 13.22%). Our results suggest that this AHL-degrading bacterium may have biotechnological applications in aquaculture. PMID:27242684

  5. Potential Role of Exoglucanase Genes (WaEXG1 and WaEXG2) in the Biocontrol Activity of Wickerhamomyces anomalus.

    PubMed

    Parafati, Lucia; Cirvilleri, Gabriella; Restuccia, Cristina; Wisniewski, Michael

    2016-11-05

    The use of yeasts, including Wickerhamomyces anomalus, as biocontrol agents of fungi responsible for postharvest diseases of fruits and vegetables has been investigated for the past two decades. Among a variety of mechanisms, the production of glucanases coded by the "killer genes" WaEXG1 and WaEXG2 have been reported to play a role in the ability of yeast to inhibit other fungi. The objective of the present study was to determine the expression of these genes by RT-qPCR, utilizing gene-specific primers, when W. anomalus was grown on grape berries and oranges that were either non-inoculated or inoculated with Botrytis cinerea or Penicillium digitatum, or in minimal media supplemented with cell walls of various plant pathogens and different amounts of glucose. Results indicated that WaEXG2 was more responsive than WaEXG1 to the nutritional environment (including the addition of glucose to cell wall-amended media) in vitro and appeared to play a greater role in the cellular metabolism of W. anomalus. WaEXG2 expression also appeared to be more responsive to the presence of cell walls of P. digitatum and B. cinerea than other fungal species, whereas the same level of induction was not seen in vivo when the yeast was grown in wounded/pathogen-inoculated fruits.

  6. Pectin Enhances Bio-Control Efficacy by Inducing Colonization and Secretion of Secondary Metabolites by Bacillus amyloliquefaciens SQY 162 in the Rhizosphere of Tobacco

    PubMed Central

    Guo, Rong; Pan, Bin; Shi, Wen; Yuan, Saifei; Guan, Huilin; Gong, Ming; Shen, Biao; Shen, Qirong

    2015-01-01

    Bacillus amyloliquefaciens is a plant-beneficial Gram-positive bacterium involved in suppressing soil-borne pathogens through the secretion of secondary metabolites and high rhizosphere competence. Biofilm formation is regarded as a prerequisite for high rhizosphere competence. In this work, we show that plant extracts affect the chemotaxis and biofilm formation of B. amyloliquefaciens SQY 162 (SQY 162). All carbohydrates tested induced the chemotaxis and biofilm formation of the SQY 162 strain; however, the bacterial growth rate was not influenced by the addition of carbohydrates. A strong chemotactic response and biofilm formation of SQY 162 were both induced by pectin through stimulation of surfactin synthesis and transcriptional expression of biofilm formation related matrix genes. These results suggested that pectin might serve as an environmental factor in the stimulation of the biofilm formation of SQY 162. Furthermore, in pot experiments the surfactin production and the population of SQY 162 in the rhizosphere significantly increased with the addition of sucrose or pectin, whereas the abundance of the bacterial pathogen Ralstonia decreased. With increased production of secondary metabolites in the rhizosphere of tobacco by SQY 162 and improved colonization density of SQY 162 in the pectin treatment, the disease incidences of bacterial wilt were efficiently suppressed. The present study revealed that certain plant extracts might serve as energy sources or environmental cues for SQY 162 to enhance the population density on tobacco root and bio-control efficacy of tobacco bacterial wilt. PMID:25996156

  7. Potential of Burkholderia seminalis TC3.4.2R3 as Biocontrol Agent Against Fusarium oxysporum Evaluated by Mass Spectrometry Imaging

    NASA Astrophysics Data System (ADS)

    Araújo, Francisca Diana da Silva; Araújo, Welington Luiz; Eberlin, Marcos Nogueira

    2017-02-01

    Species of genus Burkholderia display different interaction profiles in the environment, causing either several diseases in plants and animals or being beneficial to some plants, promoting their growth, and suppressing phytopathogens. Burkholderia spp. also produce many types of biomolecules with antimicrobial activity, which may be commercially used to protect crops of economic interest, mainly against fungal diseases. Herein we have applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate secondary metabolites produced by B. seminalis TC3.4.2R3 in monoculture and coculture with plant pathogen Fusarium oxysporum. The siderophore pyochelin and the rhamnolipid Rha-Rha-C15-C14 were detected in wild-type B. seminalis strain, and their productions were found to vary in mutant strains carrying disruptions in gene clusters associated with antimicrobial compounds. Two mycotoxins were detected in F. oxysporum. During coculture with B. seminalis, metabolites probably related to defense mechanisms of these microorganisms were observed in the interspecies interaction zone. Our findings demonstrate the effective application of MALDI-MSI in the detection of bioactive molecules involved in the defense mechanism of B. seminalis, and these findings suggest the potential use of this bacterium in the biocontrol of plant diseases caused by F. oxysporum.

  8. Solid-state fermentation of agro-industrial wastes to produce bioorganic fertilizer for the biocontrol of Fusarium wilt of cucumber in continuously cropped soil.

    PubMed

    Chen, Lihua; Yang, Xingming; Raza, Waseem; Luo, Jia; Zhang, Fengge; Shen, Qirong

    2011-02-01

    Agro-industrial wastes of cattle dung, vinegar-production residue and rice