A new necessary condition for Turing instabilities.

PubMed

Elragig, Aiman; Townley, Stuart

2012-09-01

Reactivity (a.k.a initial growth) is necessary for diffusion driven instability (Turing instability). Using a notion of common Lyapunov function we show that this necessary condition is a special case of a more powerful (i.e. tighter) necessary condition. Specifically, we show that if the linearised reaction matrix and the diffusion matrix share a common Lyapunov function, then Turing instability is not possible. The existence of common Lyapunov functions is readily checked using semi-definite programming. We apply this result to the Gierer-Meinhardt system modelling regenerative properties of Hydra, the Oregonator, to a host-parasite-hyperparasite system with diffusion and to a reaction-diffusion-chemotaxis model for a multi-species host-parasitoid community. Copyright © 2012 Elsevier Inc. All rights reserved.

Development of Pasteuria penetrans in Meloidogyne javanica females as affected by constantly high vs fluctuating temperature in an in-vivo system.

PubMed

Darban, D A; Gowen, S R; Pembroke, B; Mahar, A N

2005-03-01

Growth room and glasshouse experiment was conducted to investigate the effect of constant and fluctuating temperatures on the development of Pasteuria penetrans a hyperparasite of root-knot nematodes. Tomato plants (Lycopersicon esculentum Mill) were inoculated with Meloidogyne javanica second-stage juveniles attached with endospores of P. penetrans and were grown in growth room at 26-29 degrees C and in glasshouse at 20-32 degrees C. The tomato plants were sampled from the growth room after 600 degree-days based on 17 degrees C/d, accumulating each day above a base temperature of 10 degrees C and from the glasshouse after 36 calendar days. Temperature affected the development of P. penetrans directly. The rate of development at constant temperature in growth room was faster than that in the glasshouse at fluctuating temperatures.

Development of Pasteuria penetrans in Meloidogyne javanica females as affected by constantly high vs fluctuating temperature in an in-vivo system

PubMed Central

Darban, D.A.; Gowen, S.R.; Pembroke, B.; Mahar, A.N.

2005-01-01

Growth room and glasshouse experiment was conducted to investigate the effect of constant and fluctuating temperatures on the development of Pasteuria penetrans a hyperparasite of root-knot nematodes. Tomato plants (Lycopersicon esculentum Mill) were inoculated with Meloidogyne javanica second-stage juveniles attached with endospores of P. penetrans and were grown in growth room at 26–29 °C and in glasshouse at 20–32 °C. The tomato plants were sampled from the growth room after 600 degree-days based on 17 °C/d, accumulating each day above a base temperature of 10 °C and from the glasshouse after 36 calendar days. Temperature affected the development of P. penetrans directly. The rate of development at constant temperature in growth room was faster than that in the glasshouse at fluctuating temperatures. PMID:15682497

Morphological and molecular characteristics of a new species of Pasteuria parasitic on Meloidogyne ardenensis.

PubMed

Bishop, Alistair H; Gowen, Simon R; Pembroke, Barbara; Trotter, James R

2007-09-01

A species of the hyper-parasitic bacterium Pasteuria was isolated from the root-knot nematode Meloidogyne ardenensis infecting the roots of ash (Fraxinus excelsior). It is morphologically different from some other Pasteuria pathogens of nematodes in that the spores lack a basal ring on the ventral side of the spore and have a unique clumping nature. Transmission electron microscopy (TEM) showed that the clumps of spores are not random aggregates but result from the disintegration of the suicide cells of the thalli. Sporulation within each vegetative mycelium was shown to be asynchronous. In addition to the novel morphological features 16S rRNA sequence analysis showed this to be a new species of Pasteuria which we have called P. hartismeri. Spores of P. hartismeri attach to juveniles of root-knot nematodes infecting a wide range of plants such as mint (Meloidogyne hapla), rye grass (unidentified Meloidogyne sp.) and potato (Meloidogyne fallax).

Hyperparasitism by the bacteriophage (Caudovirales) infecting Candidatus Xenohaliotis californiensis (Rickettsiales-like prokaryote) parasite of wild abalone Haliotis fulgens and Haliotis corrugata from the Peninsula of Baja California, Mexico.

PubMed

Cruz-Flores, Roberto; Cáceres-Martínez, Jorge; Muñoz-Flores, Monserrat; Vásquez-Yeomans, Rebeca; Hernández Rodriguez, Mónica; Ángel Del Río-Portilla, Miguel; Rocha-Olivares, Axayácatl; Castro-Longoria, Ernestina

2016-10-01

Candidatus Xenohaliotis californiensis (CXc) is a Rickettsiales-like prokaryote that is considered the causal agent of Withering Syndrome (WS), a chronic disease of abalone, from the west coast of North America and it is listed by the International Organization for Animal Health (OIE) as a reportable agent due to its pathogenicity. This bacterium in red abalone Haliotis rufescens, black abalone Haliotis cracherodii, and yellow abalone Haliotis corrugata from California, US and Baja California, Mexico has been found to be infected by a bacteriophage. To date, there is no information on the epizootiology of CXc and its bacteriophage in natural populations of abalone; furthermore, it is unknown if the bacteriophage was also present in CXc infecting blue abalone Haliotis fulgens. The objective of this study was to determine the distribution, prevalence and intensity of CXc, as well as to determine the distribution and prevalence of the bacteriophage and to study interactions between host sex and hyperparasitism in blue abalone and yellow abalone. Tissue samples were obtained from seven localities where the commercial capture of wild abalone is carried out. Samplings were conducted throughout the 2012-2013 capture seasons and a total of 182 blue abalone and 170 yellow abalone were obtained. The prevalence and intensity of CXc and the prevalence of the bacteriophage were determined by histology. The identity of CXc was confirmed by PCR, product sequence analysis and in situ hybridization while the identity of the bacteriophage was corroborated by TEM. The prevalence of CXc infected and uninfected by the bacteriophage was 80% in blue abalone and 62% in yellow abalone. Low infection intensities were found in 86% of blue abalone and 82% of yellow abalone. Infection intensity was significantly higher in undifferentiated yellow abalone. The bacteriophage in CXc showed a prevalence of 22% and 31% in blue abalone and yellow abalone respectively. These results show that CXc and its bacteriophage are widely distributed in the peninsula of Baja California and that they are well established in natural populations of blue abalone and yellow abalone. Additionally, this data constitutes the first record of a bacteriophage in blue abalone. Copyright © 2016 Elsevier Inc. All rights reserved.

Novel Paraconiothyrium species on stone fruit trees and other woody hosts.

PubMed

Damm, U; Verkley, G J M; Crous, P W; Fourie, P H; Haegi, A; Riccioni, L

2008-06-01

Coniothyrium-like fungi are common wood and soil inhabitants and hyperparasites on other fungi. They belong to different fungal genera within the Pleosporales. Several isolates were obtained on wood of different Prunus species (plum, peach and nectarine) from South Africa, on Actinidia species from Italy and on Laurus nobilis from Turkey. Morphological and cultural characteristics as well as DNA sequence data (5.8S nrDNA, ITS1, ITS2, partial SSU nrDNA) were used to characterise them. The isolates belonged to three species of the recently established genus Paraconiothyrium. This is the first report of Paraconiothyrium brasiliense on Prunus spp. from South Africa. Two new species are described, namely Paraconiothyrium variabile sp. nov. on Prunus persica and Prunus salicina from South Africa, on Actinidia spp. from Italy and on Laurus nobilis from Turkey, and Paraconiothyrium africanum sp. nov. on Prunus persica from South Africa. Although other known species of Paraconiothyrium commonly produce aseptate conidia, those of P. africanum and P. hawaiiense comb. nov. are predominantly two-celled.

Changes in Cryphonectria parasitica Populations Affect Natural Biological Control of Chestnut Blight.

PubMed

Ježić, Marin; Mlinarec, Jelena; Vuković, Rosemary; Katanić, Zorana; Krstin, Ljiljana; Nuskern, Lucija; Poljak, Igor; Idžojtić, Marilena; Tkalec, Mirta; Ćurković-Perica, Mirna

2018-07-01

Invasive species, especially plant pathogens, have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interactions among sweet chestnut (Castanea sativa), chestnut blight-causing invasive fungus Cryphonectria parasitica, and hyperparasitic virus Cryphonectria hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the 10 years, while the hypovirulence incidence dropped in one population and slightly increased in the other one. Over the course of our 3-year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly (i.e., more hypovirulent isolates were being obtained from the same cankers over time). Within studied cankers, considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers and, occasionally, reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both short- and long-term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.

Microbial Inhibition of Fusarium Pathogens and Biological Modification of Trichothecenes in Cereal Grains

PubMed Central

Wachowska, Urszula; Packa, Danuta

2017-01-01

Fungi of the genus Fusarium infect cereal crops during the growing season and cause head blight and other diseases. Their toxic secondary metabolites (mycotoxins) contaminate grains. Several dozen toxic compounds produced by fungal pathogens have been identified to date. Type B trichothecenes—deoxynivalenol, its acetyl derivatives and nivalenol (produced mainly by F. graminearum and F. culmorum)—are most commonly detected in cereal grains. “T-2 toxin” (produced by, among others, F. sporotrichioides) belongs to type-A trichothecenes which are more toxic than other trichothecenes. Antagonistic bacteria and fungi can affect pathogens of the genus Fusarium via different modes of action: direct (mycoparasitism or hyperparasitism), mixed-path (antibiotic secretion, production of lytic enzymes) and indirect (induction of host defense responses). Microbial modification of trichothecenes involves acetylation, deacetylation, oxidation, de-epoxidation, and epimerization, and it lowers the pathogenic potential of fungi of the genus Fusarium. Other modifing mechanisms described in the paper involve the physical adsorption of mycotoxins in bacterial cells and the conjugation of mycotoxins to glucose and other compounds in plant and fungal cells. The development of several patents supports the commercialization and wider application of microorganisms biodegrading mycotoxins in grains and, consequently, in feed additives. PMID:29261142

Phylogeny of the Haplosporidia (Eukaryota: Alveolata) based on small subunit ribosomal RNA gene sequence.

PubMed

Flores, B S; Siddall, M E; Burreson, E M

1996-08-01

The phylogenetic position of the phylum Haplosporidia was investigated with the complete small subunit rRNA gene sequences from 5 species in the phylum: Haplosporidium nelsoni and Haplosporidium costale, parasites of the eastern oyster Crassostrea virginica; Haplosporidium louisiana, a parasite of the mudcrab Panopeus herbstii; Minchinia teredinis, a parasite of shipworms (Teredo spp.) and Urosporidium crescens, a hyperparasite found in metacercariae of the trematode Megalophallus sp. in the blue crab, Callinectes sapidus. Multiple alignments of small subunit rRNA gene sequences included the 5 haplosporidian taxa and 14 taxa in the alveolate phyla Ciliophora, Dinoflagellida, and Apicomplexa. Maximum parsimony analysis placed the phylum Haplosporidia as a monophyletic group within the alveolate clade, as a taxon of equal rank with the other 3 alveolate phyla, and as a sister taxon to the clade composed of the phyla Dinoflagellida and Apicomplexa. Transversionally weighted parsimony placed the haplosporidians as a sister taxon to the ciliates. A separate analysis focused on the relationships of species in the genus Haplosporidium. Analyses were conducted with the haplosporidians as a functional ingroup, using each of the alveolate phyla individually as functional outgroups. The results indicated that species in the genus Haplosporidium do not form a monophyletic assemblage. As such, the present morphological criteria for distinguishing the genera Haplosporidium and Minchinia are insufficient.

Prevalence, geographic distribution, and fitness effects of Microphallus turgidus (trematoda: Microphallidae) in grass shrimp (Palaemonetes spp.) from coastal Georgia.

PubMed

Pung, Oscar J; Khan, Ritindra N; Vives, Stephen P; Walker, Casey B

2002-02-01

Grass shrimp, Palaemonetes pugio Holthuis and P. vilgaris (Say), were collected at 11 localities along the coast of Georgia and surveyed for digenetic trematode metacercariae. The effect of trematode infection on grass shrimp fitness was also examined. Microphallus turgidas (Leigh) was the only trematode observed. The prevalence of metacercarial cysts of this parasite in P. pugio (75%) was higher than in P. vulgaris (24%), as were the mean intensity, abundance, and population density (no. cysts/cm host body length) of the parasite. Infected shrimp were found at every collection locality and parasite prevalence and density were greatest in P. pugio from higher salinity localities (> or = 20 parts per thousand [ppt]). There was no relation between host body size and parasite density in P. vulgaris, and parasite density increased with host body size in P. pugio, suggesting that the parasite does not affect host survival. There was no relation between parasite density and shrimp egg mass, but nonovigerous female P. pugio were more heavily infected than ovigerous ones. In addition, 1 metacercaria of M. turgidus in each of 2 specimens of P. vulgaris was parasitized by the haplosporidian Urosporidium crescens De Turk. This represents a new shrimp host record for this hyperparasite.

Present status of Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) in the Mariana Islands and its control by two fortuitously introduced natural enemies.

PubMed

Reddy, G V P; Muniappan, R; Cruz, Z T; Naz, F; Bamba, J P; Tenorio, J

2009-08-01

The mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), attacks ornamental and fruit crops in the Mariana Islands. Insecticides cannot penetrate the heavy layers of wax that protect the insect's body. We surveyed the mealybug's locally recruited natural enemies and their effects on its population on Guam, Rota, Saipan, and Tinian to assess the need for introduction of exotic natural enemies. We monitored population densities of M. hirsutus, those of its natural enemies, and parasitism rates for 3 yr, 2005-2007. Our surveys revealed the presence of two parasitoids, Anagyrus kamali Moursi (Hymenoptera: Encyrtidae) and Allotropa sp. near mecrida (Walker) (Hymenoptera: Platygastridae), fortuitously introduced to the Mariana Islands with M. hirsutus. The predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) also was often found feeding on M. hirsutus. Population density of M. hirsutus was below the economic threshold at all locations. Rainfall seemed to affect mean numbers of M. hirsutus and mean numbers of eggs at some locations. On all four islands, the two parasitoids, complemented by the predator, were effectively controlling the M. hirsutus population. No evidence of hyperparasitism was recorded. Currently, economic damage by M. hirsutus is not a concern in the Mariana Islands, and additional parasitoids need not be introduced to control M. hirsutus.

Host availability affects the interaction between pupal parasitoid Coptera haywardi (Hymenoptera: Diiapridae) and larval-pupal parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae).

PubMed

Montoya, P; Gálvez, C; Díaz-Fleischer, F

2018-02-12

The use of multiple species in biological control programmes is controversial when interactions among them are not fully understood. We determined the response of the pupal parasitoid Coptera haywardi (Oglobin) to different availability of Anastrepha ludens (Loew) pupae previously parasitized or not by larval-pupal Diachasmimorpha longicaudata (Ashmead). The two types of pupae were exposed at different ages and proportions to different numbers of C. haywardi females for 48 h. The performance of C. haywardi adults emerging from parasitized and unparasitized pupae was measured. Coptera haywardi prefers to attack unparasitized A. ludens pupae rather than pupae parasitized by D. longicaudata. However, when the availability of unparasitized pupae was low or the number of foraging females was high, C. haywardi competed against early immature stages of the D. longicaudata, or hyperparasitized, feeding directly on the advanced-immature developmental stages of the early acting species. Adults of C. haywardi emerging as hyperparasitoids were no different in size, fecundity and longevity from those emerging as primary parasitoids. Our data suggest that simultaneous use of these species in augmentative biological control projects may be feasible but should be carefully planned in order to avoid any detrimental effect of its interaction.

Antibiosis of Trichoderma spp strains native to northeastern Mexico against the pathogenic fungus Macrophomina phaseolina

PubMed Central

Mendoza, José Luis Hernández; Pérez, María Isabel Sánchez; Prieto, Juan Manuel González; Velásquez, Jesús DiCarlo Quiroz; Olivares, Jesús Gerardo García; Langarica, Homar Rene Gill

2015-01-01

Abstract Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS) 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen. PMID:26691467

Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust.

PubMed

Torres, David Eduardo; Rojas-Martínez, Reyna Isabel; Zavaleta-Mejía, Emma; Guevara-Fefer, Patricia; Márquez-Guzmán, G Judith; Pérez-Martínez, Carolina

2017-01-01

Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust.

Cladosporium cladosporioides and Cladosporium pseudocladosporioides as potential new fungal antagonists of Puccinia horiana Henn., the causal agent of chrysanthemum white rust

PubMed Central

Guevara-Fefer, Patricia; Márquez-Guzmán, G. Judith; Pérez-Martínez, Carolina

2017-01-01

Puccinia horiana Hennings, the causal agent of chrysanthemum white rust, is a worldwide quarantine organism and one of the most important fungal pathogens of Chrysanthemum × morifolium cultivars, which are used for cut flowers and as potted plants in commercial production regions of the world. It was previously reported to be controlled by Lecanicillium lecanii, Cladosporium sphaerospermum, C. uredinicola and Aphanocladium album, due to their antagonistic and hyperparasitic effects. We report novel antagonist species on Puccinia horiana. Fungi isolated from rust pustules in a commercial greenhouse from Villa Guerrero, México, were identified as Cladosporium cladosporioides and Cladosporium pseudocladosporioides based upon molecular analysis and morphological characters. The antagonism of C. cladosporioides and C. pseudocladosporioides on chrysanthemum white rust was studied using light and electron microscopy in vitro at the host/parasite interface. Cladosporium cladosporioides and C. pseudocladosporioides grew towards the white rust teliospores and colonized the sporogenous cells, but no direct penetration of teliospores was observed; however, the structure and cytoplasm of teliospores were altered. The two Cladosporium spp. were able to grow on media containing laminarin, but not when chitin was used as the sole carbon source; these results suggest that they are able to produce glucanases. Results from the study indicate that both Cladosporium species had potential as biological control agents of chrysanthemum white rust. PMID:28141830

Meloidogyne incognita Fatty Acid- and Retinol- Binding Protein (Mi-FAR-1) Affects Nematode Infection of Plant Roots and the Attachment of Pasteuria penetrans Endospores.

PubMed

Phani, Victor; Shivakumara, Tagginahalli N; Davies, Keith G; Rao, Uma

2017-01-01

Root-knot nematode (RKN) Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans , is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition, development and reproduction; they are also a component of the nematode cuticle and thought to be involved in the interface between hosts and parasites. Attachment of endospores to the cuticle of second stage juveniles of RKN is the primary step of infection and several factors have been identified to facilitate attachment. In this study, the full length of Mi-far-1 (573 bp) was cloned from M. incognita and characterized. Analysis revealed that the Mi-far-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a glycosylation site. Quantitative PCR showed the highest expression in the fourth stage juveniles and in situ hybridization revealed the presence of Mi-far-1 mRNA in the hypodermis below the cuticle. Single copy insertion pattern of Mi-far-1 in M. incognita genome was detected by Southern blotting. Knockdown of Mi-far-1 showed significantly increased attachment of P. penetrans' endospores on juvenile cuticle surface and also affected host finding, root infection and nematode fecundity.

Identification of New Single Nucleotide Polymorphism-Based Markers for Inter- and Intraspecies Discrimination of Obligate Bacterial Parasites (Pasteuria spp.) of Invertebrates ▿ †

PubMed Central

Mauchline, Tim H.; Knox, Rachel; Mohan, Sharad; Powers, Stephen J.; Kerry, Brian R.; Davies, Keith G.; Hirsch, Penny R.

2011-01-01

Protein-encoding and 16S rRNA genes of Pasteuria penetrans populations from a wide range of geographic locations were examined. Most interpopulation single nucleotide polymorphisms (SNPs) were detected in the 16S rRNA gene. However, in order to fully resolve all populations, these were supplemented with SNPs from protein-encoding genes in a multilocus SNP typing approach. Examination of individual 16S rRNA gene sequences revealed the occurrence of “cryptic” SNPs which were not present in the consensus sequences of any P. penetrans population. Additionally, hierarchical cluster analysis separated P. penetrans 16S rRNA gene clones into four groups, and one of which contained sequences from the most highly passaged population, demonstrating that it is possible to manipulate the population structure of this fastidious bacterium. The other groups were made from representatives of the other populations in various proportions. Comparison of sequences among three Pasteuria species, namely, P. penetrans, P. hartismeri, and P. ramosa, showed that the protein-encoding genes provided greater discrimination than the 16S rRNA gene. From these findings, we have developed a toolbox for the discrimination of Pasteuria at both the inter- and intraspecies levels. We also provide a model to monitor genetic variation in other obligate hyperparasites and difficult-to-culture microorganisms. PMID:21803895

Meloidogyne incognita Fatty Acid- and Retinol- Binding Protein (Mi-FAR-1) Affects Nematode Infection of Plant Roots and the Attachment of Pasteuria penetrans Endospores

PubMed Central

Phani, Victor; Shivakumara, Tagginahalli N.; Davies, Keith G.; Rao, Uma

2017-01-01

Root-knot nematode (RKN) Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans, is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition, development and reproduction; they are also a component of the nematode cuticle and thought to be involved in the interface between hosts and parasites. Attachment of endospores to the cuticle of second stage juveniles of RKN is the primary step of infection and several factors have been identified to facilitate attachment. In this study, the full length of Mi-far-1 (573 bp) was cloned from M. incognita and characterized. Analysis revealed that the Mi-far-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a glycosylation site. Quantitative PCR showed the highest expression in the fourth stage juveniles and in situ hybridization revealed the presence of Mi-far-1 mRNA in the hypodermis below the cuticle. Single copy insertion pattern of Mi-far-1 in M. incognita genome was detected by Southern blotting. Knockdown of Mi-far-1 showed significantly increased attachment of P. penetrans’ endospores on juvenile cuticle surface and also affected host finding, root infection and nematode fecundity. PMID:29209280

Identification of new single nucleotide polymorphism-based markers for inter- and intraspecies discrimination of obligate bacterial parasites (Pasteuria spp.) of invertebrates.

PubMed

Mauchline, Tim H; Knox, Rachel; Mohan, Sharad; Powers, Stephen J; Kerry, Brian R; Davies, Keith G; Hirsch, Penny R

2011-09-01

Protein-encoding and 16S rRNA genes of Pasteuria penetrans populations from a wide range of geographic locations were examined. Most interpopulation single nucleotide polymorphisms (SNPs) were detected in the 16S rRNA gene. However, in order to fully resolve all populations, these were supplemented with SNPs from protein-encoding genes in a multilocus SNP typing approach. Examination of individual 16S rRNA gene sequences revealed the occurrence of "cryptic" SNPs which were not present in the consensus sequences of any P. penetrans population. Additionally, hierarchical cluster analysis separated P. penetrans 16S rRNA gene clones into four groups, and one of which contained sequences from the most highly passaged population, demonstrating that it is possible to manipulate the population structure of this fastidious bacterium. The other groups were made from representatives of the other populations in various proportions. Comparison of sequences among three Pasteuria species, namely, P. penetrans, P. hartismeri, and P. ramosa, showed that the protein-encoding genes provided greater discrimination than the 16S rRNA gene. From these findings, we have developed a toolbox for the discrimination of Pasteuria at both the inter- and intraspecies levels. We also provide a model to monitor genetic variation in other obligate hyperparasites and difficult-to-culture microorganisms.

Freezing as a treatment to prevent the spread of Hypothenemus hampei (Coleoptera: Curculionidae), in coffee.

PubMed

Hollingsworth, Robert C; Jang, Eric B; Follett, Peter A

2013-04-01

Coffee berry borer, Hypothenemus hampei (Ferrari) is the most serious insect pest of coffee around the world. Although it is already present in most of the world's major coffee growing regions, it is important to delay further spread and to prevent reintroductions that might include hyperparasites or improve the genetic base of existing populations. Green coffee is shipped around the world for custom blending and roasting and such shipments carry the risk of spreading H. hampei. We used heavily infested coffee berries as a surrogate for green coffee to test the freezing tolerance of H. hampei. After freezing, all life stages of H. hampei were dissected from coffee berries and mortality was assessed. Counting all life stages, > 15,000 insects were measured in this study. A temperature of approximately -15 degrees C (range, -13.9 to -15.5) for 48 h provided 100% control of all life stages. A logit regression model predicted < or = 1 survivor in a million for treatments of -20 degrees C for 5 d or -15 degrees C for 6 d. A freezing treatment for green coffee might be more economical and acceptable compared with fumigation with methyl bromide, especially for small-scale and organic growers and millers in Hawaii who ship green coffee beans to other islands for custom roasting. Freezing treatments could also be used to kill H. hampei in coffee seeds before export with minimal effects on seed germination if coffee seeds are first dried to critical water content levels in accordance with published methods.

A tripartite survey of hyperparasitic fungi associated with ectoparasitic flies on bats (Mammalia: Chiroptera) in a neotropical cloud forest in Panama.

PubMed

Walker, Melissa J; Dorrestein, Annabel; Camacho, Jasmin J; Meckler, Lauren A; Silas, Kirk A; Hiller, Thomas; Haelewaters, Danny

2018-01-01

The Darién province in eastern Panama is one of the most unexplored and biodiverse regions in the world. The Chucantí Nature Reserve, in Serranía de Majé, consists of a diverse tropical cloud forest ecosystem. The aim of this research was to explore and study host associations of a tripartite system of bats, ectoparasitic flies on bats (Diptera, Streblidae), and ectoparasitic fungi (Ascomycota, Laboulbeniales) that use bat flies as hosts. We captured bats at Chucantí, screened each bat for presence of bat flies, and screened collected bat flies for presence of Laboulbeniales. We mistnetted for 68 mistnet hours and captured 227 bats representing 17 species. We captured Micronycteris schmidtorum, a species previously unreported in Darién. In addition, we encountered the rarely collected Platyrrhinus dorsalis, representing the westernmost report for this species. Of all captured bats, 148 carried bat flies (65%). The number of sampled bat flies was 437, representing 16 species. One species represents a new country record (Trichobius anducei) and five species represent first reports for Darién (Basilia anceps, Anatrichobius scorzai, Nycterophilia parnelli, T. johnsonae, T. parasiticus). All 74 bat fly species currently reported in Panama are presented in tabulated form. Of all screened bat flies, 30 bore Laboulbeniales fungi (7%). Based on both morphology and large ribosomal subunit (LSU) sequence data, we delimited 7 species of Laboulbeniales: Gloeandromyces nycteribiidarum (newly reported for Panama), G. pageanus, G. streblae, Nycteromyces streblidinus, and 3 undescribed species. Of the 30 infected flies, 21 were Trichobius joblingi. This species was the only host on which we observed double infections of Laboulbeniales. © M.J. Walker et al., published by EDP Sciences, 2018.

A new species of Temnocephala (Platyhelminthes) with an unusual pharynx, including an amendment of the diagnosis of the genus.

PubMed

De leÓn, Rodrigo Ponce; Volonterio, Odile

2018-02-08

Three species of Temnocephala have been reported on Aegla from Uruguay: Temnocephala axenos, Temnocephala mertoni and Temnocephala talicei. As part of a systematic review of the Uruguayan species of Temnocephala, a fourth species was found on Aegla platensis and Aegla uruguayana. This species, new for the genus, has the following diagnostic characters: Large temnocephalan; slightly curved penial stylet (225 µm in length) with a symmetrical introvert (27 long by 18 µm in diameter) that has at least 44 spine-like projections, each bearing 7 rows of internal spines; a seminal vesicle that opens sub-polarly into the contractile vesicle; a muscular vagina with a strong asymmetrical sphincter; preequatorial nephridiopores close to the internal borders of the elongate-oval excretory syncytia; a large pharynx with anterior and posterior sphincters of about the same diameter and a narrow pharyngeal lumen with nearly uniform width. To contemplate the characters of the pharynx, an amendment of the genus Temnocephala is given. The new species resembles Temnocephala cyanoglandula, which also has a very long, slightly curved penial stylet, but differs from it by having a shorter penial stylet, a lower number of rows of spines in the introvert, a larger, different type of pharynx, a smaller contractile vesicle and a larger sucker. The new species is carnivorous and feeds on whole preys, which are mainly annelids (Stratiodrilus) and other species of Temnocephala. The new species was found to be hyperparasitised by plerocercoid and nematode larvae, but hyperparasites were not found in the other sympatric species of Temnocephala. Based on the findings presented here, it is clear that detailed histological descriptions of the pharynx should be contemplated as part of the normal work in taxonomy of temnocephalans.

A tripartite survey of hyperparasitic fungi associated with ectoparasitic flies on bats (Mammalia: Chiroptera) in a neotropical cloud forest in Panama

PubMed Central

Walker, Melissa J.; Dorrestein, Annabel; Camacho, Jasmin J.; Meckler, Lauren A.; Silas, Kirk A.; Hiller, Thomas; Haelewaters, Danny

2018-01-01

The Darién province in eastern Panama is one of the most unexplored and biodiverse regions in the world. The Chucantí Nature Reserve, in Serranía de Majé, consists of a diverse tropical cloud forest ecosystem. The aim of this research was to explore and study host associations of a tripartite system of bats, ectoparasitic flies on bats (Diptera, Streblidae), and ectoparasitic fungi (Ascomycota, Laboulbeniales) that use bat flies as hosts. We captured bats at Chucantí, screened each bat for presence of bat flies, and screened collected bat flies for presence of Laboulbeniales. We mistnetted for 68 mistnet hours and captured 227 bats representing 17 species. We captured Micronycteris schmidtorum, a species previously unreported in Darién. In addition, we encountered the rarely collected Platyrrhinus dorsalis, representing the westernmost report for this species. Of all captured bats, 148 carried bat flies (65%). The number of sampled bat flies was 437, representing 16 species. One species represents a new country record (Trichobius anducei) and five species represent first reports for Darién (Basilia anceps, Anatrichobius scorzai, Nycterophilia parnelli, T. johnsonae, T. parasiticus). All 74 bat fly species currently reported in Panama are presented in tabulated form. Of all screened bat flies, 30 bore Laboulbeniales fungi (7%). Based on both morphology and large ribosomal subunit (LSU) sequence data, we delimited 7 species of Laboulbeniales: Gloeandromyces nycteribiidarum (newly reported for Panama), G. pageanus, G. streblae, Nycteromyces streblidinus, and 3 undescribed species. Of the 30 infected flies, 21 were Trichobius joblingi. This species was the only host on which we observed double infections of Laboulbeniales. PMID:29633707

Hyperparasitoids Use Herbivore-Induced Plant Volatiles to Locate Their Parasitoid Host

PubMed Central

Poelman, Erik H.; Bruinsma, Maaike; Zhu, Feng; Weldegergis, Berhane T.; Boursault, Aline E.; Jongema, Yde; van Loon, Joop J. A.; Vet, Louise E. M.; Harvey, Jeffrey A.; Dicke, Marcel

2012-01-01

Plants respond to herbivory with the emission of induced plant volatiles. These volatiles may attract parasitic wasps (parasitoids) that attack the herbivores. Although in this sense the emission of volatiles has been hypothesized to be beneficial to the plant, it is still debated whether this is also the case under natural conditions because other organisms such as herbivores also respond to the emitted volatiles. One important group of organisms, the enemies of parasitoids, hyperparasitoids, has not been included in this debate because little is known about their foraging behaviour. Here, we address whether hyperparasitoids use herbivore-induced plant volatiles to locate their host. We show that hyperparasitoids find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. Moreover, only one of two species of parasitoids affected herbivore-induced plant volatiles resulting in the attraction of more hyperparasitoids than volatiles from plants damaged by healthy caterpillars. This resulted in higher levels of hyperparasitism of the parasitoid that indirectly gave away its presence through its effect on plant odours induced by its caterpillar host. Here, we provide evidence for a role of compounds in the oral secretion of parasitized caterpillars that induce these changes in plant volatile emission. Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species in the fourth trophic level to improve our understanding of the ecological functions of volatile release by plants. Furthermore, these findings suggest that the impact of species in the fourth trophic level should also be considered when developing Integrated Pest Management strategies aimed at optimizing the control of insect pests using parasitoids. PMID:23209379

Ectoparasitism on deep-sea fishes in the western North Atlantic: In situ observations from ROV surveys.

PubMed

Quattrini, Andrea M; Demopoulos, Amanda W J

2016-12-01

A complete understanding of how parasites influence marine ecosystem functioning requires characterizing a broad range of parasite-host interactions while determining the effects of parasitism in a variety of habitats. In deep-sea fishes, the prevalence of parasitism remains poorly understood. Knowledge of ectoparasitism, in particular, is limited because collection methods often cause dislodgment of ectoparasites from their hosts. High-definition video collected during 43 remotely operated vehicle surveys (2013-2014) provided the opportunity to examine ectoparasitism on fishes across habitats (open slope, canyon, seamount, cold seep) and depths (494-4689 m) off the northeastern U.S., while providing high-resolution images and valuable observations of fish behavior. Only 9% (n = 125 individuals) of all observed fishes (25 species) were confirmed with ectoparasites, but higher percentages (∼33%) were observed for some of the most abundant fish species (e.g., Antimora rostrata). Ectoparasites included two copepod families (Lernaeopodidae, Sphyriidae) that infected four host species, two isopod families (Cymothoidae, Aegidae) that infected three host species, and one isopod family (Gnathiidae) that infected 19 host species. Hyperparasitism was also observed. As host diversity declined with depth, ectoparasite diversity declined; only gnathiids were observed at depths down to 3260 m. Thus, gnathiids appear to be the most successful group to infect a diversity of fishes across a broad depth range in the deep sea. For three dominant fishes (A. rostrata, Nezumia bairdii, Synaphobranchus spp.), the abundance and intensity of ectoparasitism peaked in different depths and habitats depending on the host species examined. Notably, gnathiid infections were most intense on A. rostrata, particularly in submarine canyons, suggesting that these habitats may increase ectoparasite infections. Although ectoparasitism is often overlooked in deep-sea benthic communities, our results demonstrate that it occurs widely across a variety of habitats, depths, and locations and is a significant component of deep-sea biodiversity.

Ectoparasitism on deep-sea fishes in the western North Atlantic: In situ observations from ROV surveys

USGS Publications Warehouse

Quattrini, Andrea; Demopoulos, Amanda W.J.

2016-01-01

A complete understanding of how parasites influence marine ecosystem functioning requires characterizing a broad range of parasite-host interactions while determining the effects of parasitism in a variety of habitats. In deep-sea fishes, the prevalence of parasitism remains poorly understood. Knowledge of ectoparasitism, in particular, is limited because collection methods often cause dislodgment of ectoparasites from their hosts. High-definition video collected during 43 remotely operated vehicle surveys (2013–2014) provided the opportunity to examine ectoparasitism on fishes across habitats (open slope, canyon, seamount, cold seep) and depths (494–4689 m) off the northeastern U.S., while providing high-resolution images and valuable observations of fish behavior. Only 9% (n = 125 individuals) of all observed fishes (25 species) were confirmed with ectoparasites, but higher percentages (∼33%) were observed for some of the most abundant fish species (e.g., Antimora rostrata). Ectoparasites included two copepod families (Lernaeopodidae, Sphyriidae) that infected four host species, two isopod families (Cymothoidae, Aegidae) that infected three host species, and one isopod family (Gnathiidae) that infected 19 host species. Hyperparasitism was also observed. As host diversity declined with depth, ectoparasite diversity declined; only gnathiids were observed at depths down to 3260 m. Thus, gnathiids appear to be the most successful group to infect a diversity of fishes across a broad depth range in the deep sea. For three dominant fishes (A. rostrata, Nezumia bairdii, Synaphobranchus spp.), the abundance and intensity of ectoparasitism peaked in different depths and habitats depending on the host species examined. Notably, gnathiid infections were most intense on A. rostrata, particularly in submarine canyons, suggesting that these habitats may increase ectoparasite infections. Although ectoparasitism is often overlooked in deep-sea benthic communities, our results demonstrate that it occurs widely across a variety of habitats, depths, and locations and is a significant component of deep-sea biodiversity.

Parasites of parasites of bats: Laboulbeniales (Fungi: Ascomycota) on bat flies (Diptera: Nycteribiidae) in central Europe.

PubMed

Haelewaters, Danny; Pfliegler, Walter P; Szentiványi, Tamara; Földvári, Mihály; Sándor, Attila D; Barti, Levente; Camacho, Jasmin J; Gort, Gerrit; Estók, Péter; Hiller, Thomas; Dick, Carl W; Pfister, Donald H

2017-02-21

Bat flies (Streblidae and Nycteribiidae) are among the most specialized families of the order Diptera. Members of these two related families have an obligate ectoparasitic lifestyle on bats, and they are known disease vectors for their hosts. However, bat flies have their own ectoparasites: fungi of the order Laboulbeniales. In Europe, members of the Nycteribiidae are parasitized by four species belonging to the genus Arthrorhynchus. We carried out a systematic survey of the distribution and fungus-bat fly associations of the genus in central Europe (Hungary, Romania). We encountered the bat fly Nycteribia pedicularia and the fungus Arthrorhynchus eucampsipodae as new country records for Hungary. The following bat-bat fly associations are for the first time reported: Nycteribia kolenatii on Miniopterus schreibersii, Myotis blythii, Myotis capaccinii and Rhinolophus ferrumequinum; Penicillidia conspicua on Myotis daubentonii; and Phthiridium biarticulatum on Myotis capaccinii. Laboulbeniales infections were found on 45 of 1,494 screened bat flies (3.0%). We report two fungal species: Arthrorhynchus eucampsipodae on Nycteribia schmidlii, and A. nycteribiae on N. schmidlii, Penicillidia conspicua, and P. dufourii. Penicillidia conspicua was infected with Laboulbeniales most frequently (25%, n = 152), followed by N. schmidlii (3.1%, n = 159) and P. dufourii (2.0%, n = 102). Laboulbeniales seem to prefer female bat fly hosts to males. We think this might be due to a combination of factors: female bat flies have a longer life span, while during pregnancy female bat flies are significantly larger than males and accumulate an excess of fat reserves. Finally, ribosomal DNA sequences for A. nycteribiae are presented. We screened ectoparasitic bat flies from Hungary and Romania for the presence of ectoparasitic Laboulbeniales fungi. Arthrorhynchus eucampsipodae and A. nycteribiae were found on three species of bat flies. This study extends geographical and host ranges of both bat flies and Laboulbeniales fungi. The sequence data generated in this work contribute to molecular phylogenetic studies of the order Laboulbeniales. Our survey shows a complex network of bats, bat flies and Laboulbeniales fungi, of which the hyperparasitic fungi are rare and species-poor. Their host insects, on the other hand, are relatively abundant and diverse.

Cryphonectria parasitica, the causal agent of chestnut blight: invasion history, population biology and disease control.

PubMed

Rigling, Daniel; Prospero, Simone

2018-01-01

Chestnut blight, caused by Cryphonectria parasitica, is a devastating disease infecting American and European chestnut trees. The pathogen is native to East Asia and was spread to other continents via infected chestnut plants. This review summarizes the current state of research on this pathogen with a special emphasis on its interaction with a hyperparasitic mycovirus that acts as a biological control agent of chestnut blight. Cryphonectria parasitica (Murr.) Barr. is a Sordariomycete (ascomycete) fungus in the family Cryphonectriaceae (Order Diaporthales). Closely related species that can also be found on chestnut include Cryphonectria radicalis, Cryphonectria naterciae and Cryphonectria japonica. Major hosts are species in the genus Castanea (Family Fagaceae), particularly the American chestnut (C. dentata), the European chestnut (C. sativa), the Chinese chestnut (C. mollissima) and the Japanese chestnut (C. crenata). Minor incidental hosts include oaks (Quercus spp.), maples (Acer spp.), European hornbeam (Carpinus betulus) and American chinkapin (Castanea pumila). Cryphonectria parasitica causes perennial necrotic lesions (so-called cankers) on the bark of stems and branches of susceptible host trees, eventually leading to wilting of the plant part distal to the infection. Chestnut blight cankers are characterized by the presence of mycelial fans and fruiting bodies of the pathogen. Below the canker the tree may react by producing epicormic shoots. Non-lethal, superficial or callusing cankers on susceptible host trees are usually associated with mycovirus-induced hypovirulence. After the introduction of C. parasitica into a new area, eradication efforts by cutting and burning the infected plants/trees have mostly failed. In Europe, the mycovirus Cryphonectria hypovirus 1 (CHV-1) acts as a successful biological control agent of chestnut blight by causing so-called hypovirulence. CHV-1 infects C. parasitica and reduces its parasitic growth and sporulation capacity. Individual cankers can be therapeutically treated with hypovirus-infected C. parasitica strains. The hypovirus may subsequently spread to untreated cankers and become established in the C. parasitica population. Hypovirulence is present in many chestnut-growing regions of Europe, either resulting naturally or after biological control treatments. In North America, disease management of chestnut blight is mainly focused on breeding with the goal to backcross the Chinese chestnut's blight resistance into the American chestnut genome. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields-An ecofriendly approach.

PubMed

Ghosh, Swapan Kumar; Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013-2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%-98.57%) but decreased during the winter, December-January (35.71-46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013-15), Trichoderma application restricted the disease to the smallest area (PDI 24.00-29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields.

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields—An ecofriendly approach

PubMed Central

Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013–2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%–98.57%) but decreased during the winter, December-January (35.71–46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013–15), Trichoderma application restricted the disease to the smallest area (PDI 24.00–29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T. viride and T. harzianum, standardized at a rate of 2.5 L / plot (36 sq ft) (108 spores/ mL) are suggested for the ecofriendly management of this epidemic leaf spot disease of Aloe vera in agricultural fields. PMID:29579070

First insight into the heritable variation of the resistance to infection with the bacteria causing the withering syndrome disease in Haliotis rufescens abalone.

PubMed

Brokordt, Katherina; González, Roxana; Farías, William; Winkler, Federico E; Lohrmann, Karin B

2017-11-01

Withering syndrome disease has experienced worldwide spread in the last decade. This fatal disease for abalone is produced by a rickettsia-like organism (WS-RLO), the bacterium "Candidatus Xenohaliotis californiensis". To evaluate the potential of the red abalone (Haliotis rufescens) to improve its resistance to infection by WS-RLO, the additive genetic component in the variation of this trait was estimated. For this, the variation in infection intensity with WS-RLOs and WS-RLOv (phage-infected RLOs) was analyzed in 56 families of full-sibs maintained for three years in a host-parasite cohabitation aquaculture system. A WS-RLO prevalence of 65% was observed in the analysed population; and from the total WS-RLO inclusions 60% were hyperparasited with the phage (WS-RLOv). The decrease in the food ingestion rate was the sole negative effect associated with increasing WS-RLO intensity of infection, suggesting that the high level of WS-RLOv load may have diminished the symptoms of WS disease in the analyzed abalones. The estimated heritabilities were moderate to mid, but significant, varying from 0.21 to 0.23 and 0.36 for WS-RLO and WS-RLOv infections, respectively. This suggests that variation in resistance to infection with WS-RLO may respond to selection in the evaluated red abalone population. Estimated response to selection (G) for the level of infection by WS-RLO indicated that if the 10% of red abalone with the lowest infection level is selected as broodstock, a 90% reduction in the intensity of infection in the progeny can be expected, even with the lowest estimation of heritability (h 2 =0.21). This strong response would be also due to the large phenotypic variance of this trait. Strong positive correlations, both phenotypic and genotypic, were observed between infection intensities with WS-RLO and WS-RLOv, indicating that selection to increase resistance to one of the types of RLOs will affect resistance in the other in the same direction. This is the first study that demonstrates the existence of additive genetic variation for resistance to WS-RLO in abalone. Consequently, it is possible to increase the resistance to WS-RLO in H. rufescens by selective breeding, which can be an economically attractive and environmentally friendly manner to reduce mortalities and growth effects caused by WS in abalone farms. Copyright © 2017 Elsevier Inc. All rights reserved.

Biocontrol of foliar pathogens: mechanisms and application.

PubMed

Elad, Y

2003-01-01

Biocontrol offers attractive alternatives or supplements to the use of conventional methods for plant disease management. Vast experience has been gained in the biocontrol of plant diseases. Prevention of infection by biocontrol agents or suppression of disease is based on various modes of action. Pathogens are typically affected by certain modes of actions and not by others according to their nature (i.e. biotrophs vs. necrotrophs). Resistance in the host plant may be induced locally or systemically by either live or dead cells of the biocontrol agent and may affect pathogens of various groups. As some pathogens are negatively affected by lake of nutrients in the infection court, competition for nutrients and space was long recognized as antagonism trait. Antibiosis and hyperparasitism affect pathogens of various groups. Other valid mechanisms are reduction of the saprophytic ability and reducing spore dissemination. Recently it was revealed that restraining of pathogenicity factors of the pathogens, i.e. host hydrolyzing proteins or reactive oxygen species takes place when biocontrol is used. It is likely that several modes of action concomitantly participate in pathogens suppression but the relative importance of each one of them is not clear. Examples of effective prevention of infection in the phyllosphere that rely on multiple modes of action will be demonstrated with Trichodermo harzianum T39 (TRICHODEX), Bacillus mycoides and Pichia guilermondii, a filamentous fungus, bacterium and yeast biocontrol agents, respectively. Several commercial products based on microorganisms have been developed and are starting to penetrate the market. However, large-scale use is still limited because of variability and inconsistency of biocontrol activity. In some cases this may be caused by sensitivity of the biocontrol agents to environmental influences. Ways to overcome biocontrol limitations and to improve its efficacy are i. integration of biocontrol with chemical fungicides on a calendar basis or according to ecological requirements of the biocontrol agents relying on the advise of a decision support system; ii. introduction of two or more biocontrol agents in a mixture, assuming that each one of them has different ecological requirements and/or different modes of action. Implementation of one (or more) of these approaches, using biocontrol preparations mentioned above lowered the variability and increased the consistency of disease suppression. The expected long-term result of the implementation of these suggested strategies is reduced risk of uncontrolled epidemics and increase of confidence of growers in using this non-chemical control measure on a large scale.

Fungal Planet description sheets: 469-557.

PubMed

Crous, P W; Wingfield, M J; Burgess, T I; Hardy, G E St J; Crane, C; Barrett, S; Cano-Lira, J F; Le Roux, J J; Thangavel, R; Guarro, J; Stchigel, A M; Martín, M P; Alfredo, D S; Barber, P A; Barreto, R W; Baseia, I G; Cano-Canals, J; Cheewangkoon, R; Ferreira, R J; Gené, J; Lechat, C; Moreno, G; Roets, F; Shivas, R G; Sousa, J O; Tan, Y P; Wiederhold, N P; Abell, S E; Accioly, T; Albizu, J L; Alves, J L; Antoniolli, Z I; Aplin, N; Araújo, J; Arzanlou, M; Bezerra, J D P; Bouchara, J-P; Carlavilla, J R; Castillo, A; Castroagudín, V L; Ceresini, P C; Claridge, G F; Coelho, G; Coimbra, V R M; Costa, L A; da Cunha, K C; da Silva, S S; Daniel, R; de Beer, Z W; Dueñas, M; Edwards, J; Enwistle, P; Fiuza, P O; Fournier, J; García, D; Gibertoni, T B; Giraud, S; Guevara-Suarez, M; Gusmão, L F P; Haituk, S; Heykoop, M; Hirooka, Y; Hofmann, T A; Houbraken, J; Hughes, D P; Kautmanová, I; Koppel, O; Koukol, O; Larsson, E; Latha, K P D; Lee, D H; Lisboa, D O; Lisboa, W S; López-Villalba, Á; Maciel, J L N; Manimohan, P; Manjón, J L; Marincowitz, S; Marney, T S; Meijer, M; Miller, A N; Olariaga, I; Paiva, L M; Piepenbring, M; Poveda-Molero, J C; Raj, K N A; Raja, H A; Rougeron, A; Salcedo, I; Samadi, R; Santos, T A B; Scarlett, K; Seifert, K A; Shuttleworth, L A; Silva, G A; Silva, M; Siqueira, J P Z; Souza-Motta, C M; Stephenson, S L; Sutton, D A; Tamakeaw, N; Telleria, M T; Valenzuela-Lopez, N; Viljoen, A; Visagie, C M; Vizzini, A; Wartchow, F; Wingfield, B D; Yurchenko, E; Zamora, J C; Groenewald, J Z

2016-12-01

Novel species of fungi described in this study include those from various countries as follows: Australia : Apiognomonia lasiopetali on Lasiopetalum sp., Blastacervulus eucalyptorum on Eucalyptus adesmophloia , Bullanockia australis (incl. Bullanockia gen. nov.) on Kingia australis , Caliciopsis eucalypti on Eucalyptus marginata , Celerioriella petrophiles on Petrophile teretifolia , Coleophoma xanthosiae on Xanthosia rotundifolia , Coniothyrium hakeae on Hakea sp., Diatrypella banksiae on Banksia formosa , Disculoides corymbiae on Corymbia calophylla , Elsinoë eelemani on Melaleuca alternifolia , Elsinoë eucalyptigena on Eucalyptus kingsmillii , Elsinoë preissianae on Eucalyptus preissiana , Eucasphaeria rustici on Eucalyptus creta , Hyweljonesia queenslandica (incl. Hyweljonesia gen. nov.) on the cocoon of an unidentified microlepidoptera, Mycodiella eucalypti (incl. Mycodiella gen. nov.) on Eucalyptus diversicolor , Myrtapenidiella sporadicae on Eucalyptus sporadica , Neocrinula xanthorrhoeae (incl. Neocrinula gen. nov.) on Xanthorrhoea sp., Ophiocordyceps nooreniae on dead ant, Phaeosphaeriopsis agavacearum on Agave sp., Phlogicylindrium mokarei on Eucalyptus sp., Phyllosticta acaciigena on Acacia suaveolens , Pleurophoma acaciae on Acacia glaucoptera , Pyrenochaeta hakeae on Hakea sp., Readeriella lehmannii on Eucalyptus lehmannii , Saccharata banksiae on Banksia grandis , Saccharata daviesiae on Daviesia pachyphylla , Saccharata eucalyptorum on Eucalyptus bigalerita , Saccharata hakeae on Hakea baxteri , Saccharata hakeicola on Hakea victoria , Saccharata lambertiae on Lambertia ericifolia , Saccharata petrophiles on Petrophile sp., Saccharata petrophilicola on Petrophile fastigiata , Sphaerellopsis hakeae on Hakea sp., and Teichospora kingiae on Kingia australis. Brazil : Adautomilanezia caesalpiniae (incl . Adautomilanezia gen. nov.) on Caesalpina echinata , Arthrophiala arthrospora (incl. Arthrophiala gen. nov.) on Sagittaria montevidensis , Diaporthe caatingaensis (endophyte from Tacinga inamoena ), Geastrum ishikawae on sandy soil, Geastrum pusillipilosum on soil, Gymnopus pygmaeus on dead leaves and sticks, Inonotus hymenonitens on decayed angiosperm trunk, Pyricularia urashimae on Urochloa brizantha , and Synnemellisia aurantia on Passiflora edulis . Chile : Tubulicrinis australis on Lophosoria quadripinnata. France : Cercophora squamulosa from submerged wood, and Scedosporium cereisporum from fluids of a wastewater treatment plant. Hawaii : Beltraniella acaciae , Dactylaria acaciae , Rhexodenticula acaciae , Rubikia evansii and Torula acaciae (all on Acacia koa ) . India : Lepidoderma echinosporum on dead semi-woody stems, and Rhodocybe rubrobrunnea from soil. Iran : Talaromyces kabodanensis from hypersaline soil. La Réunion : Neocordana musarum from leaves of Musa sp. Malaysia : Anungitea eucalyptigena on Eucalyptus grandis × pellita , Camptomeriphila leucaenae (incl. Camptomeriphila gen. nov.) on Leucaena leucocephala , Castanediella communis on Eucalyptus pellita , Eucalyptostroma eucalypti (incl. Eucalyptostroma gen. nov.) on Eucalyptus pellita , Melanconiella syzygii on Syzygium sp., Mycophilomyces periconiae (incl. Mycophilomyces gen. nov.) as hyperparasite on Periconia on leaves of Albizia falcataria , Synnemadiella eucalypti (incl. Synnemadiella gen. nov.) on Eucalyptus pellita , and Teichospora nephelii on Nephelium lappaceum. Mexico : Aspergillus bicephalus from soil. New Zealand : Aplosporella sophorae on Sophora microphylla , Libertasomyces platani on Platanus sp., Neothyronectria sophorae (incl. Neothyronectria gen. nov.) on Sophora microphylla , Parastagonospora phoenicicola on Phoenix canariensis , Phaeoacremonium pseudopanacis on Pseudopanax crassifolius , Phlyctema phoenicis on Phoenix canariensis , and Pseudoascochyta novae-zelandiae on Cordyline australis. Panama : Chalara panamensis from needle litter of Pinus cf. caribaea . South Africa : Exophiala eucalypti on leaves of Eucalyptus sp., Fantasmomyces hyalinus (incl. Fantasmomyces gen. nov.) on Acacia exuvialis , Paracladophialophora carceris (incl. Paracladophialophora gen. nov.) on Aloe sp., and Umthunziomyces hagahagensis (incl. Umthunziomyces gen. nov.) on Mimusops caffra. Spain : Clavaria griseobrunnea on bare ground in Pteridium aquilinum field, Cyathus ibericus on small fallen branches of Pinus halepensis , Gyroporus pseudolacteus in humus of Pinus pinaster , and Pseudoascochyta pratensis (incl. Pseudoascochyta gen. nov.) from soil. Thailand : Neoascochyta adenii on Adenium obesum , and Ochroconis capsici on Capsicum annuum . UK : Fusicolla melogrammae from dead stromata of Melogramma campylosporum on bark of Carpinus betulus . Uruguay : Myrmecridium pulvericola from house dust. USA : Neoscolecobasidium agapanthi (incl. Neoscolecobasidium gen. nov.) on Agapanthus sp . , Polyscytalum purgamentum on leaf litter, Pseudopithomyces diversisporus from human toenail, Saksenaea trapezispora from knee wound of a soldier, and Sirococcus quercus from Quercus sp . Morphological and culture characteristics along with DNA barcodes are provided.