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

Particle film affects black pecan aphid (Homoptera: Aphididae) on pecan.

PubMed

Cottrell, Ted E; Wood, Bruce W; Reilly, Charles C

2002-08-01

Three species of aphids attack pecan foliage, Carya illinoensis (Wang.) K. Koch, and cause economic damage. We tested a kaolin-based particle film against one of these aphid species, black pecan aphid, Melanocallis caryaefoliae (Davis). Effect of particle film on host selection, adult mortality, and production of nymphs by M. caryaefoliae was tested on seedling pecans in the laboratory. Fewer M. caryaefoliae adults selected treated foliage compared with untreated foliage. A higher percentage of adults that did select treated foliage were recovered from upper leaf surfaces compared with the percentage of adults recovered from upper leaf surfaces of untreated leaves. Observations with a microscope revealed an accumulation of particle film on aphid body parts, especially on tarsi, and strongly suggests that aphid mobility was restricted. Adult mortality was higher on treated foliage and led to an overall decrease in production of nymphs on those seedlings. In addition, we measured spectral properties of treated seedling pecan foliage. Light reflectance by treated foliage was increased and absorptance decreased compared with control foliage whereas transmittance of light through control and particle film-treated leaves was similar. We did not detect any phytotoxic effect on pecan due to application of particle film.

Transmission of Pandora neoaphidis in the presence of co-occurring arthropods.

PubMed

Baverstock, J; Baverstock, K E; Clark, S J; Pell, J K

2008-07-01

Transmission of the entomopathogenic fungus Pandora neoaphidis to the nettle aphid Microlophium carnosum was assessed in the presence of arthropods that co-exist with the fungus within the habitat but do not compete for aphid hosts. The presence of a parasitoid significantly enhanced transmission, and transmission rates were similar for both enemy and non-enemy parasitoids. Although herbivory of nettle leaves by Peacock butterfly (Inchis io) caterpillars indirectly reduced the number of M. carnosum by >30% due to a reduction in leaf area for feeding, the addition of I. io significantly increased transmission of P. neoaphidis in the remaining aphids. It is likely that enhanced transmission in the presence of A. rhopalosiphii and I. io is due to disturbance and subsequent movement of the aphid, resulting in contact with conidia deposited on the leaf surface. The presence and impact of co-occurring arthropods should be taken into consideration when assessing the transmission of fungal entomopathogens.

Viral metagenomics of aphids present in bean and maize plots on mixed-use farms in Kenya reveals the presence of three dicistroviruses including a novel Big Sioux River virus-like dicistrovirus.

PubMed

Wamonje, Francis O; Michuki, George N; Braidwood, Luke A; Njuguna, Joyce N; Musembi Mutuku, J; Djikeng, Appolinaire; Harvey, Jagger J W; Carr, John P

2017-10-02

Aphids are major vectors of plant viruses. Common bean (Phaseolus vulgaris L.) and maize (Zea mays L.) are important crops that are vulnerable to aphid herbivory and aphid-transmitted viruses. In East and Central Africa, common bean is frequently intercropped by smallholder farmers to provide fixed nitrogen for cultivation of starch crops such as maize. We used a PCR-based technique to identify aphids prevalent in smallholder bean farms and next generation sequencing shotgun metagenomics to examine the diversity of viruses present in aphids and in maize leaf samples. Samples were collected from farms in Kenya in a range of agro-ecological zones. Cytochrome oxidase 1 (CO1) gene sequencing showed that Aphis fabae was the sole aphid species present in bean plots in the farms visited. Sequencing of total RNA from aphids using the Illumina platform detected three dicistroviruses. Maize leaf RNA was also analysed. Identification of Aphid lethal paralysis virus (ALPV), Rhopalosiphum padi virus (RhPV), and a novel Big Sioux River virus (BSRV)-like dicistrovirus in aphid and maize samples was confirmed using reverse transcription-polymerase chain reactions and sequencing of amplified DNA products. Phylogenetic, nucleotide and protein sequence analyses of eight ALPV genomes revealed evidence of intra-species recombination, with the data suggesting there may be two ALPV lineages. Analysis of BSRV-like virus genomic RNA sequences revealed features that are consistent with other dicistroviruses and that it is phylogenetically closely related to dicistroviruses of the genus Cripavirus. The discovery of ALPV and RhPV in aphids and maize further demonstrates the broad occurrence of these dicistroviruses. Dicistroviruses are remarkable in that they use plants as reservoirs that facilitate infection of their insect replicative hosts, such as aphids. This is the first report of these viruses being isolated from either organism. The BSRV-like sequences represent a potentially novel dicistrovirus infecting A. fabae.

Geographic variation and evolution in the life cycle of the witch-hazel leaf gall aphid, Hormaphis hamamelidis.

PubMed

von Dohlen, C D; Gill, D E

1989-02-01

Two divergent life cycles associated with different elevations and latitudes have been documented for the witch-hazel leaf gall aphid, Hormaphis hamamelidis. At low elevation in northern Virginia, the aphid had seven distinct generations alternating between the primary host, witchhazel (Hamamelis virginiana), and a secondary host, river birch (Betula nigra). These findings confirm the original published life cycle description for the same locality. A second, abbreviated life cycle consisting of only three generations restricted to witch-hazel was discovered at high elevation (1000 m) in north central and northwestern Virginia. Aphids of both life cycles were sympatric at a middle elevation site. The life cycles and morphology suggest that the two forms are separate species. Although monoecious life cycles on primary hosts in aphids generally are thought to be ancestral to complex host-alternating ones, it is certainly possible that monoecious cycles are sometimes secondarily derived from complex cycles. By constructing a preliminary phylogeny of the described species in the tribe Hormaphidini, we propose that the abbreviated life cycle is derived from the complex one in the case of these witchhazel gall aphids. Our findings are discussed in the context of current theory regarding the evolutionary stability of complex life cycles.

Changes of oxidase and hydrolase activities in pecan leaves elicited by black pecan aphid (Hemiptera: Aphididae) feeding.

PubMed

Chen, Yigen; Ni, Xinzhi; Cottrell, Ted E; Wood, Bruce W; Buntin, G David

2009-06-01

The black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), is a foliar feeder of pecan, Carya illinoinensis (Wangenh.) K. Koch (Juglandaceae). The pest causes chlorosis of leaflet lamina, physiological damage to foliage and trees, and commonly limits the profitability of commercial pecan orchard enterprises. However, key aspects of this host-pest interaction are poorly understood. We report here the effects of M. caryaefoliae feeding on the foliar activity of oxidative (i.e., catalase, lipoxygenase [LOX]-1 and 3, and peroxidase) and hydrolytic (i.e., esterase) enzymes in relation to the degree of aphid resistance among pecan varieties. The 2-yr study showed that M. caryaefoliae-infested foliage exhibited elevated peroxidase activity only in susceptible ('Desirable', 'Sumner', and 'Schley'), but not in resistant ('Cape Fear', 'Gloria Grande', and 'Money Maker') genotypes. Susceptible genotypes also exhibited more severe leaf chlorosis in response to M. caryaefoliae feeding than the resistant genotypes; however, the aphid feeding did not influence catalase or esterase activity in all varieties, except the increase of esterase activity in Desirable and Gloria Grande. Melanocallis caryaefoliae feeding also influences activity of two lipoxygenase isozymes, with LOX3 being more frequently induced than LOX1. Foliar LOX3 activity was more frequently induced by M. caryaefoliae feeding in the moderately resistant 'Oconee' and highly resistant Money Maker and Cape Fear than in the susceptible genotypes. Therefore, the elevation of peroxidase is likely to be associated with aphid susceptibility and contributed to the severe leaf chlorosis, whereas the increase of LOX3 activity might be associated with aphid resistance in pecan. These findings contribute to our understanding of the etiology of M. caryaefoliae-elicited leaf chlorosis on pecan foliage. Such information may also be used to develop enzyme markers for identifying black pecan aphid resistance and/or susceptibility in pecan germplasm.

Host Plant Resistance and Insect Pest Management in Chickpea

USDA-ARS?s Scientific Manuscript database

Nearly 60 insect species feed on chickpea worldwide, of which cutworms (black cutworm - Agrotis ipsilon and turnip moth - Agrotis segetum), leaf feeding caterpillars (leaf caterpillar - Spodoptera exigua and hairy caterpillar - Spilarctia oblique), leaf miners (Liriomyza cicerina), aphids (Aphis cr...

Gene expression profiles responses to aphid feeding in chrysanthemum (Chrysanthemum morifolium).

PubMed

Xia, Xiaolong; Shao, Yafeng; Jiang, Jiafu; Ren, Liping; Chen, Fadi; Fang, Weimin; Guan, Zhiyong; Chen, Sumei

2014-12-02

Chrysanthemum is an important ornamental plant all over the world. It is easily attacked by aphid, Macrosiphoniella sanbourni. The molecular mechanisms of plant defense responses to aphid are only partially understood. Here, we investigate the gene expression changes in response to aphid feeding in chrysanthemum leaf by RNA-Seq technology. Three libraries were generated from pooled leaf tissues of Chrysanthemum morifolium 'nannongxunzhang' that were collected at different time points with (Y) or without (CK) aphid infestations and mock puncture treatment (Z), and sequenced using an Illumina HiSeqTM 2000 platform. A total of 7,363,292, 7,215,860 and 7,319,841 clean reads were obtained in library CK, Y and Z, respectively. The proportion of clean reads was >97.29% in each library. Approximately 76.35% of the clean reads were mapped to a reference gene database including all known chrysanthemum unigene sequences. 1,157, 527 and 340 differentially expressed genes (DEGs) were identified in the comparison of CK-VS-Y, CK-VS-Z and Z-VS-Y, respectively. These DEGs were involved in phytohormone signaling, cell wall biosynthesis, photosynthesis, reactive oxygen species (ROS) pathway and transcription factor regulatory networks, and so on. Changes in gene expression induced by aphid feeding are shown to be multifaceted. There are various forms of crosstalk between different pathways those genes belonging to, which would allow plants to fine-tune its defense responses.

Natural infection of Sorghum bicolor germplasm by Sugarcane yellow leaf virus in Florida

USDA-ARS?s Scientific Manuscript database

Sugarcane yellow leaf virus (SCYLV), the causal agent of sugarcane yellow leaf, is vectored by the aphid Melanaphis sacchari. Although sugarcane is the primary host of SCYLV, two new natural hosts were recently identified in Florida: the weed Columbus grass (Sorghum almum) and grain sorghum (Sorghum...

Volatile aldehydes are promising broad-spectrum postharvest insecticides.

PubMed

Hammond, D G; Rangel, S; Kubo, I

2000-09-01

A variety of naturally occurring aldehydes common in plants have been evaluated for their insecticidal activity and for phytotoxicity to postharvest fruits, vegetables, and grains. Twenty-nine compounds were initially screened for their activity against aphids on fava bean leaf disks. Application under reduced pressure (partial vacuum) for the first quarter of fumigation increased insecticidal activity severalfold. The 11 best aldehydes were assayed against aphids placed under the third leaf of whole heads of iceberg lettuce using the same two-tier reduced-pressure regime, which caused no additional detriment to the commodity over fumigation at atmospheric pressure. Phytotoxicity to naked and wrapped iceburg lettuce, green and red table grapes, lemon, grapefruit, orange, broccoli, avocado, cabbage, pinto bean, and rice at doses that killed 100% of aphids was recorded for three promising fumigants: propanal, (E)-2-pentenal, and 2-methyl-(E)-2-butenal. These three compounds have excellent potential as affordable postharvest insect control agents, killing 100% of the aphids with little or no detectable harm to a majority of the commodities tested. Preliminary assays indicate that similar doses are also effective against mealybugs, thrips, and whitefly.

Accumulation of 5-hydroxynorvaline in maize (Zea mays) leaves is induced by insect feeding and abiotic stress.

PubMed

Yan, Jian; Lipka, Alexander E; Schmelz, Eric A; Buckler, Edward S; Jander, Georg

2015-02-01

Plants produce a wide variety of defensive metabolites to protect themselves against herbivores and pathogens. Non-protein amino acids, which are present in many plant species, can have a defensive function through their mis-incorporation during protein synthesis and/or inhibition of biosynthetic pathways in primary metabolism. 5-Hydroxynorvaline was identified in a targeted search for previously unknown non-protein amino acids in the leaves of maize (Zea mays) inbred line B73. Accumulation of this compound increases during herbivory by aphids (Rhopalosiphum maidis, corn leaf aphid) and caterpillars (Spodoptera exigua, beet armyworm), as well as in response to treatment with the plant signalling molecules methyl jasmonate, salicylic acid and abscisic acid. In contrast, ethylene signalling reduced 5-hydroxynorvaline abundance. Drought stress induced 5-hydroxynorvaline accumulation to a higher level than insect feeding or treatment with defence signalling molecules. In field-grown plants, the 5-hydroxynorvaline concentration was highest in above-ground vegetative tissue, but it was also detectable in roots and dry seeds. When 5-hydroxynorvaline was added to aphid artificial diet at concentrations similar to those found in maize leaves and stems, R. maidis reproduction was reduced, indicating that this maize metabolite may have a defensive function. Among 27 tested maize inbred lines there was a greater than 10-fold range in the accumulation of foliar 5-hydroxynorvaline. Genetic mapping populations derived from a subset of these inbred lines were used to map quantitative trait loci for 5-hydroxynorvaline accumulation to maize chromosomes 5 and 7. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Sugarcane Aphid Population Growth, Plant Injury, and Natural Enemies on Selected Grain Sorghum Hybrids in Texas and Louisiana.

PubMed

Brewer, Michael J; Gordy, John W; Kerns, David L; Woolley, James B; Rooney, William L; Bowling, Robert D

2017-10-01

In response to the 2013 outbreak of sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), on sorghum, Sorghum bicolor (L.), in North America, experiments were conducted at three southern U.S. grain sorghum production locations (Corpus Christi, TX; Winnsboro, LA; Rosenberg, TX). The objectives were to authenticate yield decline on susceptible hybrids (2014 and 2015) and to measure aphid population growth and natural enemy prevalence on susceptible and resistant hybrids with similar genetic background (2014). Yield decline on susceptible hybrids (Tx 2752/Tx430 and DKS53-67) was more substantial when aphid population growth accelerated quickly and peaked above 300 aphids per leaf (50 to nearly 100% yield decline). Location and year variation in maximum aphid density and cumulative aphid-days was high, with doubling time values on the susceptible hybrids ranging between 3.9 and 7.9 d. On resistant Tx2752/Tx2783, leaf injury and yield decline were not seen or less severe than on its paired susceptible Tx2752/Tx430. Aphids declined on Tx2752/Tx2783 after initial colony establishment (Corpus Christi) or took about 60% longer to double in population size when compared with Tx2572/Tx430 (Winnsboro). The predominant natural enemy taxa were aphelinid mummies (Hymenoptera: Aphelinidae), ladybird beetles (Coleoptera: Coccinellidae), and sryphid flies (Diptera: Syrphidae), and they were more prevalent during flowering than prior to flowering. They were generally responsive to changes in aphid density of both susceptible and resistant hybrids, but variability points to need for further study. In future research, full season observations should continue as well as more detailed study of potential compatibility of sorghum resistance and biological control. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Spectral Detection of Soybean Aphid (Hemiptera: Aphididae) and Confounding Insecticide Effects in Soybean

NASA Astrophysics Data System (ADS)

Alves, Tavvs Micael

Soybean aphid, Aphis glycines (Hemiptera: Aphididae) is the primary insect pest of soybean in the northcentral United States. Soybean aphid may cause stunted plants, leaf discoloration, plant death, and decrease soybean yield by 40%. Sampling plans have been developed for supporting soybean aphid management. However, growers' perception about time involved in direct insect counts has been contributing to a lower adoption of traditional pest scouting methods and may be associated with the use of prophylactic insecticide applications in soybean. Remote sensing of plant spectral (light-derived) responses to soybean aphid feeding is a promising alternative to estimate injury without direct insect counts and, thus, increase adoption and efficiency of scouting programs. This research explored the use of remote sensing of soybean reflectance for detection of soybean aphids and showed that foliar insecticides may have implications for subsequent use of soybean spectral reflectance for pest detection. (Abstract shortened by ProQuest.).

Natural variation in maize aphid resistance is associated with 2,4-Dihydroxy-7-Methoxy-1,4-Benzoxazin-3-One Glucoside Methyltransferase activity

USDA-ARS?s Scientific Manuscript database

Plants differ greatly in their susceptibility to insect herbivory, suggesting both local adaptation and resistance tradeoffs. We used maize (Zea mays) recombinant inbred lines to map a quantitative trait locus (QTL) for the maize leaf aphid (Rhopalosiphum maidis) susceptibility to maize Chromosome 1...

Behavior Performance of Diuraphis noxia (Homoptera: Aphididae) on Fungal Endophyte-Infected and Uninfected Perennial Ryegrass

Treesearch

S.L. Clement; D.G. Lester; A. Dan Wilson; K.S. Pike

1992-01-01

The behavior and performance of the Russian wheat aphid, Diuraphis noxia (Mordvilko), on fungal endophyte-infected and endophyte-free perennial ryegrass, Lolium perenne L., was investigated in the laboratory and field. Aphids did not select endophyte-free over endophyte-infected leaf sheaths and stem segments in petri dish preference tests....

Field screening of sugarcane varieties for sugarcane yellow leaf in Louisiana

USDA-ARS?s Scientific Manuscript database

The causal agent of sugarcane yellow leaf is the Sugarcane yellow leaf virus (SCYLV), a member of Luteoviridae family. As with other luteoviruses, SCYLV is only transmitted by specific aphids in a circulative, non-propagative manner. In Louisiana, the primary vector of SCYLV is believed to be the su...

Impact of UV-A radiation on the performance of aphids and whiteflies and on the leaf chemistry of their host plants.

PubMed

Dáder, Beatriz; Gwynn-Jones, Dylan; Moreno, Aránzazu; Winters, Ana; Fereres, Alberto

2014-09-05

Ultraviolet (UV) radiation directly regulates a multitude of herbivore life processes, in addition to indirectly affecting insect success via changes in plant chemistry and morphogenesis. Here we looked at plant and insect (aphid and whitefly) exposure to supplemental UV-A radiation in the glasshouse environment and investigated effects on insect population growth. Glasshouse grown peppers and eggplants were grown from seed inside cages covered by novel plastic filters, one transparent and the other opaque to UV-A radiation. At a 10-true leaf stage for peppers (53 days) and 4-true leaf stage for eggplants (34 days), plants were harvested for chemical analysis and infested by aphids and whiteflies, respectively. Clip-cages were used to introduce and monitor the insect fitness and populations of the pests studied. Insect pre-reproductive period, fecundity, fertility and intrinsic rate of natural increase were assessed. Crop growth was monitored weekly for 7 and 12 weeks throughout the crop cycle of peppers and eggplants, respectively. At the end of the insect fitness experiment, plants were harvested (68 days and 18-true leaf stage for peppers, and 104 days and 12-true leaf stage for eggplants) and leaves analysed for secondary metabolites, soluble carbohydrates, amino acids, total proteins and photosynthetic pigments. Our results demonstrate for the first time, that UV-A modulates plant chemistry with implications for insect pests. Both plant species responded directly to UV-A by producing shorter stems but this effect was only significant in pepper whilst UV-A did not affect the leaf area of either species. Importantly, in pepper, the UV-A treated plants contained higher contents of secondary metabolites, leaf soluble carbohydrates, free amino acids and total content of protein. Such changes in tissue chemistry may have indirectly promoted aphid performance. For eggplants, chlorophylls a and b, and carotenoid levels decreased with supplemental UV-A over the entire crop cycle but UV-A exposure did not affect leaf secondary metabolites. However, exposure to supplemental UV-A had a detrimental effect on whitefly development, fecundity and fertility presumably not mediated by plant cues as compounds implied in pest nutrition - proteins and sugars - were unaltered. Copyright © 2014 Elsevier B.V. All rights reserved.

The complete nucleotide sequence of the genome of Barley yellow dwarf virus-RMV reveals it to be a new Polerovirus distantly related to other yellow dwarf viruses

PubMed Central

Krueger, Elizabeth N.; Beckett, Randy J.; Gray, Stewart M.; Miller, W. Allen

2013-01-01

The yellow dwarf viruses (YDVs) of the Luteoviridae family represent the most widespread group of cereal viruses worldwide. They include the Barley yellow dwarf viruses (BYDVs) of genus Luteovirus, the Cereal yellow dwarf viruses (CYDVs) and Wheat yellow dwarf virus (WYDV) of genus Polerovirus. All of these viruses are obligately aphid transmitted and phloem-limited. The first described YDVs (initially all called BYDV) were classified by their most efficient vector. One of these viruses, BYDV-RMV, is transmitted most efficiently by the corn leaf aphid, Rhopalosiphum maidis. Here we report the complete 5612 nucleotide sequence of the genomic RNA of a Montana isolate of BYDV-RMV (isolate RMV MTFE87, Genbank accession no. KC921392). The sequence revealed that BYDV-RMV is a polerovirus, but it is quite distantly related to the CYDVs or WYDV, which are very closely related to each other. Nor is BYDV-RMV closely related to any other particular polerovirus. Depending on the gene that is compared, different poleroviruses (none of them a YDV) share the most sequence similarity to BYDV-RMV. Because of its distant relationship to other YDVs, and because it commonly infects maize via its vector, R. maidis, we propose that BYDV-RMV be renamed Maize yellow dwarf virus-RMV (MYDV-RMV). PMID:23888156

The complete nucleotide sequence of the genome of Barley yellow dwarf virus-RMV reveals it to be a new Polerovirus distantly related to other yellow dwarf viruses.

PubMed

Krueger, Elizabeth N; Beckett, Randy J; Gray, Stewart M; Miller, W Allen

2013-01-01

The yellow dwarf viruses (YDVs) of the Luteoviridae family represent the most widespread group of cereal viruses worldwide. They include the Barley yellow dwarf viruses (BYDVs) of genus Luteovirus, the Cereal yellow dwarf viruses (CYDVs) and Wheat yellow dwarf virus (WYDV) of genus Polerovirus. All of these viruses are obligately aphid transmitted and phloem-limited. The first described YDVs (initially all called BYDV) were classified by their most efficient vector. One of these viruses, BYDV-RMV, is transmitted most efficiently by the corn leaf aphid, Rhopalosiphum maidis. Here we report the complete 5612 nucleotide sequence of the genomic RNA of a Montana isolate of BYDV-RMV (isolate RMV MTFE87, Genbank accession no. KC921392). The sequence revealed that BYDV-RMV is a polerovirus, but it is quite distantly related to the CYDVs or WYDV, which are very closely related to each other. Nor is BYDV-RMV closely related to any other particular polerovirus. Depending on the gene that is compared, different poleroviruses (none of them a YDV) share the most sequence similarity to BYDV-RMV. Because of its distant relationship to other YDVs, and because it commonly infects maize via its vector, R. maidis, we propose that BYDV-RMV be renamed Maize yellow dwarf virus-RMV (MYDV-RMV).

Comparative role of neem seed extract, moringa leaf extract and imidacloprid in the management of wheat aphids in relation to yield losses in Pakistan

PubMed Central

Shah, Farhan Mahmood; Razaq, Muhammad; Han, Peng; Chen, Julian

2017-01-01

Wheat being staple food of Pakistan is constantly attacked by major wheat aphid species, Schizaphis graminum (R.), Rhopalosiphum padi (L.) and Sitobion avenae (F.). Due to concern on synthetic chemical use in wheat, it is imperative to search for alternative environment- and human- friendly control measures such as botanical pesticides. In the present study, we evaluated the comparative role of neem seed extract (NSE), moringa leaf extract (MLE) and imidacloprid (I) in the management of the aphid as well as the yield losses parameters in late planted wheat fields. Imidacloprid reduced significantly aphids infestation compared to the other treatments, hence resulting in higher yield, particularly when applied with MLE. The percentages of yield increase in I+MLE treated plots over the control were 19.15–81.89% for grains per spike, 5.33–37.62% for thousand grain weight and 27.59–61.12% for yield kg/ha. NSE was the second most effective control measure in suppressing aphid population, but the yield protected by NSE treatment over the control was comparable to that by imidacloprid. Population densities of coccinellids and syrphids in the plots treated with NSE-2 were higher than those treated with imidacloprid in two out of three experiments during 2013–14. Low predator density in imidacloprid-treated plots was attributed to the lower availability of prey aphids. The efficacy of NSE against aphids varied depending on degree of synchronization among the application timing, the activity of aphids, crop variety and environmental conditions. Despite that, we suggested NSE to be a promising alternative botanical insecticide compared to the most commonly recommended imidiacloprid. Further studies should consider the side effects of biopesticides on non-target organisms in order to provide better management practices in the field. PMID:28953894

Comparative role of neem seed extract, moringa leaf extract and imidacloprid in the management of wheat aphids in relation to yield losses in Pakistan.

PubMed

Shah, Farhan Mahmood; Razaq, Muhammad; Ali, Abid; Han, Peng; Chen, Julian

2017-01-01

Wheat being staple food of Pakistan is constantly attacked by major wheat aphid species, Schizaphis graminum (R.), Rhopalosiphum padi (L.) and Sitobion avenae (F.). Due to concern on synthetic chemical use in wheat, it is imperative to search for alternative environment- and human- friendly control measures such as botanical pesticides. In the present study, we evaluated the comparative role of neem seed extract (NSE), moringa leaf extract (MLE) and imidacloprid (I) in the management of the aphid as well as the yield losses parameters in late planted wheat fields. Imidacloprid reduced significantly aphids infestation compared to the other treatments, hence resulting in higher yield, particularly when applied with MLE. The percentages of yield increase in I+MLE treated plots over the control were 19.15-81.89% for grains per spike, 5.33-37.62% for thousand grain weight and 27.59-61.12% for yield kg/ha. NSE was the second most effective control measure in suppressing aphid population, but the yield protected by NSE treatment over the control was comparable to that by imidacloprid. Population densities of coccinellids and syrphids in the plots treated with NSE-2 were higher than those treated with imidacloprid in two out of three experiments during 2013-14. Low predator density in imidacloprid-treated plots was attributed to the lower availability of prey aphids. The efficacy of NSE against aphids varied depending on degree of synchronization among the application timing, the activity of aphids, crop variety and environmental conditions. Despite that, we suggested NSE to be a promising alternative botanical insecticide compared to the most commonly recommended imidiacloprid. Further studies should consider the side effects of biopesticides on non-target organisms in order to provide better management practices in the field.

Plant immunity in plant–aphid interactions

PubMed Central

Jaouannet, Maëlle; Rodriguez, Patricia A.; Lenoir, Camille J. G.; MacLeod, Ruari; Escudero-Martinez, Carmen; Bos, Jorunn I.B.

2014-01-01

Aphids are economically important pests that cause extensive feeding damage and transmit viruses. While some species have a broad host range and cause damage to a variety of crops, others are restricted to only closely related plant species. While probing and feeding aphids secrete saliva, containing effectors, into their hosts to manipulate host cell processes and promote infestation. Aphid effector discovery studies pointed out parallels between infection and infestation strategies of plant pathogens and aphids. Interestingly, resistance to some aphid species is known to involve plant resistance proteins with a typical NB-LRR domain structure. Whether these resistance proteins indeed recognize aphid effectors to trigger ETI remains to be elucidated. In addition, it was recently shown that unknown aphid derived elicitors can initiate reactive oxygen species (ROS) production and callose deposition and that these responses were dependent on BAK1 (BRASSINOSTERIOD INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1) which is a key component of the plant immune system. In addition, BAK-1 contributes to non-host resistance to aphids pointing to another parallel between plant-pathogen and – aphid interactions. Understanding the role of plant immunity and non-host resistance to aphids is essential to generate durable and sustainable aphid control strategies. Although insect behavior plays a role in host selection and non-host resistance, an important observation is that aphids interact with non-host plants by probing the leaf surface, but are unable to feed or establish colonization. Therefore, we hypothesize that aphids interact with non-host plants at the molecular level, but are potentially not successful in suppressing plant defenses and/or releasing nutrients. PMID:25520727

The integrative effects of population density, photoperiod, temperature, and host plant on the induction of alate aphids in Schizaphis graminum.

PubMed

An, Chunju; Fei, Xiaodong; Chen, Wenfeng; Zhao, Zhangwu

2012-04-01

The wheat aphid Schizaphis graminum (Rondani) displays wing dimorphism with both winged and wingless adult morphs. The winged morph is an adaptive microevolutionary response to undesirable environmental conditions, including undesirable population density, photoperiod, temperature, and host plant. Here we studied the integrative effects of population density, photoperiod, temperature, and host plant on the induction of alate aphids in S. graminum. The present results show that these four factors all play roles in inducing alate aphids in S. graminum but population density is the most important under almost all circumstances. In importance, population density is followed by photoperiod, host plant, and temperature, in that order. These results indicate that ambient environmental factors are highly important to stimulation of alate aphids in S. graminum, especially when population density reaches 64 individuals per leaf. © 2012 Wiley Periodicals, Inc.

Response of Solanum tuberosum to Myzus persicae infestation at different stages of foliage maturity.

PubMed

Alvarez, Adriana E; Alberti D'Amato, Anahí M; Tjallingii, W Fred; Dicke, Marcel; Vosman, Ben

2014-12-01

Young leaves of the potato Solanum tuberosum L. cultivar Kardal contain resistance factors to the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) and normal probing behavior is impeded. However, M. persicae can survive and reproduce on mature and senescent leaves of the cv. Kardal plant without problems. We compared the settling of M. persicae on young and old leaves and analyzed the impact of aphids settling on the plant in terms of gene expression. Settling, as measured by aphid numbers staying on young or old leaves, showed that after 21 h significantly fewer aphids were found on the young leaves. At earlier time points there were no difference between young and old leaves, suggesting that the young leaf resistance factors are not located at the surface level but deeper in the tissue. Gene expression was measured in plants at 96 h postinfestation, which is at a late stage in the interaction and in compatible interactions this is long enough for host plant acceptance to occur. In old leaves of cv. Kardal (compatible interaction), M. persicae infestation elicited a higher number of differentially regulated genes than in young leaves. The plant response to aphid infestation included a larger number of genes induced than repressed, and the proportion of induced versus repressed genes was larger in young than in old leaves. Several genes changing expression seem to be involved in changing the metabolic state of the leaf from source to sink. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Localization, Concentration, and Transmission Efficiency of Banana bunchy top virus in Four Asexual Lineages of Pentalonia aphids

PubMed Central

Watanabe, Shizu; Greenwell, April M.; Bressan, Alberto

2013-01-01

Banana bunchy top virus (BBTV) is the most destructive pathogenic virus of banana plants worldwide. The virus is transmitted in a circulative non-propagative manner by the banana aphid, Pentalonia nigronervosa Coquerel. In this work, we examined the localization, accumulation, and transmission efficiency of BBTV in four laboratory-established lineages of Pentalonia aphids derived from four different host plants: taro (Colocasia esculenta), heliconia (Heliconia spp.), red ginger (Alpinia purpurata), and banana (Musa sp.). Mitochondrial sequencing identified three and one lineages as Pentalonia caladii van der Goot, a recently proposed species, and P. nigronervosa, respectively. Microsatellite analysis separated the aphid lineages into four distinct genotypes. The transmission of BBTV was tested using leaf disk and whole-plant assays, both of which showed that all four lineages are competent vectors of BBTV, although the P. caladii from heliconia transmitted BBTV to the leaf disks at a significantly lower rate than did P. nigronervosa. The concentration of BBTV in dissected guts, haemolymph, and salivary glands was quantified by real-time PCR. The BBTV titer reached similar concentrations in the guts, haemolymph, and salivary glands of aphids from all four lineages tested. Furthermore, immunofluorescence assays showed that BBTV antigens localized to the anterior midguts and the principal salivary glands, demonstrating a similar pattern of translocations across the four lineages. The results reported in this study showed for the first time that P. caladii is a competent vector of BBTV. PMID:23435241

Localization, concentration, and transmission efficiency of Banana bunchy top virus in four asexual lineages of Pentalonia aphids.

PubMed

Watanabe, Shizu; Greenwell, April M; Bressan, Alberto

2013-02-22

Banana bunchy top virus (BBTV) is the most destructive pathogenic virus of banana plants worldwide. The virus is transmitted in a circulative non-propagative manner by the banana aphid, Pentalonia nigronervosa Coquerel. In this work, we examined the localization, accumulation, and transmission efficiency of BBTV in four laboratory-established lineages of Pentalonia aphids derived from four different host plants: taro (Colocasia esculenta), heliconia (Heliconia spp.), red ginger (Alpinia purpurata), and banana (Musa sp.). Mitochondrial sequencing identified three and one lineages as Pentalonia caladii van der Goot, a recently proposed species, and P. nigronervosa, respectively. Microsatellite analysis separated the aphid lineages into four distinct genotypes. The transmission of BBTV was tested using leaf disk and whole-plant assays, both of which showed that all four lineages are competent vectors of BBTV, although the P. caladii from heliconia transmitted BBTV to the leaf disks at a significantly lower rate than did P. nigronervosa. The concentration of BBTV in dissected guts, haemolymph, and salivary glands was quantified by real-time PCR. The BBTV titer reached similar concentrations in the guts, haemolymph, and salivary glands of aphids from all four lineages tested. Furthermore, immunofluorescence assays showed that BBTV antigens localized to the anterior midguts and the principal salivary glands, demonstrating a similar pattern of translocations across the four lineages. The results reported in this study showed for the first time that P. caladii is a competent vector of BBTV.

The effect of leaf size on the microwave backscattering by corn

NASA Technical Reports Server (NTRS)

Paris, J. F.

1986-01-01

Attema and Ulaby (1978) proposed the cloud model to predict the microwave backscattering properties of vegetation. This paper describes a modification in which the biophysical properties and microwave properties of vegetation are related at the level of the individual scatterer (e.g., the leaf or the stalk) rather than at the level of the aggregated canopy (e.g., the green leaf area index). Assuming that the extinction cross section of an average leaf was proportional to its water content, that a power law relationship existed between the backscattering cross section of an average green corn leaf and its area, and that the backscattering coefficient of the surface was a linear function of its volumetric soil moisture content, it is found that the explicit inclusion of the effects of corn leaf size in the model led to an excellent fit between the observed and predicted backscattering coefficients. Also, an excellent power law relationship existed between the backscattering cross section of a corn leaf and its area.

Novel member of the Luteoviridae associated with raspberry leaf curl disease

USDA-ARS?s Scientific Manuscript database

Raspberry leaf curl virus (RLCV) was first reported in the 1920s, is limited to the genus Rubus and is transmitted in a persistent manner by the small raspberry aphid, Aphis rubicola. It is only reported from North America, principally in the northeastern United States and southeastern Canada, and i...

Production of methanol from heat-stressed pepper and corn leaf disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, J.A.

Early Calwonder'' pepper (Capsicum annuum L.) and Jubilee'' corn (Zea mays L.) leaf disks exposed to high temperature stress produced ethylene, ethane, methanol, acetaldehyde, and ethanol based on comparison of retention times during gas chromatography to authentic standards. Methanol, ethanol, and acetaldehyde were also identified by mass spectroscopy. Corn leaf disks produced lower levels of ethylene, ethane, and methanol, but more acetaldehyde and ethanol than pepper. Production of ethane, a by-product of lipid peroxidation, coincided with an increase in electrolyte leakage (EL) in pepper but not in corn. Compared with controls, pepper leaf disks infiltrated with linolenic acid evolved significantlymore » greater amounts of ethane, acetaldehyde, and methanol and similar levels of ethanol. EL and volatile hydrocarbon production were not affected by fatty acid infiltration in corn. Infiltration of pepper leaves with buffers increasing in pH from 5.5 to 9.5 increased methanol production.« less

Aphid watery saliva counteracts sieve-tube occlusion: a universal phenomenon?

PubMed

Will, Torsten; Kornemann, Sarah R; Furch, Alexandra C U; Tjallingii, W Fred; van Bel, Aart J E

2009-10-01

Ca2+-binding proteins in the watery saliva of Megoura viciae counteract Ca2+-dependent occlusion of sieve plates in Vicia faba and so prevent the shut-down of food supply in response to stylet penetration. The question arises whether this interaction between aphid saliva and sieve-element proteins is a universal phenomenon as inferred by the coincidence between sieve-tube occlusion and salivation. For this purpose, leaf tips were burnt in a number of plant species from four different families to induce remote sieve-plate occlusion. Resultant sieve-plate occlusion in these plant species was counteracted by an abrupt switch of aphid behaviour. Each of the seven aphid species tested interrupted its feeding behaviour and started secreting watery saliva. The protein composition of watery saliva appeared strikingly different between aphid species with less than 50% overlap. Secretion of watery saliva seems to be a universal means to suppress sieve-plate occlusion, although the protein composition of watery saliva seems to diverge between species.

Temporal relationships between spectral response and agronomic variables of a corn canopy

NASA Technical Reports Server (NTRS)

Kimes, D. S.; Markham, B. L.; Tucker, C. J.; Mcmurtrey, J. E., III

1981-01-01

Attention is given to an experiment in which spectral radiance data collected in three spectral regions are related to corn canopy variables. The study extends the work of Tucker et al. (1979) in that more detailed measurements of corn canopy variables were made using quantitative techniques. Wet and dry green leaf biomass is considered along with the green leaf area index, chlorotic leaf biomass, chlorotic leaf area, and leaf water content. In addition, spectral data were collected with a hand-held radiometer having Landsat-D Thematic Mapper (TM) bands TM3 (0.63-0.69 micrometers), TM4 (0.76-0.90 micrometers), and TM5 (1.55-1.75 micrometers). TM3, TM4, and TM5 seem to be well situated spectrally for making remotely sensed measurements related to chlorophyll concentration, leaf density, and leaf water content.

Analysis of an RNA-seq Strand-Specific Library from an East Timorese Cucumber Sample Reveals a Complete Cucurbit aphid-borne yellows virus Genome

PubMed Central

Maina, Solomon; Edwards, Owain R.; de Almeida, Luis; Ximenes, Abel

2017-01-01

ABSTRACT Analysis of an RNA-seq library from cucumber leaf RNA extracted from a fast technology for analysis of nucleic acids (FTA) card revealed the first complete genome of Cucurbit aphid-borne yellows virus (CABYV) from East Timor. We compare it with 35 complete CABYV genomes from other world regions. It most resembled the genome of the South Korean isolate HD118. PMID:28495776

A magical biological insecticide extracted from seeds of Millettia pachyarpa to kill cabbage aphids

NASA Astrophysics Data System (ADS)

Lin, Tianxing; Gong, Mingfu; Guan, Qinlan

2018-04-01

Millettia pachycarpa Benth is a perennial climbing shrub belonging to the genus Millettia, as it is widely used in traditional practices like agricultural pesticides, blood tonics, fish poison, and treatments for cancer and infertility. The crude extract of the seeds of M. pachycarpa had insecticidal activity on cabbage aphids. The conventional extract approach with three kinds of organic solvents: methanol, ethanol, and acetone was used for extracting of crude extract of seeds of M. pachycarpa. The leaf immersion method in a petri dish was used to measure contact activity on cabbage aphids. The field measurement method in a cabbage field was used to measure the control effect. The result indicated that the average mortality rate of cabbage aphids reached 91.3 percent under the action of crude extract of the seeds of M. pachycarpa, indicating that contacting activity against cabbage aphid was strong. After the crude extract was sprayed for 2 days, the proofread control effect of 1000 μg / mL ethanol crude extract against cabbage aphid was 85.0 percent. After 7 days of spraying, this number increased to 92.2 percent. The study concluded that crude extract of the seeds of M. pachyarpa extracted with methanol, ethanol, acetone had demonstrable contact activity against cabbage aphid and 1000 μg / mL ethanol crude extract had significant control effect against the larvae of cabbage aphid.

Transgenic tobacco expressing Pinellia ternata agglutinin confers enhanced resistance to aphids.

PubMed

Yao, Jianhong; Pang, Yongzhen; Qi, Huaxiong; Wan, Bingliang; Zhao, Xiuyun; Kong, Weiwen; Sun, Xiaofen; Tang, Kexuan

2003-12-01

Tobacco leaf discs were transformed with a plasmid, pBIPTA, containing the selectable marker neomycin phosphotransferase gene (nptII) and Pinellia ternata agglutinin gene (pta) via Agrobacterium tumefaciens-mediated transformation. Thirty-two independent transgenic tobacco plants were regenerated. PCR and Southern blot analyses confirmed that the pta gene had integrated into the plant genome and northern blot analysis revealed transgene expression at various levels in transgenic plants. Genetic analysis confirmed Mendelian segregation of the transgene in T1 progeny. Insect bioassays showed that transgenic plants expressing PTA inhibited significantly the growth of peach potato aphid (Myzus persicae Sulzer). This is the first report that transgenic plants expressing pta confer enhanced resistance to aphids. Our study indicates that the pta gene can be used as a supplement to the snowdrop (Galanthus nivalis) lectin gene (gna) in the control of aphids, a sap-sucking insect pest causing significant yield losses of crops.

Insecticide use and competition shape the genetic diversity of the aphid Aphis gossypii in a cotton-growing landscape.

PubMed

Brévault, T; Carletto, J; Tribot, J; Vanlerberghe-Masutti, F

2011-08-01

Field populations of the cotton aphid, Aphis gossypii Glover, are structured into geographically widespread host races. In the cotton-producing regions of West and Central Africa (WCA), two genotypes have been repeatedly detected within the cotton host race, one of which (Burk1) is prevalent (>90%) and resistant to several insecticides, as opposed to the second one (Ivo). Here, we conducted whole plant and field cage experiments to test hypotheses for such low genetic diversity, including selection from insecticide treatments, interclonal competition and adaptation to host plant, or climatic conditions. To assess the genetic diversity of immigrant aphids, alatae were trapped and collected on cotton and relay host plants (okra and roselle) in the early cropping season. Individuals were genotyped at eight specific microsatellite loci and characterized by a multilocus genotype (MLG). When independently transferred from cotton (Gossypium hirustum L.) leaf discs to whole plants (G. hirsutum and G. arboreum, roselle and okra), Ivo and Burk1 performed equally well. When concurrently transferred from cotton leaf discs to the same plant species, Ivo performed better than Burk1, indicating that competition favoured Ivo. This was also the case on G. hirsutum growing outdoors. Conversely, Burk1 prevailed when cotton plants were sprayed with insecticides. In experiments where aphids were allowed to move to neighbouring plants, Burk1 was better represented than Ivo on low-populated plants, suggesting that dispersal may be a way to avoid competition on crowded plants. Most cotton aphids collected on cotton or relay host plants in the early cropping season were Burk1 (>90%), indicating high dispersal ability and, probably reflecting high frequency on host plants from which they dispersed. In the agricultural landscape of WCA, the use of broad-range insecticides on both cotton and relay host plants has led to the prevalence of one genotype of A. gossypii resistant to different classes of insecticides. Deployment of widespread and integrated pest management strategies are needed to restore cotton aphid control.

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper.

PubMed

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-07-01

Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper

PubMed Central

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-01-01

Background and Aims Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Methods Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Key Results Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. Conclusions The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks. PMID:22437662

Analysis of an RNA-seq Strand-Specific Library from an East Timorese Cucumber Sample Reveals a Complete Cucurbit aphid-borne yellows virus Genome.

PubMed

Maina, Solomon; Edwards, Owain R; de Almeida, Luis; Ximenes, Abel; Jones, Roger A C

2017-05-11

Analysis of an RNA-seq library from cucumber leaf RNA extracted from a fast technology for analysis of nucleic acids (FTA) card revealed the first complete genome of Cucurbit aphid-borne yellows virus (CABYV) from East Timor. We compare it with 35 complete CABYV genomes from other world regions. It most resembled the genome of the South Korean isolate HD118. Copyright © 2017 Maina et al.

Variation between Ethiopian and North American barley varieties (Hordeum vulgare) in response to Russian wheat aphid (Diuraphis noxia) populations.

PubMed

Araya, Alemu; Belay, Tesfay; Hussein, Temam

2014-03-15

The Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae), causes severe damage to barley, Hordeum vulgare L. (Poales: Poaceae), in the highlands of Ethiopia. Little information is available on the control of this pest in Ethiopia. An experiment aimed at evaluating the resistance of barley varieties from the USA to D. noxia populations and determining biotypic variation between Ethiopian and North American D. noxia populations was conducted. The D. noxia-resistant barley varieties Burton and RWA-1758 from the USA, the resistant barley line 3296-15 from Ethiopia, and a local Ethiopian susceptible variety were included in a randomized design in a greenhouse under natural light conditions. There were highly significant differences (P < 0.001) in the mean D. noxia population, leaf chlorosis, leaf rolling, plant stunting, number of tillers per plant, and the percentage of infested tillers per plant between the resistant and susceptible varieties. The aphid population per tiller was lower on the resistant barley plants than on the susceptible plants. Severe plant damage was observed on the local barley variety, while the least damage was observed on Burton, followed by RWA-1758. Burton and RWA-1758 were therefore highly resistant and moderately resistant, respectively, to the northern Ethiopian D. noxia populations, indicating similarities in biotypes between the United States and northern Ethiopian D. noxia populations. The damage to variety 3296-15 was greater than to Burton and RWA-1758. Leaf chlorosis scores and leaf rolling scores for variety 3296-15 upon treatment with the north Ethiopian D. noxia population indicate likely biotypic variation between D. noxia populations of northern and central Ethiopia. This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.

Prospecting sugarcane resistance to Sugarcane yellow leaf virus by genome-wide association.

PubMed

Debibakas, S; Rocher, S; Garsmeur, O; Toubi, L; Roques, D; D'Hont, A; Hoarau, J-Y; Daugrois, J H

2014-08-01

Using GWAS approaches, we detected independent resistant markers in sugarcane towards a vectored virus disease. Based on comparative genomics, several candidate genes potentially involved in virus/aphid/plant interactions were pinpointed. Yellow leaf of sugarcane is an emerging viral disease whose causal agent is a Polerovirus, the Sugarcane yellow leaf virus (SCYLV) transmitted by aphids. To identify quantitative trait loci controlling resistance to yellow leaf which are of direct relevance for breeding, we undertook a genome-wide association study (GWAS) on a sugarcane cultivar panel (n = 189) representative of current breeding germplasm. This panel was fingerprinted with 3,949 polymorphic markers (DArT and AFLP). The panel was phenotyped for SCYLV infection in leaves and stalks in two trials for two crop cycles, under natural disease pressure prevalent in Guadeloupe. Mixed linear models including co-factors representing population structure fixed effects and pairwise kinship random effects provided an efficient control of the risk of inflated type-I error at a genome-wide level. Six independent markers were significantly detected in association with SCYLV resistance phenotype. These markers explained individually between 9 and 14 % of the disease variation of the cultivar panel. Their frequency in the panel was relatively low (8-20 %). Among them, two markers were detected repeatedly across the GWAS exercises based on the different disease resistance parameters. These two markers could be blasted on Sorghum bicolor genome and candidate genes potentially involved in plant-aphid or plant-virus interactions were localized in the vicinity of sorghum homologs of sugarcane markers. Our results illustrate the potential of GWAS approaches to prospect among sugarcane germplasm for accessions likely bearing resistance alleles of significant effect useful in breeding programs.

Evidence for compensatory photosynthetic and yield response of soybeans to aphid herbivory

DOE PAGES

Kucharik, Christopher J.; Mork, Amelia C.; Meehan, Timothy D.; ...

2016-04-13

The soybean aphid, Aphis glycines Matsumura, an exotic species in North America that has been detected in 21 U.S. states and Canada, is a major pest for soybean that can reduce maximum photosynthetic capacity and yields. Our existing knowledge is based on relatively few studies that do not span a wide variety of environmental conditions, and often focus on relatively high and damaging population pressure. We examined the effects of varied populations and duration of soybean aphids on soybean photosynthetic rates and yield in two experiments. In a 2011 field study, we found that plants with low cumulative aphid daysmore » (CAD, less than 2,300) had higher yields than plants not experiencing significant aphid pressure, suggesting a compensatory growth response to low aphid pressure. This response did not hold at higher CAD, and yields declined. In a 2013 controlled-environment greenhouse study, soybean plants were well-watered and fertilized with nitrogen (N), and aphid populations were manipulated to reach moderate to high levels (8,000–50,000 CAD). Plants tolerated these population levels when aphids were introduced during the vegetative or reproductive phenological stages of the plant, showing no significant reduction in yield. Leaf N concentration and CAD were positively and significantly correlated with increasing ambient photosynthetic rates. Our findings suggest that, given the right environmental conditions, modern soybean plants can withstand higher aphid pressure than previously assumed. Moreover, soybean plants also responded positively through a compensatory photosynthetic effect to moderate population pressure, contributing to stable or increased yield.« less

Differential Life History Trait Associations of Aphids with Nonpersistent Viruses in Cucurbits.

PubMed

Angelella, G M; Egel, D S; Holland, J D; Nemacheck, J A; Williams, C E; Kaplan, I

2015-06-01

The diversity of vectors and fleeting nature of virus acquisition and transmission renders nonpersistent viruses a challenge to manage. We assessed the importance of noncolonizing versus colonizing vectors with a 2-yr survey of aphids and nonpersistent viruses on commercial pumpkin farms. We quantified aphid alightment using pan traps, while testing leaf samples with multiplex RT-PCR targeting cucumber mosaic virus (CMV), zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and papaya ringspot virus (PRSV). Overall, we identified 53 aphid species (3,899 individuals), from which the melon aphid, Aphis gossypii Glover, a pumpkin-colonizing species, predominated (76 and 37% of samples in 2010 and 2011, respectively). CMV and ZYMV were not detected, but WMV and PRSV were prevalent, both regionally (WMV: 28/29 fields, PRSV: 21/29 fields) and within fields (infection rates = 69 and 55% for WMV in 2010 and 2011; 28 and 25% for PRSV in 2010 and 2011). However, early-season samples showed extremely low infection levels, suggesting cucurbit viruses are not seed-transmitted and implicating aphid activity as a causal factor driving virus spread. Interestingly, neither noncolonizer and colonizer alightment nor total aphid alightment were good predictors of virus presence, but community analyses revealed species-specific relationships. For example, cowpea aphid (Aphis craccivora Koch) and spotted alfalfa aphid (Therioaphis trifolii Monell f. maculata) were associated with PRSV infection, whereas the oleander aphid (Aphis nerii Bover de Fonscolombe) was associated with WMV spread within fields. These outcomes highlight the need for tailored management plans targeting key vectors of nonpersistent viruses in agricultural systems. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Susceptibility of field populations of the fall armyworm (Lepidoptera: Noctuidae) from Florida and Puerto Rico to purified Cry1F protein and corn leaf tissue containing single and pyramided Bt genes

USDA-ARS?s Scientific Manuscript database

Larval survival of Cry1F-susceptible (FL), -resistant (PR and Cry1F-RR), and -heterozygous (FL x PR and Cry1F-RS) populations of the fall armyworm, Spodoptera frugiperda (J.E. Smith) to purified Cry1F protein and corn leaf tissue of seven Bacillus thuringiensis (Bt) corn hybrids and five non-Bt corn...

Determination of active ingredients in corn silk, leaf, and kernel by capillary electrophoresis with electrochemicaI detection.

PubMed

Lin, Miao; Chu, Qing-Cui; Tian, Xiu-Hui; Ye, Jian-Nong

2007-01-01

Corn has been known for its accumulation of flavones and phenolic acids. However, many parts of corn, except kernel, have not drawn much attention. In this work, a method based on capillary zone electrophoresis with electrochemical detection has been used for the separation and determination of epicatechin, rutin, ascorbic acid (Vc), kaempferol, chlorogenic acid, and quercetin in corn silk, leaf, and kernel. The distribution comparison of the ingredients among silk, leaf, and kernel is discussed. Several important factors--including running buffer acidity, separation voltage, and working electrode potential--were evaluated to acquire the optimum analysis conditions. Under the optimum conditions, the analytes could be well separated within 19 min in a 40-mmol/L borate buffer (pH 9.2). The response was linear over three orders of magnitude with detection limits (S/N = 3) ranging from 4.97 x 10(-8) to 9.75 x 10(-8) g/mL. The method has been successfully applied for the analysis of corn silk, leaf, and kernel with satisfactory results.

Interspecific variation within the genus Asclepias in response to herbivory by a phloem-feeding insect herbivore.

PubMed

Zehnder, Caralyn B; Hunter, Mark D

2007-11-01

Induced plant responses to leaf-chewing insects have been well studied, but considerably less is known about the effects of phloem-feedings insects on induction. In a set of laboratory experiments, we examined density-dependent induction by the milkweed-oleander aphid, Aphis nerii, of putative defenses in four milkweed species (Asclepias incarnata, Asclepias syriaca, Asclepias tuberosa, and Asclepias viridis). We hypothesized that high aphid density would lead to increased cardenolide expression in species with low constitutive levels of cardenolides (e.g., A. tuberosa), but that there would be no induction in high constitutive cardenolide species (e.g., A. viridis). Based on previous studies, we did not expect cardenolide induction in A. incarnata. Contrary to our predictions, we observed feeding-induced declines of cardenolide concentrations in A. viridis. Cardenolide concentrations did not respond to aphid feeding in the other three milkweed species. Aphids also caused reductions in biomass accumulation by two of four Asclepias species, A. viridis and A. incarnata. High aphid density led to a decrease in A. viridis foliar nitrogen concentration. However, aphids had no effect on the defensive chemistry, growth, or nutritional quality of either A. syriaca or A. tuberosa. Our results highlight that congeneric plant species may respond differently to the same levels of herbivore damage.

Trophic transfer of soil arsenate and associated toxic effects in a plant-aphid-parasitoid system

NASA Astrophysics Data System (ADS)

Lee, Y. S.; Wee, J.; Lee, M.; Hong, J.; Cho, K.

2017-12-01

Terrestrial toxic effects of soil arsenic were studied using a model system consisting of soil which artificially treated with arsenic, Capsicum annum,Myzus persicae and Aphidus colemani. We investigated the transfer of arsenic in a soil-plant-aphid system and toxic effect of elevated arsenic through a plant-aphid-parasitoid system. To remove the effect of poor plant growth on aphid performance, test concentrations which have a no effect on health plant growth were selected. Arsenic concentration of growth medium, plant tissues (root, stem, leaf) aphids were measured to observe the arsenic transfer. Correlation matrix was made with arsenic in growth medium which extracted with three extractants (aquaregia, 0.01 M CaCl2 and deionized water), arsenic in plant tissues and plant performance. Toxic effects of elevated arsenic concentrations on each species were investigated at population level. Studied plant performances were dry weight of each tissue, elongation of roots and stems, area of leaves, chlorophyll content of leaves, protein content of leaves and sugar content of leaves. Mean development time, fecundity and honeydew excretion of the aphids and host choice capacity and parasitism success of the parasitoids were examined. In addition, enzyme activities of the plants and the aphids against reactive oxygen species (ROS) induced by arsenic stress were also investigated. The results suggest that arsenic concentration in plant tissues and aphids were elevated with increased concentration of arsenic in soil. Decreased fecundity and honeydew excretion of aphids were observed and decreased eclosion rate of parasitoids were observed with increased arsenic treatment in growth medium. The results showed low concentration of arsenic in soil can transfer through food chain and can impact on higher trophic level species.

Deciphering the role of NADPH oxidase in complex interactions between maize (Zea mays L.) genotypes and cereal aphids.

PubMed

Sytykiewicz, Hubert

2016-07-22

Plant NADPH oxidases (NOXs) encompass a group of membrane-bound enzymes participating in formation of reactive oxygen species (ROS) under physiological conditions as well as in response to environmental stressors. The purpose of the survey was to unveil the role of NADPH oxidase in pro-oxidative responses of maize (Zea mays L.) seedling leaves exposed to cereal aphids' infestation. The impact of apteral females of bird cherry-oat aphid (Rhopalosiphum padi L.) and grain aphid (Sitobion avenae F.) feeding on expression levels of all four NADPH oxidase genes (rbohA, rbohB, rbohC, rbohD) and total activity of NOX enzyme in maize plants were investigated. In addition, inhibitory effect of diphenylene iodonium (DPI) pre-treatment on NOX activity and hydrogen peroxide content in aphid-stressed maize seedlings was studied. Leaf infestation biotests were accomplished on 14-day-old seedlings representing two aphid-resistant varieties (Ambrozja and Waza) and two aphid-susceptible ones (Tasty Sweet and Złota Karłowa). Insects' attack led to profound upregulation of rbohA and rbohD genes in tested host plants, lower elevations were noted in level of rbohB mRNA, whereas abundance of rbohC transcript was not significantly altered. It was uncovered aphid-induced enhancement of NOX activity in examined plants. Higher increases in expression of all investigated rboh genes and activity of NADPH oxidase occurred in tissues of more resistant maize cultivars than in susceptible ones. Furthermore, DPI treatment resulted in strong reduction of NOX activity and H2O2 accumulation in aphid-infested Z. mays plants, thus evidencing circumstantial role of the enzyme in insect-elicited ROS generation. Copyright © 2016 Elsevier Inc. All rights reserved.

Monitoring corn and soybean crop development by remote sensing techniques

NASA Technical Reports Server (NTRS)

Tucker, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

1978-01-01

A system for spectrally monitoring the stages of crop development for corn and soybeans based upon red and photographic infrared spectral radiances is proposed. The red and photographic infrared spectral radiance, highly correlated with the green leaf area index or green leaf biomass, enable nondestructive monitoring of the crop canopy throughout the growing season. Five distinct periods are apparent which are related to crop development for corn and soybeans.

Lettuce breeding

USDA-ARS?s Scientific Manuscript database

In the 2016-2017 period, major efforts targeted resistance to lettuce drop caused by Sclerotinia species, Verticillium wilt, Fusarium wilt, bacterial leaf spot, corky root, downy mildew, drought tolerance, lettuce aphid, tipburn, shelf-life of salad-cut lettuce, and multiple disease resistance. Resi...

Leaf transpiration efficiency of sweet corn varieties from three eras of breeding

USDA-ARS?s Scientific Manuscript database

When measured under midday field conditions, modern varieties of corn often have sub-stomatal concentrations of carbon dioxide in excess of those required to saturate photosynthesis. This results in lower leaf transpiration efficiency, the ratio of photosynthesis to transpiration, than potentially ...

Does aphid salivation affect phloem sieve element occlusion in vivo?

PubMed

Medina-Ortega, Karla J; Walker, G P

2013-12-01

To protect against loss of photo-assimilate-rich phloem sap, plants have evolved several mechanisms to plug phloem sieve tubes in response to damage. In many Fabaceae, each sieve element contains a discrete proteinaceous body called a forisome, which, in response to damage, rapidly transforms from a condensed configuration that does not impede the flow of sap to a dispersed configuration that plugs the sieve element. Aphids and other specialized phloem sap feeders can ingest phloem sap from a single sieve element for hours or days, and to do this, they must be able to suppress or reverse phloem plugging. A recent study provided in vitro evidence that aphid saliva can reverse forisome plugs. The present study tested this hypothesis in vivo by inducing forisome plugs which triggered aphids to switch behaviour from phloem sap ingestion to salivation into the sieve element. After salivating into the sieve element for various periods of time, the aphids were instantaneously cryofixed (freeze fixed) in situ on their leaf. The state of the forisome was then determined in the penetrated sieve element and in nearby non-penetrated sieve elements which served as controls for sieve elements not subjected to direct aphid salivation. Forisomes were almost always in close contact with the stylet tips and thus came into direct contact with the saliva. Nonetheless, forisome plugs in the penetrated sieve element did not revert back to a non-plugging state any faster than those in neighbouring sieve elements that were not subjected to direct aphid salivation.

Does aphid salivation affect phloem sieve element occlusion in vivo?

PubMed Central

Medina-Ortega, Karla J.

2013-01-01

To protect against loss of photo-assimilate-rich phloem sap, plants have evolved several mechanisms to plug phloem sieve tubes in response to damage. In many Fabaceae, each sieve element contains a discrete proteinaceous body called a forisome, which, in response to damage, rapidly transforms from a condensed configuration that does not impede the flow of sap to a dispersed configuration that plugs the sieve element. Aphids and other specialized phloem sap feeders can ingest phloem sap from a single sieve element for hours or days, and to do this, they must be able to suppress or reverse phloem plugging. A recent study provided in vitro evidence that aphid saliva can reverse forisome plugs. The present study tested this hypothesis in vivo by inducing forisome plugs which triggered aphids to switch behaviour from phloem sap ingestion to salivation into the sieve element. After salivating into the sieve element for various periods of time, the aphids were instantaneously cryofixed (freeze fixed) in situ on their leaf. The state of the forisome was then determined in the penetrated sieve element and in nearby non-penetrated sieve elements which served as controls for sieve elements not subjected to direct aphid salivation. Forisomes were almost always in close contact with the stylet tips and thus came into direct contact with the saliva. Nonetheless, forisome plugs in the penetrated sieve element did not revert back to a non-plugging state any faster than those in neighbouring sieve elements that were not subjected to direct aphid salivation. PMID:24127515

Two-Spotted Ladybeetle Adalia bipunctata L. (Coleoptera: Coccinellidae): A Commercially Available Predator to Control Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae).

PubMed

Khan, Azhar A; Qureshi, Jawwad A; Afzal, Muhammad; Stansly, Philip A

2016-01-01

The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an economically important pest of citrus because it serves as a vector of the causal pathogens of huanglongbing (HLB) also known as citrus greening disease. The increased use of insecticides for control of D. citri negatively impacts several natural enemies including some effective ladybeetle species which are not available commercially. The two-spotted ladybeetle, Adalia bipunctata (Coleoptera: Coccinellidae) is found in some crop and forest ecosystems of Asia, Europe and North America and available commercially. It is known to attack aphids and mealybugs but there are no published records of feeding on psyllids. We evaluated suitability and preference of A. bipunctata for nymphs of D. citri compared to corn leaf aphid Rhopalosiphum maidis (Hemiptera: Aphididae) a global pest of cereal crops and prey for many predaceous insects. We also compared development and reproduction of A. bipunctata on these two species with frozen eggs of the Mediterranean flour moth Ephestia kuehniella (Lepidoptera: Pyralidae) at 25°C. Initially, more D. citri than R. maidis nymphs were consumed in the no-choice tests although final consumption by larva and adult of A. bipunctata did not differ in the choice and no-choice tests. Larval development was prolonged by one day on D. citri compared to R. maidis nymphs but did not differ between either of these diets and E. kuehniella. Larval survival to adult averaged 93-100% and was not impacted by diet. Adult life span did not differ between diets although those on D. citri and R. maidis nymphs weighed less and produced fewer but more fertile eggs than on E. kuehniella eggs. Significant reduction of D. citri nymphs averaging 54% was observed in colonies caged with adult A. bipunctata on field planted citrus. R° (net reproductive rate) was least for beetles fed R. maidis, but otherwise there were no significant differences in demographic parameters. Successful feeding, development and reproductive performance of A. bipunctata suggest its usefulness as biological control agent of D. citri as well as aphid species exemplified by R. maidis.

Two-Spotted Ladybeetle Adalia bipunctata L. (Coleoptera: Coccinellidae): A Commercially Available Predator to Control Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

PubMed Central

Afzal, Muhammad; Stansly, Philip A.

2016-01-01

The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an economically important pest of citrus because it serves as a vector of the causal pathogens of huanglongbing (HLB) also known as citrus greening disease. The increased use of insecticides for control of D. citri negatively impacts several natural enemies including some effective ladybeetle species which are not available commercially. The two-spotted ladybeetle, Adalia bipunctata (Coleoptera: Coccinellidae) is found in some crop and forest ecosystems of Asia, Europe and North America and available commercially. It is known to attack aphids and mealybugs but there are no published records of feeding on psyllids. We evaluated suitability and preference of A. bipunctata for nymphs of D. citri compared to corn leaf aphid Rhopalosiphum maidis (Hemiptera: Aphididae) a global pest of cereal crops and prey for many predaceous insects. We also compared development and reproduction of A. bipunctata on these two species with frozen eggs of the Mediterranean flour moth Ephestia kuehniella (Lepidoptera: Pyralidae) at 25°C. Initially, more D. citri than R. maidis nymphs were consumed in the no-choice tests although final consumption by larva and adult of A. bipunctata did not differ in the choice and no-choice tests. Larval development was prolonged by one day on D. citri compared to R. maidis nymphs but did not differ between either of these diets and E. kuehniella. Larval survival to adult averaged 93–100% and was not impacted by diet. Adult life span did not differ between diets although those on D. citri and R. maidis nymphs weighed less and produced fewer but more fertile eggs than on E. kuehniella eggs. Significant reduction of D. citri nymphs averaging 54% was observed in colonies caged with adult A. bipunctata on field planted citrus. R° (net reproductive rate) was least for beetles fed R. maidis, but otherwise there were no significant differences in demographic parameters. Successful feeding, development and reproductive performance of A. bipunctata suggest its usefulness as biological control agent of D. citri as well as aphid species exemplified by R. maidis. PMID:27631730

Leaf transpiration efficiency in corn varieties grown at elevated carbon dioxide

USDA-ARS?s Scientific Manuscript database

Higher leaf transpiration efficiency (TE) without lower photosynthesis has been identified in some varieties of corn in field tests, and could be a useful trait to improve yield under dry conditions without sacrificing yield under favorable conditions. However, because the carbon dioxide concentrat...

[Potential of Metarhizium anisopliae and Beauveria bassiana isolates and neem oil to control the Aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae)].

PubMed

de Araujo, José M; Marques, Edmilson J; de Oliveira, José V

2009-01-01

This work aimed to determine the efficiency of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana to control the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae) in kale Brassica oleracea var acephala D.C., as well as their compatibility with a neem oil formulation (Neemseto). Ten isolates of both fungi were tested and the most pathogenic ones were B. bassiana CG001 and M. anisopliae CG30 with 90% and 4.4 days, and 64% and 3.8 days of mortality and median lethal time, respectively. Bioassays with neem at concentrations of 0.5, 1.0 and 2.0% were done either by leaf discs dipping or spraying the aphids on the leaf discs. The neem spraying treatment at 2.0% provided 90% mortality. The use of B. bassiana isolate CG001 or M. anisopliae isolate CG30 with neem at 0.125, 0.25, and 0.5%, demonstrated that these isolates could have their spore viability or colony growth affected when exposed to neem concentrations higher than 0.25%. In absolute values, the isolates B. bassiana CG001 and M. anisopliae CG30 are the most virulent to L. erysimi, and could be utilized in the management of this pest.

Two volatile organic compounds trigger plant self-defense against a bacterial pathogen and a sucking insect in cucumber under open field conditions.

PubMed

Song, Geun Cheol; Ryu, Choong-Min

2013-05-08

Systemic acquired resistance (SAR) is a plant self-defense mechanism against a broad-range of pathogens and insect pests. Among chemical SAR triggers, plant and bacterial volatiles are promising candidates for use in pest management, as these volatiles are highly effective, inexpensive, and can be employed at relatively low concentrations compared with agrochemicals. However, such volatiles have some drawbacks, including the high evaporation rate of these compounds after application in the open field, their negative effects on plant growth, and their inconsistent levels of effectiveness. Here, we demonstrate the effectiveness of volatile organic compound (VOC)-mediated induced resistance against both the bacterial angular leaf spot pathogen, Pseudononas syringae pv. lachrymans, and the sucking insect aphid, Myzus persicae, in the open field. Using the VOCs 3-pentanol and 2-butanone where fruit yields increased gave unexpectedly, a significant increase in the number of ladybird beetles, Coccinella septempunctata, a natural enemy of aphids. The defense-related gene CsLOX was induced by VOC treatment, indicating that triggering the oxylipin pathway in response to the emission of green leaf volatiles can recruit the natural enemy of aphids. These results demonstrate that VOCs may help prevent plant disease and insect damage by eliciting induced resistance, even in open fields.

Consumption and utilization of experimentally altered corn by southern armyworm: Iron, nitrogen, and cyclic hydroxamates.

PubMed

Manuwoto, S; Scriber, J M

1985-11-01

The effects of differential leaf water, leaf nitrogen and cyclic hydroxamate (DIMBOA) concentrations in corn seedlings were analyzed for a polyphagous insect, the southern armyworm (Spodoptera eridania Cram.). Six different combinations of nutrients and allelochemicals [DIMBOA = 2,4-dihydroxy-7-methoxy(2H)-benzoxazin-3(4H)-one] were generated using two corn genotypes (WF9 and CI3IA) and three fertility regimes (complete nutrient, Fe-deficient, and N-deficient solutions) in the University Biotron. Poorest larval growth was observed in the low-nitrogen treatments (1.2% and 1.7% leaf N) and was the result of both low consumption rates and high metabolic costs (low efficiency of conversion of digested food, ECD). Fastest growth rates were observed forthe larvae fed leaves from the high-nitrogen treatments (4.6% and 4.4% leaf N). It is noteworthy that these treatments also contained the highest concentration of cyclic hydroxamates, which are generally believed to be the primary defensive chemicals mediating resistance against the European corn borer,Ostrinia nubilalis (Hubner). If these hydroxamates do have any deleterious or costly effects (perhaps accounting for a large portion of metabolic expenditures), the high digestibility of the leaf tissue and the increased consumption rates more than compensate, resulting in rapid growth (growth rate = consumption rate × approximate digestibility × efficiency of conversion of the digested food). These studies illustrate that variation in key nutrients and allelochemicals within a single plant species (Zea mays L.) may have significantly different effects upon various potential leaf-chewing caterpillars, such as these armyworms versus corn borers (which cannot handle the cyclic hydroxamates, even if provided with young nutritious leaf tissues).

40 CFR 180.609 - Fluoxastrobin; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of fluoxastrobin. Commodity Parts per million Berry, low growing, subgroup 13-07G 1.9 Corn, field, forage 3.0 Corn, field, grain 0.02 Corn, field, stover 4.5 Corn, sweet, forage 13 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet, stover 10 Grain, aspirated grain fractions 60 Leaf...

40 CFR 180.609 - Fluoxastrobin; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of fluoxastrobin. Commodity Parts per million Berry, low growing, subgroup 13-07G 1.9 Corn, field, forage 3.0 Corn, field, grain 0.02 Corn, field, stover 4.5 Corn, sweet, forage 13 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet, stover 10 Grain, aspirated grain fractions 60 Leaf...

40 CFR 180.609 - Fluoxastrobin; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of fluoxastrobin. Commodity Parts per million Berry, low growing, subgroup 13-07G 1.9 Corn, field, forage 3.0 Corn, field, grain 0.02 Corn, field, stover 4.5 Corn, sweet, forage 13 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet, stover 10 Grain, aspirated grain fractions 60 Leaf...

40 CFR 180.609 - Fluoxastrobin; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... of fluoxastrobin. Commodity Parts per million Berry, low growing, subgroup 13-07G 1.9 Corn, field, forage 3.0 Corn, field, grain 0.02 Corn, field, stover 4.5 Corn, sweet, forage 13 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet, stover 10 Grain, aspirated grain fractions 60 Leaf...

On-Plant Larval Movement and Feeding Behavior of Fall Armyworm (Lepidoptera: Noctuidae) on Reproductive Corn Stages.

PubMed

Pannuti, L E R; Baldin, E L L; Hunt, T E; Paula-Moraes, S V

2016-02-01

Spodoptera frugiperda J.E. Smith (fall armyworm) is considered one of the most destructive pests of corn throughout the Americas. Although this pest has been extensively studied, little is known about its larval movement and feeding behavior on reproductive compared to vegetative corn stages. Thus, we conducted studies with two corn stages (R1 and R3) and four corn plant zones (tassel, above ear, ear zone, and below ear) in the field at Concord, NE (USA), and in the field and greenhouse at Botucatu, SP (Brazil), to investigate on-plant larval movement. The effects of different corn tissues (opened tassel, closed tassel, silk, kernel, and leaf), two feeding sequence scenarios (closed tassel-leaf-silk-kernel and leaf-silk-kernel), and artificial diet (positive control) on larval survival and development were also evaluated in the laboratory. Ear zone has a strong effect on feeding choice and survival of fall armyworm larvae regardless of reproductive corn stage. Feeding site choice is made by first-instar. Corn leaves of reproductive plants were not suitable for early instar development, but silk and kernel tissues had a positive effect on survival and development of fall armyworm larvae on reproductive stage corn. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Herbivore specificity and the chemical basis of plant-plant communication in Baccharis salicifolia (Asteraceae).

PubMed

Moreira, Xoaquín; Nell, Colleen S; Katsanis, Angelos; Rasmann, Sergio; Mooney, Kailen A

2016-09-06

It is well known that plant damage by leaf-chewing herbivores can induce resistance in neighbouring plants. It is unknown whether such communication occurs in response to sap-feeding herbivores, whether communication is specific to herbivore identity, and the chemical basis of communication, including specificity. We carried out glasshouse experiments using the California-native shrub Baccharis salicifolia and two ecologically distinct aphid species (one a dietary generalist and the other a specialist) to test for specificity of plant-plant communication and to document the underlying volatile organic compounds (VOCs). We show specificity of plant-plant communication to herbivore identity, as each aphid-damaged plant only induced resistance in neighbours against the same aphid species. The amount and composition of induced VOCs were markedly different between plants attacked by the two aphid species, providing a putative chemical mechanism for this specificity. Furthermore, a synthetic blend of the five major aphid-induced VOCs (ethanone, limonene, methyl salicylate, myrcene, ocimene) triggered resistance in receiving plants of comparable magnitude to aphid damage of neighbours, and the effects of the blend exceeded those of individual compounds. This study significantly advances our understanding of plant-plant communication by demonstrating the importance of sap-feeding herbivores and herbivore identity, as well as the chemical basis for such effects. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Non-pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid-induced plant volatiles via jasmonic acid signalling.

PubMed

Pineda, Ana; Soler, Roxina; Weldegergis, Berhane T; Shimwela, Mpoki M; VAN Loon, Joop J A; Dicke, Marcel

2013-02-01

Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it remains unknown how plants mediate the interactions between soil microbes and carnivorous insects, that is, the third trophic level. Using Arabidopsis thaliana Col-0 and the aphid Myzus persicae, we evaluate here the underlying mechanisms involved in the plant-mediated interaction between the non-pathogenic rhizobacterium Pseudomonas fluorescens and the parasitoid Diaeretiella rapae, by combining ecological, chemical and molecular approaches. Rhizobacterial colonization modifies the composition of the blend of herbivore-induced plant volatiles. The volatile blend from rhizobacteria-treated aphid-infested plants is less attractive to an aphid parasitoid, in terms of both olfactory preference behaviour and oviposition, than the volatile blend from aphid-infested plants without rhizobacteria. Importantly, the effect of rhizobacteria on both the emission of herbivore-induced volatiles and parasitoid response to aphid-infested plants is lost in an Arabidopsis mutant (aos/dde2-2) that is impaired in jasmonic acid production. By modifying the blend of herbivore-induced plant volatiles that depend on the jasmonic acid-signalling pathway, root-colonizing microbes interfere with the attraction of parasitoids of leaf herbivores. © 2012 Blackwell Publishing Ltd.

A three-part geometric model to predict the radar backscatter from wheat, corn, and sorghum

NASA Technical Reports Server (NTRS)

Ulaby, F. T. (Principal Investigator); Eger, G. W., III; Kanemasu, E. T.

1982-01-01

A model to predict the radar backscattering coefficient from crops must include the geometry of the canopy. Radar and ground-truth data taken on wheat in 1979 indicate that the model must include contributions from the leaves, from the wheat head, and from the soil moisture. For sorghum and corn, radar and ground-truth data obtained in 1979 and 1980 support the necessity of a soil moisture term and a leaf water term. The Leaf Area Index (LAI) is an appropriate input for the leaf contribution to the radar response for wheat and sorghum, however the LAI generates less accurate values for the backscattering coefficient for corn. Also, the data for corn and sorghum illustrate the importance of the water contained in the stalks in estimating the radar response.

Leaf application of a sprayable bioplastic-based formulation of biocontrol Aspergillus flavus strains for reduction of aflatoxins in corn.

PubMed

Accinelli, Cesare; Abbas, Hamed K; Vicari, Alberto; Shier, W Thomas

2016-08-01

Applying non-aflatoxin-producing Aspergillus flavus isolates to the soil has been shown to be effective in reducing aflatoxin levels in harvested crops, including peanuts, cotton and corn. The aim of this study was to evaluate the possibility of controlling aflatoxin contamination using a novel sprayable formulation consisting of a partially gelatinized starch-based bioplastic dispersion embedded with spores of biocontrol A. flavus strains, which is applied to the leaf surfaces of corn plants. The formulation was shown to be adherent, resulting in colonization of leaf surfaces with the biocontrol strain of A. flavus, and to reduce aflatoxin contamination of harvested kernels by up to 80% in Northern Italy and by up to 89% in the Mississippi Delta. The percentage of aflatoxin-producing isolates in the soil reservoir under leaf-treated corn was not significantly changed, even when the soil was amended with additional A. flavus as a model of changes to the soil reservoir that occur in no-till agriculture. This study indicated that it is not necessary to treat the soil reservoir in order to achieve effective biocontrol of aflatoxin contamination in kernel corn. Spraying this novel bioplastic-based formulation to leaves can be an effective alternative in the biocontrol of A. flavus in corn. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Turning in mid-air allows aphids that flee the plant to avoid reaching the risky ground.

PubMed

Meresman, Yonatan; Ben-Ari, Matan; Inbar, Moshe

2017-09-01

When forced to drop from the plant, flightless arboreal insects can avoid reaching the risky ground by maneuvering their body through the air. When wingless pea aphids (Acyrthosiphon pisum) are threatened by natural enemies, they often drop off their host plant while assuming a stereotypic posture that rotates them in mid-air, aligning them with their feet pointing downwards. This position may increase their chances of re-clinging onto lower plant parts and avoid facing the dangers on the ground, although its effectiveness in realistic field conditions has not been tested. We performed both laboratory and outdoor experiments, in which we dropped aphids upon host plants to quantify clinging success in plants with different characteristics such as height and leaf size. Live aphids had twofold higher clinging rates than dead ones, indicating that clinging success is indeed affected by the active aerial-righting of dropping aphids. The ability to cling was positively dependent on the plants' foliage cover as viewed in vertical direction from above. Therefore, we released aphids in commercial alfalfa (Medicago sativa) fields with varying plant heights and foliage cover and induced them to drop. Most (up to 75%) of the aphids avoided reaching the ground in taller plants (65 cm), and 17% in shorter plants (21 cm), demonstrating the efficiency of the aphids' response in averting risks: both those of an approaching enemy on the plant and the plethora of new risks on the ground. Evidently, even in complex field environment, the aerial-righting mechanism can substantially reduce the possible risks following escape from a predator. © 2017 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Virus movement within grafted watermelon plants

USDA-ARS?s Scientific Manuscript database

Watermelon production in Florida is impacted by several viruses including whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit yellow stunting disorder virus and Cucurbit leaf crumple virus, and aphid-transmitted Papaya ringspot virus type W (PRSV-W). While germplasm resistant to some...

Mapping of quantitative trait loci for resistance to fall armyworm and southwestern corn borer leaf-feeding damage in maize.

USDA-ARS?s Scientific Manuscript database

Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), and southwestern corn borer (SWCB), Diatraea grandiosella Dyar are damaging insect pests of maize resulting in significant yield and economic losses. A previous study identified quantitative trait loci (QTL) that contribute to reduced leaf-fe...

Southern corn leaf blight a story worth retelling

USDA-ARS?s Scientific Manuscript database

The Southern Corn Leaf Blight Epidemic of 1970-1971 was one of the most costly disease outbreaks to affect North American agriculture, destroying 15% of the crop at a cost of $1.0 billion (US). It resulted from an over reliance on cytoplasmic Texas male sterile (cms-T) lines in hybrid seed producti...

Emerging viruses in Florida and the Caribbean

USDA-ARS?s Scientific Manuscript database

Multiple thrips-, whitefly- and aphid-transmitted viruses have recently emerged or re-emerged in vegetable and ornamental crops in Florida and the Caribbean. Tomato spotted wilt virus (a thrips-transmitted tospovirus) and Tomato yellow leaf curl virus (a whitefly-transmitted begomovirus) have histor...

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress

PubMed Central

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-01-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter aphid fecundity in water stresses plants. PMID:26546578

Enhancing growth, phytochemical constituents and aphid resistance capacity in cabbage with foliar application of eckol--a biologically active phenolic molecule from brown seaweed.

PubMed

Rengasamy, Kannan R R; Kulkarni, Manoj G; Pendota, Srinivasa C; Van Staden, Johannes

2016-03-25

Although foliar application of seaweed extracts on plant growth and development has and is extensively studied, reliable knowledge and understanding of the mode of action of particular compound(s) responsible for enhancing plant growth is lacking. A brown seaweed Ecklonia maxima is widely used commercially as a biostimulant to improve plant growth and crop protection. Eckol, a phenolic compound isolated from E. maxima has recently shown stimulatory effects in maize, indicating its potential use as a plant biostimulant. Cabbage is a widely cultivated vegetable crop throughout the world, which requires high input of fertilizers and is susceptible to several aphid borne diseases. This study was conducted to evaluate the effect of foliar application of eckol on the growth, phytochemical constituents and myrosinase activity (aphid resistance capacity) of commercially cultivated cabbage. Foliar application of eckol (10(-6) M) significantly enhanced shoot and root length, shoot and root fresh and dry weight, leaf area and leaf number. This treatment also showed a significant increase in photosynthetic pigments (chlorophyll 'a', chlorophyll 'b', total chlorophyll and carotenoid) compared to the untreated plants. The levels of protein, proline and iridoid glycosides were significantly higher in cabbage leaves with eckol treatment. All the control plants were severely infested with cabbage aphid (Brevicoryne brassicae) but no infestation was observed on the eckol-sprayed plants, which can be attributed to an increase in myrosinase activity. This study reveals dual effects (plant growth promoting and insect repelling) of eckol on cabbage plants that need further investigations both under field conditions and in other brassicaceous species. Copyright © 2015 Elsevier B.V. All rights reserved.

Cyanide in the chemical arsenal of garlic mustard, Alliaria petiolata.

PubMed

Cipollini, Don; Gruner, Bill

2007-01-01

Cyanide production has been reported from over 2500 plant species, including some members of the Brassicaceae. We report that the important invasive plant, Alliaria petiolata, produces levels of cyanide in its tissues that can reach 100 ppm fresh weight (FW), a level considered toxic to many vertebrates. In a comparative study, levels of cyanide in leaves of young first-year plants were 25 times higher than in leaves of young Arabidopsis thaliana plants and over 150 times higher than in leaves of young Brassica kaber, B. rapa, and B. napus. In first-year plants, cyanide levels were highest in young leaves of seedlings and declined with leaf age on individual plants. Leaves of young plants infested with green peach aphids (Myzus persicae) produced just over half as much cyanide as leaves of healthy plants, suggesting that aphid feeding led to loss of cyanide from intact tissues before analysis, or that aphid feeding inhibited cyanide precursor production. In a developmental study, levels of cyanide in the youngest and oldest leaf of young garlic mustard plants were four times lower than in the youngest and oldest leaf of young Sorghum sudanense (cv. Cadan 97) plants, but cyanide levels did not decline in these leaves with plant age as in S. sudanense. Different populations of garlic mustard varied moderately in the constitutive and inducible expression of cyanide in leaves, but no populations studied were acyanogenic. Although cyanide production could result from breakdown products of glucosinolates, no cyanide was detected in vitro from decomposition of sinigrin, the major glucosinolate of garlic mustard. These studies indicate that cyanide produced from an as yet unidentified cyanogenic compound is a part of the battery of chemical defenses expressed by garlic mustard.

Effects of root herbivory by nematodes on the performance and preference of a leaf-infesting generalist aphid depend on nitrate fertilization.

PubMed

Kutyniok, Magdalene; Persicke, Marcus; Müller, Caroline

2014-02-01

The performance and behavior of herbivores is strongly affected by the quality of their host plants, which is determined by various environmental conditions. We investigated the performance and preference of the polyphagous shoot-infesting aphid Myzus persicae on the host-plant Arabidopsis thaliana in a two-factorial design in which nitrate fertilization was varied by 33 %, and the root-infesting cyst-nematode Heterodera schachtii was present or absent. Aphid performance was influenced by these abiotic and biotic factors in an interactive way. Nematode presence decreased aphid performance when nitrate levels were low, whereas nematode infestation did not influence aphid performance under higher nitrate fertilization. Aphids followed the "mother knows best" principle when given a choice, settling preferentially on those plants on which they performed best. Hence, they preferred nematode-free over nematode-infested plants in the low fertilization treatment but host choice was not affected by nematodes under higher nitrate fertilization. The amino acid composition of the phloem exudates was significantly influenced by fertilization but also by the interaction of the two treatments. Various glucosinolates in the leaves, which provide an estimate of phloem glucosinolates, were not affected by the individual treatments but by the combination of fertilization and herbivory. These changes in primary and secondary metabolites may be decisive for the herbivore responses. Our data demonstrate that abiotic and biotic factors can interactively affect herbivores, adding a layer of complexity to plant-mediated herbivore interactions.

Proteomic analysis shows that stress response proteins are significantly up-regulated in resistant diploid wheat (Triticum monococcum) in response to attack by the grain aphid (Sitobion avenae).

PubMed

Guan, Wenzhu; Ferry, Natalie; Edwards, Martin G; Bell, Howard A; Othman, Hamizah; Gatehouse, John A; Gatehouse, Angharad M R

2015-01-01

The grain aphid Sitobion avenae (F.) is a major pest of wheat, acting as a virus vector as well as causing direct plant damage. Commonly grown wheat varieties in the UK have only limited resistance to this pest. The present study was carried out to investigate the potential of a diploid wheat line (ACC20 PGR1755), reported as exhibiting resistance to S. avenae, to serve as a source of resistance genes. The diploid wheat line was confirmed as partially resistant, substantially reducing the fecundity, longevity and growth rate of the aphid. Proteomic analysis showed that approximately 200 protein spots were reproducibly detected in leaf extracts from both the resistant line and a comparable susceptible line (ACC5 PGR1735) using two-dimensional gel electrophoresis and image comparison software. Twenty-four spots were significantly up-regulated (>2-fold) in the resistant line after 24 h of aphid feeding (13 and 11 involved in local and systemic responses, respectively). Approximately 50 % of all differentially expressed protein spots were identified by a combination of database searching with MS and MS/MS data, revealing that the majority of proteins up-regulated by aphid infestation were involved in metabolic processes (including photosynthesis) and transcriptional regulation. However, in the resistant line only, several stress response proteins (including NBS-LRR-like proteins) and oxidative stress response proteins were identified as up-regulated in response to aphid feeding, as well as proteins involved in DNA synthesis/replication/repair. This study indicates that the resistant diploid line ACC20 PGR1755 may provide a valuable resource in breeding wheat for resistance to aphids.

Ultrastructure of compatible and incompatible interactions in phloem sieve elements during the stylet penetration by cotton aphids in melon.

PubMed

Garzo, Elisa; Fernández-Pascual, Mercedes; Morcillo, Cesar; Fereres, Alberto; Gómez-Guillamón, M Luisa; Tjallingii, W Fred

2017-02-18

Resistance of the melon line TGR-1551 to the aphid Aphis gossypii is based on preventing aphids from ingesting phloem sap. In electrical penetration graphs (EPGs), this resistance has been characterized with A. gossypii showing unusually long phloem salivation periods (waveform E1) mostly followed by pathway activities (waveform C) or if followed by phloem ingestion (waveform E2), ingestion was not sustained for more than 10 min. Stylectomy with aphids on susceptible and resistant plants was performed during EPG recording while the stylet tips were phloem inserted. This was followed by dissection of the penetrated leaf section, plant tissue fixation, resin embedding, and ultrathin sectioning for transmission electron microscopic observation in order to study the resistance mechanism in the TGR. The most obvious aspect appeared to be the coagulation of phloem proteins inside the stylet canals and the punctured sieve elements. Stylets of 5 aphids per genotype were amputated during sieve element (SE) salivation (E1) and SE ingestion (E2). Cross-sections of stylet bundles in susceptible melon plants showed that the contents of the stylet canals were totally clear and also, no coagulated phloem proteins occurred in their punctured sieve elements. In contrast, electron-dense coagulations were found in both locations in the resistant plants. Due to calcium binding, aphid saliva has been hypothesized to play an essential role in preventing/suppressing such coagulations that cause occlusion of sieves plate and in the food canal of the aphid's stylets. Doubts about this role of E1 salivation are discussed on the basis of our results. © 2017 Institute of Zoology, Chinese Academy of Sciences.

Corn blight watch experiment results

NASA Technical Reports Server (NTRS)

Johannsen, C. J.; Bauer, M. E.

1972-01-01

Results pertaining to the detection and assessment of the severity and extent of southern corn leaf blight in the Corn Belt area are discussed. Ground observations, interpretation of color infrared photography, and machine analysis of multispectral scanner data were used to identify the blight.

Transgenic expression of a functional fragment of harpin protein Hpa1 in wheat induces the phloem-based defence against English grain aphid.

PubMed

Fu, Maoqiang; Xu, Manyu; Zhou, Ting; Wang, Defu; Tian, Shan; Han, Liping; Dong, Hansong; Zhang, Chunling

2014-04-01

The harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing resistance to pathogens and insect pests. For these effects, the 10-40 residue fragment (Hpa1₁₀₋₄₂) isolated from the Hpa1 sequence is 1.3- to 7.5-fold more effective than the full-length protein. Here it is reported that the expression of Hpa1₁₀₋₄₂ under the direction of an insect-induced promoter induces the phloem-based defence to English grain aphid, a dominant species of wheat aphids. The expression of Hpa1₁₀₋₄₂ was found to compromise the colonization preference of aphids on the plant and further inhibit aphid reproduction in leaf colonies. In Hpa1₁₀₋₄₂-expressing wheat lines, moreover, aphid feeding from the phloem was repressed in correlation with the phloem-based defence. This defensive mechanism was shown as enhanced expression of wheat genes encoding phloem lectin proteins (PP2-A1 and PP2-A2) and β-1,3-glucan synthase-like enzymes (GSL2, GSL10, and GSL12). Both PP2-A and β-1,3-glucan formed high molecular mass polymers to block phloem sieve plate pores and therefore impede aphid feeding from the phloem. However, the phloem-based defence was impaired by treating plants with ethylene signalling inhibitors, suggesting the requirement for the ethylene signalling pathway. In addition, if Hpa1₁₀₋₄₂-expressing plants were subjected to attack by a small number of aphids, they newly acquired agriculturally beneficial characters, such as enhanced vegetative growth and increased tiller numbers and grain output values. These results suggest that the defensive and developmental roles of Hpa1₁₀₋₄₂ can be integrated into the germplasm of this agriculturally significant crop.

Transgenic expression of a functional fragment of harpin protein Hpa1 in wheat induces the phloem-based defence against English grain aphid

PubMed Central

Fu, Maoqiang; Xu, Manyu; Zhang, Chunling

2014-01-01

The harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing resistance to pathogens and insect pests. For these effects, the 10–40 residue fragment (Hpa110–42) isolated from the Hpa1 sequence is 1.3- to 7.5-fold more effective than the full-length protein. Here it is reported that the expression of Hpa110–42 under the direction of an insect-induced promoter induces the phloem-based defence to English grain aphid, a dominant species of wheat aphids. The expression of Hpa110–42 was found to compromise the colonization preference of aphids on the plant and further inhibit aphid reproduction in leaf colonies. In Hpa110–42-expressing wheat lines, moreover, aphid feeding from the phloem was repressed in correlation with the phloem-based defence. This defensive mechanism was shown as enhanced expression of wheat genes encoding phloem lectin proteins (PP2-A1 and PP2-A2) and β-1,3-glucan synthase-like enzymes (GSL2, GSL10, and GSL12). Both PP2-A and β-1,3-glucan formed high molecular mass polymers to block phloem sieve plate pores and therefore impede aphid feeding from the phloem. However, the phloem-based defence was impaired by treating plants with ethylene signalling inhibitors, suggesting the requirement for the ethylene signalling pathway. In addition, if Hpa110–42-expressing plants were subjected to attack by a small number of aphids, they newly acquired agriculturally beneficial characters, such as enhanced vegetative growth and increased tiller numbers and grain output values. These results suggest that the defensive and developmental roles of Hpa110–42 can be integrated into the germplasm of this agriculturally significant crop. PMID:24676030

Elevated CO2 impacts bell pepper growth with consequences to Myzus persicae life history, feeding behaviour and virus transmission ability.

PubMed

Dáder, Beatriz; Fereres, Alberto; Moreno, Aránzazu; Trębicki, Piotr

2016-01-08

Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the performance and feeding of insects is affected by plant nutritional quality and resistance traits. Life history and feeding behaviour of Myzus persicae were studied on pepper plants under ambient (aCO2, 400 ppm) or elevated CO2 (eCO2, 650 ppm), as well as the direct impact on plant growth and leaf chemistry. Plant parameters were significantly altered by eCO2 with a negative impact on aphid's life history. Their pre-reproductive period was 11% longer and fecundity decreased by 37%. Peppers fixed significantly less nitrogen, which explains the poor aphid performance. Plants were taller and had higher biomass and canopy temperature. There was decreased aphid salivation into sieve elements, but no differences in phloem ingestion, indicating that the diminished fitness could be due to poorer tissue quality and unfavourable C:N balance, and that eCO2 was not a factor impeding feeding. Aphid ability to transmit Cucumber mosaic virus (CMV) was studied by exposing source and receptor plants to ambient (427 ppm) or elevated (612 ppm) CO2 before or after virus inoculation. A two-fold decrease on transmission was observed when receptor plants were exposed to eCO2 before aphid inoculation when compared to aCO2.

Pea aphid infestation induces changes in flavonoids, antioxidative defence, soluble sugars and sugar transporter expression in leaves of pea seedlings.

PubMed

Morkunas, Iwona; Woźniak, Agnieszka; Formela, Magda; Mai, Van Chung; Marczak, Łukasz; Narożna, Dorota; Borowiak-Sobkowiak, Beata; Kühn, Christina; Grimm, Bernhard

2016-07-01

The perception of aphid infestation induces highly coordinated and sequential defensive reactions in plants at the cellular and molecular levels. The aim of the study was to explore kinetics of induced antioxidative defence responses in leaf cells of Pisum sativum L.cv. Cysterski upon infestation of the pea aphid Acyrthosiphon pisum at varying population sizes, including accumulation of flavonoids, changes of carbon metabolism, and expression of nuclear genes involved in sugar transport. Within the first 96 h, after A. pisum infestation, flavonoid accumulation and increased peroxidase activity were observed in leaves. The level of pisatin increased after 48 h of infestation and reached a maximum at 96 h. At this time point, a higher concentration of flavonols was observed in the infested tissue than in the control. Additionally, strong post-infestation accumulation of chalcone synthase (CHS) and isoflavone synthase (IFS) transcription products was also found. The levels of sucrose and fructose in 24-h leaves infested by 10, 20, and 30 aphids were significantly lower than in the control. Moreover, in leaves infested by 30 aphids, the reduced sucrose level observed up to 48 h was accompanied by a considerable increase in the expression level of the PsSUT1 gene encoding the sucrose transporter. In conclusion, A. pisum infestation on pea leads to stimulation of metabolic pathways associated with defence.

Epidemiology and Association of Four Insect-Vectored Viruses in Florida Watermelon

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit leaf crumple virus (CuLCrV), Cucurbit yellow stunting disorder virus (CYSDV) and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in the pa...

Patterns of Virus Distribution in Single and Mixed Infections of Florida Watermelons

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. Tissue blot nucleic acid hybridizati...

Investigations of Crown Gall in the Commercial Propagation of Weeping Fig

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. Tissue blot nucleic acid hybridizati...

Pepo aphid-borne yellows virus: a new species in the genus Polerovirus.

PubMed

Ibaba, Jacques D; Laing, Mark D; Gubba, Augustine

2017-02-01

Pepo aphid-borne yellows virus (PABYV) has been proposed as a putative representative of a new species in the genus Polerovirus in the family Luteoviridae. The genomes of two South African (SA) isolates of cucurbit-infecting PABYV were described in this record. Total RNA, extracted from a pattypan (Cucurbita pepo L.) and a baby marrow (C. pepo L.) leaf samples, was subjected to next-generation sequencing (NGS) on the HiSeq Illumina platform. Sanger sequencing was subsequently used to authenticate the integrity of PABYV's genome generated from de novo assembly of the NGS data. PABYV genome of SA isolates consists of 5813 nucleotides and displays an organisation typical of poleroviruses. Genome sequence comparisons of the SA PABYV isolates to other poleroviruses support the classification of PABYV as a new species in the genus Polerovirus. Recombination analyses showed that PABYV and Cucurbit aphid-borne yellows virus (CABYV) shared the same ancestor for the genome part situated between breaking points. Phylogenetic analyses of the RNA-dependent RNA polymerase and the coat protein genes showed that SA PABYV isolates shared distant relationship with CABYV and Suakwa aphid-borne yellows virus. Based on our results, we propose that PABYV is a distinct species in the genus Polerovirus.

Colonization of Corn, Zea mays, by the Entomopathogenic Fungus Beauveria bassiana†

PubMed Central

Wagner, Bruce L.; Lewis, Leslie C.

2000-01-01

Light and electron microscopy were used to describe the mode of penetration by the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin into corn, Zea mays L. After inoculation with a foliar spray of conidia, germinating hyphae grew randomly across the leaf surface. Often a germ tube formed from a conidium and elongated only a short distance before terminating its growth. Not all developing hyphae on the leaf surface penetrated the cuticle. However, when penetration did occur, the penetration site(s) was randomly located, indicating that B. bassiana does not require specific topographic signals at an appropriate entry site as do some phytopathogenic fungi. Long hyphal structures were observed to follow the leaf apoplast in any direction from the point of penetration. A few hyphae were observed within xylem elements. Because vascular bundles are interconnected throughout the corn plant, this may explain how B. bassiana travels within the plant and ultimately provides overall insecticidal protection. Virulency bioassays demonstrate that B. bassiana does not lose virulence toward the European corn borer, Ostrinia nubilalis (Hübner), once it colonizes corn. This endophytic relationship between an entomopathogenic fungus and a plant suggests possibilities for biological control, including the use of indigenous fungal inocula as insecticides. PMID:10919808

Characterization and 2D structural model of corn straw and poplar leaf biochars.

PubMed

Zhao, Nan; Lv, YiZhong; Yang, XiXiang; Huang, Feng; Yang, JianWen

2017-12-22

The integrated experimental methods were used to analyze the physicochemical properties and structural characteristics and to build the 2D structural model of two kinds of biochars. Corn straw and poplar leaf biochars were gained by pyrolysing the raw materials slowly in a furnace at 300, 500, and 700 °C under oxygen-deficient conditions. Scanning electron microscope was applied to observe the surface morphology of the biochars. High temperatures destroyed the pore structures of the biochars, forming a particle mixture of varying sizes. The ash content, yield, pH, and surface area were also observed to describe the biochars' properties. The yield decreases as the pyrolysis temperature increases. The biochars are neutral to alkaline. The biggest surface area is 251.11 m 2 /g for 700 °C corn straw biochar. Elemental analysis, infrared microspectroscopy, solid-state C-13 NMR spectroscopy, and pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) were also used to study the structural characteristics and build the 2D structural models of biochars. The C content in the corn straw and poplar leaf biochars increases with the increase of the pyrolysis temperature. A higher pyrolysis temperature makes the aryl carbon increase, and C=O, OH, and aliphatic hydrocarbon content decrease in the IR spectra. Solid-state C-13 NMR spectra show that a higher pyrolysis temperature makes the alkyl carbon and alkoxy carbon decrease and the aryl carbon increase. The results of IR microspectra and solid-state C-13 NMR spectra reveal that some noticeable differences exist in these two kinds of biochars and in the same type of biochar but under different pyrolysis temperatures. The conceptual elemental compositions of 500 °C corn straw and poplar leaf biochars are C 61 H 33 NO 13 and C 59 H 41 N 3 O 12 , respectively. Significant differences exist in the SEM images, physicochemical properties, and structural characteristics of corn straw and poplar leaf biochars.

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

PubMed

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-02-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter aphid fecundity in water stresses plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Costs of measuring leaf area index of corn

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Hollinger, S. E.

1984-01-01

The magnitude of plant-to-plant variability of leaf area of corn plants selected from uniform plots was examined and four representative methods for measuring leaf area index (LAI) were evaluated. The number of plants required and the relative costs for each sampling method were calculated to detect 10, 20, and 50% differences in LAI using 0.05 and 0.01 tests of significance and a 90% probability of success (beta = 0.1). The natural variability of leaf area per corn plant was nearly 10%. Additional variability or experimental error may be introduced by the measurement technique employed and by nonuniformity within the plot. Direct measurement of leaf area with an electronic area meter had the lowest CV, required that the fewest plants be sampled, but required approximately the same amount of time as the leaf area/weight ratio method to detect comparable differences. Indirect methods based on measurements of length and width of leaves required more plants but less total time than the direct method. Unless the coefficients for converting length and width to area are verified frequently, the indirect methods may be biased. When true differences in LAI among treatments exceed 50% of mean, all four methods are equal. The method of choice depends on the resources available, the differences to be detected, and what additional information, such as leaf weight or stalk weight, is also desired.

Operating characteristics of full count and binomial sampling plans for green peach aphid (Hemiptera: Aphididae) in potato.

PubMed

Kabaluk, J Todd; Binns, Michael R; Vernon, Robert S

2006-06-01

Counts of green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), in potato, Solanum tuberosum L., fields were used to evaluate the performance of the sampling plan from a pest management company. The counts were further used to develop a binomial sampling method, and both full count and binomial plans were evaluated using operating characteristic curves. Taylor's power law provided a good fit of the data (r2 = 0.95), with the relationship between the variance (s2) and mean (m) as ln(s2) = 1.81(+/- 0.02) + 1.55(+/- 0.01) ln(m). A binomial sampling method was developed using the empirical model ln(m) = c + dln(-ln(1 - P(T))), to which the data fit well for tally numbers (T) of 0, 1, 3, 5, 7, and 10. Although T = 3 was considered the most reasonable given its operating characteristics and presumed ease of classification above or below critical densities (i.e., action thresholds) of one and 10 M. persicae per leaf, the full count method is shown to be superior. The mean number of sample sites per field visit by the pest management company was 42 +/- 19, with more than one-half (54%) of the field visits involving sampling 31-50 sample sites, which was acceptable in the context of operating characteristic curves for a critical density of 10 M. persicae per leaf. Based on operating characteristics, actual sample sizes used by the pest management company can be reduced by at least 50%, on average, for a critical density of 10 M. persicae per leaf. For a critical density of one M. persicae per leaf used to avert the spread of potato leaf roll virus, sample sizes from 50 to 100 were considered more suitable.

Distribution of Four Viruses in Single and Mixed Infections Within Infected Watermelon Plants in Florida

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. Tissue blot nucleic acid hybridizati...

Patterns of Virus Distribution in Single and Mixed Infections of Florida Watermelons

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. To determine the distribution of vir...

Epidemiological Analysis of Multi-Virus Infections of Watermelon in Experimental Fields in Southwest Florida

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. Tissue blot nucleic acid hybridizati...

Partial leaf chemical profiles of a desert watermelon species (Citrullus colocynthis) and heirloom watermelon cultivars (Citrullus lanatus var. lanatus)

USDA-ARS?s Scientific Manuscript database

Whiteflies [Bemisia tabaci (Gennadius)] and aphids [Aphis gossypii Glover and Myzus persicae (Sulzer)] are serious threats to watermelon by direct feeding and by transmitting viruses of important virus diseases. The desert watermelon Citrullus colocynthis (L.) has been shown to exhibit resistance t...

The corn blight problem: 1970 and 1971

NASA Technical Reports Server (NTRS)

Bauer, M. E.

1972-01-01

Southern corn leaf blight is caused by the fungus, Helminthosporium maydis. Race T of H maydis adapted itself to the Texas male sterile cytoplasm corn. The problems caused by this variety of the blight in 1970 and 1971 are discussed, as well as the symptoms and development of the disease.

Enhanced efficiency fertilizers: Effects on agronomic performance of corn in Iowa

USDA-ARS?s Scientific Manuscript database

Management of N in corn (Zea mays L.) production systems attempts to increase crop yields and minimize environment impact. This study evaluated enhanced efficiency fertilizers (EEFs) compared to their non-EEF forms on grain yield and corn biomass at the beginning of the grain-filling period, leaf ch...

Both heavy metal-amendment of soil and aphid-infestation increase Cd and Zn concentrations in phloem exudates of a metal-hyperaccumulating plant.

PubMed

Stolpe, Clemens; Giehren, Franziska; Krämer, Ute; Müller, Caroline

2017-07-01

Plants that are able to hyperaccumulate heavy metals show increased concentrations of these metals in their leaf tissue. However, little is known about the concentrations of heavy metals and of organic defence metabolites in the phloem sap of these plants in response to either heavy metal-amendment of the soil or biotic challenges such as aphid-infestation. In this study, we investigated the effects of heavy metal-exposure and of aphid-infestation on phloem exudate composition of the metal hyperaccumulator species Arabidopsis halleri L. O'Kane & Al-Shehbaz (Brassicaceae). The concentrations of elements and of organic defence compounds, namely glucosinolates, were measured in phloem exudates of young and old (mature) leaves of plants challenged either by amendment of the soil with cadmium and zinc and/or by an infestation with the generalist aphid Myzus persicae. Metal-amendment of the soil led to increased concentrations of Cd and Zn, but also of two other elements and one indole glucosinolate, in phloem exudates. This enhanced defence in the phloem sap of heavy metal-hyperaccumulating plants can thus potentially act as effective protection against aphids, as predicted by the elemental defence hypothesis. Aphid-infestation also caused enhanced Cd and Zn concentrations in phloem exudates. This result provides first evidence that metal-hyperaccumulating plants can increase heavy metal concentrations tissue-specifically in response to an attack by phloem-sucking herbivores. Overall, the concentrations of most elements, including the heavy metals, and glucosinolates were higher in phloem exudates of young leaves than in those of old leaves. This defence distribution highlights that the optimal defence theory, which predicts more valuable tissue to be better defended, is applicable for both inorganic and organic defences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of petroleum-derived substances on life history traits of black bean aphid (Aphis fabae Scop.) and on the growth and chemical composition of broad bean.

PubMed

Rusin, Milena; Gospodarek, Janina; Nadgórska-Socha, Aleksandra; Barczyk, Gabriela

2017-04-01

The aim of the study was to determine the effects of various petroleum-derived substances, namely petrol, diesel fuel and spent engine oil, on life history traits and population dynamics of the black bean aphid Aphis fabae Scop. and on growth and chemical composition of its host plant Vicia faba L. Each substance was tested separately, using two concentrations (9 g kg -1 and 18 g kg -1 ). The experiment was conducted in four replications (four pots with five plants in each pot per treatment). Plants were cultivated in both control and contaminated soils. After six weeks from soil contamination and five weeks from sowing the seeds, observations of the effect of petroleum-derived substances on traits of three successive generations of aphids were conducted. Aphids were inoculated separately on leaves using cylindrical cages hermetically closed on both sides. Contamination of aphid occurred through its host plant. Results showed that all tested substances adversely affected A. fabae life history traits and population dynamics: extension of the prereproductive period, reduction of fecundity and life span, reduction of the population intrinsic growth rate. In broad bean, leaf, roots, and shoot growth was also impaired in most conditions, whereas nutrient and heavy metal content varied according to substances, their concentration, as well as plant part analysed. Results indicate that soil contamination with petroleum-derived substances entails far-reaching changes not only in organisms directly exposed to these pollutants (plants), but also indirectly in herbivores (aphids) and consequently provides information about potential negative effects on further links of the food chain, i.e., for predators and parasitoids.

Effects of light and the regulatory B-subunit composition of protein phosphatase 2A on the susceptibility of Arabidopsis thaliana to aphid (Myzus persicae) infestation

PubMed Central

Rasool, Brwa; Karpinska, Barbara; Konert, Grzegorz; Durian, Guido; Denessiouk, Konstantin; Kangasjärvi, Saijaliisa; Foyer, Christine H.

2014-01-01

The interactions between biotic and abiotic stress signaling pathways are complex and poorly understood but protein kinase/phosphatase cascades are potentially important components. Aphid fecundity and susceptibility to Pseudomonas syringae infection were determined in the low light-grown Arabidopsis thaliana wild type and in mutant lines defective in either the protein phosphatase (PP)2A regulatory subunit B'γ (gamma; pp2a-b'γ) or B'ζ (zeta; pp2a-b'ζ1-1 and pp2a-b'ζ 1-2) and in gamma zeta double mutants (pp2a-b'γζ) lacking both subunits. All the mutants except for pp2a-b'ζ 1-1 had significantly lower leaf areas than the wild type. Susceptibility to P. syringae was similar in all genotypes. In contrast, aphid fecundity was significantly decreased in the pp2a-b'γ mutant relative to the wild type but not in the pp2a-b'γζ double mutant. A high light pre-treatment, which led to a significant increase in rosette growth in all mutant lines but not in the wild type, led to a significant decrease in aphid fecundity in all genotypes. The high light pre-treatment abolished the differences in aphid resistance observed in the pp2a-b'γ mutant relative to the wild type. The light and CO2 response curves for photosynthesis were changed in response to the high light pre-treatment, but the high light effects were similar in all genotypes. These data demonstrate that a pre-exposure to high light and the composition of B-subunits on the trimeric PP2A holoenzymes are important in regulating plant resistance to aphids. The functional specificity for the individual regulatory B-subunits may therefore limit aphid colonization, depending on the prevailing abiotic stress environment. PMID:25191331

Corn response to climate stress detected with satellite-based NDVI time series

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ruoyu; Cherkauer, Keith; Bowling, Laura

Corn growth conditions and yield are closely dependent on climate variability. Leaf growth, measured as the leaf area index, can be used to identify changes in crop growth in response to climate stress. This research was conducted to capture patterns of spatial and temporal corn leaf growth under climate stress for the St. Joseph River watershed, in northeastern Indiana. Leaf growth is represented by the Normalized Difference Vegetative Index (NDVI) retrieved from multiple years (2000–2010) of Landsat 5 TM images. By comparing NDVI values for individual image dates with the derived normal curve, the response of crop growth to environmentalmore » factors is quantified as NDVI residuals. Regression analysis revealed a significant relationship between yield and NDVI residual during the pre-silking period, indicating that NDVI residuals reflect crop stress in the early growing period that impacts yield. Both the mean NDVI residuals and the percentage of image pixels where corn was under stress (risky pixel rate) are significantly correlated with water stress. Dry weather is prone to hamper potential crop growth, with stress affecting most of the observed corn pixels in the area. Oversupply of rainfall at the end of the growing season was not found to have a measurable effect on crop growth, while above normal precipitation earlier in the growing season reduces the risk of yield loss at the watershed scale. Furthermore, the spatial extent of stress is much lower when precipitation is above normal than under dry conditions, masking the impact of small areas of yield loss at the watershed scale.« less

Corn response to climate stress detected with satellite-based NDVI time series

DOE PAGES

Wang, Ruoyu; Cherkauer, Keith; Bowling, Laura

2016-03-23

Corn growth conditions and yield are closely dependent on climate variability. Leaf growth, measured as the leaf area index, can be used to identify changes in crop growth in response to climate stress. This research was conducted to capture patterns of spatial and temporal corn leaf growth under climate stress for the St. Joseph River watershed, in northeastern Indiana. Leaf growth is represented by the Normalized Difference Vegetative Index (NDVI) retrieved from multiple years (2000–2010) of Landsat 5 TM images. By comparing NDVI values for individual image dates with the derived normal curve, the response of crop growth to environmentalmore » factors is quantified as NDVI residuals. Regression analysis revealed a significant relationship between yield and NDVI residual during the pre-silking period, indicating that NDVI residuals reflect crop stress in the early growing period that impacts yield. Both the mean NDVI residuals and the percentage of image pixels where corn was under stress (risky pixel rate) are significantly correlated with water stress. Dry weather is prone to hamper potential crop growth, with stress affecting most of the observed corn pixels in the area. Oversupply of rainfall at the end of the growing season was not found to have a measurable effect on crop growth, while above normal precipitation earlier in the growing season reduces the risk of yield loss at the watershed scale. Furthermore, the spatial extent of stress is much lower when precipitation is above normal than under dry conditions, masking the impact of small areas of yield loss at the watershed scale.« less

On-plant movement and feeding of western bean cutworm (Lepidoptera: Noctuidae) early instars on corn.

PubMed

Paula-Moraes, S V; Hunt, T E; Wright, R J; Hein, G L; Blankenship, E E

2012-12-01

Western bean cutworm, Striacosta albicosta (Smith), has undergone a recent eastward expansion from the western U.S. Corn Belt to Pennsylvania and parts of Canada. Little is known about its ecology and behavior, particularly during the early instars, on corn (Zea mays L.). There is a narrow treatment window for larvae, and early detection of the pest in the field is essential. An understanding of western bean cutworm larval feeding and early-instar dispersal is essential to understand larval survival and establishment in corn. Studies were conducted in 2009 through 2011 in Nebraska to determine the feeding and dispersal of early-instar western bean cutworm on corn. The treatment design was a factorial with three corn stages (pretassel, tassel, and posttassel) and five corn plant zones (tassel, above ear, primary ear, secondary ear, and below ear) in a randomized complete block design. The effects of different corn tissues on larval survival and development were investigated in laboratory studies in a randomized complete block design during 2009 and 2011. Treatments were different corn tissues (leaf alone, leaf with developing tassel, pollen, pollen plus silk, and silk alone). Results demonstrated that neonate larvae move to the upper part of the plant, independent of corn stage. Larval growth was optimal when fed on tassel tissue. Overall results indicated a selective benefit for movement of the early instar to upper part of the plant.

Coherent optical determination of the leaf angle distribution of corn

NASA Technical Reports Server (NTRS)

Ulaby, F. T. (Principal Investigator); Pihlman, M.

1981-01-01

A coherent optical technique for the diffraction analysis of an image is presented. Developments in radar remote sensing shows a need to understand plant geometry and its relationship to plant moisture, soil moisture, and the radar backscattering coefficient. A corn plant changes its leaf angle distribution, as a function of time, from a uniform distribution to one that is strongly vertical. It is shown that plant and soil moisture may have an effect on plant geometry.

Attraction of Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae) to eugenol-baited traps in soybean

USDA-ARS?s Scientific Manuscript database

Diabrotica barberi Smith and Lawrence (the northern corn rootworm) is a native North American leaf beetle and a major pest of corn. However, adult D. barberi forage in various habitats outside of corn, including soybean, roadside vegetation, and prairie. Eugenol is a common floral volatile that ha...

Results of the 1971 Corn Blight Watch experiment

NASA Technical Reports Server (NTRS)

Macdonald, R. B.; Allen, R. D.; Bauer, M. E.; Clifton, J. W.; Frickson, J. D.; Landgrebe, D. A.

1972-01-01

Advanced remote sensing techniques are used to: (1)Detect development and spread of corn leaf blight during the growing season; (2) assess the extent and severity of blight infection; (3) assess the impact of blight on corn production; and (4) estimate the applicability of these techniques to similar situations occurring in the future.

Molecular markers linked to genes important for Hard Winter Wheat production and marketing in the U.S. Great Plains

USDA-ARS?s Scientific Manuscript database

Biotic stresses including diseases [leaf, stem and stripe rusts, and wheat streak mosaic virus (WSMV)] and insects [greenbug (GB), Hessian fly (Hf), Russian wheat aphid (RWA) and wheat curl mite (WCM)] significantly affect grain yield and end-use quality of hard winter wheat (HWW, Triticum aestivum ...

Diversity of formyltetrahydrofolate synthetase genes in the rumens of roe deer (Capreolus pygargus) and sika deer (Cervus nippon) fed different diets.

PubMed

Li, Zhipeng; Henderson, Gemma; Yang, Yahan; Li, Guangyu

2017-01-01

Reductive acetogenesis by homoacetogens represents an alternative pathway to methanogenesis to remove metabolic hydrogen during rumen fermentation. In this study, we investigated the occurrence of homoacetogen in the rumens of pasture-fed roe deer (Capreolus pygargus) and sika deer (Cervus nippon) fed either oak-leaf-based (tannin-rich, 100 mg/kg dried matter), corn-stover-based, or corn-silage-based diets, by using formyltetrahydrofolate synthetase (FTHFS) gene sequences as a marker. The diversity and richness of FTHFS sequences was lowest in animals fed oak leaf, indicating that tannin-containing plants may affect rumen homoacetogen diversity. FTHFS amino acid sequences in the rumen of roe deer significantly differed from those of sika deer. The phylogenetic analyses showed that 44.8% of sequences in pasture-fed roe deer, and 72.1%, 81.1%, and 37.5% of sequences in sika deer fed oak-leaf-, corn-stover-, and corn-silage-based diets, respectively, may represent novel bacteria that have not yet been cultured. These results demonstrate that the rumens of roe deer and sika deer harbor potentially novel homoacetogens and that diet may influence homoacetogen community structure.

Three odorant binding proteins may regulate the behavioural response of Chrysopa pallens to plant volatiles and the aphid alarm pheromone (E)-β-farnesene.

PubMed

Li, Z-Q; Zhang, S; Cai, X-M; Luo, J-Y; Dong, S-L; Cui, J-J; Chen, Z-M

2017-06-01

Artificial Chrysopa pallens release is a well-known method for suppressing aphids, but it is difficult to establish lacewing populations in the field. Understanding the functions of C. pallens odorant-binding proteins (CpalOBPs) and behavioural responses of C. pallens to plant volatiles and aphid alarm pheromone (E)-ß-farnesene has important implications for population establishment after lacewing release. Based on our previous study, five antennae-enriched CpalOBPs were selected. Sequence alignment and phylogenetic analysis revealed that these five CpalOBPs were Classic OBPs and separated into different clades. Of them, CpalOBP10 clustered in the same clade with aphid OBP7, which mediates the perception of green leaf volatiles and (E)-ß-farnesene. Ligand-binding assays showed 31 compounds, including plant-derived compounds, pest-induced volatiles and (E)-ß-farnesene, had high binding affinities for at least one of these five CpalOBPs. Of the 31 compounds, the pest-induced volatiles (Z)-3-hexenyl hexanoate and 2-hexyl-1-decanol, used in host location by the black bean aphid, elicited significant attractive behavioural responses from C. pallens. Conversely, (E)-ß-farnesene elicited strongly repellent behavioural responses. It is conceivable that C. pallens utilizes plant-derived compounds, pest-induced volatiles and (E)-ß-farnesene as foraging cues. Our studies provide new insights into the interrelationships amongst C. pallens, its prey and the host plants. Compounds that elicited significant behavioural responses from C. pallens were also identified. © 2017 The Royal Entomological Society.

Satellite retrievals of leaf chlorophyll and photosynthetic capacity for improved modeling of GPP

USDA-ARS?s Scientific Manuscript database

This study investigates the utility of in-situ and satellite-based leaf chlorophyll (Chl) estimates for quantifying leaf photosynthetic capacity and for constraining model simulations of Gross Primary Productivity (GPP) over a corn field in Maryland, U.S.A. The maximum rate of carboxylation (Vmax) r...

Recent advances in research of some pest problems of hybrid populus in Michigan and Wisconsin

Treesearch

Lincoln M. Moore; Louis F. Wilson

1983-01-01

Hybrid Populus clones were examined for impact from and resistance to attack from several insects and diseases. Cottonwood leaf beetle, poplar-and-willow borer, and Septoria canker were most injurious. The spotted poplar aphid and poplar-gall saperda, even when abundant, caused only minor impact. The tarnished plant bug, a newly identified pest of...

Ectopic expression of class 1 KNOX genes induce adventitious shoot regeneration and alter growth and development of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L).

PubMed

Srinivasan, C; Liu, Zongrang; Scorza, Ralph

2011-04-01

Transgenic plants of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L) were produced by transforming with the apple class 1 KNOX genes (MdKN1 and MdKN2) or corn KNOX1 gene. Transgenic tobacco plants were regenerated in vitro from transformed leaf discs cultured in a medium lacking cytokinin. Ectopic expression of KNOX genes retarded shoot growth by suppressing elongation of internodes in transgenic tobacco plants. Expression of each of the three KNOX1 genes induced malformation and extensive lobbing in tobacco leaves. In situ regeneration of adventitious shoots was observed from leaves and roots of transgenic tobacco plants expressing each of the three KNOX genes. In vitro culture of leaf explants and internode sections excised from in vitro grown MdKN1 expressing tobacco shoots regenerated adventitious shoots on MS (Murashige and Skoog 1962) basal medium in the absence of exogenous cytokinin. Transgenic plum plants that expressed the MdKN2 or corn KNOX1 gene grew normally but MdKN1 caused a significant reduction in plant height, leaf shape and size and produced malformed curly leaves. A high frequency of adventitious shoot regeneration (96%) was observed in cultures of leaf explants excised from corn KNOX1-expressing transgenic plum shoots. In contrast to KNOX1-expressing tobacco, leaf and internode explants of corn KNOX1-expressing plum required synthetic cytokinin (thidiazuron) in the culture medium to induce adventitious shoot regeneration. The induction of high-frequency regeneration of adventitious shoots in vitro from leaves and stem internodal sections of plum through the ectopic expression of a KNOX1 gene is the first such report for a woody perennial fruit trees.

The sky is falling III: The effect of deposition from static solid rocket motor tests on juvenile crops.

PubMed

Doucette, William J; Curry, Eric; McNeill, Laurie S; Heavilin, Justin

2017-12-01

A mixture of combustion products (mainly hydrogen chloride, aluminum oxide, and water) and entrained soil, referred to as Test Fire Soil (TFS), can be deposited on crops during static solid rocket motor tests. The impact of a reported worst-case event was previously evaluated by exposing corn and alfalfa to 3200-gTFS/m 2 at 54days after emergence. Exposures via soil and leaves were evaluated separately. Reduced growth (soil exposure) and leaf "scorch" (leaf exposure) were attributed mainly to the high chloride concentrations in the TFS (56,000mg/kg). A follow-up study was conducted to evaluate the effect of a typical deposition event (70-gTFS/m 2 , estimated by radar during several tests) and exposure (soil and leaves simultaneously) on juvenile corn, alfalfa, and winter wheat. Younger crops were used to examine potential age sensitivity differences. Impact was evaluated by comparing the growth, elemental composition, and leaf chlorophyll content of treated and untreated plants. The relationship between deposition exposure and response was also addressed. Growth of corn, alfalfa, and winter wheat exposed to a typical TFS loading was not impacted, although slightly elevated concentrations of aluminum and iron were found in the leaves. At the highest loadings used for the exposure-response experiment, concentrations of chloride and calcium were higher in TFS-exposed corn leaves than in the untreated leaves. Overall results indicate that exposure to a typical deposition event does not adversely impact juvenile crops and that younger plants may be less vulnerable to TFS. However, higher TFS loadings can cause leaf scorch and increase the leaf concentrations of some elements. Copyright © 2017 Elsevier B.V. All rights reserved.

Elevated CO2 impacts bell pepper growth with consequences to Myzus persicae life history, feeding behaviour and virus transmission ability

NASA Astrophysics Data System (ADS)

Dáder, Beatriz; Fereres, Alberto; Moreno, Aránzazu; Trębicki, Piotr

2016-01-01

Increasing atmospheric carbon dioxide (CO2) impacts plant growth and metabolism. Indirectly, the performance and feeding of insects is affected by plant nutritional quality and resistance traits. Life history and feeding behaviour of Myzus persicae were studied on pepper plants under ambient (aCO2, 400 ppm) or elevated CO2 (eCO2, 650 ppm), as well as the direct impact on plant growth and leaf chemistry. Plant parameters were significantly altered by eCO2 with a negative impact on aphid’s life history. Their pre-reproductive period was 11% longer and fecundity decreased by 37%. Peppers fixed significantly less nitrogen, which explains the poor aphid performance. Plants were taller and had higher biomass and canopy temperature. There was decreased aphid salivation into sieve elements, but no differences in phloem ingestion, indicating that the diminished fitness could be due to poorer tissue quality and unfavourable C:N balance, and that eCO2 was not a factor impeding feeding. Aphid ability to transmit Cucumber mosaic virus (CMV) was studied by exposing source and receptor plants to ambient (427 ppm) or elevated (612 ppm) CO2 before or after virus inoculation. A two-fold decrease on transmission was observed when receptor plants were exposed to eCO2 before aphid inoculation when compared to aCO2.

Within-Plant Distribution of Adult Brown Stink Bug (Hemiptera: Pentatomidae) in Corn and Its Implications on Stink Bug Sampling and Management in Corn.

PubMed

Babu, Arun; Reisig, Dominic D

2018-05-29

Brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), has emerged as a significant pest of corn, Zea mays L., in the southeastern United States. A 2-year study was conducted to quantify the within-plant vertical distribution of adult E. servus in field corn, to examine potential plant phenological characteristics associated with their observed distribution, and to select an efficient partial plant sampling method for adult E. servus population estimation. Within-plant distribution of adult E. servus was influenced by corn phenology. On V4- and V6-stage corn, most of the individuals were found at the base of the plant. Mean relative vertical position of adult E. servus population in corn plants trended upward between the V6 and V14 growth stages. During the reproductive corn growth stages (R1, R2, and R4), a majority of the adult E. servus were concentrated around developing ears. Based on the multiple selection criteria, during V4-V6 corn growth stages, either the corn stalk below the lowest green leaf or basal stratum method could employ for efficient E. servus sampling. Similarly, on reproductive corn growth stages (R1-R4), the plant parts between two leaves above and three leaves below the primary ear leaf were found to be areas to provide the most precise and cost-efficient sampling method. The results from our study successfully demonstrate that in the early vegetative and reproductive stages of corn, scouts can replace the current labor-intensive whole-plant search method with a more efficient, specific partial plant sampling method for E. servus population estimation.

Consequences of omnivory for trophic interactions on a salt marsh shrub.

PubMed

Ho, Chuan-Kai; Pennings, Steven C

2008-06-01

Although omnivory is common in nature, its impact on trophic interactions is variable. Predicting the food web consequences of omnivory is complicated because omnivores can simultaneously produce conflicting direct and indirect effects on the same species or trophic level. We conducted field and laboratory experiments testing the top-down impacts of an omnivorous salt marsh crab, Armases cinereum, on the shrub Iva frutescens and its herbivorous and predatory arthropod fauna. Armases is a "true omnivore," consuming both Iva and arthropods living on Iva. We hypothesized that Armases would benefit Iva through a top-down trophic cascade, and that this benefit would be stronger than the direct negative effect of Armases on Iva. A field experiment on Sapelo Island, Georgia (USA), supported this hypothesis. Although Armases suppressed predators (spiders), it also suppressed herbivores (aphids), and benefited Iva, increasing leaf number, and reducing the proportion of dead shoots. A one-month laboratory experiment, focusing on the most common species in the food web, also supported this hypothesis. Armases strongly suppressed aphids and consumed fewer Iva leaves if aphids were available as an alternate diet. Armases gained more body mass if they could feed on aphids as well as on Iva. Although Armases had a negative effect on Iva when aphids were not present, Armases benefited Iva if aphids were present, because Armases controlled aphid populations, releasing Iva from herbivory. Although Armases is an omnivore, it produced strong top-down forces and a trophic cascade because it fed preferentially on herbivores rather than plants when both were available. At the same time, the ability of Armases to subsist on a plant diet allows it to persist in the food web when animal food is not available. Because omnivores feed on multiple trophic levels, their effects on food webs may differ from those predicted by standard trophic models that assume that each species feeds only on a single trophic level. To better understand the complexity of real food webs, the variable feeding habits and feeding preferences of different omnivorous species must be taken into consideration.

40 CFR 180.609 - Fluoxastrobin; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., subgroup 13-07G 1.9 Corn, field, forage 3.0 Corn, field, grain 0.02 Corn, field, stover 4.5 Leaf petioles subgroup 4B 4.0 Peanut 0.010 Peanut, hay 20.0 Peanut, refined oil 0.030 Soybean, forage 9.0 Soybean, hay 1.2 Soybean, hulls 0.20 Soybean, seed 0.05 Tomato, paste 1.5 Vegetable, fruiting, group 8 1.0...

Understanding N timing in corn yield and fertilizer N recovery: An insight from an isotopic labeled-N determination

PubMed Central

de Almeida, Rodrigo Estevam Munhoz; Pierozan Junior, Clovis; Lago, Bruno Cocco; Trivelin, Paulo Cesar Ocheuze

2018-01-01

Early fertilizer nitrogen (N) application on cover crops or their residues during the off-season is a practice adopted in Brazil subtropical conditions under no-tillage corn (Zea mays L.) systems. However, the effect of early N application on yield, plant N content, and N recovery efficiency (NRE) for corn is not yet well documented. Five fertilizer N timings in an oat-corn system were evaluated in two studies utilizing an isotopic-labeled N determination, 15N isotope. The N fertilization timings were: (i) oat tillering, (ii) 15 days before corn planting time, over the oat residues, (iii) at corn planting time, (iv) in-season at the three-leaf growth stage (V3), and (v) in-season split application at V3 and six-leaf (V6) growth stages. Based on the statistical analysis, the N fertilization timings were separated into three groups: 1) N-OATS, designated to N applied at oat; 2) N-PLANT, referred to pre-plant and planting N applications; and 3) N-CORN, designated to in-season corn N applications. Corn yield was not affected by the N fertilization timing. However, the N-CORN N fertilization timings enhanced NRE by 17% and 35% and final N recovery system (plant plus soil) by 16% and 24% all relative to N-OATS and N-PLANT groups, respectively. Overall, N-OATS resulted in the largest N derived from fertilizer (NDFF) amount in the deeper soil layer, in overall a delta of 10 kg N ha-1 relative to the rest of the groups. Notwithstanding corn yield was not affected, early N fertilization under subtropical conditions is not a viable option since NRE was diminished and the non-recovery N increased relative to the in-season N applications. PMID:29462178

FORAGES AND PASTURES SYMPOSIUM: Optimizing the use of fibrous residues in beef and dairy diets.

PubMed

Watson, A K; MacDonald, J C; Erickson, G E; Kononoff, P J; Klopfenstein, T J

2015-06-01

Increased corn prices over the past decade have altered land use away from traditional forage in favor of corn. Accordingly, beef and dairy producers have had to adopt nontraditional forage resources into their production systems, many of which have become available as a result of increased corn production. Corn residues have become more available due to increases in corn hectares and yield. The individual plant components (i.e., husk, leaf, and stem) vary in fiber digestibility (NDF digestibility estimates = 40.5, 31.4, and 0.6% ± 0.8 for husk, leaf, and stalk, respectively). Stocking cattle to consume 3.6 kg forage/25.5 kg of grain allows cattle to graze selectively; selection of husks and leaves improves cattle performance. Byproducts of the wet and dry milling industries can be supplemented to calves grazing corn residues to provide protein and energy. Optimal gains were observed when these byproducts were supplemented at approximately 2.5 kg/d to 250-kg growing calves. Gestating beef cows do not require supplemental inputs when grazing corn residue, if stocked appropriately. Alkaline treatment of crop residues improves their feeding value. Concentrations of up to 20% harvested corn residue treated with calcium oxide can be included in finishing diets with an average of 1.3% reduction in G:F when diets contain 40% wet or modified distillers grains. Conversely, when untreated corn residues are included in similar finishing diets, G:F is reduced by 13.4%. Calcium oxide-treated residues included in beef growing diets increases DMI and ADG without significant improvements in G:F. Calcium oxide treatment of corn residues has been evaluated in dairy diets by replacing corn or corn silage with variable results. Efficient use of nontraditional fiber sources, such as corn milling byproducts and corn residue, are critical to the future viability of ruminant animal production.

Influence of brick air scrubber by-product on growth and development of corn and hybrid poplar.

PubMed

Thomas, Carla N; Bauerle, William L; Owino, Tom O; Chastain, John P; Klaine, Stephen J

2007-03-01

Studies were conducted to determine the effects of spent reagent from air pollution control scrubbers used at a brick manufacturing facility on emergence, growth, and physiological responses of corn and hybrid poplar plants. Scrubber by-product was obtained from General Shale Brick, Louisville, KY. Potting substrate was weighed and quantities of scrubber by-product were added to the substrate to obtain treatments of 0%, 6.25%, 12.5%, 25%, 50%, 75%, and 100% scrubber by-product (w:w) for the corn study. Each treatment mix was potted into nine replicate polyethylene pots and four corn seeds were sown per pot. The pots were randomized in a greenhouse at Clemson University and the number of seedlings emerging from each treatment, dark-adapted leaf chlorophyll a fluorescence, and shoot heights were measured at the end of a 21-day growth period. Then, dry shoot biomass was determined for plants from each treatment and plant tissues were analyzed for selected constituents. For the poplar study, nine-inch cuttings of hybrid poplar clone 15-29 (Populus trichocarpa x P. deltoides) and clone OP367 (P. deltoides x P. nigra) were planted in treatments of scrubber by-product-potting soil mixes of 0% , 5% , 10% , and 25% w:w. Leaf chlorophyll a fluorescence was measured over six weeks and cumulative leaf area, dry biomass, and nutrient content of tissues were determined upon harvest. Results of these studies indicate that percent seedling emergence for corn plants decreased with increasing scrubber by-product application rates. Application rates up to 12.5% scrubber by-product w:w had no adverse effect on corn seedling emergence. Shoot elongation, biomass production, and the status of the photosynthetic apparatus of the seedlings were also not severely impaired at applications below this level. A critical value of 58.2% w:w scrubber by-product was estimated to cause 25% inhibition of seedling emergence. Biomass production, cumulative leaf area, and chlorophyll a fluorescence of hybrid poplar plants were not affected by scrubber by-product applications of up to 5% w:w.

Effects of agricultural intensification on ability of natural enemies to control aphids

PubMed Central

Zhao, Zi-Hua; Hui, Cang; He, Da-Han; Li, Bai-Lian

2015-01-01

Agricultural intensification through increasing fertilization input and cropland expansion has caused rapid loss of semi-natural habitats and the subsequent loss of natural enemies of agricultural pests. It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales. Based on a two-year study of seventeen 1500 m-radius sites, we analyzed the relative importance of nitrogen input and cropland expansion on cereal aphids and their natural enemies. Both the input of nitrogen fertilizer and cropland expansion benefited cereal aphids more than primary parasitoids and leaf-dwelling predators, while suppressing ground-dwelling predators, leading to an disturbance of the interspecific relationship. The responses of natural enemies to cropland expansion were asymmetric and species-specific, with an increase of primary parasitism but a decline of predator/pest ratio with the increasing nitrogen input. As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss. To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales. PMID:25620737

Relative Water Content, Bidirectional Reflectance and Bidirectional Transmittance of the Interior of Detached Leaves During Dry Down.

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2015-01-01

Remotely sensing the water status of plants and the water content of canopies remain long-term goals of remote sensing research [1]. Estimates of canopy water content commonly involve measurements in the 900nm to 2000nm portion of the optical spectrum [1]. We have used optical polarization techniques to remove leaf surface reflection and to demonstrate that the visible light reflected by the interior of green healthy corn leaves measured in situ inversely depends upon the leaf relative water content (RWC) [2]. In the research reported here, we again used optical polarization techniques in order to remove the leaf surface reflection from our measurements. This allowed us to monitor the interiors of detached corn leaf samples during leaf dry down measuring for each sample the RWC, bidirectional spectral reflectance and bidirectional spectral transmittance over the wavelength range 450nm to 2,500nm. Our new results like our earlier results show light scattered by the leaf interior measured in the visible wavelength region generally increased as leaf RWC decreased. However, the spectral character and the much improved signal noise of our new results shows the RWC-linked visible light scattering changes are due to leaf structural changes. Our new results show that scattering changes that occur with changing leaf RWC are not attributable to molecular configuration changes in cellular pigments.

Within-plant distribution of Aulacorthum solani (Hemiptera: Aphididae), on various greenhouse plants with implications for control.

PubMed

Jandricic, S E; Mattson, N S; Wraight, S P; Sanderson, J P

2014-04-01

Foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), has recently undergone a status change from an occasional pest to a serious pest in greenhouses of North America and the United Kingdom. Little nonanecdotal information exists on the ecology of this insect in greenhouse crops. To help improve integrated pest management decisions for A. solani, the within-plant distribution of this pest was explored on a variety of common greenhouse plants in both the vegetative and flowering stage. This aphid generally was found on lower leaves of vegetative plants, but was found higher in the canopy on reproductive plants (on flowers, flower buds, or upper leaves). Aphid numbers were not consistently positively correlated with total leaf surface areas within plant strata across plant species. Thus, the observed differences in preferred feeding sites on vegetative versus flowering plants are possibly a response to differences in nutritional quality of the various host-plant tissues. Despite being anecdotally described as a "stem-feeding aphid," A. solani was rarely found feeding on stems at the population densities established in our tests, with the exception of racemes of scarlet sage (Salvia splendans). Although some previous reports suggested that A. solani prefers to feed on new growth of plants, our results indicate that mature leaves are preferred over growing tips and young leaves. The implications of the within-plant feeding preferences of A. solani populations with respect to both biological and chemical control are discussed.

Association of spectral development patterns with development stages of corn

NASA Technical Reports Server (NTRS)

Crist, E. P. (Principal Investigator)

1982-01-01

Association is made between the development stages of corn as defined by Hanway and the temporal-spectral development pattern of corn in a transformed data space derived from Landsat-MSS band reflectance values, using field-collected reflectance and associated data. Results indicate that the spectral vegetation index used (a reflectance equivalent of Tasseled Cap Greenness) reaches a maximum well before the stage at which corn is expected to achieve its peak leaf area index. Possible physiological and canopy geometry related causes for this and other results are presented.

Investigation of the Spectroscopic Information on Functional Groups Related to Carbohydrates in Different Morphological Fractions of Corn Stover and Their Relationship to Nutrient Supply and Biodegradation Characteristics.

PubMed

Xin, Hangshu; Ding, Xue; Zhang, Liyang; Sun, Fang; Wang, Xiaofan; Zhang, Yonggen

2017-05-24

The objectives of this study were to investigate (1) nutritive values and biodegradation characteristics and (2) mid-IR spectroscopic features within the regions associated with carbohydrate functional groups (including cellulosic component (CELC), structural carbohydrate (STCHO), and total carbohydrate (CHO)) in different morphological fractions of corn stover. Furthermore, correlation and regression analyses were also applied to determine the relationship between nutritional values and spectroscopic parameters. The results showed that different morphological sections of corn stover had different nutrient supplies, in situ biodegradation characteristics, and spectral structural features within carbohydrate regions. The stem rind and ear husk were both high in fibrous content, which led to the lowest effective degradabilities (ED) among these stalk fractions. The ED values of NDF were ranked ear husk > stem pith > leaf blade > leaf sheath > whole plant > stem rind. Intensities of peak height and area within carbohydrate regions were relatively more stable compared with spectral ratio profiles. Significant difference was found only in peak area intensity of CELC, which was at the highest level for stem rind, followed by stem pith, leaf sheath, whole plant, leaf blade, and ear husk. Correlation results showed that changes in some carbohydrate spectral ratios were highly associated with carbohydrate chemical profiles and in situ rumen degradation kinetics. Among the various carbohydrate molecular spectral parameters that were tested in multiple regression analysis, CHO height ratios, and area ratios of CELC:CHO and CELC:STCHO as well as CELC area were mostly sensitive to nutrient supply and biodegradation characteristics in different morphological fractions of corn stover.

Remote sensing of agricultural crops and soils

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator)

1983-01-01

Research in the correlative and noncorrelative approaches to image registration and the spectral estimation of corn canopy phytomass and water content is reported. Scene radiation research results discussed include: corn and soybean LANDSAT MSS classification performance as a function of scene characteristics; estimating crop development stages from MSS data; the interception of photosynthetically active radiation in corn and soybean canopies; costs of measuring leaf area index of corn; LANDSAT spectral inputs to crop models including the use of the greenness index to assess crop stress and the evaluation of MSS data for estimating corn and soybean development stages; field research experiment design data acquisition and preprocessing; and Sun-view angles studies of corn and soybean canopies in support of vegetation canopy reflection modeling.

Multispectral determination of vegetative cover in corn crop canopy

NASA Technical Reports Server (NTRS)

Stoner, E. R.; Baumgardner, M. F.

1972-01-01

The relationship between different amounts of vegetative ground cover and the energy reflected by corn canopies was investigated. Low altitude photography and an airborne multispectral scanner were used to measure this reflected energy. Field plots were laid out, representing four growth stages of corn. Two plot locations were chosen-on a very dark and a very light surface soil. Color and color infrared photographs were taken from a vertical distance of 10 m. Estimates of ground cover were made from these photographs and were related to field measurements of leaf area index. Ground cover could be predicted from leaf area index measurements by a second order equation. Microdensitometry and digitzation of the three separated dye layers of color infrared film showed that the near infrared dye layer is most valuable in ground cover determinations. Computer analysis of the digitized photography provided an accurate method of determining precent ground cover.

Plant Water Stress Affects Interactions Between an Invasive and a Naturalized Aphid Species on Cereal Crops.

PubMed

Foote, N E; Davis, T S; Crowder, D W; Bosque-Pérez, N A; Eigenbrode, S D

2017-06-01

In cereal cropping systems of the Pacific Northwestern United States (PNW), climate change is projected to increase the frequency of drought during summer months, which could increase water stress for crop plants. Yet, it remains uncertain how interactions between herbivore species are affected by drought stress. Here, interactions between two cereal aphids present in PNW cereal systems, Metopolophium festucae (Theobald) subsp. cerealium (a newly invasive species) and Rhopalosiphum padi L. (a naturalized species), were tested relative to wheat water stress. When aphids were confined in leaf cages on wheat, asymmetrical facilitation occurred; per capita fecundity of R. padi was increased by 46% when M. festucae cerealium was also present, compared to when only R. padi was present. Imposed water stress did not influence this interaction. When aphids were confined on whole wheat plants, asymmetrical competition occurred; cocolonization inhibited M. festucae cerealium population growth but did not affect R. padi population growth. Under conditions of plant water stress, however, the inhibitory effect of R. padi on M. festucae cerealium was not observed. We conclude that beneficial effects of cocolonization on R. padi are due to a localized plant response to M. festucae cerealium feeding, and that cocolonization of plants is likely to suppress M. festucae cerealium populations under ample water conditions, but not when plants are water stressed. This suggests that plant responses to water stress alter the outcome of competition between herbivore species, with implications for the structure of pest communities on wheat during periods of drought. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Intraspecific variation in aphid resistance and constitutive phenolics exhibited by the wild blueberry Vaccinium darrowi.

PubMed

Ranger, C M; Singh, A P; Johnson-Cicalese, J; Polavarapu, S; Vorsa, N

2007-04-01

Illinoia pepperi (MacGillivray) infests cultivated highbush blueberries, Vaccinium corymbosum L., in the Northeastern United States. Allopatric resistance to I. pepperi was examined in Vaccinium darrowi Camp, which evolved in the absence of I. pepperi in the Southeastern U.S. V. corymbosum cv. "Elliott", was used as a susceptible control. Between population variability in I. pepperi resistance was assessed by measuring length of the prereproductive period, fecundity, and survivorship on 14 V. darrowi accessions representing 11 discrete wild populations. Length of I. pepperi's prereproductive period and survivorship were not significantly affected. However, differences were detected in fecundity and the intrinsic rate of increase (r ( m )). Within population variability in resistance was measured by confining first instars to 24 accessions from a single wild population of V. darrowi (NJ88-06). Significant differences in the mean total number of aphids occurring after 20 d were only detected between 2 of the 24 V. darrowi accessions. A greater degree of diversity in I. pepperi resistance exists between populations of V. darrowi compared to within a population. Constitutive leaf and stem polyphenolics were identified by HPLC-MS and quantified from 14 of the V. darrowi accessions. The accessions varied in concentrations of five phenolic acids and seven flavonol glycosides, but a correlation was not found between individual or total phenolics and aphid performance. Overall, screening within and between populations of V. darrowi identified promising sources of aphid resistance, but phenolic acid and flavonol glycoside profiles did not predict resistance levels. The mechanism of resistance remains to be identified.

An epidemiological model for externally sourced vector-borne viruses applied to Bean yellow mosaic virus in lupin crops in a Mediterranean-type environment.

PubMed

Maling, T; Diggle, A J; Thackray, D J; Siddique, K H M; Jones, R A C

2008-12-01

A hybrid mechanistic/statistical model was developed to predict vector activity and epidemics of vector-borne viruses spreading from external virus sources to an adjacent crop. The pathosystem tested was Bean yellow mosaic virus (BYMV) spreading from annually self-regenerating, legume-based pastures to adjacent crops of narrow-leafed lupin (Lupinus angustifolius) in the winter-spring growing season in a region with a Mediterranean-type environment where the virus persists over summer within dormant seed of annual clovers. The model uses a combination of daily rainfall and mean temperature during late summer and early fall to drive aphid population increase, migration of aphids from pasture to lupin crops, and the spread of BYMV. The model predicted time of arrival of aphid vectors and resulting BYMV spread successfully for seven of eight datasets from 2 years of field observations at four sites representing different rainfall and geographic zones of the southwestern Australian grainbelt. Sensitivity analysis was performed to determine the relative importance of the main parameters that describe the pathosystem. The hybrid mechanistic/statistical approach used created a flexible analytical tool for vector-mediated plant pathosystems that made useful predictions even when field data were not available for some components of the system.

Wounding, insect chewing and phloem sap feeding differentially alter the leaf proteome of potato, Solanum tuberosum L.

PubMed Central

2012-01-01

Background Various factors shape the response of plants to herbivorous insects, including wounding patterns, specific chemical effectors and feeding habits of the attacking herbivore. Here we performed a comparative proteomic analysis of the plant's response to wounding and herbivory, using as a model potato plants (Solanum tuberosum L.) subjected to mechanical wounding, defoliation by the Colorado potato beetle Leptinotarsa decemlineata Say, or phloem sap feeding by the potato aphid Macrosiphum euphorbiae Thomas. Results Out of ~500 leaf proteins monitored by two-dimensional gel electrophoresis (2-DE), 31 were up- or downregulated by at least one stress treatment compared to healthy control plants. Of these proteins, 29 were regulated by beetle chewing, 8 by wounding and 8 by aphid feeding. Some proteins were up- or downregulated by two different treatments, while others showed diverging expression patterns in response to different treatments. A number of modulated proteins identified by mass spectrometry were typical defense proteins, including wound-inducible protease inhibitors and pathogenesis-related proteins. Proteins involved in photosynthesis were also modulated, notably by potato beetle feeding inducing a strong decrease of some photosystem I proteins. Quantitative RT PCR assays were performed with nucleotide primers for photosynthesis-related proteins to assess the impact of wounding and herbivory at the gene level. Whereas different, sometimes divergent, responses were observed at the proteome level in response to wounding and potato beetle feeding, downregulating effects were systematically observed for both treatments at the transcriptional level. Conclusions These observations illustrate the differential impacts of wounding and insect herbivory on defense- and photosynthesis-related components of the potato leaf proteome, likely associated with the perception of distinct physical and chemical cues in planta. PMID:23268880

Risk of spider predation alters food web structure and reduces local herbivory in the field.

PubMed

Bucher, Roman; Menzel, Florian; Entling, Martin H

2015-06-01

Predators can indirectly enhance plant performance via herbivore suppression, with both prey consumption and changes in prey traits (e.g. changes in foraging behaviour) contributing to the reduction in herbivory. We performed a field experiment to determine the extent of such non-consumptive effects which consisted of repeatedly placing spiders (Pisaura mirabilis) on enclosed plants (Urtica dioica) for cue deposition. Control plants were enclosed in the same way but without spiders. After cue deposition, the enclosures were removed to allow arthropods to colonize the plants and feed on them. Arthropods were removed from the plants before the subsequent spider deposition or control enclosure. During six cycles of enclosure, we quantified leaf damage on the plants. After a seventh cycle, the colonizing arthropods were sampled to determine community composition in relation to the presence/absence of spider cues. We found that the presence of chemotactile spider cues reduced leaf damage by 50 %. In addition, spider cues led to changes in the arthropod community: smaller spiders avoided plants with spider cues. In contrast, the aphid-tending ant Myrmica rubra showed higher recruitment of workers on cue-bearing plants, possibly to protect aphids. Our results show that the risk of spider predation can reduce herbivory on wild plants and also demonstrate that non-consumptive effects can be particularly strong within the predator guild.

Spectral-agronomic relationships of corn, soybean and wheat canopies

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Daughtry, C. S. T.; Vanderbilt, V. C.

1981-01-01

During the past six years several thousand reflectance spectra of corn, soybean, and wheat canopies were acquired and analyzed. The relationships of biophysical variables, including leaf area index, percent soil cover, chlorophyll and water content, to the visible and infrared reflectance of canopies are described. The effects on reflectance of cultural, environmental, and stress factors such as planting data, seeding rate, row spacing, cultivar, soil type and nitrogen fertilization are also examined. The conclusions are that several key agronomic variables including leaf area index, development stage and degree of stress are strongly related to spectral reflectance and that it should be possible to estimate these descriptions of crop condition from satellite acquired multispectral data.

Canopy cover and leaf area index relationships for wheat, triticale, and corn

USDA-ARS?s Scientific Manuscript database

The AquaCrop model requires canopy cover (CC) measurements to define crop growth and development. Some previously collected data sets that would be useful for calibrating and validating AquaCrop contain only leaf area index (LAI) data, but could be used if relationships were available relating LAI t...

A transgenic approach to control hemipteran insects by expressing insecticidal genes under phloem-specific promoters.

PubMed

Javaid, Shaista; Amin, Imran; Jander, Georg; Mukhtar, Zahid; Saeed, Nasir A; Mansoor, Shahid

2016-10-06

The first generation transgenic crops used strong constitutive promoters for transgene expression. However, tissue-specific expression is desirable for more precise targeting of transgenes. Moreover, piercing/sucking insects, which are generally resistant to insecticidal Bacillus thuringiensis (Bt) proteins, have emerged as a major pests since the introduction of transgenic crops expressing these toxins. Phloem-specific promoters isolated from Banana bunchy top virus (BBTV) were used for the expression of two insecticidal proteins, Hadronyche versuta (Blue Mountains funnel-web spider) neurotoxin (Hvt) and onion leaf lectin, in tobacco (Nicotiana tabacum). Here we demonstrate that transgenic plants expressing Hvt alone or in combination with onion leaf lectin are resistant to Phenacoccus solenopsis (cotton mealybug), Myzus persicae (green peach aphids) and Bemisia tabaci (silver leaf whitefly). The expression of both proteins under different phloem-specific promoters resulted in close to 100% mortality and provided more rapid protection than Hvt alone. Our results suggest the employment of the Hvt and onion leaf lectin transgenic constructs at the commercial level will reduce the use of chemical pesticides for control of hemipteran insect pests.

Effects of Methanolic Extracts of Annona Species on the Development and Reproduction of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

PubMed

Freitas, A F; Pereira, F F; Formagio, A S N; Lucchetta, J T; Vieira, M C; Mussury, R M

2014-10-01

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) causes significant losses in corn crops and necessitates the use of alternative control strategies, such as the application of bioinsecticides. We report the effect of methanolic leaf extracts of Annona dioica, Annona cacans, and Annona coriacea on the development and reproduction of S. frugiperda. A quantitative analysis was carried out to determine the total concentration of phenolics, flavonoids, and condensed tannin (CT) in leaf extracts. Corn leaves were immersed in a 1% methanolic leaf extract solution and fed to second instars of S. frugiperda. Leaf disks dipped in the synthetic insecticide Connect® (Bayer CropScience Ltda) composed of a neonicotinoid (imidacloprid) and a pyrethroid (β-cyfluthrin), which are harmful to S. frugiperda, was used as positive control. Distilled water was used as a negative control treatment. The leaf extract of A. coriacea decreased larval survivorship, arrested pupal development, and affected the weight gain of S. frugiperda. A. dioica also affected larval survivorship, but its effects were more pronounced for the adult stage, as fecundity, fertility, egg hatchability, and embryonic development were severely affected. Leaf extracts from A. cacans had no effect on S. frugiperda. The leaf extracts of A. dioica and A. coriacea showed a higher content of flavonoids and phenols, respectively. Our results indicated that both A. dioica and A. coriacea have the potential for development as botanical insecticides.

Leaf Colour as a Signal of Chemical Defence to Insect Herbivores in Wild Cabbage (Brassica oleracea).

PubMed

Green, Jonathan P; Foster, Rosie; Wilkins, Lucas; Osorio, Daniel; Hartley, Susan E

2015-01-01

Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour.

Leaf Colour as a Signal of Chemical Defence to Insect Herbivores in Wild Cabbage (Brassica oleracea)

PubMed Central

Wilkins, Lucas; Osorio, Daniel; Hartley, Susan E.

2015-01-01

Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour. PMID:26353086

Single- versus Multiple-Pest Infestation Affects Differently the Biochemistry of Tomato (Solanum lycopersicum 'Ailsa Craig').

PubMed

Errard, Audrey; Ulrichs, Christian; Kühne, Stefan; Mewis, Inga; Drungowski, Mario; Schreiner, Monika; Baldermann, Susanne

2015-11-25

Tomato is susceptible to pest infestations by both spider mites and aphids. The effects of each individual pest on plants are known, whereas multiple-pest infestations have received little interest. We studied the effects of single- versus multiple-pest infestation by Tetranychus urticae and Myzus persicae on tomato biochemistry (Solanum lycopersicum) by combining a metabolomic approach and analyses of carotenoids using UHPLC-ToF-MS and volatiles using GC-MS. Plants responded differently to aphids and mites after 3 weeks of infestation, and a multiple infestation induced a specific metabolite composition in plants. In addition, we showed that volatiles emissions differed between the adaxial and abaxial leaf epidermes and identified compounds emitted particularly in response to a multiple infestation (cyclohexadecane, dodecane, aromadendrene, and β-elemene). Finally, the carotenoid concentrations in leaves and stems were more affected by multiple than single infestations. Our study highlights and discusses the interplay of biotic stressors within the terpenoid metabolism.

A project to evaluate moisture stress and phenological factors in corn and soybean areas of southwestern and south-central Minnesota

NASA Technical Reports Server (NTRS)

Rust, R. H.; Robert, P. (Principal Investigator)

1981-01-01

The capability of aerial color infrared photography for identifying and locating soilscapes most susceptible to drought development or those having different soil drainages was evaluated. Although west central and southwestern Minnesota had a significant precipitation deficit during the 1980 crop season, indications of plant stress were not observed either from ground observation or through interpretation of imagery at the selected sampling sites. Well-drained soil was more depleted during the "maximium green peak" period than the poorly drained soil. The recharge was more evident on the poorly drained site in the fall. Measurements of leaf water potential and leaf temperature for corn and soybean leaves were made by multispectral band scanner and recorded for analysis.

Validation of Leaf Area Index measurements based on the Wireless Sensor Network platform

NASA Astrophysics Data System (ADS)

Song, Q.; Li, X.; Liu, Q.

2017-12-01

The leaf area index (LAI) is one of the important parameters for estimating plant canopy function, which has significance for agricultural analysis such as crop yield estimation and disease evaluation. The quick and accurate access to acquire crop LAI is particularly vital. In the study, LAI measurement of corn crops is mainly through three kinds of methods: the leaf length and width method (LAILLW), the instruments indirect measurement method (LAII) and the leaf area index sensor method(LAIS). Among them, LAI value obtained from LAILLW can be regarded as approximate true value. LAI-2200,the current widespread LAI canopy analyzer,is used in LAII. LAIS based on wireless sensor network can realize the automatic acquisition of crop images,simplifying the data collection work,while the other two methods need person to carry out field measurements.Through the comparison of LAIS and other two methods, the validity and reliability of LAIS observation system is verified. It is found that LAI trend changes are similar in three methods, and the rate of change of LAI has an increase with time in the first two months of corn growth when LAIS costs less manpower, energy and time. LAI derived from LAIS is more accurate than LAII in the early growth stage,due to the small blade especially under the strong light. Besides, LAI processed from a false color image with near infrared information is much closer to the true value than true color picture after the corn growth period up to one and half months.

Brachycorynella asparagi (Mordv.) Induced—Oxidative Stress and Antioxidative Defenses of Asparagus officinalis L.

PubMed Central

Borowiak-Sobkowiak, Beata; Woźniak, Agnieszka; Bednarski, Waldemar; Formela, Magda; Samardakiewicz, Sławomir; Morkunas, Iwona

2016-01-01

The aim of this study was to investigate whether and to what extent oxidative stress is induced in leaves of one- and two-month-old plants of Asparagus officinalis L. cv. Argenteuil infested by Brachycorynella asparagi (Mordvilko) at a varied population size. The pest B. asparagi has been described as the most damaging species feeding on asparagus. Analyses using electron paramagnetic resonance (EPR) demonstrated generally higher concentrations of semiquinone radicals with g-values of 2.0045 ± 0.0005 and 2.0026 ± 0.0005 in Asparagus officinalis (A. officinalis) leaves after Brachycorynella asparagi (B. asparagi) infestation than in the control. Observations of leaves under a confocal microscope showed a post-infestation enhanced generation of the superoxide anion radical (O2•−) and hydrogen peroxide (H2O2) in comparison to the control. Strong fluctuations in Mn2+ ion levels detected by EPR spectroscopy versus time were detected in leaves infested by aphids, which may indicate the involvement of these ions in the control of O2•− production. An enhanced superoxide dismutase activity is an important element in leaf defense against oxidative stress. Visible symptoms were found in aphid-infested A. officinalis. Damage to leaves of one- and two-month-old A. officinalis plants by the aphid B. asparagi was dependent on the intensity, duration of infestation and plant age. PMID:27775613

Outcomes of co-infection by two potyviruses: implications for the evolution of manipulative strategies

PubMed Central

Salvaudon, Lucie; De Moraes, Consuelo M.; Mescher, Mark C.

2013-01-01

Recent studies have documented effects of plant viruses on host plants that appear to enhance transmission by insect vectors. But, almost no empirical work has explored the implications of such apparent manipulation for interactions among co-infecting pathogens. We examined single and mixed infections of two potyviruses, watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV), that frequently co-occur in cucurbitaceae populations and share the same aphid vectors. We found that ZYMV isolates replicated at similar rates in single and mixed infections, whereas WMV strains accumulated to significantly lower levels in the presence of ZYMV. Furthermore, ZYMV induced changes in leaf colour and volatile emissions that enhanced aphid (Aphis gossypii) recruitment to infected plants. By contrast, WMV did not elicit strong effects on plant–aphid interactions. Nevertheless, WMV was still readily transmitted from mixed infections, despite fairing poorly in in-plant competition. These findings suggest that pathogen effects on host–vector interactions may well influence competition among co-infecting pathogens. For example, if non-manipulative pathogens benefit from the increased vector traffic elicited by manipulative competitors, their costs of competition may be mitigated to some extent. Conversely, the benefits of manipulation may be limited by free-rider effects in systems where there is strong competition among pathogens for host resources and/or access to vectors. PMID:23407835

The plant hormone salicylic acid interacts with the mechanism of anti-herbivory conferred by fungal endophytes in grasses.

PubMed

Bastías, Daniel A; Alejandra Martínez-Ghersa, M; Newman, Jonathan A; Card, Stuart D; Mace, Wade J; Gundel, Pedro E

2018-02-01

The plant hormone salicylic acid (SA) is recognized as an effective defence against biotrophic pathogens, but its role as regulator of beneficial plant symbionts has received little attention. We studied the relationship between the SA hormone and leaf fungal endophytes on herbivore defences in symbiotic grasses. We hypothesize that the SA exposure suppresses the endophyte reducing the fungal-produced alkaloids. Because of the role that alkaloids play in anti-herbivore defences, any reduction in their production should make host plants more susceptible to herbivores. Lolium multiflorum plants symbiotic and nonsymbiotic with the endophyte Epichloë occultans were exposed to SA followed by a challenge with the aphid Rhopalosiphum padi. We measured the level of plant resistance to aphids, and the defences conferred by endophytes and host plants. Symbiotic plants had lower concentrations of SA than did the nonsymbiotic counterparts. Consistent with our prediction, the hormonal treatment reduced the concentration of loline alkaloids (i.e., N-formyllolines and N-acetylnorlolines) and consequently decreased the endophyte-conferred resistance against aphids. Our study highlights the importance of the interaction between the plant immune system and endophytes for the stability of the defensive mutualism. Our results indicate that the SA plays a critical role in regulating the endophyte-conferred resistance against herbivores. © 2017 John Wiley & Sons Ltd.

Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2016-01-01

Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

Deriving chlorophyll fluorescence emissions of vegetation canopies from high resolution field reflectance spectra

NASA Astrophysics Data System (ADS)

Middleton, Elizabeth M.; Corp, Lawrence A.; Daughtry, Craig S.; Entcheva Campbell, Petya K.; Butcher, L. Maryn

2005-11-01

Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll fluorescence (ChlF) peaks centered at 685 nm and 735 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SIF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops and small tree plots of three deciduous species (red maple, tulip poplar, sweet gum). Leaf level measurements were also made of foliage which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and nitrogen (N) contents). As part of ongoing experiments, measurements were made on N application plots within corn (280, 140, 70, and 0 kg N/ha) and tree (0, 37.5, 75, 112.5, 150 kg N /ha) sites at the USDA/Agriculture Research Service in Beltsville, MD. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrow- band regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red SIF ratio (SIFratio) derived from these field reflectance spectra successfully discriminated foliar pigment ratios altered by N application rates in both corn crops. This ratio was also positively correlated to the C/N ratio at leaf and canopy levels, for the available corn data (e.g., 2004). No consistent N treatment or species differences in SIF were detected in the tree foliage, but additional 2005 data are forthcoming. This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation

PubMed Central

Kim, Min Jeong; Shim, Chang Ki; Kim, Yong Ki; Hong, Sung Jun; Park, Jong Ho; Han, Eun Jung; Kim, Jin Ho; Kim, Suk Chul

2015-01-01

This study investigated the chemical characteristics and microbial population during incubation of four kinds of aerated compost teas based on oriental medicinal herbs compost, vermicompost, rice straw compost, and mixtures of three composts (MOVR). It aimed to determine the effects of the aerated compost tea (ACT) based on MOVR on the growth promotion of red leaf lettuce, soybean and sweet corn. Findings showed that the pH level and EC of the compost tea slightly increased based on the incubation time except for rice straw compost tea. All compost teas except for oriental medicinal herbs and rice straw compost tea contained more NO−3-N than NH+4-N. Plate counts of bacteria and fungi were significantly higher than the initial compost in ACT. Microbial communities of all ACT were predominantly bacteria. The dominant bacterial genera were analyzed as Bacillus (63.0%), Ochrobactrum (13.0%), Spingomonas (6.0%) and uncultured bacterium (4.0%) by 16S rDNA analysis. The effect of four concentrations, 0.1%, 0.2%, 0.4% and 0.8% MOVR on the growth of red leaf lettuce, soybean and sweet corn was also studied in the greenhouse. The red leaf lettuce with 0.4% MOVR had the most effective concentration on growth parameters in foliage part. However, 0.8% MOVR significantly promoted the growth of root and shoot of both soybean and sweet corn. The soybean treated with higher MOVR concentration was more effective in increasing the root nodule formation by 7.25 times than in the lower MOVR concentrations Results indicated that ACT could be used as liquid nutrient fertilizer with active microorganisms for culture of variable crops under organic farming condition. PMID:26361474

Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation.

PubMed

Kim, Min Jeong; Shim, Chang Ki; Kim, Yong Ki; Hong, Sung Jun; Park, Jong Ho; Han, Eun Jung; Kim, Jin Ho; Kim, Suk Chul

2015-09-01

This study investigated the chemical characteristics and microbial population during incubation of four kinds of aerated compost teas based on oriental medicinal herbs compost, vermicompost, rice straw compost, and mixtures of three composts (MOVR). It aimed to determine the effects of the aerated compost tea (ACT) based on MOVR on the growth promotion of red leaf lettuce, soybean and sweet corn. Findings showed that the pH level and EC of the compost tea slightly increased based on the incubation time except for rice straw compost tea. All compost teas except for oriental medicinal herbs and rice straw compost tea contained more NO(-) 3-N than NH(+) 4-N. Plate counts of bacteria and fungi were significantly higher than the initial compost in ACT. Microbial communities of all ACT were predominantly bacteria. The dominant bacterial genera were analyzed as Bacillus (63.0%), Ochrobactrum (13.0%), Spingomonas (6.0%) and uncultured bacterium (4.0%) by 16S rDNA analysis. The effect of four concentrations, 0.1%, 0.2%, 0.4% and 0.8% MOVR on the growth of red leaf lettuce, soybean and sweet corn was also studied in the greenhouse. The red leaf lettuce with 0.4% MOVR had the most effective concentration on growth parameters in foliage part. However, 0.8% MOVR significantly promoted the growth of root and shoot of both soybean and sweet corn. The soybean treated with higher MOVR concentration was more effective in increasing the root nodule formation by 7.25 times than in the lower MOVR concentrations Results indicated that ACT could be used as liquid nutrient fertilizer with active microorganisms for culture of variable crops under organic farming condition.

Field measurements, simulation modeling and development of analysis for moisture stressed corn and soybeans, 1982 studies

NASA Technical Reports Server (NTRS)

Blad, B. L.; Norman, J. M.; Gardner, B. R.

1983-01-01

The experimental design, data acquisition and analysis procedures for agronomic and reflectance data acquired over corn and soybeans at the Sandhills Agricultural Laboratory of the University of Nebraska are described. The following conclusions were reached: (1) predictive leaf area estimation models can be defined which appear valid over a wide range of soils; (2) relative grain yield estimates over moisture stressed corn were improved by combining reflectance and thermal data; (3) corn phenology estimates using the model of Badhwar and Henderson (1981) exhibited systematic bias but were reasonably accurate; (4) canopy reflectance can be modelled to within approximately 10% of measured values; and (5) soybean pubescence significantly affects canopy reflectance, energy balance and water use relationships.

Silver Uptake, Distribution, and Effect on Calcium, Phosphorus, and Sulfur Uptake 1

PubMed Central

Koontz, Harold V.; Berle, Karen L.

1980-01-01

Bean, corn, and tomato plants were grown in a nutrient solution labeled with 32P, 45Ca, or 35S and varying concentrations of AgNO3. Following a 6-hour treatment period, plants were harvested and analyzed. A low Ag+ concentration (50 nanomolar) inhibited the shoot uptake of the ions investigated. In the roots, Ca uptake increased whereas P and S uptake decreased. Autoradiograms of bean and corn plants, using 110mAg, showed that Ag+ was uniformly deposited in the bean shoot, but corn shoots had regions of high activity along the leaf margins and at the tips where guttation had occurred. Roots were heavily labeled and shoots (especially the new growth) continued to accumulate Ag+ even after the intact plant was returned to Ag-free solution. Silver was believed to be phloem-mobile since it was exported from a treated leaf. Bean plants removed one-half the Ag+ from 4 liters of nutrient solution containing 50 nanomolar AgNO3 within 1.5 hours, but took 16 hours for 20 liters of solution. Images PMID:16661185

Development of insect resistant maize plants expressing a chitinase gene from the cotton leaf worm, Spodoptera littoralis

PubMed Central

Osman, Gamal H.; Assem, Shireen K.; Alreedy, Rasha M.; El-Ghareeb, Doaa K.; Basry, Mahmoud A.; Rastogi, Anshu; Kalaji, Hazem M.

2015-01-01

Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents. Targeting chitin associated with the extracellular matrices or cell wall by insect chitinases may be an effective approach for controlling pest insects and pathogenic fungi. The ability of chitinases to attack and digest chitin in the peritrophic matrix or exoskeleton raises the possibility to use them as insect control method. In this study, an insect chitinase cDNA from cotton leaf worm (Spodoptera littoralis) has been synthesized. Transgenic maize plant system was used to improve its tolerance against insects. Insect chitinase transcripts and proteins were expressed in transgenic maize plants. The functional integrity and expression of chitinase in progenies of the transgenic plants were confirmed by insect bioassays. The bioassays using transgenic corn plants against corn borer (Sesamia cretica) revealed that ~50% of the insects reared on transgenic corn plants died, suggesting that transgenic maize plants have enhanced resistance against S. cretica. PMID:26658494

Spectral estimators of absorbed photosynthetically active radiation in corn canopies

NASA Technical Reports Server (NTRS)

Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

1985-01-01

Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a Landsat MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95 percent of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50 percent of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73 percent of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

Spectral estimators of absorbed photosynthetically active radiation in corn canopies

NASA Technical Reports Server (NTRS)

Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

1984-01-01

Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a LANDSAT MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95% of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50% of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73% of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

Effect of dilute alkaline pretreatment on the conversion of different parts of corn stalk to fermentable sugars and its application in acetone-butanol-ethanol fermentation.

PubMed

Cai, Di; Li, Ping; Luo, Zhangfeng; Qin, Peiyong; Chen, Changjing; Wang, Yong; Wang, Zheng; Tan, Tianwei

2016-07-01

To investigate the effect of dilute alkaline pretreatment on different parts of biomass, corn stalk was separated into flower, leaf, cob, husk and stem, which were treated by NaOH in range of temperature and chemical loading. The NaOH-pretreated solid was then enzymatic hydrolysis and used as the substrate for batch acetone-butanol-ethanol (ABE) fermentation. The results demonstrated the five parts of corn stalk could be used as potential feedstock separately, with vivid performances in solvents production. Under the optimized conditions towards high product titer, 7.5g/L, 7.6g/L, 9.4g/L, 7g/L and 7.6g/L of butanol was obtained in the fermentation broth of flower, leaf, cob, husk and stem hydrolysate, respectively. Under the optimized conditions towards high product yield, 143.7g/kg, 126.3g/kg, 169.1g/kg, 107.7g/kg and 116.4g/kg of ABE solvent were generated, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating Leaf Water Status from Vis-Nir Reflectance and Transmittance

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2017-01-01

Remotely sensing the water status of plant canopies remains a long term goal of remote sensing research. Established approaches involve measurements in the thermal infrared and the 900-2000nm reflective infrared. Less popular UV-visible-NIR techniques presumably deserve research attention, because photochemical changes linked to plant water status manifest spectral light scattering and absorption changes. Here we monitored the visible and NIR light reflected from the leaf interior as well as the leaf transmittance as the relative water content of corn (Zeamays L.) leaves decreased. Our results highlight the importance of both scattering effects and effects due to absorption by leaf pigments.

HCH, endosulfan, and fluvalinate residue behavior in pigeonpea (Cajanus cajan L. Millsp)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukherjee, I.; Gopal, M.; Yaduraju, N.T.

Pigeonpea (Cajanus cajan L. Millsp) is one of the major pulse crop of India. The loss of pigeonpea crop due to pod and foliage pests is significant, the major pests being pod fly, hairy caterpillar, aphids, white fly, plume moth borer, leaf caterpillar and jassids. It is imperative to save every grain by chemical control methods but these toxicants should not leave unusually high residues on the edible parts. In this paper the authors report the residue behavior of three different insecticides namely, hexachlorocyclohexane, endosulfan and fluvalinate on this crop.

Hydrolyzabilities of different corn stover fractions after aqueous ammonia pretreatment.

PubMed

Sun, Zongping; Ge, Xiaoyan; Xin, Donglin; Zhang, Junhua

2014-02-01

The effect of aqueous ammonia pretreatment on the hydrolysis of different corn stover fractions (rind, husk, leaf, and pith) by xylanase (XYL) with cellulases (CELs) was evaluated. The aqueous ammonia pretreatment had excellent delignification ability (above 66%) for different corn stover fractions. The corn rind exhibited the lowest susceptibility to aqueous ammonia pretreatment. The pretreated rind showed the lowest hydrolyzability by CEL and XYL, which was supported by a high content of crystalline cellulose in the hydrolyzed residues of rind, as confirmed by X-ray diffraction (XRD). With the addition of 1 mg XYL/g dry matter, a high glucose yield (above 90%) could be obtained from the pretreated rind by CEL. The results revealed that a high hydrolyzate yield of corn rind after aqueous ammonia pretreatment could be obtained with 1 mg xylanase/g dry matter, showing that aqueous ammonia pretreatment and xylanase addition to cellulases have great potential for the efficient hydrolysis of corn stover without previous fractionation.

Bidirectional reflectance modeling of non-homogeneous plant canopies

NASA Technical Reports Server (NTRS)

Norman, John M.

1986-01-01

The objective of this research is to develop a 3-dimensional radiative transfer model for predicting the bidirectional reflectance distribution function (BRDF) for heterogeneous vegetation canopies. Leaf bidirectional reflectance and transmittance distribution functions were measured for corn and soybean leaves. The measurements clearly show that leaves are complex scatterers and considerable specular reflectance is possible. Because of the character of leaf reflectance, true leaf reflectance is larger than the nadir reflectances that are normally used to represent leaves. A 3-dimensional reflectance model, named BIGAR (Bidirectional General Array Model), was developed and compared with measurements from corn and soybean. The model is based on the concept that heterogeneous canopies can be described by a combination of many subcanopies, which contain all the foliage, and these subcanopy envelopes can be characterized by ellipsoids of various sizes and shapes. The model/measurement comparison results indicate that this relatively simple model captures the essential character of row crop BRDF's. Finally, two soil BDRF models were developed: one represents soil particles as rectangular blocks and the other represents soil particles as spheres. The sphere model was found to be superior.

Ozone Sensitivity in Sweet Corn (Zea mays L.) Plants: A Possible Relationship to Water Balance

PubMed Central

Harris, Michael J.; Heath, Robert L.

1981-01-01

Stomatal characteristics affecting gas exchange were compared in two sweet corn hybrids (var. Bonanza and Monarch Advance) which differ in foliar ozone sensitivity. No significant differences were observed in stomatal frequencies, guard cell lengths, or conductances to water vapor diffusion. When plant water status was compared, leaf-water potentials for the ozone-resistant cultivar, Bonanza, were lower. A comparison of the relationship between soil- and leaf-water potential indicated that the leaf-water potential of Bonanza was more sensitive to declines in soil-water potential. Additionally, a comparison of stomatal conductance to water vapor diffusion as soil moisture declined and following root detachment indicated that stomata of Bonanza were, likewise, more sensitive to increasing water stress. Data suggest that these differences are attributable to a greater shoot-to-root fresh weight ratio and higher resistance to water movement in the water-conducting tissues for Bonanza. Our observations suggest that root and water delivery system characteristics play a major contributory role in the determination of foliar ozone sensitivity in this species. PMID:16662019

Ants defend aphids against lethal disease

PubMed Central

Nielsen, Charlotte; Agrawal, Anurag A.; Hajek, Ann E.

2010-01-01

Social insects defend their own colonies and some species also protect their mutualist partners. In mutualisms with aphids, ants typically feed on honeydew produced by aphids and, in turn guard and shelter aphid colonies from insect natural enemies. Here we report that Formica podzolica ants tending milkweed aphids, Aphis asclepiadis, protect aphid colonies from lethal fungal infections caused by an obligate aphid pathogen, Pandora neoaphidis. In field experiments, bodies of fungal-killed aphids were quickly removed from ant-tended aphid colonies. Ant workers were also able to detect infective conidia on the cuticle of living aphids and responded by either removing or grooming these aphids. Our results extend the long-standing view of ants as mutualists and protectors of aphids by demonstrating focused sanitizing and quarantining behaviour that may lead to reduced disease transmission in aphid colonies. PMID:19923138

The durable wheat disease resistance gene Lr34 confers common rust and northern corn leaf blight resistance in maize.

PubMed

Sucher, Justine; Boni, Rainer; Yang, Ping; Rogowsky, Peter; Büchner, Heike; Kastner, Christine; Kumlehn, Jochen; Krattinger, Simon G; Keller, Beat

2017-04-01

Maize (corn) is one of the most widely grown cereal crops globally. Fungal diseases of maize cause significant economic damage by reducing maize yields and by increasing input costs for disease management. The most sustainable control of maize diseases is through the release and planting of maize cultivars with durable disease resistance. The wheat gene Lr34 provides durable and partial field resistance against multiple fungal diseases of wheat, including three wheat rust pathogens and wheat powdery mildew. Because of its unique qualities, Lr34 became a cornerstone in many wheat disease resistance programmes. The Lr34 resistance is encoded by a rare variant of an ATP-binding cassette (ABC) transporter that evolved after wheat domestication. An Lr34-like disease resistance phenotype has not been reported in other cereal species, including maize. Here, we transformed the Lr34 resistance gene into the maize hybrid Hi-II. Lr34-expressing maize plants showed increased resistance against the biotrophic fungal disease common rust and the hemi-biotrophic disease northern corn leaf blight. Furthermore, the Lr34-expressing maize plants developed a late leaf tip necrosis phenotype, without negative impact on plant growth. With this and previous reports, it could be shown that Lr34 is effective against various biotrophic and hemi-biotrophic diseases that collectively parasitize all major cereal crop species. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Plant Essential Oils Synergize and Antagonize Toxicity of Different Conventional Insecticides against Myzus persicae (Hemiptera: Aphididae)

PubMed Central

Faraone, Nicoletta; Hillier, N. Kirk; Cutler, G. Christopher

2015-01-01

Plant-derived products can play an important role in pest management programs. Essential oils from Lavandula angustifolia (lavender) and Thymus vulgaris (thyme) and their main constituents, linalool and thymol, respectively, were evaluated for insecticidal activity and synergistic action in combination with insecticides against green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The essential oils and their main constituents exerted similar insecticidal activity when aphids were exposed by direct sprays, but were non-toxic by exposure to treated leaf discs. In synergism experiments, the toxicity of imidacloprid was synergized 16- to 20-fold by L. angustifolia and T. vulgaris essential oils, but far less synergism occurred with linalool and thymol, indicating that secondary constituents of the oils were probably responsible for the observed synergism. In contrast to results with imidacloprid, the insecticidal activity of spirotetramat was antagonized by L. angustifolia and T. vulgaris essential oils, and linalool and thymol. Our results demonstrate the potential of plant essential oils as synergists of insecticides, but show that antagonistic action against certain insecticides may occur. PMID:26010088

Aphid egg protection by ants: a novel aspect of the mutualism between the tree-feeding aphid Stomaphis hirukawai and its attendant ant Lasius productus

NASA Astrophysics Data System (ADS)

Matsuura, Kenji; Yashiro, Toshihisa

2006-10-01

Aphids often form mutualistic associations with ants, in which the aphids provide the ants with honeydew and the ants defend the aphids from predators. In this paper, we report aphid egg protection by ants as a novel aspect of the deeply interdependent relationship between a tree-feeding aphid and its attendant ant. The ant Lasius productus harbours oviparous females, males, and eggs of the hinoki cypress-feeding aphid Stomaphis hirukawai in its nests in winter. We investigated the behaviour of ants kept with aphid eggs in petri dishes to examine whether the ants recognise the aphid eggs and tend them or only provide a refuge for the aphids. Workers carried almost all of the aphid eggs into the nest within 24 h. The ants indiscriminately tended aphid eggs collected from their own colonies and those from other ant colonies. The ants cleaned the eggs and piled them up in the nest, and egg tending by ants dramatically increased aphid egg survival rates. Starving the ants showed no significant effect on aphid egg survivorship. Without ants, aphid eggs were rapidly killed by fungi. These results suggested that grooming by the ants protected the aphid eggs, at least, against pathogenic fungi. This hygienic service afforded by the ants seems indispensable for egg survival of these aphids in an environment rich in potentially pathogenic microorganisms.

Aphid egg protection by ants: a novel aspect of the mutualism between the tree-feeding aphid Stomaphis hirukawai and its attendant ant Lasius productus.

PubMed

Matsuura, Kenji; Yashiro, Toshihisa

2006-10-01

Aphids often form mutualistic associations with ants, in which the aphids provide the ants with honeydew and the ants defend the aphids from predators. In this paper, we report aphid egg protection by ants as a novel aspect of the deeply interdependent relationship between a tree-feeding aphid and its attendant ant. The ant Lasius productus harbours oviparous females, males, and eggs of the hinoki cypress-feeding aphid Stomaphis hirukawai in its nests in winter. We investigated the behaviour of ants kept with aphid eggs in petri dishes to examine whether the ants recognise the aphid eggs and tend them or only provide a refuge for the aphids. Workers carried almost all of the aphid eggs into the nest within 24 h. The ants indiscriminately tended aphid eggs collected from their own colonies and those from other ant colonies. The ants cleaned the eggs and piled them up in the nest, and egg tending by ants dramatically increased aphid egg survival rates. Starving the ants showed no significant effect on aphid egg survivorship. Without ants, aphid eggs were rapidly killed by fungi. These results suggested that grooming by the ants protected the aphid eggs, at least, against pathogenic fungi. This hygienic service afforded by the ants seems indispensable for egg survival of these aphids in an environment rich in potentially pathogenic microorganisms.

Barley yellow dwarf virus: Luteoviridae or Tombusviridae?

PubMed

Miller, W Allen; Liu, Sijun; Beckett, Randy

2002-07-01

Summary Barley yellow dwarf virus (BYDV), the most economically important virus of small grains, features highly specialised relationships with its aphid vectors, a plethora of novel translation mechanisms mediated by long-distance RNA interactions, and an ambiguous taxonomic status. The structural and movement proteins of BYDV that confer aphid transmission and phloem-limitation properties resemble those of the Luteoviridae, the family in which BYDV is classified. In contrast, many genes and cis-acting signals involved in replication and gene expression most closely resemble those of the Tombusviridae. BYDV is in genus Luteovirus, family Luteoviridae. BYDV includes at least two serotypes or viruses: BYDV-PAV and BYDV-MAV. The former BYDV-RPV is now Cereal yellow dwarf virus-RPV (CYDV-RPV). CYDV is in genus Polerovirus, family Luteoviridae. Genus Luteovirus shares many features with family Tombusviridae. Physical properties: approximately 25 nm icosahedral (T = 3) virions. One major (22 kDa) and one minor (50-55 kDa) coat protein. 5.6-5.8 kb positive sense RNA genome with no 5'-cap and no poly(A) tail. Most grasses. Most important in oats, barley and wheat. Also infects maize and rice. Yellowing and dwarfing in barley, stunting in wheat; reddening, yellowing and blasting in oats. Some isolates cause leaf notching and curling. Key attractions: Model for the study of circulative transmission of aphid-transmitted viruses. Plethora of unusual translation mechanisms. Evidence of recombination in recent evolutionary history creates taxonomic ambiguity. Economically important virus of wheat, barley and oats, worldwide. Useful websites/meetings: International symposium: 'Barley Yellow Dwarf Disease: Recent Advances and Future Strategies', CIMMYT, El Batan, Mexico, 1-5 September 2002, http://www.cimmyt.cgiar.org/Research/wheat/Conf_BYD_02/invitation.htm http://www.cimmyt.org/Research/wheat/BYDVNEWS/htm/BYDVNEWS.htm Aphid transmission animation: http://www.ppws.vt.edu/~sforza/tmv/bydv_aph.html.

Techniques for the estimation of leaf area index using spectral data

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Shen, S. S.

1984-01-01

Based on the radiative transport theory of a homogeneous canopy, a new approach for obtaining transformations of spectral data used to estimate leaf area index (LAI), is developed. The transformations which are obtained without any ground knowledge of LAI show low sensitivity to soil variability, and are linearly related to LAI with relationships which are predictable from leaf reflectance, transmittance properties, and canopy reflectance models. Evaluation of the SAIL (scattering by arbitrarily inclined leaves) model is considered. Using only nadir view data, results obtained on winter and spring wheat and corn crops are presented.

Relating thematic mapper bands TM3, TM4, and TM5 to agronomic variables for corn, cotton, sugarbeet, soybean, sorghum, sunflower and tobacco

NASA Technical Reports Server (NTRS)

Fan, C. J. (Principal Investigator)

1982-01-01

Red, photographic infrared, near infrared spectral data of corn, cotton, soybeans, sugar beets, sorghum, sunflowers and tobacco were collected throughout the entire growing season by using a three band handheld radiometer. Different radiance patterns were found among these crops based on their morphology, green biomass duration and leaf size. Results show near infrared radiance is a good indicator of water content in plant tissue under small scale experimental conditions.

Corn pollen deposition on milkweeds in and near cornfields.

PubMed

Pleasants, J M; Hellmich, R L; Dively, G P; Sears, M K; Stanley-Horn, D E; Mattila, H R; Foster, J E; Clark, P; Jones, G D

2001-10-09

The density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. The purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with Bt corn pollen. Pollen density was highest (average 170.6 grains per cm(2)) inside the cornfield and was progressively lower from the field edge outward, falling to 14.2 grains per cm(2) at 2 m. Inside the cornfield, and for each distance from the field edge, a frequency distribution is presented showing the proportion of leaf samples with different pollen densities. Inside cornfields, 95% of leaf samples had pollen densities below 600 grains per cm(2) and the highest pollen density observed was 1400 grains per cm(2), which occurred in a study with a rainless anthesis period. All other studies had rainfall events during the anthesis period. A single rain event can remove 54-86% of the pollen on leaves. Leaves on the upper portion of milkweed plants, where young monarch larvae tend to feed, had only 30-50% of the pollen density levels of middle leaves.

Determination of the genotoxic effects of Convolvulus arvensis extracts on corn (Zea mays L.) seeds.

PubMed

Sunar, Serap; Yildirim, Nalan; Aksakal, Ozkan; Agar, Guleray

2013-06-01

In this research, the methanolic extracts of Convolvulus arvensis were tested for genotoxic and inhibitor activity on the total soluble protein content and the genomic template stability against corn Zea mays L. seed. The methanol extracts of leaf, stem and root of C. arvensis were diluted to 50, 75 and 100 μl concentrations and applied to corn seed. The total soluble protein and genomic template stability results were compared with the control. The results showed that especially 100 μl extracts of diluted leaf, stem and root had a strong inhibitory activity on the genomic template stability. The changes occurred in random amplification of polymorphic DNA (RAPD) profiles of C. arvensis extract treatment included variation in band intensity, loss of bands and appearance of new bands compared with control. Also, the results obtained from this study revealed that the increase in the concentrations of C. arvensis extract increased the total soluble protein content in maize. The results suggested that RAPD analysis and total protein analysis could be applied as a suitable biomarker assay for the detection of genotoxic effects of plant allelochemicals.

Shortwave infrared detection of vegetation

NASA Technical Reports Server (NTRS)

Goward, S. N. (Principal Investigator)

1985-01-01

The potential of short wave infrared (SWIR) measurements in vegetation discrimination is further substantiated through a discussion of field studies and an examination of the physical bases which cause SWIR measurements to vary with the vegetation type observed. The research reported herein supported the AGRISTARS program objective to incorporate TM measurements in the analysis of agricultural activity. Field measurements on corn and soybeans in Iowa were conducted, and the mean and variance of canopy reflectance were computed for each observation date. The Suits canopy reflectance model was used to evaluate possible explanations of the observed corn/soybeans reflectance patterns /39/. The SWIR measurements were shown to effectively discriminate corn and soybeans on the basis of leaf absorption properties.

Efficacy of Chemical Mimicry by Aphid Predators Depends on Aphid-Learning by Ants.

PubMed

Hayashi, Masayuki; Nomura, Masashi; Nakamuta, Kiyoshi

2016-03-01

Chemical mimicry is an effective strategy when signal receivers recognize and discriminate models by relying on chemical cues. Some aphid enemies mimic the cuticular chemicals of aphids through various means thus avoiding detection and attack by aphid-tending ants. However, because ants have been reported to learn the chemical signatures of aphids in order to distinguish the aphids, the efficacy of chemical mimicry is predicted to depend on the experience of the ants that had tended aphids. The present study tested this hypothesis using two predator species: larvae of the green lacewing Mallada desjardinsi, and larvae of the ladybeetle Scymnus posticalis. Lacewing larvae carry the carcasses of aphids on which they have preyed upon their backs, and these function via chemical camouflage to reduce the aggressiveness of aphid-tending ants toward the larvae. Ladybeetle larvae reportedly produce a covering of wax structures, and their chemicals appear to attenuate ant aggression. We examined whether the behavior of the ant Tetramorium tsushimae toward these predators changed depending on their aphid-tending experience. Ants moderated their aggressiveness toward both predators when they had previously tended aphids, indicating that chemical mimicry by both aphid predators is dependent on previous experience of the ants in tending aphids. Chemical mimicry by the predators of ant-tended aphids is therefore considered to exploit learning-dependent aphid recognition systems of ants.

Effects of nitrogen nutrition on the growth, yield and reflectance characteristics of corn canopies. [Purdue Agronomy Farm, Indiana

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Walburg, G.; Daughtry, C. S. T.

1981-01-01

Spectral and agronomic measurements were collected from corn (Zea mays L.) canopies under four nitrogen treatment levels (0, 67, 134, and 202 kg/ha) on 11 dates during 1978 and 12 dates during 1979. Data were analyzed to determine the relationship between the spectral responses of canopies and their argonomic characteristics as well as the spectral separability of the four treatments. Red reflectance was increased, while the near infrared reflectance was decreased for canopies under nitrogen deprivation. Spectral differences between treatments were seen throughout each growing season. The near infrared/red reflectance ratio increased spectral treatment differences over those shown by single band reflectance measures. Of the spectral variables examined, the near infrared/red reflectance ratio most effectively separated the treatments. Differences in spectral response between treatments were attributed to varying soil cover, leaf area index, and leaf pigmentation values, all of which changed with N treatment.

A Study of the Relation Between Crop Growth and Spectra Reflectance Parameters

NASA Technical Reports Server (NTRS)

Badhwar, G.

1984-01-01

A differential equation describing the temporal behavior of greenness, G(t), with time was developed. The basic equation, dG(t)/dt=k(t)(1-G/G sub m) where G sub m is the saturation value of greenness at time, t sub p. It demonstrated that k(t) is linearly proportional to the rate of change of leaf area index. It was also demonstrated that G sub m, t sub p and profile width, are the key to vegetation identification and that the inflection points of the profile are related to the ontogenic state of the plant. These profile features were shown to hold not only throughout the United States corn/soybean growing area, but for the first time in Argentina. A mathematical technique that maximizes the sensitivity of spectral transformation to Leaf Area Index and simultaneously minimizes the sensitivity to all other variables was formulated. Initial results on corn and wheat were obtained.

Phylogenetic ecology of leaf surface traits in the milkweeds (Asclepias spp.): chemistry, ecophysiology, and insect behavior.

PubMed

Agrawal, Anurag A; Fishbein, Mark; Jetter, Reinhard; Salminen, Juha-Pekka; Goldstein, Jessica B; Freitag, Amy E; Sparks, Jed P

2009-08-01

The leaf surface is the contact point between plants and the environment and plays a crucial role in mediating biotic and abiotic interactions. Here, we took a phylogenetic approach to investigate the function, trade-offs, and evolution of leaf surface traits in the milkweeds (Asclepias). Across 47 species, we found trichome densities of up to 3000 trichomes cm(-2) and epicuticular wax crystals (glaucousness) on 10 species. Glaucous species had a characteristic wax composition dominated by very-long-chain aldehydes. The ancestor of the milkweeds was probably a glaucous species, from which there have been several independent origins of glabrous and pubescent types. Trichomes and wax crystals showed negatively correlated evolution, with both surface types showing an affinity for arid habitats. Pubescent and glaucous milkweeds had a higher maximum photosynthetic rate and lower stomatal density than glabrous species. Pubescent and glaucous leaf surfaces impeded settling behavior of monarch caterpillars and aphids compared with glabrous species, although surface types did not show consistent differentiation in secondary chemistry. We hypothesize that pubescence and glaucousness have evolved as alternative mechanisms with similar functions. The glaucous type, however, appears to be ancestral, lost repeatedly, and never regained; we propose that trichomes are a more evolutionarily titratable strategy.

Geographic variation in apparent competition between native and invasive Phragmites australis.

PubMed

Bhattarai, Ganesh P; Meyerson, Laura A; Cronin, James T

2017-02-01

Apparent competition, the negative interaction between species mediated by shared natural enemies, is thought to play an important role in shaping the structure and dynamics of natural communities. However, its importance in driving species invasions, and whether the strength of this indirect interaction varies across the latitudinal range of the invasion, has not been fully explored. We performed replicated field experiments at four sites spanning 900 km along the Atlantic Coast of the United States to assess the presence and strength of apparent competition between sympatric native and invasive lineages of Phragmites australis. Four herbivore guilds were considered: stem-feeders, leaf-miners, leaf-chewers and aphids. We also tested the hypothesis that the strength of this interaction declines with increasing latitude. Within each site, native and invasive plants of P. australis were cross-transplanted between co-occurring native and invasive patches in the same marsh habitat and herbivore damage was evaluated at the end of the growing season. Apparent competition was evident for both lineages and involved all but the leaf-chewer guild. For native plants, total aphids per plant was 296% higher and the incidence of stem-feeding and leaf-mining herbivores was 34% and 221% higher, respectively, when transplanted into invasive than native patches. These data suggest that invasive P. australis has a negative effect on native P. australis via apparent competition. Averaged among herbivore types, the indirect effects of the invasive lineage on the native lineage was 57% higher than the reverse situation, suggesting that apparent competition was asymmetric. We also found that the strength of apparent competition acting against the native lineage was comparable to the benefits to the invasive lineage from enemy release (i.e., proportionately lower mean herbivory of the invasive relative to the native taxa). Finally, we found the first evidence that the strength of apparent competition acting against the native lineage (from stem-feeders only) decreased with increasing latitude. These results suggest that not only could apparent competition be of tantamount importance to enemy release in enhancing the establishment and spread of invasive taxa, but also that these indirect and direct herbivore effects could vary over the invasion range. © 2016 by the Ecological Society of America.

Tripartite Interactions of Barley Yellow Dwarf Virus, Sitobion avenae and Wheat Varieties

PubMed Central

Liu, Xiao-Feng; Hu, Xiang-Shun; Keller, Mike A.; Zhao, Hui-Yan; Wu, Yun-Feng; Liu, Tong-Xian

2014-01-01

The tripartite interactions in a pathosystem involving wheat (Triticum aestivum L.), the Barley yellow dwarf virus (BYDV), and the BYDV vector aphid Sitobion avenae were studied under field conditions to determine the impact of these interactions on aphid populations, virus pathology and grain yield. Wheat varietal resistance to BYDV and aphids varied among the three wheat varieties studied over two consecutive years. The results demonstrated that (1) aphid peak number (APN) in the aphid + BYDV (viruliferous aphid) treatment was greater and occurred earlier than that in the non-viruliferous aphid treatment. The APN and the area under the curve of population dynamics (AUC) on a S. avenae-resistant variety 98-10-30 was significantly lower than on two aphid-susceptible varieties Tam200(13)G and Xiaoyan6. (2) The production of alatae (PA) was greater on the variety 98-10-30 than on the other varieties, and PA was greater in the aphid + BYDV treatment on 98-10-30 than in the non-viruliferous aphid treatment, but this trend was reversed on Tam200(13)G and Xiaoyan6. (3) The BYDV disease incidence (DIC) on the variety 98-10-30 was greater than that on the other two varieties in 2012, and the disease index (DID) on Tam200(13)G was lower than on the other varieties in the aphid + BYDV and BYDV treatments in 2012, but not in 2011 when aphid vector numbers were generally lower. (4) Yield loss in the aphid + BYDV treatment tended to be greater than that in the aphid or BYDV alone treatments across varieties and years. We suggested that aphid population development and BYDV transmission tend to promote each other under field conditions. The aphids + BYDV treatment caused greater yield reductions than non-viruliferous aphids or virus treatment. Wheat varietal resistance in 98-10-30 affects the aphid dispersal, virus transmission and wheat yield loss though inhibits aphid populations from increasing. PMID:25184214

The whole genome sequence assembly of the soybean aphid, Aphis glycines

USDA-ARS?s Scientific Manuscript database

Aphids are emerging as model organisms for both basic and applied research. Of the 5,000 estimated species, only two aphids have published whole genome sequences: the pea aphid Acyrthosiphon pisum, and the Russian wheat aphid, Diuraphis noxia. The soybean aphid (Aphis glycines) is an extreme special...

Volatile communication in plant-aphid interactions.

PubMed

de Vos, Martin; Jander, Georg

2010-08-01

Volatile communication plays an important role in mediating the interactions between plants, aphids, and other organisms in the environment. In response to aphid infestation, many plants initiate indirect defenses through the release of volatiles that attract ladybugs, parasitoid wasps, and other aphid-consuming predators. Aphid-induced volatile release in the model plant Arabidopsis thaliana requires the jasmonate signaling pathway. Volatile release is also induced by infection with aphid-transmitted viruses. Consistent with mathematical models of optimal transmission, viruses that are acquired rapidly by aphids induce volatile release to attract migratory aphids, but discourage long-term aphid feeding. Although the ecology of these interactions is well-studied, further research is needed to identify the molecular basis of aphid-induced and virus-induced changes in plant volatile release. Copyright 2010 Elsevier Ltd. All rights reserved.

Assessment of RapidEye vegetation indices for estimation of leaf area index and biomass in corn and soybean crops

NASA Astrophysics Data System (ADS)

Kross, Angela; McNairn, Heather; Lapen, David; Sunohara, Mark; Champagne, Catherine

2015-02-01

Leaf area index (LAI) and biomass are important indicators of crop development and the availability of this information during the growing season can support farmer decision making processes. This study demonstrates the applicability of RapidEye multi-spectral data for estimation of LAI and biomass of two crop types (corn and soybean) with different canopy structure, leaf structure and photosynthetic pathways. The advantages of Rapid Eye in terms of increased temporal resolution (∼daily), high spatial resolution (∼5 m) and enhanced spectral information (includes red-edge band) are explored as an individual sensor and as part of a multi-sensor constellation. Seven vegetation indices based on combinations of reflectance in green, red, red-edge and near infrared bands were derived from RapidEye imagery between 2011 and 2013. LAI and biomass data were collected during the same period for calibration and validation of the relationships between vegetation indices and LAI and dry above-ground biomass. Most indices showed sensitivity to LAI from emergence to 8 m2/m2. The normalized difference vegetation index (NDVI), the red-edge NDVI and the green NDVI were insensitive to crop type and had coefficients of variations (CV) ranging between 19 and 27%; and coefficients of determination ranging between 86 and 88%. The NDVI performed best for the estimation of dry leaf biomass (CV = 27% and r2 = 090) and was also insensitive to crop type. The red-edge indices did not show any significant improvement in LAI and biomass estimation over traditional multispectral indices. Cumulative vegetation indices showed strong performance for estimation of total dry above-ground biomass, especially for corn (CV ≤ 20%). This study demonstrated that continuous crop LAI monitoring over time and space at the field level can be achieved using a combination of RapidEye, Landsat and SPOT data and sensor-dependant best-fit functions. This approach eliminates/reduces the need for reflectance resampling, VIs inter-calibration and spatial resampling.

Absence of plant uptake and translocation of polybrominated biphenyls (PBBs).

PubMed

Chou, S F; Jacobs, L W; Penner, D; Tiedje, J M

1978-04-01

Studies of polybrominated biphenyl (PBB) uptake by plants have been conducted in hydroponic solutions and in greenhouse experiments with soil. Autoradiograms of corn and soybean seedlings grown in hydroponic solutions showed no translocation of 14C-PBB from 14C-PBB-treated solutions to plant tops or within the leaf from 14C-PBB-treated spots on the upper leaf surface. A significant portion of the 14C-PBB associated with the roots was removed when the roots were dipped in acetone. Three root crops (radishes, carrots, and onions) were grown in two soils, each treated with a mixture of FireMaster BP-6 (PBB) and 14C-PBB to achieve final concentrations of 100 ppm and 100 ppb. All roots showed more PBB when grown in the soil with the lower clay and organic matter content than they did when grown in the soil with more clay and organic matter. In the latter soil (clay loam) no PBB was detected in any roots from the 100 ppb treatment. More PBB was associated with roots of carrot than of radish or onion. Corn leaf whorls containing dust from a PBB contamination soil and washed radishes from a heavily contaminated garden showed no PBB.

Evaluation and interpretation of Thematic Mapper ratios in equations for estimating corn growth parameters

NASA Technical Reports Server (NTRS)

Dardner, B. R.; Blad, B. L.; Thompson, D. R.; Henderson, K. E.

1985-01-01

Reflectance and agronomic Thematic Mapper (TM) data were analyzed to determine possible data transformations for evaluating several plant parameters of corn. Three transformation forms were used: the ratio of two TM bands, logarithms of two-band ratios, and normalized differences of two bands. Normalized differences and logarithms of two-band ratios responsed similarly in the equations for estimating the plant growth parameters evaluated in this study. Two-term equations were required to obtain the maximum predictability of percent ground cover, canopy moisture content, and total wet phytomass. Standard error of estimate values were 15-26 percent lower for two-term estimates of these parameters than for one-term estimates. The terms log(TM4/TM2) and (TM4/TM5) produced the maximum predictability for leaf area and dry green leaf weight, respectively. The middle infrared bands TM5 and TM7 are essential for maximizing predictability for all measured plant parameters except leaf area index. The estimating models were evaluated over bare soil to discriminate between equations which are statistically similar. Qualitative interpretations of the resulting prediction equations are consistent with general agronomic and remote sensing theory.

AphidBase: A centralized bioinformatic resource for annotation of the pea aphid genome

PubMed Central

Legeai, Fabrice; Shigenobu, Shuji; Gauthier, Jean-Pierre; Colbourne, John; Rispe, Claude; Collin, Olivier; Richards, Stephen; Wilson, Alex C. C.; Tagu, Denis

2015-01-01

AphidBase is a centralized bioinformatic resource that was developed to facilitate community annotation of the pea aphid genome by the International Aphid Genomics Consortium (IAGC). The AphidBase Information System designed to organize and distribute genomic data and annotations for a large international community was constructed using open source software tools from the Generic Model Organism Database (GMOD). The system includes Apollo and GBrowse utilities as well as a wiki, blast search capabilities and a full text search engine. AphidBase strongly supported community cooperation and coordination in the curation of gene models during community annotation of the pea aphid genome. AphidBase can be accessed at http://www.aphidbase.com. PMID:20482635

A peptide that binds the pea aphid gut impedes entry of Pea enation mosaic virus into the aphid hemocoel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Sijun, E-mail: sliu@iastate.ed; Sivakumar, S., E-mail: sivaento@iastate.ed; Sparks, Wendy O., E-mail: wosparks@iastate.ed

2010-05-25

Development of ways to block virus transmission by aphids could lead to novel and broad-spectrum means of controlling plant viruses. Viruses in the Luteoviridae enhanced are obligately transmitted by aphids in a persistent manner that requires virion accumulation in the aphid hemocoel. To enter the hemocoel, the virion must bind and traverse the aphid gut epithelium. By screening a phage display library, we identified a 12-residue gut binding peptide (GBP3.1) that binds to the midgut and hindgut of the pea aphid Acyrthosiphon pisum. Binding was confirmed by labeling the aphid gut with a GBP3.1-green fluorescent protein fusion. GBP3.1 reduced uptakemore » of Pea enation mosaic virus (Luteoviridae) from the pea aphid gut into the hemocoel. GBP3.1 also bound to the gut epithelia of the green peach aphid and the soybean aphid. These results suggest a novel strategy for inhibiting plant virus transmission by at least three major aphid pest species.« less

Aphid performance changes with plant defense mediated by Cucumber mosaic virus titer.

PubMed

Shi, Xiaobin; Gao, Yang; Yan, Shuo; Tang, Xin; Zhou, Xuguo; Zhang, Deyong; Liu, Yong

2016-04-22

Cucumber mosaic virus (CMV) causes appreciable losses in vegetables, ornamentals and agricultural crops. The green peach aphid, Myzus persicae Sulzer (Aphididae) is one of the most efficient vectors for CMV. The transmission ecology of aphid-vectored CMV has been well investigated. However, the detailed description of the dynamic change in the plant-CMV-aphid interaction associated with plant defense and virus epidemics is not well known. In this report, we investigated the relationship of virus titer with plant defense of salicylic acid (SA) and jasmonic acid (JA) during the different infection time and their interaction with aphids in CMV-infected tobacco plants. Our results showed that aphid performance changed with virus titer and plant defense on CMV-inoculated plants. At first, plant defense was low and aphid number increased gradually. The plant defense of SA signaling pathway was induced when virus titer was at a high level, and aphid performance was correspondingly reduced. Additionally, the winged aphids were increased. Our results showed that aphid performance was reduced due to the induced plant defense mediated by Cucumber mosaic virus titer. Additionally, some wingless aphids became to winged aphids. In this way CMV could be transmitted with the migration of winged aphids. We should take measures to prevent aphids in the early stage of their occurrence in the field to prevent virus outbreak.

The efficacy of a novel insecticidal protein, Allium sativum leaf lectin (ASAL), against homopteran insects monitored in transgenic tobacco.

PubMed

Dutta, Indrajit; Saha, Prasenjit; Majumder, Pralay; Sarkar, Anindya; Chakraborti, Dipankar; Banerjee, Santanu; Das, Sampa

2005-11-01

The homopteran group of polyphagous sucking insect pests causes severe damage to many economically important plants including tobacco. Allium sativum leaf lectin (ASAL), a mannose-binding 25-kDa homodimeric protein, has recently been found to be antagonistic to various sucking insects in the homopteran group through artificial diet bioassay experiments. The present study describes, for the first time, the expression of the ASAL coding sequence under the control of the cauliflower mosaic virus (CaMV) 35S promoter in tobacco by Agrobacterium-mediated transformation technology. Molecular analyses demonstrated the integration of the chimeric ASAL gene in tobacco and its inheritance in the progeny plants. Western blot analysis followed by enzyme-linked immunosorbent assay (ELISA) determined the level of ASAL expression in different lines to be in the range of approximately 0.68%-2% of total soluble plant protein. An in planta bioassay conducted with Myzus persicae, peach potato aphid (a devastating pest of tobacco and many other important plants), revealed that the percentage of insect survival decreased significantly to 16%-20% in T0 plants and T1 progeny, whilst approximately 75% of insects survived on untransformed tobacco plants after 144 h of incubation. Ligand analyses of insect brush border membrane vesicle receptors and expressed ASAL in transgenic tobacco showed that the expressed ASAL binds to the aphid gut receptor in the same manner as native ASAL, pointing to the fact that ASAL maintains the biochemical characteristics even in the transgenic situation. These findings in a model plant open up the possibility of expressing the novel ASAL gene in a wide range of crop plants susceptible to various sap-sucking insects.

Aphid Alarm Pheromone as a Cue for Ants to Locate Aphid Partners

PubMed Central

Verheggen, François J.; Diez, Lise; Sablon, Ludovic; Fischer, Christophe; Bartram, Stefan; Haubruge, Eric; Detrain, Claire

2012-01-01

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to provide additional information on the use of Aphis fabae alarm pheromone, i.e. (E)-β-farnesene (EβF), by ant scouts. The perception and behavioral impact of EβF on Lasius niger were investigated using electroantennography and two bio-assays measuring their attraction and orientation towards aphid semiochemicals. Pronounced electrical depolarizations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone, while other sesquiterpenes elicited weak or no responses. L. niger scouts were significantly attracted toward EβF in a four-arm olfactometer, as well as in an two-choice bioassay. These laboratory results suggest for the first time that low amounts of aphid alarm pheromone can be used by L. niger scouts as a cue indicating the presence of aphid colonies and could therefore mediate the aphid-ant partnership in the field. PMID:22870255

The Green Lacewing, Chrysoperla carnea: Preference between Lettuce Aphids, Nasonovia ribisnigri, and Western Flower Thrips, Frankliniella occidentalis

PubMed Central

Shrestha, Govinda; Enkegaard, Annie

2013-01-01

This study investigated the prey preference of 3rd instar green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), between western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and lettuce aphids, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) in laboratory experiments at 25 ± 1° C and 70 ± 5% RH with five prey ratios (10 aphids:80 thrips, 25 aphids:65 thrips, 45 aphids:45 thrips, 65 aphids:25 thrips, and 80 aphids:10 thrips). Third instar C. carnea larvae readily preyed upon both thrips and aphids, with thrips mortality varying between 40 and 90%, and aphid mortality between 52 and 98%. Chrysoperla carnea had a significant preference for N. ribisnigri at two ratios (10 aphids:80 thrips, 65 aphids:25 thrips), but no preference for either prey at the other ratios. There was no significant linear relationship between preference index and prey ratio, but a significant intercept of the linear regression indicated an overall preference of C. carnea for aphids with a value of 0.651 ± 0.054. The possible implications of these findings for control of N. ribisnigri and F. occidentalis by C. carnea are discussed. PMID:24205864

The green lacewing, Chrysoperla carnea: preference between lettuce aphids, Nasonovia ribisnigri, and Western flower thrips, Frankliniella occidentalis.

PubMed

Shrestha, Govinda; Enkegaard, Annie

2013-01-01

This study investigated the prey preference of 3(rd) instar green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), between western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and lettuce aphids, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) in laboratory experiments at 25 ± 1° C and 70 ± 5% RH with five prey ratios (10 aphids:80 thrips, 25 aphids:65 thrips, 45 aphids:45 thrips, 65 aphids:25 thrips, and 80 aphids:10 thrips). Third instar C. carnea larvae readily preyed upon both thrips and aphids, with thrips mortality varying between 40 and 90%, and aphid mortality between 52 and 98%. Chrysoperla carnea had a significant preference for N. ribisnigri at two ratios (10 aphids:80 thrips, 65 aphids:25 thrips), but no preference for either prey at the other ratios. There was no significant linear relationship between preference index and prey ratio, but a significant intercept of the linear regression indicated an overall preference of C. carnea for aphids with a value of 0.651 ± 0.054. The possible implications of these findings for control of N. ribisnigri and F. occidentalis by C. carnea are discussed.

Leaf bidirectional reflectance and transmittance in corn and soybean

NASA Technical Reports Server (NTRS)

Walter-Shea, E. A.; Norman, J. M.; Blad, B. L.

1989-01-01

Bidirectional optical properties of leaves must be adequately characterized to develop comprehensive and reliably predictive canopy radiative-transfer models. Directional reflectance and transmittance factors of individual corn and soybean leaves were measured at source incidence angles (SIAs) 20, 45, and 70 deg and numerous view angles in the visible and NIR. Bidirectional reflectance distributions changed with increasing SIA, with forward scattering most pronounced at 70 deg. Directional-hemispherical reflectance generally increased and transmittance decreased with increased SIA. Directional-hemispherical reflectance factors were higher and transmittances were lower than the nadir-viewed reflectance component.

Host Plants Indirectly Influence Plant Virus Transmission by Altering Gut Cysteine Protease Activity of Aphid Vectors*

PubMed Central

Pinheiro, Patricia V.; Ghanim, Murad; Rebelo, Ana Rita; Santos, Rogerio S.; Orsburn, Benjamin C.; Gray, Stewart

2017-01-01

The green peach aphid, Myzus persicae, is a vector of the Potato leafroll virus (PLRV, Luteoviridae), transmitted exclusively by aphids in a circulative manner. PLRV transmission efficiency was significantly reduced when a clonal lineage of M. persicae was reared on turnip as compared with the weed physalis, and this was a transient effect caused by a host-switch response. A trend of higher PLRV titer in physalis-reared aphids as compared with turnip-reared aphids was observed at 24 h and 72 h after virus acquisition. The major difference in the proteomes of these aphids was the up-regulation of predicted lysosomal enzymes, in particular the cysteine protease cathepsin B (cathB), in aphids reared on turnip. The aphid midgut is the site of PLRV acquisition, and cathB and PLRV localization were starkly different in midguts of the aphids reared on the two host plants. In viruliferous aphids that were reared on turnip, there was near complete colocalization of cathB and PLRV at the cell membranes, which was not observed in physalis-reared aphids. Chemical inhibition of cathB restored the ability of aphids reared on turnip to transmit PLRV in a dose-dependent manner, showing that the increased activity of cathB and other cysteine proteases at the cell membrane indirectly decreased virus transmission by aphids. Understanding how the host plant influences virus transmission by aphids is critical for growers to manage the spread of virus among field crops. PMID:27932519

Impacts of transgenic poplar-cotton agro-ecosystems upon target pests and non-target insects under field conditions.

PubMed

Zhang, D J; Liu, J X; Lu, Z Y; Li, C L; Comada, E; Yang, M S

2015-07-27

Poplar-cotton agro-ecosystems are the main agricultural planting modes of cotton fields in China. With increasing acres devoted to transgenic insect-resistant poplar and transgenic insect-resistant cotton, studies examining the effects of transgenic plants on target and non-target insects become increasingly important. We systematically surveyed populations of both target pests and non-target insects for 4 different combinations of poplar-cotton eco-systems over 3 years. Transgenic Bt cotton strongly resisted the target insects Fall webworm moth [Hyphantria cunea (Drury)], Sylepta derogata Fabrieius, and American bollworm (Heliothis armigera), but no clear impact on non-target insect cotton aphids (Aphis gossypii). Importantly, intercrops containing transgenic Pb29 poplar significantly increased the inhibitory effects of Bt cotton on Fall webworm moth in ecosystem IV. Highly resistant Pb29 poplar reduced populations of the target pests Grnsonoma minutara Hubner and non-target insect poplar leaf aphid (Chaitophorus po-pulialbae), while Fall webworm moth populations were unaffected. We determined the effects of Bt toxin from transgenic poplar and cotton on target and non-target pests in different ecosystems of cotton-poplar intercrops and identified the synergistic effects of such combinations toward both target and non-target insects.

Weather Effects on Crop Diseases in Eastern Germany

NASA Astrophysics Data System (ADS)

Conradt, Tobias

2017-04-01

Since the 1970s there are several long-term monitoring programmes for plant diseases and pests in Germany. Within the framework of a national research project, some otherwise confidential databases comprising 77 111 samples from numerous sites accross Eastern Germany could be accessed and analysed. The pest data covered leaf rust (Puccinia triticina) and powdery mildew (Blumeria graminis) in winter wheat, aphids (Aphididae, four genera) on wheat and other cereal crops, late blight (Phytophthora infestans) in potatoes, and pollen beetles (Brassicogethes aeneus) on rape. These data were complemented by daily weather observations from the German Weather Service (DWD). In a first step, Pearson correlations between weather variables and pest frequencies were calculated for seasonal time periods of different start months and durations and ordered into so-called correlograms. This revealed principal weather effects on disease spread - e. g. that wind is favourable for mildew throughout the year or that rape pollen beetles like it warm, but not during wintertime. Secondly, the pest frequency samples were found to resemble gamma distributions, and a generalised linear model was fitted to describe their parameter shift depending on end-of-winter temperatures for aphids on cereals. The method clearly shows potential for systematic pest risk assessments regarding climate change.

Field and laboratory evaluations of soybean lines against soybean aphid (Hemiptera: Aphididae).

PubMed

Hesler, Louis S; Prischmann, Deirdre A; Dashiell, Kenton E

2012-04-01

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a major pest of soybean, Glycine max (L.). Merr., that significantly reduces yield in northern production areas of North America. Insecticides are widely used to control soybean aphid outbreaks, but efforts are underway to develop host plant resistance as an effective alternative management strategy. Here, previously identified resistant lines were evaluated in laboratory tests against field-collected populations of soybean aphid and in field-plot tests over 2 yr in South Dakota. Six lines previously identified with resistance to soybean aphid--Jackson, Dowling, K1639, Cobb, Palmetto and Sennari--were resistant in this study, but relatively high aphid counts on Tie-feng 8 in field plots contrasted with its previously reported resistance. Bhart-PI 165989 showed resistance in one of two laboratory tests, but it had relatively large aphid infestations in both years of field tests. Intermediate levels of soybean aphid occurred in field plots on lines previously shown to have strong (Sugao Zairai, PI 230977, and D75-10169) or moderate resistance to soybean aphid (G93-9223, Bragg, Braxton, and Tracy-M). Sugao Zairai also failed to have a significant proportion of resistant plants in two laboratory tests against aphids field-collected in 2008, but it was resistant in laboratory tests with aphids collected in 2002, 2005, and 2006. Overall, results showed that lines with Rag (i.e., Jackson) or Rag1 gene (i.e., Dowling) had low aphid numbers, whereas lines with Rag2 (i.e., Sugao Zairai, Sennari) had mixed results. Collectively, responses of soybean aphid populations in laboratory and field tests in 2008 resembled a virulence pattern reported previously for biotype 3 soybean aphids, but virulence in soybean aphid populations was variable and dynamic over years of the study. These results, coupled with previous reports of biotypes virulent to Rag1, suggest that deployment of lines with a single aphid-resistance gene is limited for soybean aphid management, and that deployment strategies relying on multiple resistance genes may be needed to effectively use plant resistance against soybean aphid.

Spatial and Temporal Dynamics of Aphids (Hemiptera: Aphididae) in the Columbia Basin and Northeastern Oregon.

PubMed

Klein, Mathew L; Rondon, Silvia I; Walenta, Darrin L; Zeb, Qamar; Murphy, Alexzandra F

2017-08-01

Aphid species, such as the potato aphid, Macrosiphum euphorbiae Thomas, and the green peach aphid, Myzus persicae Sulzer, are routinely considered the most important pests of potatoes. Potato aphid, green peach aphid, and more recently, other aphids such as the bird cherry-oat aphid Rhopalosiphum padi L. have been identified as vectors of multiple plant pathogenic viruses in potatoes. Since 2006, an area-wide trapping network consisting of ∼60 sites was developed through collaboration between researchers, extension faculty, and stakeholders, to monitor aphid populations in the Columbia Basin of Oregon (Umatilla and Morrow counties) and in northeastern Oregon (Union and Baker counties). Over a 9-yr period (2006 to 2014), aphid specimens were collected weekly using yellow bucket traps and specimens were then identified and counted to determine population levels during the growing season (May-September). Thus, aphid population data were compiled and subjected to spatial and temporal distribution analysis. Weather data, obtained from an established network of weather stations located in the monitoring areas, were used in a nonparametric multiplicative regression analysis to determine which abiotic variables may impact aphid populations. Weather conditions were characterized using confidence intervals (CIs) established based on weather data from 1999 to 2005 for each environmental variable. Aphid populations were found to have a heterogeneous distribution in most years; a few sites had high aphid populations while low numbers were observed at most sites; aphids were also found to correlate with several abiotic variables, namely, elevation, previous season temperature, and previous season dew point. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Armet is an effector protein mediating aphid-plant interactions.

PubMed

Wang, Wei; Dai, Huaien; Zhang, Yi; Chandrasekar, Raman; Luo, Lan; Hiromasa, Yasuaki; Sheng, Changzhong; Peng, Gongxin; Chen, Shaoliang; Tomich, John M; Reese, John; Edwards, Owain; Kang, Le; Reeck, Gerald; Cui, Feng

2015-05-01

Aphid saliva is predicted to contain proteins that modulate plant defenses and facilitate feeding. Armet is a well-characterized bifunctional protein in mammalian systems. Here we report a new role of Armet, namely as an effector protein in the pea aphid, Acyrthosiphon pisum. Pea aphid Armet's physical and chemical properties and its intracellular role are comparable to those reported for mammalian Armets. Uniquely, we detected Armet in aphid watery saliva and in the phloem sap of fava beans fed on by aphids. Armet's transcript level is several times higher in the salivary gland when aphids feed on bean plants than when they feed on an artificial diet. Knockdown of the Armet transcript by RNA interference disturbs aphid feeding behavior on fava beans measured by the electrical penetration graph technique and leads to a shortened life span. Inoculation of pea aphid Armet protein into tobacco leaves induced a transcriptional response that included pathogen-responsive genes. The data suggest that Armet is an effector protein mediating aphid-plant interactions. © FASEB.

Proposal to conserve the name Bipolaris against Cochliobolus (Ascomycota: Pleosporales: Pleosporaceae)

USDA-ARS?s Scientific Manuscript database

The fungal genera Bipolaris Shoemaker and Cochliobolus Drechsler have been applied to economically important plant pathogens causing diseases of cereal crops worldwide, especially southern corn leaf blight. There are major accounts of these genera including those incorporating molecular phylogenetic...

[Sowing date of corn in semiarid region of Jilin Province, Northeast China in adapting to climate change].

PubMed

Jin, Ying-Hua; Zhou, Dao-Wei; Qin, Li-Jie

2012-10-01

Under the background of global climate change, the climate in semiarid region of west Jilin Province changed greatly, producing a profound impact on the corn production in this region. In this study, the corn seeds were under three treatments (accelerating germination at 10 and 25 degrees C, and dry seeds), and a field experiment with early sowing and traditional sowing was conducted in 2008 to investigate the effects of early sowing these seeds on the seedling emergence, growth, and yield, and compare the effects of early sowing and traditional sowing dates on the corn production and yield. In 1961-2010, the first day of the growth season of corn in semiarid region of west Jilin Province was advanced, the air temperature increased significantly, and the precipitation displayed a decreasing trend. At present, the corn sowing date in this region could be advanced to 11th, April. Accelerating germination at 10 degrees C, directly sowing dry seeds, and bed-irrigation sowing all benefited the seedling emergence and cold resistance of early-sown seeds, and the corn plant height and leaf area under early sowing were significantly higher, with the yield increased by 35% - 48%, compared with those under traditional sowing.

Host Plants Indirectly Influence Plant Virus Transmission by Altering Gut Cysteine Protease Activity of Aphid Vectors.

PubMed

Pinheiro, Patricia V; Ghanim, Murad; Alexander, Mariko; Rebelo, Ana Rita; Santos, Rogerio S; Orsburn, Benjamin C; Gray, Stewart; Cilia, Michelle

2017-04-01

The green peach aphid, Myzus persicae , is a vector of the Potato leafroll virus (PLRV, Luteoviridae), transmitted exclusively by aphids in a circulative manner. PLRV transmission efficiency was significantly reduced when a clonal lineage of M. persicae was reared on turnip as compared with the weed physalis, and this was a transient effect caused by a host-switch response. A trend of higher PLRV titer in physalis-reared aphids as compared with turnip-reared aphids was observed at 24 h and 72 h after virus acquisition. The major difference in the proteomes of these aphids was the up-regulation of predicted lysosomal enzymes, in particular the cysteine protease cathepsin B (cathB), in aphids reared on turnip. The aphid midgut is the site of PLRV acquisition, and cathB and PLRV localization were starkly different in midguts of the aphids reared on the two host plants. In viruliferous aphids that were reared on turnip, there was near complete colocalization of cathB and PLRV at the cell membranes, which was not observed in physalis-reared aphids. Chemical inhibition of cathB restored the ability of aphids reared on turnip to transmit PLRV in a dose-dependent manner, showing that the increased activity of cathB and other cysteine proteases at the cell membrane indirectly decreased virus transmission by aphids. Understanding how the host plant influences virus transmission by aphids is critical for growers to manage the spread of virus among field crops. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Ants Learn Aphid Species as Mutualistic Partners: Is the Learning Behavior Species-Specific?

PubMed

Hayashi, Masayuki; Nakamuta, Kiyoshi; Nomura, Masashi

2015-12-01

In ant-aphid associations, many aphid species provide ants with honeydew and are tended by ants, whereas others are never tended and are frequently preyed upon by ants. In these relationships, ants must have the ability to discriminate among aphid species, with mutualistic aphids being accepted as partners rather than prey. Although ants reportedly use cuticular hydrocarbons (CHCs) of aphids to differentiate between mutualistic and non-mutualistic species, it is unclear whether the ability to recognize mutualistic aphid species as partners is innate or involves learning. Therefore, we tested whether aphid recognition by ants depends on learning, and whether the learning behavior is species-specific. When workers of the ant Tetramorium tsushimae had previously tended the cowpea aphid, Aphis craccivora, they were less aggressive toward this species. In addition, ants also reduced their aggressiveness toward another mutualistic aphid species, Aphis fabae, after tending A. craccivora, whereas ants remained aggressive toward the non-mutualistic aphid, Acyrthosiphon pisum, regardless of whether or not they had previous experience in tending A. craccivora. When ants were offered glass dummies treated with CHCs of these aphid species, ants that had tended A. craccivora displayed reduced aggression toward CHCs of A. craccivora and A. fabae. Chemical analyses showed the similarity of the CHC profiles between A. craccivora and A. fabae but not with A. pisum. These results suggest that aphid recognition of ants involves learning, and that the learning behavior may not be species-specific because of the similarity of CHCs between different aphid species with which they form mutualisms.

Low bacterial community diversity in two introduced aphid pests revealed with 16S rRNA amplicon sequencing

PubMed Central

Ortiz-Martínez, Sebastían; Silva, Andrea X.; Lavandero, Blas

2018-01-01

Bacterial endosymbionts that produce important phenotypic effects on their hosts are common among plant sap-sucking insects. Aphids have become a model system of insect-symbiont interactions. However, endosymbiont research has focused on a few aphid species, making it necessary to make greater efforts to other aphid species through different regions, in order to have a better understanding of the role of endosymbionts in aphids as a group. Aphid endosymbionts have frequently been studied by PCR-based techniques, using species-specific primers, nevertheless this approach may omit other non-target bacteria cohabiting a particular host species. Advances in high-throughput sequencing technologies are complementing our knowledge of microbial communities by allowing us the study of whole microbiome of different organisms. We used a 16S rRNA amplicon sequencing approach to study the microbiome of aphids in order to describe the bacterial community diversity in introduced populations of the cereal aphids, Sitobion avenae and Rhopalosiphum padi in Chile (South America). An absence of secondary endosymbionts and two common secondary endosymbionts of aphids were found in the aphids R. padi and S. avenae, respectively. Of those endosymbionts, Regiella insecticola was the dominant secondary endosymbiont among the aphid samples. In addition, the presence of a previously unidentified bacterial species closely related to a phytopathogenic Pseudomonad species was detected. We discuss these results in relation to the bacterial endosymbiont diversity found in other regions of the native and introduced range of S. avenae and R. padi. A similar endosymbiont diversity has been reported for both aphid species in their native range. However, variation in the secondary endosymbiont infection could be observed among the introduced and native populations of the aphid S. avenae, indicating that aphid-endosymbiont associations can vary across the geographic range of an aphid species. In addition, we discuss the potential role of aphids as vectors and/or alternative hosts of phytopathogenic bacteria. PMID:29761046

Specialization of bacterial endosymbionts that protect aphids from parasitoids

USDA-ARS?s Scientific Manuscript database

Infection by the bacterial endosymbiont HAMILTONELLA DEFENSA is capable of protecting the pea aphid from parasitism by APHIDIUS ERVI and the black bean aphid from parasitism by LYSIPHLEBUS FABARUM. Here we investigate protection of a third aphid species, the cowpea aphid, APHIS CRACCIVORA, from 4 p...

National Plant Diagnostic Network, Taxonomic training videos: Introduction to Aphids - Part 2

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on important subject areas for aphid regulatory issues. Here the subject of aphids as they relate to disease transmission, biology, identification, and pathways is addressed. Aphid topi...

Adsorption Mechanisms of Dodecylbenzene Sulfonic Acid by Corn Straw and Poplar Leaf Biochars

PubMed Central

Zhao, Nan; Yang, Xixiang; Zhang, Jing; Zhu, Ling; Lv, Yizhong

2017-01-01

Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer–Emmett–Teller N2 surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA). The microscopic adsorption mechanisms were studied by using infrared spectra, 13C-nuclear magnetic resonance spectra, and electron spin resonance spectra. The surface area and pore volume of C700 (375.89 m2/g and 0.2302 cm3/g) were the highest among all samples. Elemental analysis results showed that corn straw biochars had a higher aromaticity and carbon to nitrogen (C/N) ratio than the poplar leaf biochars. High temperature caused the increase of carbon content and the decrease of oxygen content, which also gave the biochars a higher adsorption rate. Pseudo-second order kinetic provided a better fit with the experimental data. Adsorption isotherm experiments showed that the adsorption isotherm of C300 fit the linear model. For other biochars, the adsorption isotherms fitted Langmuir model. Biochars with high temperatures exhibited enhanced adsorption capacity compared with ones at low temperatures. The qmax values of biochars to DBSA followed the order of P700 > C700 > P300. The adsorption mechanisms were complex, including partition, anion exchange, the formation of H bonds, covalent bonds, and charge transfer. The adsorption by covalent bonding might be the key mechanism determining the adsorption capacity of P700. PMID:28937637

Adsorption Mechanisms of Dodecylbenzene Sulfonic Acid by Corn Straw and Poplar Leaf Biochars.

PubMed

Zhao, Nan; Yang, Xixiang; Zhang, Jing; Zhu, Ling; Lv, Yizhong

2017-09-22

Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N₂ surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA). The microscopic adsorption mechanisms were studied by using infrared spectra, 13 C-nuclear magnetic resonance spectra, and electron spin resonance spectra. The surface area and pore volume of C700 (375.89 m²/g and 0.2302 cm³/g) were the highest among all samples. Elemental analysis results showed that corn straw biochars had a higher aromaticity and carbon to nitrogen (C/N) ratio than the poplar leaf biochars. High temperature caused the increase of carbon content and the decrease of oxygen content, which also gave the biochars a higher adsorption rate. Pseudo-second order kinetic provided a better fit with the experimental data. Adsorption isotherm experiments showed that the adsorption isotherm of C300 fit the linear model. For other biochars, the adsorption isotherms fitted Langmuir model. Biochars with high temperatures exhibited enhanced adsorption capacity compared with ones at low temperatures. The q max values of biochars to DBSA followed the order of P700 > C700 > P300. The adsorption mechanisms were complex, including partition, anion exchange, the formation of H bonds, covalent bonds, and charge transfer. The adsorption by covalent bonding might be the key mechanism determining the adsorption capacity of P700.

Categorizing sugarcane cultivar resistance to the sugarcane aphid and yellow sugarcane aphid (Hemiptera: Aphididae)

USDA-ARS?s Scientific Manuscript database

Sugarcane in the U.S. is chiefly colonized by two aphid species, the sugarcane aphid, Melanaphis sacchari, and the yellow sugarcane aphid, Sipha flava, which vector economically important viruses of the crop. Greenhouse experiments were conducted to categorize commercial sugarcane cultivars for the...

Arabidopsis thaliana—Aphid Interaction

PubMed Central

Louis, Joe; Singh, Vijay; Shah, Jyoti

2012-01-01

Aphids are important pests of plants that use their stylets to tap into the sieve elements to consume phloem sap. Besides the removal of photosynthates, aphid infestation also alters source-sink patterns. Most aphids also vector viral diseases. In this chapter, we will summarize on recent significant findings in plant-aphid interaction, and how studies involving Arabidopsis thaliana and Myzus persicae (Sülzer), more commonly known as the green peach aphid (GPA), are beginning to provide important insights into the molecular basis of plant defense and susceptibility to aphids. The recent demonstration that expression of dsRNA in Arabidopsis can be used to silence expression of genes in GPA has further expanded the utility of Arabidopsis for evaluating the contribution of the aphid genome-encoded proteins to this interaction. PMID:22666177

A highly infective plant-associated bacterium influences reproductive rates in pea aphids

PubMed Central

Hendry, Tory A.; Clark, Kelley J.; Baltrus, David A.

2016-01-01

Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction. PMID:26998321

Mechanisms and evolution of plant resistance to aphids.

PubMed

Züst, Tobias; Agrawal, Anurag A

2016-01-06

Aphids are important herbivores of both wild and cultivated plants. Plants rely on unique mechanisms of recognition, signalling and defence to cope with the specialized mode of phloem feeding by aphids. Aspects of the molecular mechanisms underlying aphid-plant interactions are beginning to be understood. Recent advances include the identification of aphid salivary proteins involved in host plant manipulation, and plant receptors involved in aphid recognition. However, a complete picture of aphid-plant interactions requires consideration of the ecological outcome of these mechanisms in nature, and the evolutionary processes that shaped them. Here we identify general patterns of resistance, with a special focus on recognition, phytohormonal signalling, secondary metabolites and induction of plant resistance. We discuss how host specialization can enable aphids to co-opt both the phytohormonal responses and defensive compounds of plants for their own benefit at a local scale. In response, systemically induced resistance in plants is common and often involves targeted responses to specific aphid species or even genotypes. As co-evolutionary adaptation between plants and aphids is ongoing, the stealthy nature of aphid feeding makes both the mechanisms and outcomes of these interactions highly distinct from those of other herbivore-plant interactions.

A highly infective plant-associated bacterium influences reproductive rates in pea aphids.

PubMed

Hendry, Tory A; Clark, Kelley J; Baltrus, David A

2016-02-01

Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction.

Tetramorium tsushimae Ants Use Methyl Branched Hydrocarbons of Aphids for Partner Recognition.

PubMed

Sakata, Itaru; Hayashi, Masayuki; Nakamuta, Kiyoshi

2017-10-01

In mutualisms, partner discrimination is often the most important challenge for interacting organisms. The interaction between ants and aphids is a model system for studying mutualisms; ants are provided with honeydew by aphids and, in turn, the ants offer beneficial services to the aphids. To establish and maintain this system, ants must discriminate mutualistic aphid species correctly. Although recent studies have shown that ants recognize aphids as mutualistic partners based on their cuticular hydrocarbons (CHCs), it was unclear which CHCs are involved in recognition. Here, we tested whether the n-alkane or methylalkane fraction, or both, of aphid CHCs were utilized as partner recognition cues by measuring ant aggressiveness toward these fractions. When workers of Tetramorium tsushimae ants were presented with dummies coated with n-alkanes of their mutualistic aphid Aphis craccivora, ants displayed higher levels of aggression than to dummies treated with total CHCs or methyl alkanes of A. craccivora; responses to dummies treated with n-alkanes of A. craccivora were similar to those to control dummies or dummies treated with the CHCs of the non-mutualistic aphid Acyrthosiphon pisum. By contrast, ants exhibited lower aggression to dummies treated with either total CHCs or the methylalkane fraction of the mutualistic aphid than to control dummies or dummies treated with CHCs of the non-mutualistic aphid. These results suggest that T. tsushimae ants use methylalkanes of the mutualistic aphid's CHCs to recognize partners, and that these ants do not recognize aphids as partners on the basis of n-alkanes.

Contribution of Noncolonizing Aphids to Potato Virus Y Prevalence in Potato in Idaho.

PubMed

Mondal, Shaonpius; Wenninger, Erik J; Hutchinson, Pamela J S; Weibe, Monica A; Eigenbrode, Sanford D; Bosque-Pérez, Nilsa A

2016-12-01

Potato virus Y (PVY) is a major concern for potato production in the United States given its impact on both crop quality and yield. Although green peach aphid, Myzus persicae (Sulzer), is the most efficient PVY vector, it may be less abundant in potato-growing areas of Idaho relative to non-potato-colonizing aphid vectors of PVY that may disperse from nearby cereal fields and other crops. A field study was conducted during 2012-2013 to examine if noncolonizing aphids disperse to nearby potato fields as cereal crops dry down before harvest. The aphid fauna was sampled weekly in four different potato fields in south-central and southeastern Idaho using yellow sticky traps and yellow pan traps. Potato fields were chosen with an adjacent cereal field such that the prevailing westerly wind would facilitate aphid dispersal from cereal fields to potato. Non-potato-colonizing aphids sampled included 10 cereal aphid species, the most abundant of which were Rhopalosiphum padi L. and Metopolophium dirhodum (Walker). More than 35 species from noncereal hosts also were found. Overall, green peach aphid abundance was relatively low, ranging from 0.5-2.5% of the total aphid capture between years and among fields. In both years and all locations, cereal aphid abundance peaked in mid- to late July (cereal ripening stage) and decreased thereafter as cereal crops dried. PVY prevalence in the potato fields increased following these increases in aphid abundance. This study suggests that cereal aphids and other noncolonizing aphids are important contributors to PVY prevalence in potato in southern Idaho. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Estimation of the number of aphids carrying Citrus tristeza virus that visit adult citrus trees.

PubMed

Marroquín, Carlos; Olmos, Antonio; Teresa Gorris, María; Bertolini, Edson; Carmen Martínez, M; Carbonell, Emilio A; Hermoso de Mendoza, Alfonso; Cambra, Mariano

2004-03-01

Aphid species were counted on citrus trees in orchards in Valencia, Spain, in the spring and autumn of 1997, 1998 and 1999. Moericke yellow water traps, the 'sticky shoot' method and counts of established colonies were used in extensive surveys in which 29,502 aphids were recorded and identified. Aphis spiraecola and Aphis gossypii were the most abundant aphid species. The numbers of aphid species landing on mature trees of grapefruit, sweet orange, lemon and clementine and satsuma mandarins, were estimated by counting the numbers of young shoots/tree and aphids trapped on sticky shoots. The proportions of the different aphid species captured were: A. gossypii (53%), A. spiraecola (32%), Toxoptera aurantii (11%), Myzus persicae (1%), Aphis craccivora (1%) and other species (2%). Clementine was the most visited species with 266,700 aphids landing/tree in spring 2000, followed by lemon (147,000), sweet orange (129,150), grapefruit (103,200), and satsuma (92,400). The numbers and relative percentages of aphids carrying Citrus tristeza virus (CTV) were assessed by nested RT-PCR in single closed tubes and analysed by extraction of RNA-CTV targets from trapped aphids. An average of 37,190 CTV-carrying aphids visited each tree in spring 2000 (29 per shoot). The percentage detection of viral RNA in the aphid species that landed were 27% for A. gossypii, 23% for A. spiraecola and 19% for T. aurantii. This high incidence of aphids carrying CTV is consistent with the high prevalence and rapid spread of CTV in sweet orange, clementine, and satsuma mandarins in recent years in the region. The infection rate was proportional to the number of aphids landing/tree.

Stem nematode counteracts plant resistance of aphids in alfalfa, Medicago sativa.

PubMed

Ramirez, Ricardo A; Spears, Lori R

2014-10-01

Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. This study examined the effect of nematode-resistant varieties on aphid (Acyrthosiphon pisum) suppression, and then determined how infection by the stem nematode, Ditylenchus dipsaci, mediated ecological effects on aphids and on plant defense proteins. Four alfalfa (Medicago sativa) varieties were selected with resistance to nematodes only (+,-), aphids only (-,+), nematodes and aphids (+,+), and susceptibility to nematodes and aphids (-,-). Field and greenhouse experiments were conducted to isolate the effect of nematode infection and aphid abundance on each variety. We found that varieties resistant to nematode, regardless of aphid resistance, had the lowest aphid counts, suggesting possible cross-resistance. Aphid abundance, however, increased when plants were exposed to nematodes. Resistant varieties were associated with elevated saponins but these compounds were not affected by insect or pathogen feeding. Concentrations of peroxidases and trypsin inhibitors, however, were increased in nematode resistant varieties when exposed to nematodes and aphids, respectively. The patterns of plant defense were variable, and a combination of resistance traits and changes in nutrient availability may drive positive interactions between nematodes and aphids aboveground.

The influence of Lasius neoniger (Hymenoptera: Formicidae) on population growth and biomass of Aphis glycines (Hemiptera: Aphididae) in soybeans.

PubMed

Schwartzberg, Ezra G; Johnson, D W; Brown, G C

2010-12-01

In the United States, the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are often tended by the aphid-tending ant, Lasius neoniger Emery (Hymenoptera: Formicidae). In this study, we examined the effects of tending by ants on the density and biomass of soybean aphids on soybeans in Kentucky. We performed cage studies that limited access by ants and/or natural enemies. We used a split-plot design with natural enemy access as the main plot and ant attendance as the sub plot. We found that natural enemy access negatively affected aphid population density in the presence of tending ants, seen as a three- to four-fold increase in aphid density when natural enemies were excluded. In addition, we found that ant tending positively affected aphid biomass, both when natural enemies were given access to aphids or when natural enemies were excluded, seen by a two-fold increase in aphid biomass when ants tended aphids, both in the presence or absence of natural enemies. Biomass accumulation is seen as an important measurement for assessing aphid performance, and we argue that aphid-tending by ants can have an influence on natural field populations of soybean aphids. Agronomic practices that affect ant abundance in soybeans may influence the performance and hence pest outbreaks for this economically important pest. © 2010 Entomological Society of America

Partial aphid resistance in lettuce negatively affects parasitoids.

PubMed

Lanteigne, Marie-Eve; Brodeur, Jacques; Jenni, Sylvie; Boivin, Guy

2014-10-01

This study investigated the effects of partial plant resistance on the lettuce aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of cultivated lettuce (Lactuca sativa L.), and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids were reared on susceptible (L. sativa variety Estival; S) or partially resistant (Lactuca serriola L. PI 491093; PR) lettuce, and next parasitized by A. ervi females. Fitness proxies were measured for both aphids and parasitoids. Developmental time to adult stage took longer for alate and apterous aphids (an average of 3.5 and 1.5 additional days, respectively) on PR than on S lettuce, and fecundity of alate aphids reared on PR lettuce was reduced by 37.8% relative to those reared on S lettuce. Size (tibia length) and weight of aphids reared on PR lettuce were lower than for aphids reared on S lettuce from the third and second instar onward, respectively. Parasitism of aphids reared on PR plants resulted in lower parasitoid offspring emergence (-49.9%), lower adult female (-30.3%) and male (-27.5%) weight, smaller adult female (-17.5%) and male (-11.9%) size, and lower female fecundity (37.8% fewer eggs) than when parasitoids developed from aphids reared on S plants. Our results demonstrate that partial aphid resistance in lettuce negatively affects both the second and third trophic levels. Host plant resistance in cultivated lettuce may therefore create an ecological sink for aphid parasitoids.

Orally Delivered Scorpion Antimicrobial Peptides Exhibit Activity against Pea Aphid (Acyrthosiphon pisum) and Its Bacterial Symbionts.

PubMed

Luna-Ramirez, Karen; Skaljac, Marisa; Grotmann, Jens; Kirfel, Phillipp; Vilcinskas, Andreas

2017-08-24

Aphids are severe agricultural pests that damage crops by feeding on phloem sap and vectoring plant pathogens. Chemical insecticides provide an important aphid control strategy, but alternative and sustainable control measures are required to avoid rapidly emerging resistance, environmental contamination, and the risk to humans and beneficial organisms. Aphids are dependent on bacterial symbionts, which enable them to survive on phloem sap lacking essential nutrients, as well as conferring environmental stress tolerance and resistance to parasites. The evolution of aphids has been accompanied by the loss of many immunity-related genes, such as those encoding antibacterial peptides, which are prevalent in other insects, probably because any harm to the bacterial symbionts would inevitably affect the aphids themselves. This suggests that antimicrobial peptides (AMPs) could replace or at least complement conventional insecticides for aphid control. We fed the pea aphids ( Acyrthosiphon pisum ) with AMPs from the venom glands of scorpions. The AMPs reduced aphid survival, delayed their reproduction, displayed in vitro activity against aphid bacterial symbionts, and reduced the number of symbionts in vivo. Remarkably, we found that some of the scorpion AMPs compromised the aphid bacteriome, a specialized organ that harbours bacterial symbionts. Our data suggest that scorpion AMPs holds the potential to be developed as bio-insecticides, and are promising candidates for the engineering of aphid-resistant crops.

Orally Delivered Scorpion Antimicrobial Peptides Exhibit Activity against Pea Aphid (Acyrthosiphon pisum) and Its Bacterial Symbionts

PubMed Central

Luna-Ramirez, Karen; Skaljac, Marisa; Grotmann, Jens; Kirfel, Phillipp; Vilcinskas, Andreas

2017-01-01

Aphids are severe agricultural pests that damage crops by feeding on phloem sap and vectoring plant pathogens. Chemical insecticides provide an important aphid control strategy, but alternative and sustainable control measures are required to avoid rapidly emerging resistance, environmental contamination, and the risk to humans and beneficial organisms. Aphids are dependent on bacterial symbionts, which enable them to survive on phloem sap lacking essential nutrients, as well as conferring environmental stress tolerance and resistance to parasites. The evolution of aphids has been accompanied by the loss of many immunity-related genes, such as those encoding antibacterial peptides, which are prevalent in other insects, probably because any harm to the bacterial symbionts would inevitably affect the aphids themselves. This suggests that antimicrobial peptides (AMPs) could replace or at least complement conventional insecticides for aphid control. We fed the pea aphids (Acyrthosiphon pisum) with AMPs from the venom glands of scorpions. The AMPs reduced aphid survival, delayed their reproduction, displayed in vitro activity against aphid bacterial symbionts, and reduced the number of symbionts in vivo. Remarkably, we found that some of the scorpion AMPs compromised the aphid bacteriome, a specialized organ that harbours bacterial symbionts. Our data suggest that scorpion AMPs holds the potential to be developed as bio-insecticides, and are promising candidates for the engineering of aphid-resistant crops. PMID:28837113

Reflectance and internal structure of leaves from several crops during a growing season.

NASA Technical Reports Server (NTRS)

Sinclair, T. R.; Hoffer, R. M.; Schreiber, M. M.

1971-01-01

Measurements of spectral reflectance characteristics during a growing season of leaves from six crops are reported. These crops include soybeans, wheat, oats, sorghum, corn, and sudangrass. The characteristics measured are related to changes in leaf structure and water content.

Sun-view angle effects on reflectance factors of corn canopies

NASA Technical Reports Server (NTRS)

Ranson, K. J.; Daughtry, C. S. T.; Biehl, L. L.; Bauer, M. E.

1985-01-01

The effects of sun and view angles on reflectance factors of corn (Zea mays L.) canopies ranging from the six leaf stage to harvest maturity were studied on the Purdue University Agronomy Farm by a multiband radiometer. The two methods of acquiring spectral data, the truck system and the tower systrem, are described. The analysis of the spectral data is presented in three parts: solar angle effects on reflectance factors viewed at nadir; solar angle effects on reflectance factors viewed at a fixed sun angle; and both sun and view angles effect on reflectance factors. The analysis revealed that for nadir-viewed reflectance factors there is a strong solar angle dependence in all spectral bands for canopies with low leaf area index. Reflectance factors observed from the sun angle at different view azimuth angles showed that the position of the sensor relative to the sun is important in determining angular reflectance characteristics. For both sun and view angles, reflectance factors are maximized when the sensor view direction is towards the sun.

Detrimental and Neutral Effects of a Wild Grass-Fungal Endophyte Symbiotum on Insect Preference and Performance

PubMed Central

Clement, Stephen L.; Hu, Jinguo; Stewart, Alan V.; Wang, Bingrui; Elberson, Leslie R.

2011-01-01

Seed-borne Epichloë/Neotyphodium Glenn, Bacon, Hanlin (Ascomycota: Hypocreales: Clavicipitaceae) fungal endophytes in temperate grasses can provide protection against insect attack with the degree of host resistance related to the grass—endophyte symbiotum and the insect species involved in an interaction. Few experimental studies with wild grass—endophyte symbiota, compared to endophyte-infected agricultural grasses, have tested for anti-insect benefits, let alone for resistance against more than one insect species. This study quantified the preference and performance of the bird cherry oat-aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) and the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), two important pests of forage and cereal grasses, on Neotyphodium-infected (E+) and uninfected (E-) plants of the wild grass Alpine timothy, Phleum alpinum L. (Poales: Poaceae). The experiments tested for both constitutive and wound-induced resistance in E+ plants to characterize possible plasticity of defense responses by a wild E+ grass. The aphid, R. padi preferred E- over E+ test plants in choice experiments and E+ undamaged test plants constitutively expressed antibiosis resistance to this aphid by suppressing population growth. Prior damage of E+ test plants did not induce higher levels of resistance to R. padi. By contrast, the beetle, O. melanopus showed no preference for E+ or E- test plants and endophyte infection did not adversely affect the survival and development of larvae. These results extend the phenomenon of variable effects of E+ wild grasses on the preference and performance of phytophagous insects. The wild grass— Neotyphodium symbiotum in this study broadens the number of wild E+ grasses available for expanded explorations into the effects of endophyte metabolites on insect herbivory. PMID:21867443

Detrimental and neutral effects of a wild grass-fungal endophyte symbiotum on insect preference and performance.

PubMed

Clement, Stephen L; Hu, Jinguo; Stewart, Alan V; Wang, Bingrui; Elberson, Leslie R

2011-01-01

Seed-borne Epichloë/Neotyphodium Glenn, Bacon, Hanlin (Ascomycota: Hypocreales: Clavicipitaceae) fungal endophytes in temperate grasses can provide protection against insect attack with the degree of host resistance related to the grass-endophyte symbiotum and the insect species involved in an interaction. Few experimental studies with wild grass-endophyte symbiota, compared to endophyte-infected agricultural grasses, have tested for anti-insect benefits, let alone for resistance against more than one insect species. This study quantified the preference and performance of the bird cherry oat-aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae) and the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), two important pests of forage and cereal grasses, on Neotyphodium-infected (E+) and uninfected (E-) plants of the wild grass Alpine timothy, Phleum alpinum L. (Poales: Poaceae). The experiments tested for both constitutive and wound-induced resistance in E+ plants to characterize possible plasticity of defense responses by a wild E+ grass. The aphid, R. padi preferred E- over E+ test plants in choice experiments and E+ undamaged test plants constitutively expressed antibiosis resistance to this aphid by suppressing population growth. Prior damage of E+ test plants did not induce higher levels of resistance to R. padi. By contrast, the beetle, O. melanopus showed no preference for E+ or E- test plants and endophyte infection did not adversely affect the survival and development of larvae. These results extend the phenomenon of variable effects of E+ wild grasses on the preference and performance of phytophagous insects. The wild grass- Neotyphodium symbiotum in this study broadens the number of wild E+ grasses available for expanded explorations into the effects of endophyte metabolites on insect herbivory.

Transient alkalinization of the leaf apoplast stiffens the cell wall during onset of chloride salinity in corn leaves.

PubMed

Geilfus, Christoph-Martin; Tenhaken, Raimund; Carpentier, Sebastien Christian

2017-11-17

During chloride salinity, the pH of the leaf apoplast (pH apo ) transiently alkalizes. There is an ongoing debate about the physiological relevance of these stress-induced pH apo changes. Using proteomic analyses of expanding leaves of corn ( Zea mays L.), we show that this transition in pH apo conveys functionality by (i) adjusting protein abundances and (ii) affecting the rheological properties of the cell wall. pH apo was monitored in planta via microscopy-based ratio imaging, and the leaf-proteomic response to the transient leaf apoplastic alkalinization was analyzed via ultra-high performance liquid chromatography-MS. This analysis identified 1459 proteins, of which 44 exhibited increased abundance specifically through the chloride-induced transient rise in pH apo These elevated protein abundances did not directly arise from high tissue concentrations of Cl - or Na + but were due to changes in the pH apo Most of these proteins functioned in growth-relevant processes and in the synthesis of cell wall-building components such as arabinose. Measurements with a linear-variable differential transducer revealed that the transient alkalinization rigidified ( i.e. stiffened) the cell wall during the onset of chloride salinity. A decrease in t -coumaric and t -ferulic acids indicates that the wall stiffening arises from cross-linkage to cell wall polymers. We conclude that the pH of the apoplast represents a dynamic factor that is mechanistically coupled to cellular responses to chloride stress. By hardening the wall, the increased pH abrogates wall loosening required for cell expansion and growth. We conclude that the transient alkalinization of the leaf apoplast is related to salinity-induced growth reduction. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Identification of Conditions for Successful Aphid Control by Ladybirds in Greenhouses

PubMed Central

Riddick, Eric W.

2017-01-01

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 usually did not correlate with aphid reduction. The ratio of aphid reduction/release rate was slightly less for larvae than adults in some studies, suggesting that larvae were less effective (than adults) in suppressing aphids. Some adult releases were inside cages, thereby limiting adult dispersion from plants. Overall, the ratio of aphid reduction/release rate was greatest for ladybird adults of the normal strain (several species combined), but least for adults of a flightless Harmonia axyridis strain. The combined action of ladybirds and hymenopteran parasitoids could have a net positive effect on aphid population suppression and, consequently, on host (crop) plants. However, ladybird encounters with aphid-tending or foraging ants must be reduced. Deploying ladybirds to help manage aphids in greenhouses and similar protective structures is encouraged. PMID:28350349

Proteomic Investigation of Aphid Honeydew Reveals an Unexpected Diversity of Proteins

PubMed Central

Haubruge, Eric; Hance, Thierry; Thonart, Philippe; De Pauw, Edwin; Francis, Frédéric

2013-01-01

Aphids feed on the phloem sap of plants, and are the most common honeydew-producing insects. While aphid honeydew is primarily considered to comprise sugars and amino acids, its protein diversity has yet to be documented. Here, we report on the investigation of the honeydew proteome from the pea aphid Acyrthosiphon pisum. Using a two-Dimensional Differential in-Gel Electrophoresis (2D-Dige) approach, more than 140 spots were isolated, demonstrating that aphid honeydew also represents a diverse source of proteins. About 66% of the isolated spots were identified through mass spectrometry analysis, revealing that the protein diversity of aphid honeydew originates from several organisms (i.e. the host aphid and its microbiota, including endosymbiotic bacteria and gut flora). Interestingly, our experiments also allowed to identify some proteins like chaperonin, GroEL and Dnak chaperones, elongation factor Tu (EF-Tu), and flagellin that might act as mediators in the plant-aphid interaction. In addition to providing the first aphid honeydew proteome analysis, we propose to reconsider the importance of this substance, mainly acknowledged to be a waste product, from the aphid ecology perspective. PMID:24086359

Characterization of vegetation by microwave and optical remote sensing

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T. (Principal Investigator); Ranson, K. J.; Biehl, L. L.

1986-01-01

Two series of carefully controlled experiments were conducted. First, plots of important crops (corn, soybeans, and sorghum), prairie grasses (big bluestem, switchgrass, tal fescue, orchardgrass, bromegrass), and forage legumes (alfalfa, red clover, and crown vetch) were manipulated to produce wide ranges of phytomass, leaf area index, and canopy architecture. Second, coniferous forest canopies were simulated using small balsam fir trees grown in large pots of soil and arranged systematically on a large (5 m) platform. Rotating the platform produced many new canopies for frequency and spatial averaging of the backscatter signal. In both series of experiments, backscatter of 5.0 GHz (C-Band) was measured as a function of view angle and polarization. Biophysical measurements included leaf area index, fresh and dry phytomass, water content of canopy elements, canopy height, and soil roughness and moisture content. For a subset of the above plots, additional measurements were acquired to exercise microwave backscatter models. These measurements included size and shape of leaves, stems, and fruit and the probability density function of leaf and stem angles. The relationships of the backscattering coefficients and the biophysical properties of the canopies were evaluated using statistical correlations, analysis of variance, and regression analysis. Results from the corn density and balsam fir experiments are discussed and analyses of data from the other experiments are summarized.

Aphid facultative symbionts reduce survival of the predatory lady beetle Hippodamia convergens

PubMed Central

2014-01-01

Background Non-essential facultative endosymbionts can provide their hosts with protection from parasites, pathogens, and predators. For example, two facultative bacterial symbionts of the pea aphid (Acyrthosiphon pisum), Serratia symbiotica and Hamiltonella defensa, protect their hosts from parasitism by two species of parasitoid wasp. Previous studies have not explored whether facultative symbionts also play a defensive role against predation in this system. We tested whether feeding on aphids harboring different facultative symbionts affected the fitness of an aphid predator, the lady beetle Hippodamia convergens. Results While these aphid faculative symbionts did not deter lady beetle feeding, they did decrease survival of lady beetle larvae. Lady beetle larvae fed a diet of aphids with facultative symbionts had significantly reduced survival from egg hatching to pupation and therefore had reduced survival to adult emergence. Additionally, lady beetle adults fed aphids with facultative symbionts were significantly heavier than those fed facultative symbiont-free aphids, though development time was not significantly different. Conclusions Aphids reproduce clonally and are often found in large groups. Thus, aphid symbionts, by reducing the fitness of the aphid predator H. convergens, may indirectly defend their hosts’ clonal descendants against predation. These findings highlight the often far-reaching effects that symbionts can have in ecological systems. PMID:24555501

Do aphid colonies amplify their emission of alarm pheromone?

PubMed

Hatano, Eduardo; Kunert, Grit; Bartram, Stefan; Boland, Wilhelm; Gershenzon, Jonathan; Weisser, Wolfgang W

2008-09-01

When aphids are attacked by natural enemies, they emit alarm pheromone to alert conspecifics. For most aphids tested, (E)-beta-farnesene (EBF) is the main, or only, constituent of the alarm pheromone. In response to alarm pheromone, alerted aphids drop off the plant, walk away, or attempt to elude predators. However, under natural conditions, EBF concentration might be low due to the low amounts emitted, to rapid air movement, or to oxidative degradation. To ensure that conspecifics are warned, aphids might conceivably amplify the alarm signal by emitting EBF in response to EBF emitted by other aphids. To examine whether such amplification occurs, we synthesized deuterated EBF (DEBF), which allowed us to differentiate between applied and aphid-derived chemical. Colonies of Acyrthosiphon pisum were treated with DEBF, and headspace volatiles were collected and analyzed for evidence of aphid-derived EBF. No aphid-derived EBF was detected, suggesting that amplification of the alarm signal does not occur. We discuss the disadvantages of alarm signal reinforcement.

The significance of gut sucrase activity for osmoregulation in the pea aphid, Acyrthosiphon pisum.

PubMed

Karley, A J; Ashford, D A; Minto, L M; Pritchard, J; Douglas, A E

2005-12-01

The osmotic pressure of the body fluids of aphids is lower than in their diet of plant phloem sap. It is hypothesised that aphids reduce the osmotic pressure of ingested food by sucrase-mediated hydrolysis of dietary sucrose to glucose and fructose, and the polymerisation of glucose into oligosaccharides of low osmotic pressure per hexose unit. To test this hypothesis, the impact of the alpha-glucosidase inhibitor acarbose on the sugar relations and osmoregulation of aphids was explored. Acarbose inhibited sucrase activity in gut homogenates and the production of monosaccharides and oligosaccharides in the honeydew of live aphids. Acarbose caused an increase in the haemolymph osmotic pressure for aphids reared on a diet (containing 0.75 M sucrose) hyperosmotic to the haemolymph and not on the isoosmotic diet containing 0.2 M sucrose. It did not affect aphid feeding rate over 2 days, except at high concentrations on 0.75 M sucrose diet, and this may have been a secondary consequence of osmotic dysfunction. Acarbose-treated aphids died prematurely. With 5 microM dietary acarbose, mean survivorship on 0.2 M sucrose diet was 4.2 days, not significantly different from starved aphids, indicating that, although these aphids fed, they were deprived of utilisable carbon; and on 0.75 M sucrose diet, mean survivorship was just 2.8 days, probably as a consequence of osmotic failure. It is concluded that the aphid gut sucrase activity is essential for osmoregulation of aphids ingesting food hyperosmotic to their body fluids.

Utilizing LEAF to increase biomass feedstock supplies from agricultural land

USDA-ARS?s Scientific Manuscript database

The start-up of three full-scale corn stover bioenergy conversion facilities in 2014 will require a substantial increase in sustainable biomass feedstock. Supplying crop residues without having a negative impact on ecosystem services is indeed a “grand challenge” associated with sustainable food and...

Treatment of different parts of corn stover for high yield and lower polydispersity lignin extraction with high-boiling alkaline solvent.

PubMed

Yang, Mengyao; Rehman, Muhammad Saif Ur; Yan, Tingxuan; Khan, Asad Ullah; Oleskowicz-Popiel, Piotr; Xu, Xia; Cui, Ping; Xu, Jian

2018-02-01

The influence of different parts of corn stover on lignin extraction was investigated. Five kinds of lignin were isolated by the high boiling point solvent extraction from the whole corn stover and four different parts including leaf, husk, bark and pith. The optimal condition was obtained: 6.25 g/L NaOH, 140 °C, 1 h and 60% (v/v) 1,4-butanediol. The extracted lignins were then characterized. FT-IR analysis revealed that all of the lignins were typically herbaceous. The lignin extracted from husk contained more S unit. Gel permeation chromatography analysis showed that it was necessary to separate corn stover into different parts to obtain low polydispersity lignin. The SEM and FT-IR analysis proved that the lignin dissolution was related to the tightness structure presenting a positive correlation with hydrogen bond index. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tissue-specific biomass recalcitrance in corn stover pretreated with liquid hot-water: enzymatic hydrolysis (part 1).

PubMed

Zeng, Meijuan; Ximenes, Eduardo; Ladisch, Michael R; Mosier, Nathan S; Vermerris, Wilfred; Huang, Chia-Ping; Sherman, Debra M

2012-02-01

Lignin content, composition, distribution as well as cell wall thickness, structures, and type of tissue have a measurable effect on enzymatic hydrolysis of cellulose in lignocellulosic feedstocks. The first part of our work combined compositional analysis, pretreatment and enzyme hydrolysis for fractionated pith, rind, and leaf tissues from a hybrid stay-green corn, in order to identify the role of structural characteristics on enzyme hydrolysis of cell walls. The extent of enzyme hydrolysis follows the sequence rind < leaves < pith with 90% conversion of cellulose to glucose in 24 h in the best cases. Physical fractionation of corn stalks or other C(4) grasses into soft and hard tissue types could reduce cost of cellulose conversion by enabling reduced enzyme loadings to hydrolyze soft tissue, and directing the hard tissue to other uses such as thermal processing, combustion, or recycle to the land from which the corn was harvested. Copyright © 2011 Wiley Periodicals, Inc.

Spruce aphid (Elatobium abietinum Walker) (Hemiptera: Aphididae) [Chapter XXIV

Treesearch

Ann M. Lynch

2014-01-01

Elatobium abietinum Walker is a spruce-feeding aphid that in Europe is referred to as the green spruce aphid (Day et al., 1998a) (Fig. 1). However, in North America E. abietinum is known simply as the spruce aphid, while the common name "green spruce aphid" refers to a different species, Cinara fornacula Hottes (Hemiptera: Aphididae) (http://www.entsoc.org/...

Influences of pea morphology and interacting factors on pea aphid (Homoptera: Aphididae) reproduction.

PubMed

Buchman, N; Cuddington, K

2009-08-01

It has been claimed that plant architecture can alter aphid reproductive rates, but the mechanism driving this effect has not been identified. We studied interactions between plant architecture, aphid density, environmental conditions, and nutrient availability on the reproduction of pea aphids [Acyrthosiphon pisum (Harris)] using four near-isogenic peas (Pisum sativum L.) that differ in morphology. Manipulations of aphid density (1, 5, and 10 adults per plant) allowed us to examine any effects of plant morphology on crowding and consequently reproduction. Pea morphology per se did not alter pea aphid crowding, as measured by mean nearest neighbor distance, and there was no effect on reproduction. In addition, reproduction increased with increasing adult density, indicating positive density dependence. In a separate experiment, peas were fertilized to determine whether differences between nutrient availability of the four different morphologies might drive any observed differences in aphid reproduction. Although plant nitrogen content was altered by fertilization treatments, this did not have an impact on aphid reproduction. Greenhouse experiments, however, suggested that pea morphology can interact with environmental conditions to reduce aphid reproduction under some conditions. We conclude that plant morphology only influences aphid reproduction when environmental conditions are less than optimal.

Overexpression and Down-Regulation of Barley Lipoxygenase LOX2.2 Affects Jasmonate-Regulated Genes and Aphid Fecundity

PubMed Central

Losvik, Aleksandra; Beste, Lisa; Glinwood, Robert; Ivarson, Emelie; Stephens, Jennifer; Zhu, Li-Hua; Jonsson, Lisbeth

2017-01-01

Aphids are pests on many crops and depend on plant phloem sap as their food source. In an attempt to find factors improving plant resistance against aphids, we studied the effects of overexpression and down-regulation of the lipoxygenase gene LOX2.2 in barley (Hordeum vulgare L.) on the performance of two aphid species. A specialist, bird cherry-oat aphid (Rhopalosiphum padi L.) and a generalist, green peach aphid (Myzus persicae Sulzer) were studied. LOX2.2 overexpressing lines showed up-regulation of some other jasmonic acid (JA)-regulated genes, and antisense lines showed down-regulation of such genes. Overexpression or suppression of LOX2.2 did not affect aphid settling or the life span on the plants, but in short term fecundity tests, overexpressing plants supported lower aphid numbers and antisense plants higher aphid numbers. The amounts and composition of released volatile organic compounds did not differ between control and LOX2.2 overexpressing lines. Up-regulation of genes was similar for both aphid species. The results suggest that LOX2.2 plays a role in the activation of JA-mediated responses and indicates the involvement of LOX2.2 in basic defense responses. PMID:29257097

Changes in the Russian Wheat Aphid (Hemiptera: Aphididae) Biotype Complex in South Africa.

PubMed

Jankielsohn, Astrid

2016-04-01

Russian wheat aphid Diuraphis noxia (Kurdjumov) has spread from its native area in central Asia to all the major wheat-producing countries in the world to become an international wheat pest. Because the Russian wheat aphid is a serious threat to the wheat industry in South Africa, it is important to investigate the key factors involved in the distribution of Russian wheat aphid biotypes and in the changes of the Russian wheat aphid biotype complex in South Africa. There are currently four known Russian wheat aphid biotypes occurring in South Africa. Russian wheat aphid samples were collected from 2011 to 2014 during the wheat-growing season in spring and summer and these samples were screened to determine the biotype status. RWASA1 occurred predominantly in the Western Cape, while RWASA2 and RWASA3 occurred predominantly in the Eastern Free State. Following the first record of RWASA4 in 2011, this biotype was restricted to the Eastern Free State. The surveys suggest that the Russian wheat aphid bioype complex was more diverse in the Eastern Free State than in the other wheat production areas. There was also a shift in Russian wheat aphid biotype composition over time. The Russian wheat aphid biotype complex is dynamic, influenced by environmental factors such as host plants, altitude, and climate, and it can change and diversify over time causing fluctuation in populations over sites and years. This dynamic nature of the Russian wheat aphid will continue to challenge the development of Russian wheat aphid-resistant wheat cultivars in South Africa, and the continued monitoring of the biotypic and genetic structure, to determine genetic relatedness and variation in different biotypes, of Russian wheat aphid populations is important for protecting wheat.

Potential Overwintering Locations of Soybean Aphid (Hemiptera: Aphididae) Colonizing Soybean in Ohio and Wisconsin.

PubMed

Crossley, Michael S; Hogg, David B

2015-04-01

Soybean aphids, Aphis glycines Matsumura, depend on long-distance, wind-aided dispersal to complete their life cycle. Despite our general understanding of soybean aphid biology, little is explicitly known about dispersal of soybean aphids between winter and summer hosts in North America. This study compared genotypic diversity of soybean aphids sampled from several overwintering locations in the Midwest and soybean fields in Ohio and Wisconsin to test the hypothesis that these overwintering locations are sources of the soybean colonists. In addition, air parcel trajectory analyses were used to demonstrate the potential for long-distance dispersal events to occur to or from these overwintering locations. Results suggest that soybean aphids from overwintering locations along the Illinois-Iowa border and northern Indiana-Ohio are potential colonists of soybean in Ohio and Wisconsin, but that Ohio is also colonized by soybean aphids from other unknown overwintering locations. Soybean aphids in Ohio and Wisconsin exhibit a small degree of population structure that is not associated with the locations of soybean fields in which they occur, but that may be related to specific overwintering environments, multiple introductions to North America, or spatial variation in aphid phenology. There may be a limited range of suitable habitat for soybean aphid overwintering, in which case management of soybean aphids may be more effective at their overwintering sites. Further research efforts should focus on discovering more overwintering locations of soybean aphid in North America, and the relative impact of short- and long-distance dispersal events on soybean aphid population dynamics. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Changes in the free amino acid composition of Capsicum annuum (pepper) leaves in response to Myzus persicae (green peach aphid) infestation. A comparison with water stress.

PubMed

Florencio-Ortiz, Victoria; Sellés-Marchart, Susana; Zubcoff-Vallejo, José; Jander, Georg; Casas, José L

2018-01-01

Amino acids play a central role in aphid-plant interactions. They are essential components of plant primary metabolism, function as precursors for the synthesis of defense-related specialized metabolites, and are major growth-limiting nutrients for aphids. To quantify changes in the free amino acid content of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) feeding, plants were infested with a low (20 aphids/plant) or a high (200 aphids/plant) aphid density in time-course experiments ranging from 3 hours to 7 days. A parallel experiment was conducted with pepper plants that had been subjected to water stress. Factor Analysis of Mixed Data revealed a significant interaction of time x density in the free amino acid response of aphid-infested leaves. At low aphid density, M. persicae did not trigger a strong response in pepper leaves. Conversely, at high density, a large increase in total free amino acid content was observed and specific amino acids peaked at different times post-infestation. Comparing aphid-infested with water-stressed plants, most of the observed differences were quantitative. In particular, proline and hydroxyproline accumulated dramatically in response to water stress, but not in response to aphid infestation. Some additional differences and commonalities between the two stress treatments are discussed.

Metabolic engineering of plant-derived (E)-β-farnesene synthase genes for a novel type of aphid-resistant genetically modified crop plants.

PubMed

Yu, Xiu-Dao; Pickett, John; Ma, You-Zhi; Bruce, Toby; Napier, Johnathan; Jones, Huw D; Xia, Lan-Qin

2012-05-01

Aphids are major agricultural pests that cause significant yield losses of crop plants each year. Excessive dependence on insecticides for long-term aphid control is undesirable because of the development of insecticide resistance, the potential negative effects on non-target organisms and environmental pollution. Transgenic crops engineered for resistance to aphids via a non-toxic mode of action could be an efficient alternative strategy. (E)-β-Farnesene (EβF) synthases catalyze the formation of EβF, which for many pest aphids is the main component of the alarm pheromone involved in the chemical communication within these species. EβF can also be synthesized by certain plants but is then normally contaminated with inhibitory compounds. Engineering of crop plants capable of synthesizing and emitting EβF could cause repulsion of aphids and also the attraction of natural enemies that use EβF as a foraging cue, thus minimizing aphid infestation. In this review, the effects of aphids on host plants, plants' defenses against aphid herbivory and the recruitment of natural enemies for aphid control in an agricultural setting are briefly introduced. Furthermore, the plant-derived EβF synthase genes cloned to date along with their potential roles in generating novel aphid resistance via genetically modified approaches are discussed. © 2012 Institute of Botany, Chinese Academy of Sciences.

Chemical characteristics of normal, woolly apple aphid-damaged, and mechanically damaged twigs of six apple cultivars, measured in autumn wood.

PubMed

Zhou, Hong-Xu; Wang, Xi-Cun; Yu, Yi; Tan, Xiu-Mei; Cheng, Zai-Quan; Zhang, An-Sheng; Men, Xing-Yuan; Li-Li, Li

2013-04-01

Chemical characteristics of normal, woolly apple aphid-damaged, and mechanically damaged twigs of six apple cultivars: Red Fuji, Golden Delicious, Qinguan, Zhaojin 108, Starkrimson, and Red General, were examined in autumn wood to provide abetter understanding of factors related to cultivar resistance to the woolly apple aphid, Eriosoma lanigerum (Hausmann). Chemical measures examined included soluble sugars, soluble proteins and amino acids, total phenolics, and polyphenol oxidase (that enhances the resistance of plants to insects) and superoxide dismutase, peroxidase, and catalase (that degrade waste products in plants). Soluble sugar, protein, and amino acid contents in normal (undamaged) twigs of Red Fuji, aphid-susceptible cultivar, were higher than in mechanically damaged and aphid-damaged twigs. Total phenolic compounds, an important group of defensive compounds against aphids, increased by 30.5 and 6.0% in mechanically damaged twigs of Qinguan and Zhaojin 108, respectively, and decreased by 21.7 and 16.1% in aphid-damaged twigs of Red Fuji and Red General, respectively. Compared with normal twigs, in aphid-damaged twigs, superoxide dismutase, peroxidase, and polyphenol activity all decreased in Red Fuji. The resistance of some apple cultivars to woolly apple aphid during the growth of autumn shoots was related to several of the physiological indices we monitored. The thin epidermis of callus tissue over healed wounds showed increased susceptibility to the attack by woolly apple aphid. Apple cultivar Qinguan with the highest level of resistance to woolly apple aphid in autumn had increased in amino acid, total phenolic compound levels, and enzyme activity after aphid feeding.

Climate warming may increase aphids' dropping probabilities in response to high temperatures.

PubMed

Ma, Gang; Ma, Chun-Sen

2012-11-01

Dropping off is considered an anti-predator behavior for aphids since previous studies have shown that it reduces the risk of predation. However, little attention is paid to dropping behavior triggered by other external stresses such as daytime high temperatures which are predicted to become more frequent in the context of climate warming. Here we defined a new parameter, drop-off temperature (DOT), to describe the critical temperature at which an aphid drops off its host plant when the ambient temperature increases gradually and slowly. Detailed studies were conducted to reveal effects of short-term acclimation (temperature, exposure time at high-temperature and starvation) on DOT of an aphid species, Sitobion avenae. Our objectives were to test if the aphids dropped off host plant to avoid high temperatures and how short-term acclimation affected the aphids' dropping behavior in response to heat stress. We suggest that dropping is a behavioral thermoregulation to avoid heat stress, since aphids started to move before they dropped off and the dropped aphids were still able to control their muscles prior to knockdown. The adults starved for 12 h had higher DOT values than those that were unstarved or starved for 6 h, and there was a trade-off between behavioral thermoregulation and energy acquisition. Higher temperatures and longer exposure times at high temperatures significantly lowered the aphids' DOT, suggested that the aphids avoid heat stress by dropping when exposed to high temperatures. Climate warming may therefore increase the aphids' dropping probabilities and consequently affect the aphids' individual development and population growth. Copyright © 2012 Elsevier Ltd. All rights reserved.

Evolutionary history of aphid-plant associations and their role in aphid diversification.

PubMed

Peccoud, Jean; Simon, Jean-Christophe; von Dohlen, Carol; Coeur d'acier, Armelle; Plantegenest, Manuel; Vanlerberghe-Masutti, Flavie; Jousselin, Emmanuelle

2010-01-01

Aphids are intimately linked with their host plants that constitute their only food resource and habitat, and thus impose considerable selective pressure on their evolution. It is therefore commonly assumed that host plants have greatly influenced the diversification of aphids. Here, we review what is known about the role of host plant association on aphid speciation by examining both macroevolutionary and population-level studies. Phylogenetic studies conducted at different taxonomic levels show that, as in many phytophagous insect groups, the radiation of angiosperms has probably favoured the major Tertiary diversification of aphids. These studies also highlight many aphid lineages constrained to sets of related host plants, suggesting strong evolutionary commitment in aphids' host plant choice, but they fail to document cospeciation events between aphid and host lineages. Instead, phylogenies of several aphid genera reveal that divergence events are often accompanied by host shifts, and suggest, without constituting a formal demonstration, that aphid speciation could be a consequence of adaptation to new hosts. Experimental and field studies below the species level support reproductive isolation between host races as partly due to divergent selection by their host plants. Selected traits are mainly feeding performances and life cycle adaptations to plant phenology. Combined with behavioural preference for favourable host species, these divergent adaptations can induce pre- and post-zygotic barriers between host-specialized aphid populations. However, the hypothesis of host-driven speciation is seldom tested formally and must be weighed against overlooked explanations involving geographic isolation and non-ecological reproductive barriers in the process of speciation. Copyright 2010 Académie des sciences. Published by Elsevier SAS. All rights reserved.

The Endosymbiont Arsenophonus Is Widespread in Soybean Aphid, Aphis glycines, but Does Not Provide Protection from Parasitoids or a Fungal Pathogen

PubMed Central

Wulff, Jason A.; Buckman, Karrie A.; Wu, Kongming; Heimpel, George E.; White, Jennifer A.

2013-01-01

Aphids commonly harbor bacterial facultative symbionts that have a variety of effects upon their aphid hosts, including defense against hymenopteran parasitoids and fungal pathogens. The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is infected with the symbiont Arsenophonus sp., which has an unknown role in its aphid host. Our research goals were to document the infection frequency and diversity of the symbiont in field-collected soybean aphids, and to determine whether Arsenophonus is defending soybean aphid against natural enemies. We performed diagnostic PCR and sequenced four Arsenophonus genes in soybean aphids from their native and introduced range to estimate infection frequency and genetic diversity, and found that Arsenophonus infection is highly prevalent and genetically uniform. To evaluate the defensive role of Arsenophonus, we cured two aphid genotypes of their natural Arsenophonus infection through ampicillin microinjection, resulting in infected and uninfected isolines within the same genetic background. These isolines were subjected to parasitoid assays using a recently introduced biological control agent, Binodoxys communis [Braconidae], a naturally recruited parasitoid, Aphelinus certus [Aphelinidae], and a commercially available biological control agent, Aphidius colemani [Braconidae]. We also assayed the effect of the common aphid fungal pathogen, Pandora neoaphidis (Remaudiere & Hennebert) Humber (Entomophthorales: Entomophthoraceae), on the same aphid isolines. We did not find differences in successful parasitism for any of the parasitoid species, nor did we find differences in P. neoaphidis infection between our treatments. Our conclusion is that Arsenophonus does not defend its soybean aphid host against these major parasitoid and fungal natural enemies. PMID:23614027

Comparison of Measurements and FluorMOD Simulations for Solar Induced Chlorophyll Fluorescence and Reflectance of a Corn Crop under Nitrogen Treatments [SIF and Reflectance for Corn

NASA Technical Reports Server (NTRS)

Middleton, Elizabeth M.; Corp, Lawrence A.; Campbell, Petya K. E.

2007-01-01

The FLuorescence Explorer (FLEX) satellite concept is one of six semifinalist mission proposals selected in 2006 for pre-Phase studies by the European Space Agency (ESA). The FLEX concept proposes to measure passive solar induced chlorophyll fluorescence (SIF) of terrestrial ecosystems. A new spectral vegetation Fluorescence Model (FluorMOD) was developed to include the effects of steady state SIF on canopy reflectance. We used our laboratory and field measurements previously acquired from foliage and canopies of corn (Zea mays L.) under controlled nitrogen (N) fertilization to parameterize and evaluate FluorMOD. Our data included biophysical properties, fluorescence (F) and reflectance spectra for leaves; reflectance spectra of canopies and soil; solar irradiance; plot-level leaf area index; and canopy SIF emissions determined using the Fraunhofer Line Depth principal for the atmospheric telluric oxygen absorption features at 688 nm (O2-beta) and 760 nm (O2-alpha). FluorMOD simulations implemented in the default "look-up-table" mode did not reproduce the observed magnitudes of leaf F, canopy SIF, or canopy reflectance. However, simulations for all of these parameters agreed with observations when the default FluorMOD information was replaced with measurements, although N treatment responses were underestimated. Recommendations were provided to enhance FluorMOD's potential utility in support of SIF field experiments and studies of agriculture and ecosystems.

Assessment of MODIS-EVI, MODIS-NDVI and VEGETATION-NDVI composite data using agricultural measurements: an example at corn fields in western Mexico.

PubMed

Chen, Pei-Yu; Fedosejevs, Gunar; Tiscareño-López, Mario; Arnold, Jeffrey G

2006-08-01

Although several types of satellite data provide temporal information of the land use at no cost, digital satellite data applications for agricultural studies are limited compared to applications for forest management. This study assessed the suitability of vegetation indices derived from the TERRA-Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and SPOT-VEGETATION (VGT) sensor for identifying corn growth in western Mexico. Overall, the Normalized Difference Vegetation Index (NDVI) composites from the VGT sensor based on bi-directional compositing method produced vegetation information most closely resembling actual crop conditions. The NDVI composites from the MODIS sensor exhibited saturated signals starting 30 days after planting, but corresponded to green leaf senescence in April. The temporal NDVI composites from the VGT sensor based on the maximum value method had a maximum plateau for 80 days, which masked the important crop transformation from vegetative stage to reproductive stage. The Enhanced Vegetation Index (EVI) composites from the MODIS sensor reached a maximum plateau 40 days earlier than the occurrence of maximum leaf area index (LAI) and maximum intercepted fraction of photosynthetic active radiation (fPAR) derived from in-situ measurements. The results of this study showed that the 250-m resolution MODIS data did not provide more accurate vegetation information for corn growth description than the 500-m and 1000-m resolution MODIS data.

Herbivore Diet Breadth and Host Plant Defense Mediate the Tri-Trophic Effects of Plant Toxins on Multiple Coccinellid Predators.

PubMed

Katsanis, Angelos; Rasmann, Sergio; Mooney, Kailen A

2016-01-01

Host plant defenses are known to cascade up food chains to influence herbivores and their natural enemies, but how herbivore and predator traits and identity mediate such tri-trophic dynamics is largely unknown. We assessed the influence of plant defense on aphid and coccinellid performance in laboratory trials with low- vs. high-glucosinolate varieties of Brassica napus, a dietary specialist (Brevicoryne brassicae) and generalist (Myzus persicae) aphid, and five species of aphidophagous coccinellids. The performance of the specialist and generalist aphids was similar and unaffected by variation in plant defense. Aphid glucosinolate concentration and resistance to predators differed by aphid species and host plant defense, and these effects acted independently. With respect to aphid species, the dietary generalist aphid (vs. specialist) had 14% lower glucosinolate concentration and coccinellid predators ate three-fold more aphids. With respect to host plant variety, the high-glucosinolate plants (vs. low) increased aphid glucosinolate concentration by 21%, but had relatively weak effects on predation by coccinellids and these effects varied among coccinellid species. In turn, coccinellid performance was influenced by the interactive effects of plant defense and aphid species, as the cascading, indirect effect of plant defense was greater when feeding upon the specialist than generalist aphid. When feeding upon specialist aphids, low- (vs. high-) glucosinolate plants increased coccinellid mass gain by 78% and accelerated development by 14%. In contrast, when feeding upon generalist aphids, low- (vs. high-) glucosinolate plants increased coccinellid mass gain by only 11% and had no detectable effect on development time. These interactive effects of plant defense and aphid diet breadth on predator performance also varied among coccinellid species; the indirect negative effects of plant defenses on predator performance was consistent among the five predators when transmitted via the dietary specialist aphid, but these effects varied substantially among predators-in both the magnitude and direction-when transmitted via the dietary generalist aphid. Accordingly, the cascading effect of plant defense on predators was stronger in magnitude and more consistent among predator taxa when transmitted by the specialist than generalist herbivore. Overall, these findings support a central role of herbivore diet breadth in mediating both the strength and contingency of tri-trophic interactions.

Aphid reproductive investment in response to mortality risks

PubMed Central

2010-01-01

Background Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. An alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness loss from infection. Such a response would reduce the need to mount a potentially energetically costly immune response, and would parallel that of other hosts that alter life-history traits when there is a risk of infection. Here we examined whether pea aphids (Acyrthosiphon pisum) respond to immunological challenges by increasing reproduction. As a comparison to the response to the internal cue of risk elicited by immunological challenge, we also exposed pea aphids to an external cue of risk - the aphid alarm pheromone (E)-β-farnesene (EBF), which is released in the presence of predators. For each challenge, we also examined whether the presence of symbionts modified the host response, as maintaining host fitness in the face of challenge would benefit both the host and its dependent bacteria. Results We found that aphids stabbed abdominally with a sterile needle had reduced fecundity relative to control aphids but that aphids stabbed with a needle bearing heat-killed bacteria had reproduction intermediate, and statistically indistinguishable, to the aphids stabbed with a sterile needle and the controls. Aphids with different species of facultative symbiotic bacteria had different reproductive patterns overall, but symbionts in general did not alter aphid reproduction in response to bacterial exposure. However, in response to exposure to alarm pheromone, aphids with Hamiltonella defensa or Serratia symbiotica symbiotic infections increased reproduction but those without a facultative symbiont or with Regiella insecticola did not. Conclusions Overall, our results suggest that pea aphids are able to increase their reproduction in response to specific cues and that symbiont presence sometimes moderates this response. Such increased reproduction in response to risk of death increases the fitness of both aphids and their vertically transmitted symbionts, and since these organisms have high reproductive capacity, slight increases in reproduction could lead to a very large numerical advantage later in the season. Thus both symbiotic partners can benefit by increasing host fecundity under dangerous conditions. PMID:20716370

Effect of ant attendance by Monomorium minimum (Buckley) (Hymenoptera: Formicidae) on predation and parasitism of the soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae).

PubMed

Herbert, John J; Horn, David J

2008-10-01

Ant attendance is known to affect the population dynamics of aphids and may increase or decrease aphid populations through stimulation, predation, or protection. In this study, we performed a series of laboratory experiments to examine the effects of ant attendance on populations of the soybean aphid Aphis glycines. Aphid colonies were exposed to the predators Harmonia axyridis (Coccinellidae) and Orius insidiosus (Anthocoridae) and a parasitoid Aphidius colemani (Aphidiidae) in the presence and absence of attending Monomorium minimum (Formicidae). We also tested for direct effects of ant attendance in the absence of natural enemies. Ants attending soybean aphid populations were observed harassing or killing O. insidiosus and H. axyridis. Attendance interfered with both predator species, resulting in reduced predation and an increase in aphid numbers up to 10-fold in the presence of ants. Ants were not observed directly interfering with the parasitoid A. colemani, but the number of parasitized aphids was higher in aphid colonies that were left unattended by ants.

The photochemical reflectance index from directional cornfield reflectances: Observations and simulations

USDA-ARS?s Scientific Manuscript database

The two-layer Markov chain Analytical Canopy Reflectance Model (ACRM) was linked with in situ hyperspectral leaf optical properties to simulate the Photochemical Reflectance Index (PRI) for a corn crop canopy at three different growth stages. This is an extended study after a successful demonstratio...

Aphid Infestation Increases Fusarium langsethiae and T-2 and HT-2 Mycotoxins in Wheat

PubMed Central

Drakulic, Jassy; Ajigboye, Olubukola; Swarup, Ranjan; Bruce, Toby

2016-01-01

ABSTRACT Fusarium langsethiae is a fungal pathogen of cereal crops that is an increasing problem in northern Europe, but much of its epidemiology is poorly understood. The species produces the mycotoxins T-2 and HT-2, which are highly toxic. It was hypothesized that grain aphids, Sitobion avenae, may transmit F. langsethiae inoculum between wheat plants, and a series of transmission experiments and volatile chemical analyses was performed to test this. Manual translocation of aphids from inoculated to uninfected hosts resulted in pathogen DNA accumulation in hosts. However, the free movement of wingless aphids from infected to healthy plants did not. The addition of winged aphids reared on F. langsethiae-inoculated wheat seedlings to wheat plants also did not achieve successful pathogen transfer. While our data suggested that aphid transmission of the pathogen was not very efficient, we observed an increase in disease when aphids were present. After seedling inoculation, an increase in pathogen DNA accumulation in seedling leaves was observed upon treatment with aphids. Furthermore, the presence of aphids on wheat plants with F. langsethiae-inoculated ears not only led to a rise in the amount of F. langsethiae DNA in infected grain but also to an increase in the concentrations of T-2 and HT-2 toxins, with more than 3-fold higher toxin levels than diseased plants without aphids. This work highlights that aphids increase the susceptibility of wheat host plants to F. langsethiae and that aphid infestation is a risk factor for accumulating increased levels of T-2 and HT-2 in wheat products. IMPORTANCE Fusarium langsethiae is shown here to cause increased contamination levels of grain with toxins produced by fungus when aphids share the host plant. This effect has also recently been demonstrated with Fusarium graminearum, yet the two fungal species show stark differences in their effect on aphid populations. In both cases, aphids improve the ability of the pathogens to cause and initiate Fusarium head blight (FHB) disease in wheat, but F. langsethiae may be able to act as a dispersal agent. F. langsethiae contributes harmful toxins to wheat grain that need to be controlled, but as yet, its epidemiology is unresolved. This work reveals insights into the role aphids play in promoting the successful colonization of this species in wheat and the benefit of controlling aphid populations on crops that are at high risk of FHB. PMID:27590814

Bt crops benefit natural enemies to control non-target pests

PubMed Central

Tian, Jun-Ce; Yao, Ju; Long, Li-Ping; Romeis, Jörg; Shelton, Anthony M.

2015-01-01

Crops producing insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) control important lepidopteran pests. However, pests such as aphids not susceptible to Cry proteins may require other integrated pest management (IPM) tactics, including biological control. We fed aphids on Bt and non-Bt plants and analyzed the Bt protein residue in aphids and compared the effects of Bt plants and a pyrethroid, lambda-cyhalothrin, on the performance of three natural enemies (predators: Coleomegilla maculata and Eupeodes americanus; parasitoid Aphidius colemani) of the green peach aphid, Myzus persicae. No Bt protein residues in aphids were detected and no significant differences were recorded in the performance of pyrethroid-resistant aphids that fed on Bt broccoli expressing Cry1Ab or Cry1C, or on non-Bt broccoli plants treated or not treated with the pyrethroid. This indicated the aphids were not affected by the Cry proteins or the pyrethroid, thus removing any effect of prey quality. Tri-trophic experiments demonstrated that no C. maculata and E. americanus survived consumption of pyrethroid-treated aphids and that ovipositional behavior of A. colemani was impaired when provided with pyrethroid-treated aphids. In contrast, natural enemies were not affected when fed aphids reared on Bt broccoli, thus demonstrating the safety of these Bt plants for IPM. PMID:26559133

Bt crops benefit natural enemies to control non-target pests.

PubMed

Tian, Jun-Ce; Yao, Ju; Long, Li-Ping; Romeis, Jörg; Shelton, Anthony M

2015-11-12

Crops producing insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) control important lepidopteran pests. However, pests such as aphids not susceptible to Cry proteins may require other integrated pest management (IPM) tactics, including biological control. We fed aphids on Bt and non-Bt plants and analyzed the Bt protein residue in aphids and compared the effects of Bt plants and a pyrethroid, lambda-cyhalothrin, on the performance of three natural enemies (predators: Coleomegilla maculata and Eupeodes americanus; parasitoid Aphidius colemani) of the green peach aphid, Myzus persicae. No Bt protein residues in aphids were detected and no significant differences were recorded in the performance of pyrethroid-resistant aphids that fed on Bt broccoli expressing Cry1Ab or Cry1C, or on non-Bt broccoli plants treated or not treated with the pyrethroid. This indicated the aphids were not affected by the Cry proteins or the pyrethroid, thus removing any effect of prey quality. Tri-trophic experiments demonstrated that no C. maculata and E. americanus survived consumption of pyrethroid-treated aphids and that ovipositional behavior of A. colemani was impaired when provided with pyrethroid-treated aphids. In contrast, natural enemies were not affected when fed aphids reared on Bt broccoli, thus demonstrating the safety of these Bt plants for IPM.

Simulating crop phenology in the Community Land Model and its impact on energy and carbon fluxes

NASA Astrophysics Data System (ADS)

Chen, Ming; Griffis, Tim J.; Baker, John; Wood, Jeffrey D.; Xiao, Ke

2015-02-01

A reasonable representation of crop phenology and biophysical processes in land surface models is necessary to accurately simulate energy, water, and carbon budgets at the field, regional, and global scales. However, the evaluation of crop models that can be coupled to Earth system models is relatively rare. Here we evaluated two such models (CLM4-Crop and CLM3.5-CornSoy), both implemented within the Community Land Model (CLM) framework, at two AmeriFlux corn-soybean sites to assess their ability to simulate phenology, energy, and carbon fluxes. Our results indicated that the accuracy of net ecosystem exchange and gross primary production simulations was intimately connected to the phenology simulations. The CLM4-Crop model consistently overestimated early growing season leaf area index, causing an overestimation of gross primary production, to such an extent that the model simulated a carbon sink instead of the measured carbon source for corn. The CLM3.5-CornSoy-simulated leaf area index (LAI), energy, and carbon fluxes showed stronger correlations with observations compared to CLM4-Crop. Net radiation was biased high in both models and was especially pronounced for soybeans. This was primarily caused by the positive LAI bias, which led to a positive net long-wave radiation bias. CLM4-Crop underestimated soil water content during midgrowing season in all soil layers at the two sites, which caused unrealistic water stress, especially for soybean. Future work regarding the mechanisms that drive early growing season phenology and soil water dynamics is needed to better represent crops including their net radiation balance, energy partitioning, and carbon cycle processes.

Crop modeling: Studying the effect of water stress on the driving forces governing plant water potential

NASA Astrophysics Data System (ADS)

van Emmerik, T. H. M.; Mirfenderesgi, G.; Bohrer, G.; Steele-Dunne, S. C.; Van De Giesen, N.

2015-12-01

Water stress is one of the most important environmental factors that influence plant water dynamics. To prevent excessive water loss and physiological damage, plants can regulate transpiration by adjusting the stomatal aperture. This enhances survival, but also reduced photosynthesis and productivity. During periods of low water availability, stomatal regulation is a trade-off between optimization of either survival or production. Water stress defence mechanisms lead to significant changes in plant dynamics, e.g. leaf and stem water content. Recent research has shown that water content in a corn canopy can change up to 30% diurnally as a result of water stress, which has a considerable influence on radar backscatter from a corn canopy [1]. This highlighted the potential of water stress detection using radar. To fully explore the potential of water stress monitoring using radar, we need to understand the driving forces governing plant water potential. For this study, the recently developed the Finite-Element Tree-Crown Hydrodynamic model version 2 (FETCH2) model is applied to a corn canopy. FETCH2 is developed to resolve the hydrodynamic processes within a plant using the porous media analogy, allowing investigation of the influence of environmental stress factors on plant dynamics such as transpiration, photosynthesis, stomatal conductance, and leaf and stem water content. The model is parameterized and evaluated using a detailed dataset obtained during a three-month field experiment in Flevoland, the Netherlands, on a corn canopy. [1] van Emmerik, T., S. Steele-Dunne, J. Judge and N. van de Giesen: "Impact of Diurnal Variation in Vegetation Water Content on Radar Backscatter of Maize During Water Stress", Geosciences and Remote Sensing, IEEE Transactions on, vol. 52, issue 7, doi: 10.1109/TGRS.2014.2386142, 2015.

Spatial Distribution and Sampling Plans With Fixed Level of Precision for Citrus Aphids (Hom., Aphididae) on Two Orange Species.

PubMed

Kafeshani, Farzaneh Alizadeh; Rajabpour, Ali; Aghajanzadeh, Sirous; Gholamian, Esmaeil; Farkhari, Mohammad

2018-04-02

Aphis spiraecola Patch, Aphis gossypii Glover, and Toxoptera aurantii Boyer de Fonscolombe are three important aphid pests of citrus orchards. In this study, spatial distributions of the aphids on two orange species, Satsuma mandarin and Thomson navel, were evaluated using Taylor's power law and Iwao's patchiness. In addition, a fixed-precision sequential sampling plant was developed for each species on the host plant by Green's model at precision levels of 0.25 and 0.1. The results revealed that spatial distribution parameters and therefore the sampling plan were significantly different according to aphid and host plant species. Taylor's power law provides a better fit for the data than Iwao's patchiness regression. Except T. aurantii on Thomson navel orange, spatial distribution patterns of the aphids were aggregative on both citrus. T. aurantii had regular dispersion pattern on Thomson navel orange. Optimum sample size of the aphids varied from 30-2061 and 1-1622 shoots on Satsuma mandarin and Thomson navel orange based on aphid species and desired precision level. Calculated stop lines of the aphid species on Satsuma mandarin and Thomson navel orange ranged from 0.48 to 19 and 0.19 to 80.4 aphids per 24 shoots according to aphid species and desired precision level. The performance of the sampling plan was validated by resampling analysis using resampling for validation of sampling plans (RVSP) software. This sampling program is useful for IPM program of the aphids in citrus orchards.

National Plant Diagnostic Network, Taxonomic training videos: Introduction to Aphids - Part 1

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on important subject areas for aphid examination and identification. Aphid topics such as classification, morphology, plant disease transmission, and references are discussed. This dis...

Aphids capable of fine resolution landing

USDA-ARS?s Scientific Manuscript database

Aphids vector many devastating plant viruses, including the non-persistent papaya ringspot virus (PRSV), which reduces yield in both cucurbits and papaya. It has been demonstrated that some aphids are more attracted to colors symptomatic of virus infection, especially yellow. However, alate aphids a...

The ethylene response factor Pti5 contributes to potato aphid resistance in tomato independent of ethylene signalling

PubMed Central

Wu, Chengjun; Avila, Carlos A.; Goggin, Fiona L.

2015-01-01

Ethylene response factors (ERFs) comprise a large family of transcription factors that regulate numerous biological processes including growth, development, and response to environmental stresses. Here, we report that Pti5, an ERF in tomato [Solanum lycopersicum (Linnaeus)] was transcriptionally upregulated in response to the potato aphid Macrosiphum euphorbiae (Thomas), and contributed to plant defences that limited the population growth of this phloem-feeding insect. Virus-induced gene silencing of Pti5 enhanced aphid population growth on tomato, both on an aphid-susceptible cultivar and on a near-isogenic genotype that carried the Mi-1.2 resistance (R) gene. These results indicate that Pti5 contributes to basal resistance in susceptible plants and also can synergize with other R gene-mediated defences to limit aphid survival and reproduction. Although Pti5 contains the ERF motif, induction of this gene by aphids was independent of ethylene, since the ACC deaminase (ACD) transgene, which inhibits ethylene synthesis, did not diminish the responsiveness of Pti5 to aphid infestation. Furthermore, experiments with inhibitors of ethylene synthesis revealed that Pti5 and ethylene have distinctly different roles in plant responses to aphids. Whereas Pti5 contributed to antibiotic plant defences that limited aphid survival and reproduction on both resistant (Mi-1.2+) and susceptible (Mi-1.2–) genotypes, ethylene signalling promoted aphid infestation on susceptible plants but contributed to antixenotic defences that deterred the early stages of aphid host selection on resistant plants. These findings suggest that the antixenotic defences that inhibit aphid settling and the antibiotic defences that depress fecundity and promote mortality are regulated through different signalling pathways. PMID:25504643

Loss of Function of FATTY ACID DESATURASE7 in Tomato Enhances Basal Aphid Resistance in a Salicylate-Dependent Manner1[W][OA

PubMed Central

Avila, Carlos A.; Arévalo-Soliz, Lirio M.; Jia, Lingling; Navarre, Duroy A.; Chen, Zhaorigetu; Howe, Gregg A.; Meng, Qing-Wei; Smith, Jonathon E.; Goggin, Fiona L.

2012-01-01

We report here that disruption of function of the ω-3 FATTY ACID DESATURASE7 (FAD7) enhances plant defenses against aphids. The suppressor of prosystemin-mediated responses2 (spr2) mutation in tomato (Solanum lycopersicum), which eliminates the function of FAD7, reduces the settling behavior, survival, and fecundity of the potato aphid (Macrosiphum euphorbiae). Likewise, the antisense suppression of LeFAD7 expression in wild-type tomato plants reduces aphid infestations. Aphid resistance in the spr2 mutant is associated with enhanced levels of salicylic acid (SA) and mRNA encoding the pathogenesis-related protein P4. Introduction of the Naphthalene/salicylate hydroxylase transgene, which suppresses SA accumulation, restores wild-type levels of aphid susceptibility to spr2. Resistance in spr2 is also lost when we utilize virus-induced gene silencing to suppress the expression of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1), a positive regulator of many SA-dependent defenses. These results indicate that FAD7 suppresses defenses against aphids that are mediated through SA and NPR1. Although loss of function of FAD7 also inhibits the synthesis of jasmonate (JA), the effects of this desaturase on aphid resistance are not dependent on JA; other mutants impaired in JA synthesis (acx1) or perception (jai1-1) show wild-type levels of aphid susceptibility, and spr2 retains aphid resistance when treated with methyl jasmonate. Thus, FAD7 may influence JA-dependent defenses against chewing insects and SA-dependent defenses against aphids through independent effects on JA synthesis and SA signaling. The Arabidopsis (Arabidopsis thaliana) mutants Atfad7-2 and Atfad7-1fad8 also show enhanced resistance to the green peach aphid (Myzus persicae) compared with wild-type controls, indicating that FAD7 influences plant-aphid interactions in at least two plant families. PMID:22291202

Aphid-encoded variability in susceptibility to a parasitoid

PubMed Central

2014-01-01

Background Many animals exhibit variation in resistance to specific natural enemies. Such variation may be encoded in their genomes or derived from infection with protective symbionts. The pea aphid, Acyrthosiphon pisum, for example, exhibits tremendous variation in susceptibility to a common natural enemy, the parasitic wasp Aphidius ervi. Pea aphids are often infected with the heritable bacterial symbiont, Hamiltonella defensa, which confers partial to complete resistance against this parasitoid depending on bacterial strain and associated bacteriophages. That previous studies found that pea aphids without H. defensa (or other symbionts) were generally susceptible to parasitism, together with observations of a limited encapsulation response, suggested that pea aphids largely rely on infection with H. defensa for protection against parasitoids. However, the limited number of uninfected clones previously examined, and our recent report of two symbiont-free resistant clones, led us to explicitly examine aphid-encoded variability in resistance to parasitoids. Results After rigorous screening for known and unknown symbionts, and microsatellite genotyping to confirm clonal identity, we conducted parasitism assays using fifteen clonal pea aphid lines. We recovered significant variability in aphid-encoded resistance, with variation levels comparable to that contributed by H. defensa. Because resistance can be costly, we also measured aphid longevity and cumulative fecundity of the most and least resistant aphid lines under permissive conditions, but found no trade-offs between higher resistance and these fitness parameters. Conclusions These results indicate that pea aphid resistance to A. ervi is more complex than previously appreciated, and that aphids employ multiple tactics to aid in their defense. While we did not detect a tradeoff, these may become apparent under stressful conditions or when resistant and susceptible aphids are in direct competition. Understanding sources and amounts of variation in resistance to natural enemies is necessary to understand the ecological and evolutionary dynamics of antagonistic interactions, such as the potential for coevolution, but also for the successful management of pest populations through biological control. PMID:24916045

Differential divergences of obligately insect-pathogenic Entomophthora species from fly and aphid hosts.

PubMed

Jensen, Annette Bruun; Eilenberg, Jørgen; López Lastra, Claudia

2009-11-01

Three DNA regions (ITS 1, LSU rRNA and GPD) of isolates from the insect-pathogenic fungus genus Entomophthora originating from different fly (Diptera) and aphid (Hemiptera) host taxa were sequenced. The results documented a large genetic diversity among the fly-pathogenic Entomophthora and only minor differences among aphid-pathogenic Entomophthora. The evolutionary time of divergence of the fly and the aphid host taxa included cannot account for this difference. The host-driven divergence of Entomophthora, therefore, has been much greater in flies than in aphids. Host-range differences or a recent host shift to aphid are possible explanations.

Escherichia coli K-12 pathogenicity in the pea aphid, Acyrthosiphon pisum, reveals reduced antibacterial defense in aphids.

PubMed

Altincicek, Boran; Ter Braak, Bas; Laughton, Alice M; Udekwu, Klas I; Gerardo, Nicole M

2011-10-01

To better understand the molecular basis underlying aphid immune tolerance to beneficial bacteria and immune defense to pathogenic bacteria, we characterized how the pea aphid Acyrthosiphon pisum responds to Escherichia coli K-12 infections. E. coli bacteria, usually cleared in the hemolymph of other insect species, were capable of growing exponentially and killing aphids within a few days. Red fluorescence protein expressing E. coli K-12 laboratory strain multiplied in the aphid hemolymph as well as in the digestive tract, resulting in death of infected aphids. Selected gene deletion mutants of the E. coli K-12 predicted to have reduced virulence during systemic infections showed no difference in either replication or killing rate when compared to the wild type E. coli strain. Of note, however, the XL1-Blue E. coli K-12 strain exhibited a significant lag phase before multiplying and killing aphids. This bacterial strain has recently been shown to be more sensitive to oxidative stress than other E. coli K-12 strains, revealing a potential role for reactive oxygen species-mediated defenses in the otherwise reduced aphid immune system. Copyright © 2011 Elsevier Ltd. All rights reserved.

To feed or not to feed: plant factors located in the epidermis, mesophyll, and sieve elements influence pea aphid's ability to feed on legume species.

PubMed

Schwarzkopf, Alexander; Rosenberger, Daniel; Niebergall, Martin; Gershenzon, Jonathan; Kunert, Grit

2013-01-01

The pea aphid (Acyrthosiphon pisum Harris), a legume specialist, encompasses at least 11 genetically distinct sympatric host races. Each host race shows a preference for a certain legume species. Six pea aphid clones from three host races were used to localize plant factors influencing aphid probing and feeding behavior on four legume species. Aphid performance was tested by measuring survival and growth. The location of plant factors influencing aphid probing and feeding was determined using the electrical penetration graph (EPG) technique. Every aphid clone performed best on the plant species from which it was originally collected, as well as on Vicia faba. On other plant species, clones showed intermediate or poor performance. The most important plant factors influencing aphid probing and feeding behavior were localized in the epidermis and sieve elements. Repetitive puncturing of sieve elements might be relevant for establishing phloem feeding, since feeding periods appear nearly exclusively after these repetitive sieve element punctures. A combination of plant factors influences the behavior of pea aphid host races on different legume species and likely contributes to the maintenance of these races.

Elevated atmospheric carbon dioxide concentrations promote ant tending of aphids.

PubMed

Kremer, Jenni M M; Nooten, Sabine S; Cook, James M; Ryalls, James M W; Barton, Craig V M; Johnson, Scott N

2018-04-27

Animal mutualisms, which involve beneficial interactions between individuals of different species, are common in nature. Insect-insect mutualism, for example, is widely regarded as a keystone ecological interaction. Some mutualisms are anticipated to be modified by climate change, but the focus has largely been on plant-microbe and plant-animal mutualisms rather than those between animals. Ant-aphid mutualisms, whereby ants tend aphids to harvest their honeydew excretions and, in return, provide protection for the aphids, are widespread. The mutualism is heavily influenced by the quality and quantity of honeydew produced by aphids, which is directly affected by host plant quality. As predicted increases in concentrations of atmospheric carbon dioxide (eCO 2 ) are widely reported to affect plant nutritional chemistry, this may also alter honeydew quality and hence the nature of ant-aphid mutualisms. Using glasshouse chambers and field-based open-top chambers, we determined the effect of eCO 2 on the growth and nutritional quality (foliar amino acids) of lucerne (Medicago sativa). We determined how cowpea aphid (Aphis craccivora) populations and honeydew production were impacted when feeding on such plants and how this affected the tending behaviour of ants (Iridomyrmex sp.). eCO 2 stimulated plant growth but decreased concentrations of foliar amino acids by 29% and 14% on aphid-infested plants and aphid-free plants, respectively. Despite the deterioration in host plant quality under eCO 2 , aphids maintained performance and populations were unchanged by eCO 2 . Aphids induced higher concentrations of amino acids (glutamine, asparagine, glutamic acid and aspartic acid) important for endosymbiont-mediated synthesis of essential amino acids. Aphids feeding under eCO 2 also produced over three times more honeydew than aphids feeding under ambient CO 2 , suggesting they were imbibing more phloem sap at eCO 2 . The frequency of ant tending of aphids more than doubled in response to eCO 2 . To our knowledge, this is the first study to demonstrate the effects of atmospheric change on an ant-aphid mutualism. In particular, these results highlight how impending changes to concentrations of atmospheric CO 2 may alter mutualistic behaviour between animals. These could include positive impacts, as reported here, shifts from mutualism to antagonism, partner switches and mutualism abandonment. © 2018 The Authors. Journal of Animal Ecology © 2018 British Ecological Society.

National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - overview

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This training video provides provides an overview of general aphid morphology by using a compound microscope. The narrator discusses and highlights structures on the aphid that are important to make a species identification....

Gene expression analysis of parthenogenetic embryonic development of the pea aphid, Acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.

PubMed

Srinivasan, Dayalan G; Abdelhady, Ahmed; Stern, David L

2014-01-01

Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity.

Gene Expression Analysis of Parthenogenetic Embryonic Development of the Pea Aphid, Acyrthosiphon pisum, Suggests That Aphid Parthenogenesis Evolved from Meiotic Oogenesis

PubMed Central

Srinivasan, Dayalan G.; Abdelhady, Ahmed; Stern, David L.

2014-01-01

Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity. PMID:25501006

Aphid Species Affect Foraging Behavior of Coccinella septempunctata (Coccinellidae: Coleoptera).

PubMed

Farooq, Muhammad Umar; Qadri, Hafiz Faqir Hussain; Khan, Muhammad Ahmad

2017-01-01

Flowers are admirable in scenic good looks and artistic beautification. These are also playing necessary roles in therapeutic preparations. Aphid is an important sucking pest of various flowers in ornamental territories and it is generally controlled by predators, so it was necessary to evaluate which aphid species affect the predator more or less. Biocontrol agent Coccinella septempunctata was used against cosmos aphid (Aphis spiraecola, rose aphid (Macrosiphum rosea), gul e ashrafi aphid (Aphis fabae), kaner aphid (Aphis nerii), chandni aphid (Sitobion avenae), dahlia aphid (Myzus persicae) and annual chrysanthemum aphid (Macrosiphoniella sanborni). The grub of C. septempunctata consumed 283.8±9.04 M. rosea, 487.7±12.6 M. sanborni, 432.75±16.02 A. spiraecola, 478.2±8.07 A. fabae, 552.3±9.04 M. persicae, 142±1.32 A. nerii and 498.5±13.09 S. avenae in its whole larval life. The M. persicae and M. rosea consuming grubs showed 100% adult emergence while, M. sanborni, A. spiraecola, A. fabae and S. avenae showed 96.58, 89.02, 94.78 and 75.45% adult emergence, respectively. The C. septempunctata has significant predatory potential against A. spiraecola, M. rosea, A. fabae, S. avenae, M. persicae and M. sanborni except A. nerii. Thus, further studies are needed to find out alternate predator to control A. nerii on ornamentals.

Peroxiredoxin 1 protects the pea aphid Acyrthosiphon pisum from oxidative stress induced by Micrococcus luteus infection.

PubMed

Zhang, Yongdong; Lu, Zhiqiang

2015-05-01

Reactive oxygen species (ROSs) are generated in organisms in response to infections caused by invading microbes. However, excessive ROSs will inflict oxidative damage on the host. Peroxiredoxins (Prxs) are antioxidative enzymes that may eliminate ROSs efficiently. In this study, ApPrx1 from the pea aphid Acyrthosiphon pisum was cloned, and its function was investigated in vitro and in vivo. In the presence of DTT, recombinant ApPrx1 protein from Escherichia coli showed antioxidative activity by eliminating H2O2 effectively. The H2O2 levels were significantly higher in Micrococcus luteus-infected aphids than in uninfected aphids, and ApPrx1 expression was remarkably up-regulated when the aphids were infected with M. luteus or injected with H2O2. When ApPrx1 expression was reduced by dsRNA injection, the survival of the aphids decreased significantly after M. luteus infection. Knockdown of ApPrx1 decreased M. luteus loads inside the aphids 48h post-infection. While under infection conditions, the H2O2 levels were much higher in ApPrx1 knockdown aphids than in dsGFP-injected aphids, indicating that the decreased survival of the aphids was caused by increased oxidative stress. Taken together, our results reveal that ApPrx1 plays a protective role in oxidative stress caused by bacterial infection. Copyright © 2015 Elsevier Inc. All rights reserved.

Arabidopsis thaliana—Myzus persicae interaction: shaping the understanding of plant defense against phloem-feeding aphids

PubMed Central

Louis, Joe; Shah, Jyoti

2013-01-01

The phloem provides a unique niche for several organisms. Aphids are a large group of Hemipteran insects that utilize stylets present in their mouthparts to pierce sieve elements and drink large volumes of phloem sap. In addition, many aphids also vector viral diseases. Myzus persicae, commonly known as the green peach aphid (GPA), is an important pest of a large variety of plants that includes Arabidopsis thaliana. This review summarizes recent studies that have exploited the compatible interaction between Arabidopsis and GPA to understand the molecular and physiological mechanisms utilized by plants to control aphid infestation, as well as genes and mechanisms that contribute to susceptibility. In addition, recent efforts to identify aphid-delivered elicitors of plant defenses and novel aphid salivary components that facilitate infestation are also discussed. PMID:23847627

Transcriptome Analysis of Green Peach Aphid (Myzus persicae): Insight into Developmental Regulation and Inter-Species Divergence

PubMed Central

Ji, Rui; Wang, Yujun; Cheng, Yanbin; Zhang, Meiping; Zhang, Hong-Bin; Zhu, Li; Fang, Jichao; Zhu-Salzman, Keyan

2016-01-01

Green peach aphid (Myzus persicae) and pea aphid (Acyrthosiphon pisum) are two phylogenetically closely related agricultural pests. While pea aphid is restricted to Fabaceae, green peach aphid feeds on hundreds of plant species from more than 40 families. Transcriptome comparison could shed light on the genetic factors underlying the difference in host range between the two species. Furthermore, a large scale study contrasting gene expression between immature nymphs and fully developed adult aphids would fill a previous knowledge gap. Here, we obtained transcriptomic sequences of green peach aphid nymphs and adults, respectively, using Illumina sequencing technology. A total of 2244 genes were found to be differentially expressed between the two developmental stages, many of which were associated with detoxification, hormone production, cuticle formation, metabolism, food digestion, and absorption. When searched against publically available pea aphid mRNA sequences, 13,752 unigenes were found to have no homologous counterparts. Interestingly, many of these unigenes that could be annotated in other databases were involved in the “xenobiotics biodegradation and metabolism” pathway, suggesting the two aphids differ in their adaptation to secondary metabolites of host plants. Conversely, 3989 orthologous gene pairs between the two species were subjected to calculations of synonymous and nonsynonymous substitutions, and 148 of the genes potentially evolved in response to positive selection. Some of these genes were predicted to be associated with insect-plant interactions. Our study has revealed certain molecular events related to aphid development, and provided some insight into biological variations in two aphid species, possibly as a result of host plant adaptation. PMID:27812361

Brevicoryne brassicae aphids interfere with transcriptome responses of Arabidopsis thaliana to feeding by Plutella xylostella caterpillars in a density-dependent manner.

PubMed

Kroes, Anneke; Broekgaarden, Colette; Castellanos Uribe, Marcos; May, Sean; van Loon, Joop J A; Dicke, Marcel

2017-01-01

Plants are commonly attacked by multiple herbivorous species. Yet, little is known about transcriptional patterns underlying plant responses to multiple insect attackers feeding simultaneously. Here, we assessed transcriptomic responses of Arabidopsis thaliana plants to simultaneous feeding by Plutella xylostella caterpillars and Brevicoryne brassicae aphids in comparison to plants infested by P. xylostella caterpillars alone, using microarray analysis. We particularly investigated how aphid feeding interferes with the transcriptomic response to P. xylostella caterpillars and whether this interference is dependent on aphid density and time since aphid attack. Various JA-responsive genes were up-regulated in response to feeding by P. xylostella caterpillars. The additional presence of aphids, both at low and high densities, clearly affected the transcriptional plant response to caterpillars. Interestingly, some important modulators of plant defense signalling, including WRKY transcription factor genes and ABA-dependent genes, were differentially induced in response to simultaneous aphid feeding at low or high density compared with responses to P. xylostella caterpillars feeding alone. Furthermore, aphids affected the P. xylostella-induced transcriptomic response in a density-dependent manner, which caused an acceleration in plant response against dual insect attack at high aphid density compared to dual insect attack at low aphid density. In conclusion, our study provides evidence that aphids influence the caterpillar-induced transcriptional response of A. thaliana in a density-dependent manner. It highlights the importance of addressing insect density to understand how plant responses to single attackers interfere with responses to other attackers and thus underlines the importance of the dynamics of transcriptional plant responses to multiple herbivory.

AphID (Lucid key) http://AphID.AphidNet.org

USDA-ARS?s Scientific Manuscript database

This peer-reviewed web site concentrates on the 66 adult alate and apterous aphids that are the world's most cosmopolitan and polyphagous species. The site includes fact sheets about the various aphids species, a glossary of terms helpful to the student, hundreds of photographs and illustrations, a...

Mapping soybean aphid resistance genes in PI 567598B

USDA-ARS?s Scientific Manuscript database

The soybean aphid (Aphis glycines Matsumura) has been a major pest of soybean [Glycine max (L.) Merr.] in North America since it was first discovered in 2000. Plant introduction PI 567598B possesses strong antibiosis resistance to soybean aphids. Our previous study revealed that the aphid resistan...

Comparison of transmission efficiency of different isolates of Potato virus Y among three aphid vectors

USDA-ARS?s Scientific Manuscript database

Potato virus Y (PVY) strains are transmitted by different aphid species in a non-persistent, non-circulative manner. Green peach aphid (GPA, Myzus persicae Sulzer; Aphididae, Macrosiphini) is the most efficient vector in laboratory studies, but potato aphid (PA, Macrosiphum euphorbiae Thomas; Aphidi...

National Plant Diagnostic Network, Taxonomic training videos: Introduction to AphID

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on the use of the expert system, AphID, for aphid examination and identification. The video demonstrates the use of different training modules that allow the user to gain familiarity wi...

Variable isotopic compositions of host plant populations preclude assessment of aphid overwintering sites

USDA-ARS?s Scientific Manuscript database

Soybean aphid (Aphis glycines Matsumura) is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a...

First report of Pandora neoaphidis resting spore formation in vivo in aphid hosts under field conditions

USDA-ARS?s Scientific Manuscript database

The entomopathogenic fungus PANDORA NEOAPHIDIS is a recognized pathogen of aphids, causing natural epizootics in aphid populations, and interacts favorably with aphid predators and parasitoids. Survival of entomophthoralean fungi in periods of unsuitable weather conditions or lack of appropriate hos...

Evaluation of aphid resistance among sugarcane cultivars in Louisiana

USDA-ARS?s Scientific Manuscript database

Sugarcane, interspecific hybrids of Saccharum spp., in Louisiana is colonized by two aphid species, the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes). Five sugarcane cultivars, LCP 85-384, HoCP 91-555, Ho 95-988, HoCP 96-540, and L 97-128, rep...

Relating the radar backscattering coefficient to leaf-area index

NASA Technical Reports Server (NTRS)

Ulaby, F. T. (Principal Investigator); Allen, C.; Eger, G.; Kanemasu, E.

1983-01-01

The relationship between the radar backscattering coefficient of a vegetation canopy, sigma(0) sub can, and the canopy's leaf area index (LAI) is examined. The relationship is established through the development of a model for corn and sorghum and another for wheat. Both models are extensions of the cloud model of Attema and Ulaby (1978). Analysis of experimental data measured at 8.6, 13.0, 17.0, and 35.6 GHz indicates that most of the temporal variations of sigma(0) sub can can be accounted for through variations in green LAI alone, if the latter is greater than 0.5.

Utilizing in situ Directional Hyperpectral Measurements to Validate Bio-Indicator Simulations for a Corn Crop Canaopy

USDA-ARS?s Scientific Manuscript database

Two radiative transfer canopy models, SAIL and the Markov-Chain Canopy Reflectance Model (MRCM), were coupled with in situ leaf optical properties to simulate canopy-level spectral band ratio vegetation indices with the focus on the Photochemical Reflectance Index (PRI) in a cornfield. In situ hyper...

The Hornworm Assay: Useful in Mathematically-Based Biological Investigations

ERIC Educational Resources Information Center

Rice, Stanley A.; Griffin, Jennifer R.

2004-01-01

Hornworms are good assay organisms for leaf toxins, and can be raised on an artificial medium ("chow"), consisting of corn meal, soy flour, dry milk, yeast and other additives and preservatives. The hornworm assay is less useful in ecological and toxicological research, but is very useful in learning about experimental design and hypothesis…

First report of xanthomonas vasicola causing bacterial leaf streak on corn in the United States

USDA-ARS?s Scientific Manuscript database

In 2014 and 2015, Zea mays samples (field, seed, and popcorn) were submitted to the Plant and Pest Diagnostic Clinic at the University of Nebraska – Lincoln displaying long, dark, yellow to brown, water-soaked, linear lesions confined to the interveinal spaces of the leaves. Initial symptoms appeare...

Comparing LAI estimates of corn and soybean from vegetation indices of multi-resolution satellite images

USDA-ARS?s Scientific Manuscript database

Leaf area index (LAI) is important in explaining the ability of the crop to intercept solar energy for biomass production and in understanding the impact of crop management practices. This paper describes a procedure for estimating LAI as a function of image-derived vegetation indices from temporal ...

Phytotoxical effect of Lepidium draba L. extracts on the germination and growth of monocot (Zea mays L.) and dicot (Amaranthus retroflexus L.) seeds.

PubMed

Kaya, Yusuf; Aksakal, Ozkan; Sunar, Serap; Erturk, Filiz Aygun; Bozari, Sedat; Agar, Guleray; Erez, Mehmet Emre; Battal, Peyami

2015-03-01

Laboratory experiments were performed to determine phytotoxic potentials of white top (Lepidium draba) methanol extracts (root, stem and leaf) on germination and early growth of corn (Zea mays) and redroot pigweed (Amaranthus retroflexus). Furthermore, the effects of different methanol extracts of L. draba on the phytohormone (indole-3-acetic acid (IAA), gibberellic acid (GA), abscisic acid (ABA) and zeatin) levels of corn and redroot pigweed were investigated. It was observed that all concentrations of methanol extracts of root, stem and leaf of L. draba inhibited germination, radicle and plumule elongation when compared with the respective controls. Besides this, the degree of inhibition was increased in concert with increasing concentrations of extracts used. On the other hand, phytohormone levels changed with the application of different extract concentrations. Comparing with the control, the GA levels significantly decreased while the ABA levels increased in all the application groups. Zeatin and IAA levels showed changes depending upon the applied extracts and concentrations. © The Author(s) 2012.

Emissions of Monoterpenes and DMS from Corn and their Influence on Nighttime Chemical Processing of Nitrogen Oxides

NASA Astrophysics Data System (ADS)

Graus, M.; De Gouw, J. A.; Brown, S. S.; Williams, E. J.; Eller, A. S.; Gilman, J. B.; Lerner, B. M.; Fall, R.; Warneke, C.

2012-12-01

In the United States large amounts of corn are grown for the use as animal feed, for the food industry and for the production of fuel ethanol. In 2012 the acreage of corn planted was 390,000 km2 covering over 4.2% of the US land surface. The BioCORN 2011 field experiment took place in summer 2011 to look at ecosystem fluxes of volatile organic compounds (VOCs) from a cornfield in Colorado during the period of rapid biomass increase and the development of flowers and ears. Eddy covariance, soil and leaf cuvette measurements using various instruments including PTR-MS, NI-PT-CIMS and GC-MS were used to determine fluxes of VOCs, CO2 and NOx. Corn plants emit significant amounts of VOCs with methanol being the largest emission and smaller emissions of other VOCs such acetone, acetaldehyde, monoterpene and dimethylsulfide (DMS). During the day VOCs mainly react with hydroxyl radicals and during the night with nitrate radicals (NO3), where emissions from corn may act as a sink for reactive nitrogen. DMS, mainly emitted from oceans and to a lesser extent from terrestrial vegetation, had a diurnal cycle: mixing ratios high during the night, but fluxes high during the day. DMS was found to dominate the reactivity of NO3 followed by monoterpenes and the heterogeneous loss of N2O5, which has implications for the nighttime chemistry. Other results of BioCORN 2011 on VOC emissions from corn and their impact on atmospheric chemistry will be presented and discussed.

Prediction of County-Level Corn Yields Using an Energy-Crop Growth Index.

NASA Astrophysics Data System (ADS)

Andresen, Jeffrey A.; Dale, Robert F.; Fletcher, Jerald J.; Preckel, Paul V.

1989-01-01

Weather conditions significantly affect corn yields. while weather remains as the major uncontrolled variable in crop production, an understanding of the influence of weather on yields can aid in early and accurate assessment of the impact of weather and climate on crop yields and allow for timely agricultural extension advisories to help reduce farm management costs and improve marketing, decisions. Based on data for four representative countries in Indiana from 1960 to 1984 (excluding 1970 because of the disastrous southern corn leaf blight), a model was developed to estimate corn (Zea mays L.) yields as a function of several composite soil-crop-weather variables and a technology-trend marker, applied nitrogen fertilizer (N). The model was tested by predicting corn yields for 15 other counties. A daily energy-crop growth (ECG) variable in which different weights were used for the three crop-weather variables which make up the daily ECG-solar radiation intercepted by the canopy, a temperature function, and the ratio of actual to potential evapotranspiration-performed better than when the ECG components were weighted equally. The summation of the weighted daily ECG over a relatively short period (36 days spanning silk) was found to provide the best index for predicting county average corn yield. Numerical estimation results indicate that the ratio of actual to potential evapotranspiration (ET/PET) is much more important than the other two ECG factors in estimating county average corn yield in Indiana.

Evolutionary ecology of the interactions between aphids and their parasitoids.

PubMed

Le Ralec, Anne; Anselme, Caroline; Outreman, Yannick; Poirié, Marylène; van Baaren, Joan; Le Lann, Cécile; van Alphen, Jacques J-M

2010-01-01

Many organisms, including entomopathogenous fungi, predators or parasites, use aphids as ressources. Parasites of aphids are mostly endoparasitoid insects, i.e. insects which lay eggs inside the body of an other insect which will die as a result of their development. In this article, we review the consequences of the numerous pecularities of aphid biology and ecology for their endoparasitoids, notably the Aphidiinae (Hymenoptera: Braconidae). We first examine the various mechanisms used by aphids for defence against these enemies. We then explore the strategies used by aphidiine parasitoids to exploit their aphid hosts. Finally, we consider the responses of both aphids and parasitoids to ecological constraints induced by seasonal cycles and to environmental variations linked to host plants and climate. The fundamental and applied interest of studying these organisms is discussed. Copyright 2010 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Spectral estimates of solar radiation intercepted by corn canopies

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Daughtry, C. S. T.; Gallo, K. P.

1982-01-01

Reflectance factor data were acquired with a Landsat band radiometer throughout two growing seasons for corn (Zea mays L.) canopies differing in planting dates, populations, and soil types. Agronomic data collected included leaf area index (LAI), biomass, development stage, and final grain yields. The spectral variable, greenness, was associated with 78 percent of the variation in LAI over all treatments. Single observations of LAI or greenness have limited value in predicting corn yields. The proportions of solar radiation intercepted (SRI) by these canopies were estimated using either measured LAI or greenness. Both SRI estimates, when accumulated over the growing season, accounted for approximately 65 percent of the variation in yields. Models which simulated the daily effects of weather and intercepted solar radiation on growth had the highest correlations to grain yields. This concept of estimating intercepted solar radiation using spectral data represents a viable approach for merging spectral and meteorological data for crop yield models.

Soybean aphids making their summer appearance early

USDA-ARS?s Scientific Manuscript database

Two small, soft-bodied insects have begun showing up in South Dakota soybean. One is the soybean aphid, and the other is a mealybug. Soybean aphids are yellow to yellow/green and are usually found feeding on the underside of leaves. Incidence of soybean aphid has been a bit higher than typical fo...

Pyramiding different aphid-resistance genes in elite soybean germplasm to combat dynamic aphid populations

USDA-ARS?s Scientific Manuscript database

The soybean aphid, an invasive species, has posed a significant threat to soybean production in North America since 2001. Use of resistant cultivars is an effective tactic to protect soybean yield. However, the variability and dynamics of aphid populations could limit the effectiveness of host-resis...

Maintaining genetic diversity and population panmixia through dispersal and not gene flow in a Holocyclic heteroecious aphid species

USDA-ARS?s Scientific Manuscript database

Heteroecious holocyclic aphids alternate between sexual and asexual reproduction on primary and secondary hosts, respectively. Most of these aphids are generalists, but the aphid specialist Aphis glycines survives only on the primary host buckthorn (Rhamnus spp.) and the secondary host soybean (Gly...

Plant-Aphid Interactions Under Elevated CO2: Some Cues from Aphid Feeding Behavior.

PubMed

Sun, Yucheng; Guo, Huijuan; Ge, Feng

2016-01-01

Although the increasing concentration of atmospheric carbon dioxide (CO2) accelerates the accumulation of carbohydrates and increases the biomass and yield of C3 crop plants, it also reduces their nitrogen concentration. The consequent changes in primary and secondary metabolites affect the palatability of host plants and the feeding of herbivorous insects. Aphids are phloem feeders and are considered the only feeding guild that positively responds to elevated CO2. In this review, we consider how elevated CO2 modifies host defenses, nutrients, and water-use efficiency by altering concentrations of the phytohormones jasmonic acid, salicylic acid, ethylene, and abscisic acid. We will describe how these elevated CO2-induced changes in defenses, nutrients, and water statusfacilitate specific stages of aphid feeding, including penetration, phloem-feeding, and xylem absorption. We conclude that a better understanding of the effects of elevated CO2 on aphids and on aphid damage to crop plants will require research on the molecular aspects of the interaction between plant and aphid but also research on aphid interactions with their intra- and inter-specific competitors and with their natural enemies.

Plant–Aphid Interactions Under Elevated CO2: Some Cues from Aphid Feeding Behavior

PubMed Central

Sun, Yucheng; Guo, Huijuan; Ge, Feng

2016-01-01

Although the increasing concentration of atmospheric carbon dioxide (CO2) accelerates the accumulation of carbohydrates and increases the biomass and yield of C3 crop plants, it also reduces their nitrogen concentration. The consequent changes in primary and secondary metabolites affect the palatability of host plants and the feeding of herbivorous insects. Aphids are phloem feeders and are considered the only feeding guild that positively responds to elevated CO2. In this review, we consider how elevated CO2 modifies host defenses, nutrients, and water-use efficiency by altering concentrations of the phytohormones jasmonic acid, salicylic acid, ethylene, and abscisic acid. We will describe how these elevated CO2-induced changes in defenses, nutrients, and water statusfacilitate specific stages of aphid feeding, including penetration, phloem-feeding, and xylem absorption. We conclude that a better understanding of the effects of elevated CO2 on aphids and on aphid damage to crop plants will require research on the molecular aspects of the interaction between plant and aphid but also research on aphid interactions with their intra- and inter-specific competitors and with their natural enemies. PMID:27148325

Effects of bacterial secondary symbionts on host plant use in pea aphids

PubMed Central

McLean, A. H. C.; van Asch, M.; Ferrari, J.; Godfray, H. C. J.

2011-01-01

Aphids possess several facultative bacterial symbionts that have important effects on their hosts' biology. These have been most closely studied in the pea aphid (Acyrthosiphon pisum), a species that feeds on multiple host plants. Whether secondary symbionts influence host plant utilization is unclear. We report the fitness consequences of introducing different strains of the symbiont Hamiltonella defensa into three aphid clones collected on Lathyrus pratensis that naturally lack symbionts, and of removing symbionts from 20 natural aphid–bacterial associations. Infection decreased fitness on Lathyrus but not on Vicia faba, a plant on which most pea aphids readily feed. This may explain the unusually low prevalence of symbionts in aphids collected on Lathyrus. There was no effect of presence of symbiont on performance of the aphids on the host plants of the clones from which the H. defensa strains were isolated. Removing the symbiont from natural aphid–bacterial associations led to an average approximate 20 per cent reduction in fecundity, both on the natural host plant and on V. faba, suggesting general rather than plant-species-specific effects of the symbiont. Throughout, we find significant genetic variation among aphid clones. The results provide no evidence that secondary symbionts have a major direct role in facilitating aphid utilization of particular host plant species. PMID:20843842

Validation of a hairy roots system to study soybean-soybean aphid interactions

PubMed Central

Morriss, Stephanie C.; Studham, Matthew E.; Tylka, Gregory L.

2017-01-01

The soybean aphid (Aphis glycines) is one of the main insect pests of soybean (Glycine max) worldwide. Genomics approaches have provided important data on transcriptome changes, both in the insect and in the plant, in response to the plant-aphid interaction. However, the difficulties to transform soybean and to rear soybean aphid on artificial media have hindered our ability to systematically test the function of genes identified by those analyses as mediators of plant resistance to the insect. An efficient approach to produce transgenic soybean material is the production of transformed hairy roots using Agrobacterium rhizogenes; however, soybean aphids colonize leaves or stems and thus this approach has not been utilized. Here, we developed a hairy root system that allowed effective aphid feeding. We show that this system supports aphid performance similar to that observed in leaves. The use of hairy roots to study plant resistance is validated by experiments showing that roots generated from cotyledons of resistant lines carrying the Rag1 or Rag2 resistance genes are also resistant to aphid feeding, while related susceptible lines are not. Our results demonstrate that hairy roots are a good system to study soybean aphid-soybean interactions, providing a quick and effective method that could be used for functional analysis of the resistance response to this insect. PMID:28358854

Secondary bacterial symbiont community in aphids responds to plant diversity.

PubMed

Zytynska, Sharon E; Meyer, Sebastian T; Sturm, Sarah; Ullmann, Wiebke; Mehrparvar, Mohsen; Weisser, Wolfgang W

2016-03-01

Biodiversity is important for ecosystem functioning and biotic interactions. In experimental grasslands, increasing plant species richness is known to increase the diversity of associated herbivores and their predators. If these interactions can also involve endosymbionts that reside within a plant or animal host is currently unknown. In plant-feeding aphids, secondary bacterial symbionts can have strong fitness effects on the host, e.g. resistance to natural enemies or fungal pathogens. We examined the secondary symbiont community in three species of aphid, each feeding on a unique host plant across experimental plots that varied in plant species richness. Aphids were collected in May and June, and the symbiont community identified using species-specific PCR assays. Aphis fabae aphids were found to host six different symbiont species with individual aphids co-hosting up to four symbionts. Uroleucon jaceae and Macrosiphum rosae hosted two and three symbiont species, respectively. We found that, at the aphid population level, increasing plant species richness increased the diversity of the aphid symbiont community, whereas at the individual aphid level, the opposite was found. These effects are potentially driven by varying selective pressures across different plant communities of varying diversities, mediated by defensive protection responses and a changing cost-benefit trade-off to the aphid for hosting multiple secondary symbionts. Our work extends documented effects of plant diversity beyond visible biotic interactions to changes in endosymbiont communities, with potentially far-reaching consequences to related ecosystem processes.

Bacteria may contribute to distant species recognition in ant-aphid mutualistic relationships.

PubMed

Fischer, Christophe Y; Detrain, Claire; Thonart, Philippe; Haubruge, Eric; Francis, Frédéric; Verheggen, François J; Lognay, Georges C

2017-04-01

Mutualistic interactions between ant and aphid species have been the subject of considerable historical and contemporary investigations, the primary benefits being cleaning and protection for the aphids and carbohydrate-rich honeydew for the ants. Questions remained, however, as to the volatile semiochemical factor influencing this relationship. A recent study highlighted the role of bacterial honeydew volatile compounds in ant attraction. Here, ant's ability to distantly discriminate 2 aphid species was investigated based on bacterial honeydew semiochemicals emissions using a two-way olfactometer. Both the mutualistic aphid Aphis fabae L. and the nonmyrmecophilous aphid Acyrthosiphon pisum Harris were found to be attractive for the ant Lasius niger L. The level of attraction was similar in both assays (control vs. one of the aphid species). However, when given a choice between these 2 aphid species, ants showed a significant preference for Aphis fabae. Honeydew volatiles, mostly from bacterial origins, are known to be a key element in ant attraction. Using the same olfactometry protocol, the relative attractiveness of volatiles emitted by honeydews collected from each aphid species and by bacteria isolated from each honeydew was investigated. Again, ants significantly preferred volatiles released by Aphis fabae honeydew and bacteria. This information suggests that microbial honeydew volatiles enable ants to distantly discriminate aphid species. These results strengthen the interest of studying the occurrence and potential impact of microorganisms in insect symbioses. © 2015 Institute of Zoology, Chinese Academy of Sciences.

The Potato Aphid Salivary Effector Me47 Is a Glutathione-S-Transferase Involved in Modifying Plant Responses to Aphid Infestation

PubMed Central

Kettles, Graeme J.; Kaloshian, Isgouhi

2016-01-01

Polyphagous aphid pests cause considerable economic damage to crop plants, primarily through the depletion of photoassimilates and transfer of viruses. The potato aphid (Macrosiphum euphorbiae) is a notable pest of solanaceous crops, however, the molecular mechanisms that underpin the ability to colonize these hosts are unknown. It has recently been demonstrated that like other aphid species, M. euphorbiae injects a battery of salivary proteins into host plants during feeding. It is speculated that these proteins function in a manner analagous to secreted effectors from phytopathogenic bacteria, fungi and oomycetes. Here, we describe a novel aphid effector (Me47) which was identified from the potato aphid salivary secretome as a putative glutathione-S-transferase (GST). Expression of Me47 in Nicotiana benthamiana enhanced reproductive performance of green peach aphid (Myzus persicae). Similarly, delivery of Me47 into leaves of tomato (Solanum lycopersicum) by Pseudomonas spp. enhanced potato aphid fecundity. In contrast, delivery of Me47 into Arabidopsis thaliana reduced GPA reproductive performance, indicating that Me47 impacts the outcome of plant–aphid interactions differently depending on the host species. Delivery of Me47 by the non-pathogenic Pseudomonas fluorescens revealed that Me47 protein or activity triggers defense gene transcriptional upregulation in tomato but not Arabidopsis. Recombinant Me47 was purified and demonstrated to have GST activity against two specific isothiocyanates (ITCs), compounds implicated in herbivore defense. Whilst GSTs have previously been associated with development of aphid resistance to synthetic insecticides, the findings described here highlight a novel function as both an elicitor and suppressor of plant defense when delivered into host tissues. PMID:27536306

Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein

PubMed Central

Mulot, Michaël; Monsion, Baptiste; Boissinot, Sylvaine; Rastegar, Maryam; Meyer, Sophie; Bochet, Nicole; Brault, Véronique

2018-01-01

Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG) cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph) is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family) by Myzus persicae. The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta- or in vitro-synthesized dsRNA targeting Eph-mRNA (dsRNAEph) did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNAEph-treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNAEph acquisition was also observed for two other poleroviruses transmitted by M. persicae, suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNAEph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages. PMID:29593696

Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein.

PubMed

Mulot, Michaël; Monsion, Baptiste; Boissinot, Sylvaine; Rastegar, Maryam; Meyer, Sophie; Bochet, Nicole; Brault, Véronique

2018-01-01

Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG) cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph) is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family) by Myzus persicae . The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta - or in vitro -synthesized dsRNA targeting Eph -mRNA (dsRNA Eph ) did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNA Eph -treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNA Eph acquisition was also observed for two other poleroviruses transmitted by M. persicae , suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNA Eph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages.

The Potato Aphid Salivary Effector Me47 Is a Glutathione-S-Transferase Involved in Modifying Plant Responses to Aphid Infestation.

PubMed

Kettles, Graeme J; Kaloshian, Isgouhi

2016-01-01

Polyphagous aphid pests cause considerable economic damage to crop plants, primarily through the depletion of photoassimilates and transfer of viruses. The potato aphid (Macrosiphum euphorbiae) is a notable pest of solanaceous crops, however, the molecular mechanisms that underpin the ability to colonize these hosts are unknown. It has recently been demonstrated that like other aphid species, M. euphorbiae injects a battery of salivary proteins into host plants during feeding. It is speculated that these proteins function in a manner analagous to secreted effectors from phytopathogenic bacteria, fungi and oomycetes. Here, we describe a novel aphid effector (Me47) which was identified from the potato aphid salivary secretome as a putative glutathione-S-transferase (GST). Expression of Me47 in Nicotiana benthamiana enhanced reproductive performance of green peach aphid (Myzus persicae). Similarly, delivery of Me47 into leaves of tomato (Solanum lycopersicum) by Pseudomonas spp. enhanced potato aphid fecundity. In contrast, delivery of Me47 into Arabidopsis thaliana reduced GPA reproductive performance, indicating that Me47 impacts the outcome of plant-aphid interactions differently depending on the host species. Delivery of Me47 by the non-pathogenic Pseudomonas fluorescens revealed that Me47 protein or activity triggers defense gene transcriptional upregulation in tomato but not Arabidopsis. Recombinant Me47 was purified and demonstrated to have GST activity against two specific isothiocyanates (ITCs), compounds implicated in herbivore defense. Whilst GSTs have previously been associated with development of aphid resistance to synthetic insecticides, the findings described here highlight a novel function as both an elicitor and suppressor of plant defense when delivered into host tissues.

The Entomopathogenic Fungal Endophytes Purpureocillium lilacinum (Formerly Paecilomyces lilacinus) and Beauveria bassiana Negatively Affect Cotton Aphid Reproduction under Both Greenhouse and Field Conditions

PubMed Central

Castillo Lopez, Diana; Zhu-Salzman, Keyan; Ek-Ramos, Maria Julissa; Sword, Gregory A.

2014-01-01

The effects of two entomopathogenic fungal endophytes, Beauveria bassiana and Purpureocillium lilacinum (formerly Paecilomyces lilacinus), were assessed on the reproduction of cotton aphid, Aphis gossypii Glover (Homoptera:Aphididae), through in planta feeding trials. In replicate greenhouse and field trials, cotton plants (Gossypium hirsutum) were inoculated as seed treatments with two concentrations of B. bassiana or P. lilacinum conidia. Positive colonization of cotton by the endophytes was confirmed through potato dextrose agar (PDA) media plating and PCR analysis. Inoculation and colonization of cotton by either B. bassiana or P. lilacinum negatively affected aphid reproduction over periods of seven and 14 days in a series of greenhouse trials. Field trials were conducted in the summers of 2012 and 2013 in which cotton plants inoculated as seed treatments with B. bassiana and P. lilacinum were exposed to cotton aphids for 14 days. There was a significant overall effect of endophyte treatment on the number of cotton aphids per plant. Plants inoculated with B. bassiana had significantly lower numbers of aphids across both years. The number of aphids on plants inoculated with P. lilacinum exhibited a similar, but non-significant, reduction in numbers relative to control plants. We also tested the pathogenicity of both P. lilacinum and B. bassiana strains used in the experiments against cotton aphids in a survival experiment where 60% and 57% of treated aphids, respectively, died from infection over seven days versus 10% mortality among control insects. Our results demonstrate (i) the successful establishment of P. lilacinum and B. bassiana as endophytes in cotton via seed inoculation, (ii) subsequent negative effects of the presence of both target endophytes on cotton aphid reproduction using whole plant assays, and (iii) that the P. lilacinum strain used is both endophytic and pathogenic to cotton aphids. Our results illustrate the potential of using these endophytes for the biological control of aphids and other herbivores under greenhouse and field conditions. PMID:25093505

The entomopathogenic fungal endophytes Purpureocillium lilacinum (formerly Paecilomyces lilacinus) and Beauveria bassiana negatively affect cotton aphid reproduction under both greenhouse and field conditions.

PubMed

Castillo Lopez, Diana; Zhu-Salzman, Keyan; Ek-Ramos, Maria Julissa; Sword, Gregory A

2014-01-01

The effects of two entomopathogenic fungal endophytes, Beauveria bassiana and Purpureocillium lilacinum (formerly Paecilomyces lilacinus), were assessed on the reproduction of cotton aphid, Aphis gossypii Glover (Homoptera:Aphididae), through in planta feeding trials. In replicate greenhouse and field trials, cotton plants (Gossypium hirsutum) were inoculated as seed treatments with two concentrations of B. bassiana or P. lilacinum conidia. Positive colonization of cotton by the endophytes was confirmed through potato dextrose agar (PDA) media plating and PCR analysis. Inoculation and colonization of cotton by either B. bassiana or P. lilacinum negatively affected aphid reproduction over periods of seven and 14 days in a series of greenhouse trials. Field trials were conducted in the summers of 2012 and 2013 in which cotton plants inoculated as seed treatments with B. bassiana and P. lilacinum were exposed to cotton aphids for 14 days. There was a significant overall effect of endophyte treatment on the number of cotton aphids per plant. Plants inoculated with B. bassiana had significantly lower numbers of aphids across both years. The number of aphids on plants inoculated with P. lilacinum exhibited a similar, but non-significant, reduction in numbers relative to control plants. We also tested the pathogenicity of both P. lilacinum and B. bassiana strains used in the experiments against cotton aphids in a survival experiment where 60% and 57% of treated aphids, respectively, died from infection over seven days versus 10% mortality among control insects. Our results demonstrate (i) the successful establishment of P. lilacinum and B. bassiana as endophytes in cotton via seed inoculation, (ii) subsequent negative effects of the presence of both target endophytes on cotton aphid reproduction using whole plant assays, and (iii) that the P. lilacinum strain used is both endophytic and pathogenic to cotton aphids. Our results illustrate the potential of using these endophytes for the biological control of aphids and other herbivores under greenhouse and field conditions.

Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability.

PubMed

Canedo-Júnior, Ernesto Oliveira; Santiago, Graziele Silva; Zurlo, Luana Fonseca; Ribas, Carla Rodrigues; Carvalho, Rafaela Pereira; Alves, Guilherme Pereira; Carvalho, Mariana Comanucci Silva; Souza, Brígida

2017-01-01

Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management.

Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability

PubMed Central

Santiago, Graziele Silva; Zurlo, Luana Fonseca; Ribas, Carla Rodrigues; Carvalho, Rafaela Pereira; Alves, Guilherme Pereira; Carvalho, Mariana Comanucci Silva; Souza, Brígida

2017-01-01

Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management. PMID:28141849

Genetics coupled to quantitative intact proteomics links heritable aphid and endosymbiont protein expression to circulative polerovirus transmission.

PubMed

Cilia, M; Tamborindeguy, C; Fish, T; Howe, K; Thannhauser, T W; Gray, S

2011-03-01

Yellow dwarf viruses in the family Luteoviridae, which are the causal agents of yellow dwarf disease in cereal crops, are each transmitted most efficiently by different species of aphids in a circulative manner that requires the virus to interact with a multitude of aphid proteins. Aphid proteins differentially expressed in F2 Schizaphis graminum genotypes segregating for the ability to transmit Cereal yellow dwarf virus-RPV (CYDV-RPV) were identified using two-dimensional difference gel electrophoresis (DIGE) coupled to either matrix-assisted laser desorption ionization-tandem mass spectrometry or online nanoscale liquid chromatography coupled to electrospray tandem mass spectrometry. A total of 50 protein spots, containing aphid proteins and proteins from the aphid's obligate and maternally inherited bacterial endosymbiont, Buchnera, were identified as differentially expressed between transmission-competent and refractive aphids. Surprisingly, in virus transmission-competent F2 genotypes, the isoelectric points of the Buchnera proteins did not match those in the maternal Buchnera proteome as expected, but instead they aligned with the Buchnera proteome of the transmission-competent paternal parent. Among the aphid proteins identified, many were involved in energy metabolism, membrane trafficking, lipid signaling, and the cytoskeleton. At least eight aphid proteins were expressed as heritable, isoelectric point isoform pairs, one derived from each parental lineage. In the F2 genotypes, the expression of aphid protein isoforms derived from the competent parental lineage aligned with the virus transmission phenotype with high precision. Thus, these isoforms are candidate biomarkers for CYDV-RPV transmission in S. graminum. Our combined genetic and DIGE approach also made it possible to predict where several of the proteins may be expressed in refractive aphids with different barriers to transmission. Twelve proteins were predicted to act in the hindgut of the aphid, while six proteins were predicted to be associated with the accessory salivary glands or hemolymph. Knowledge of the proteins that regulate virus transmission and their predicted locations will aid in understanding the biochemical mechanisms regulating circulative virus transmission in aphids, as well as in identifying new targets to block transmission.

Genetics Coupled to Quantitative Intact Proteomics Links Heritable Aphid and Endosymbiont Protein Expression to Circulative Polerovirus Transmission▿ †

PubMed Central

Cilia, M.; Tamborindeguy, C.; Fish, T.; Howe, K.; Thannhauser, T. W.; Gray, S.

2011-01-01

Yellow dwarf viruses in the family Luteoviridae, which are the causal agents of yellow dwarf disease in cereal crops, are each transmitted most efficiently by different species of aphids in a circulative manner that requires the virus to interact with a multitude of aphid proteins. Aphid proteins differentially expressed in F2 Schizaphis graminum genotypes segregating for the ability to transmit Cereal yellow dwarf virus-RPV (CYDV-RPV) were identified using two-dimensional difference gel electrophoresis (DIGE) coupled to either matrix-assisted laser desorption ionization-tandem mass spectrometry or online nanoscale liquid chromatography coupled to electrospray tandem mass spectrometry. A total of 50 protein spots, containing aphid proteins and proteins from the aphid's obligate and maternally inherited bacterial endosymbiont, Buchnera, were identified as differentially expressed between transmission-competent and refractive aphids. Surprisingly, in virus transmission-competent F2 genotypes, the isoelectric points of the Buchnera proteins did not match those in the maternal Buchnera proteome as expected, but instead they aligned with the Buchnera proteome of the transmission-competent paternal parent. Among the aphid proteins identified, many were involved in energy metabolism, membrane trafficking, lipid signaling, and the cytoskeleton. At least eight aphid proteins were expressed as heritable, isoelectric point isoform pairs, one derived from each parental lineage. In the F2 genotypes, the expression of aphid protein isoforms derived from the competent parental lineage aligned with the virus transmission phenotype with high precision. Thus, these isoforms are candidate biomarkers for CYDV-RPV transmission in S. graminum. Our combined genetic and DIGE approach also made it possible to predict where several of the proteins may be expressed in refractive aphids with different barriers to transmission. Twelve proteins were predicted to act in the hindgut of the aphid, while six proteins were predicted to be associated with the accessory salivary glands or hemolymph. Knowledge of the proteins that regulate virus transmission and their predicted locations will aid in understanding the biochemical mechanisms regulating circulative virus transmission in aphids, as well as in identifying new targets to block transmission. PMID:21159868

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae

PubMed Central

2011-01-01

Background Treatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1. Results The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants. Conclusions The repression in phloem-feeding activities of M. persicae as a result of AtPP2-A1 overexpression, and as a deterrent effect of HrpNEa treatment in WT Arabidopsis rather than the atpp2-a1/E/142 mutant suggest that AtPP2-A1 plays a role in plant resistance to the insect, particularly at the phloem-feeding stage. The accompanied change of aphid population in leaf colonies suggests that the function of AtPP2-A1 is related to colonization of the plant. PMID:21226963

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae.

PubMed

Zhang, Chunling; Shi, Haojie; Chen, Lei; Wang, Xiaomeng; Lü, Beibei; Zhang, Shuping; Liang, Yuan; Liu, Ruoxue; Qian, Jun; Sun, Weiwei; You, Zhenzhen; Dong, Hansong

2011-01-13

Treatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1. The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants. The repression in phloem-feeding activities of M. persicae as a result of AtPP2-A1 overexpression, and as a deterrent effect of HrpNEa treatment in WT Arabidopsis rather than the atpp2-a1/E/142 mutant suggest that AtPP2-A1 plays a role in plant resistance to the insect, particularly at the phloem-feeding stage. The accompanied change of aphid population in leaf colonies suggests that the function of AtPP2-A1 is related to colonization of the plant.

Differential reactions of soybean isolines with combinations of aphid resistance genes Rag1, Rag2, and Rag3 to four soybean aphid biotypes

USDA-ARS?s Scientific Manuscript database

With the discovery of the soybean aphid (Aphis glycines Matsumura) as a devastating insect pest of soybean (Glycine max (L.) Merr.) in the United States, host resistance was recognized as an important management option. However, the identification of soybean aphid isolates exhibiting strong virulenc...

Discovery and targeted LC-MS/MS of purified polerovirus reveals differences in the virus-host interactome associated with altered aphid transmission

USDA-ARS?s Scientific Manuscript database

The transmission of viruses in the Luteoviridae, such as Cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus proteins, plant proteins, and aphid proteins. These viruses are retained in the phloem for aphid acquisition and are transmitted by aphids...

A protein from the salivary glands of the pea aphid, Acyrthosiphon pisum, is essential in feeding on a host plant

USDA-ARS?s Scientific Manuscript database

In feeding, aphids inject saliva into plant tissues, gaining access to phloem sap and eliciting (and sometimes overcoming) plant responses. We are examining the involvement, in this aphid-plant interaction, of individual aphid proteins and enzymes, as identified in a salivary gland cDNA library. Her...

Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding.

PubMed

Upadhyay, Santosh Kumar; Singh, Seema; Chandrashekar, Krishnappa; Tuli, Rakesh; Singh, Pradhyumna Kumar

2012-03-01

δ-Endotoxins produced by Bacillus thuringiensis (Bt) have been used as bio-pesticides for the control of lepidopteran insect pests. Garlic (Allium sativum L.) leaf agglutinin (ASAL), being toxic to several sap-sucking pests and some lepidopteran pests, may be a good candidate for pyramiding with δ-endotoxins in transgenic plants for enhancing the range of resistance to insect pests. Since ASAL shares the midgut receptors with Cry1Ac in Helicoverpa armigera, there is possibility of antagonism in their toxicity. Our study demonstrated that ASAL increased the toxicity of Cry1Ac against H. armigera while Cry1Ac did not alter the toxicity of ASAL against cotton aphids. The two toxins interacted and increased binding of each other to brush border membrane vesicle (BBMV) proteins and to the two important receptors, alkaline phosphatase (ALP) and aminopeptidase N (APN). The results indicated that the toxins had different binding sites on the ALP and APN but influenced mutual binding. We conclude that ASAL can be safely employed with Cry1Ac for developing transgenic crops for wider insect resistance.

Effects of Foliar Insecticides on Leaf-Level Spectral Reflectance of Soybean.

PubMed

Alves, Tavvs M; Marston, Zachary P; MacRae, Ian V; Koch, Robert L

2017-12-05

Pest-induced changes in plant reflectance are crucial for the development of pest management programs using remote sensing. However, it is unknown if plant reflectance data is also affected by foliar insecticides applied for pest management. Our study assessed the effects of foliar insecticides on leaf reflectance of soybean. A 2-yr field trial and a greenhouse trial were conducted using randomized complete block and completely randomized designs, respectively. Treatments consisted of an untreated check, a new systemic insecticide (sulfoxaflor), and two representatives of the most common insecticide classes used for soybean pest management in the north-central United States (i.e., λ-cyhalothrin and chlorpyrifos). Insecticides were applied at labeled rates recommended for controlling soybean aphid; the primary insect pest in the north-central United States. Leaf-level reflectance was measured using ground-based spectroradiometers. Sulfoxaflor affected leaf reflectance at some red and blue wavelengths but had no effect at near-infrared or green wavelengths. Chlorpyrifos affected leaf reflectance at some green, red, and near-infrared wavelengths but had no effect at blue wavelengths. λ-cyhalothrin had the least effect on spectral reflectance among the insecticides, with changes to only a few near-infrared wavelengths. Our results showing immediate and delayed effects of foliar insecticides on soybean reflectance indicate that application of some insecticides may confound the use of remote sensing for detection of not only insects but also plant diseases, nutritional and water deficiencies, and other crop stressors. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Spatial Imaging, Speciation, and Quantification of Selenium in theHyperaccumulator Plants Astragalus bisulcatus and Stanleya pinnata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, J.L.; Zhang, L.H.; Marcus, M.A.

2006-09-01

Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and {gamma}-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in additionmore » to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism.« less

Functional Analysis of Corn Husk Photosynthesis[W][OA

PubMed Central

Pengelly, Jasper J.L.; Kwasny, Scott; Bala, Soumi; Evans, John R.; Voznesenskaya, Elena V.; Koteyeva, Nuria K.; Edwards, Gerald E.; Furbank, Robert T.; von Caemmerer, Susanne

2011-01-01

The husk surrounding the ear of corn/maize (Zea mays) has widely spaced veins with a number of interveinal mesophyll (M) cells and has been described as operating a partial C3 photosynthetic pathway, in contrast to its leaves, which use the C4 photosynthetic pathway. Here, we characterized photosynthesis in maize husk and leaf by measuring combined gas exchange and carbon isotope discrimination, the oxygen dependence of the CO2 compensation point, and photosynthetic enzyme activity and localization together with anatomy. The CO2 assimilation rate in the husk was less than that in the leaves and did not saturate at high CO2, indicating CO2 diffusion limitations. However, maximal photosynthetic rates were similar between the leaf and husk when expressed on a chlorophyll basis. The CO2 compensation points of the husk were high compared with the leaf but did not vary with oxygen concentration. This and the low carbon isotope discrimination measured concurrently with gas exchange in the husk and leaf suggested C4-like photosynthesis in the husk. However, both Rubisco activity and the ratio of phosphoenolpyruvate carboxylase to Rubisco activity were reduced in the husk. Immunolocalization studies showed that phosphoenolpyruvate carboxylase is specifically localized in the layer of M cells surrounding the bundle sheath cells, while Rubisco and glycine decarboxylase were enriched in bundle sheath cells but also present in M cells. We conclude that maize husk operates C4 photosynthesis dispersed around the widely spaced veins (analogous to leaves) in a diffusion-limited manner due to low M surface area exposed to intercellular air space, with the functional role of Rubisco and glycine decarboxylase in distant M yet to be explained. PMID:21511990

Aphids preserved in propylene glycol can be used for reverse transcription-polymerase chain reaction detection of Potato virus Y.

PubMed

Nie, Xianzhou; Pelletier, Yvan; Mason, Nicola; Dilworth, Andrea; Giguère, Marie-Andrée

2011-08-01

The effectiveness of propylene glycol on the retention of RNA target of Potato virus Y (PVY), an aphid stylet-borne virus, in Myzus persicae was investigated in comparison to ethanol and liquid nitrogen/-80°C. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the PVY targets from the propylene glycol/ethanol/liquid nitrogen preserved single aphids after a 5min acquisition period from infected potato plants. In the liquid nitrogen/-80°C and 70% ethanol treatments, 55.6% and 38.8% aphids tested PVY-positive, respectively. In the 0-75% propylene glycol treatments, 12.2-44.7% aphids tested PVY-positive. The lowest detection rate was in the 0% (positive rate, 15.2%) and the 10% propylene glycol (positive rate, 12.2%). As the propylene glycol concentration increased to 25%, 29.8% aphids tested positive. A high PVY-positive rate was also found in 35-75% propylene glycol treatments at 44.7% (35% propylene glycol), 36.7% (50% propylene glycol) and 34.8% (75% propylene glycol), which is comparable to the rate shown in 70% ethanol. No significant difference in the positive detection rate was observed in aphids preserved in 50% propylene glycol at room temperature for 2, 4 and 10 days. These results demonstrate that propylene glycol at 25-75% can retain PVY targets effectively in aphids for an extended time period, and thus can be used in aphid traps to preserve viruliferous aphids for later RT-PCR detection of PVY. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Molecular characterization of two isoforms of a farnesyl pyrophosphate synthase gene in wheat and their roles in sesquiterpene synthesis and inducible defence against aphid infestation.

PubMed

Zhang, Yan; Li, Zhi-Xia; Yu, Xiu-Dao; Fan, Jia; Pickett, John A; Jones, Huw D; Zhou, Jing-Jiang; Birkett, Michael A; Caulfield, John; Napier, Johnathan A; Zhao, Guang-Yao; Cheng, Xian-Guo; Shi, Yi; Bruce, Toby J A; Xia, Lan-Qin

2015-05-01

Aphids are important pests of wheat (Triticum aestivum) that affect crop production globally. Herbivore-induced emission of sesquiterpenes can repel pests, and farnesyl pyrophosphate synthase (FPS) is a key enzyme involved in sesquiterpene biosynthesis. However, fps orthologues in wheat and their functional roles in sesquiterpene synthesis and defence against aphid infestation are unknown. Here, two fps isoforms, Tafps1 and Tafps2, were identified in wheat. Quantitative real-time polymerase chain reaction (qRT-PCR) and in vitro catalytic activity analyses were conducted to investigate expression patterns and activity. Heterologous expression of these isoforms in Arabidopsis thaliana, virus-induced gene silencing (VIGS) in wheat and aphid behavioural assays were performed to understand the functional roles of these two isoforms. We demonstrated that Tafps1 and Tafps2 played different roles in induced responses to aphid infestation and in sesquiterpene synthesis. Heterologous expression in A. thaliana resulted in repulsion of the peach aphid (Myzus persicae). Wheat plants with these two isoforms transiently silenced were significantly attractive to grain aphid (Sitobion avenae). Our results provide new insights into induced defence against aphid herbivory in wheat, in particular, the different roles of the two Tafps isoforms in both sesquiterpene biosynthesis and defence against aphid infestation. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage

PubMed Central

Gagic, Vesna; Petrović-Obradović, Olivera; Fründ, Jochen; Kavallieratos, Nickolas G.; Athanassiou, Christos G.; Starý, Petr; Tomanović, Željko

2016-01-01

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and host-use efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure. PMID:27309729

Aggressive mimicry coexists with mutualism in an aphid.

PubMed

Salazar, Adrián; Fürstenau, Benjamin; Quero, Carmen; Pérez-Hidalgo, Nicolás; Carazo, Pau; Font, Enrique; Martínez-Torres, David

2015-01-27

Understanding the evolutionary transition from interspecific exploitation to cooperation is a major challenge in evolutionary biology. Ant-aphid relationships represent an ideal system to this end because they encompass a coevolutionary continuum of interactions ranging from mutualism to antagonism. In this study, we report an unprecedented interaction along this continuum: aggressive mimicry in aphids. We show that two morphs clonally produced by the aphid Paracletus cimiciformis during its root-dwelling phase establish relationships with ants at opposite sides of the mutualism-antagonism continuum. Although one of these morphs exhibits the conventional trophobiotic (mutualistic) relationship with ants of the genus Tetramorium, aphids of the alternative morph are transported by the ants to their brood chamber and cared for as if they were true ant larvae. Gas chromatography-mass spectrometry analyses reveal that the innate cuticular hydrocarbon profile of the mimic morph resembles the profile of ant larvae more than that of the alternative, genetically identical nonmimic morph. Furthermore, we show that, once in the brood chamber, mimic aphids suck on ant larva hemolymph. These results not only add aphids to the limited list of arthropods known to biosynthesize the cuticular chemicals of their deceived hosts to exploit their resources but describe a remarkable case of plastic aggressive mimicry. The present work adds a previously unidentified dimension to the classical textbook paradigm of aphid-ant relationships by showcasing a complex system at the evolutionary interface between cooperation and exploitation.

Fine mapping of the soybean aphid resistance genes Rag6 and Rag3c from glycine soja 85-32

USDA-ARS?s Scientific Manuscript database

The soybean aphid, an invasive species, has significantly threatened soybean production in North America since 2001. Host-plant resistance is known as an ideal management of aphids. Two novel aphid-resistant loci, Rag6 and Rag3c, from the Glycine soja accession 85-32, were previously detected in a 1...

Toxicity of newly isolated piperideine alkaloids from the red imported fire ant, Solenopsis invicta Buren, against the green peach aphid, Myzus persicae (Sulzer)

USDA-ARS?s Scientific Manuscript database

The green peach aphid, Myzus persicae (Sulzer), is a major insect pest of many agronomic and horticultural crops and is distributed worldwide Aphid management is often based on application of insecticides. However, the aphid is now resistant to many of these and much interest has recently develope...

Blackmargined aphid (Monellia caryella (Fitch); Hemiptera: Aphididae) honeydew production in pecan (Carya illinoinesis (Koch)) and implications for managing the pecan aphid complex in Texas

USDA-ARS?s Scientific Manuscript database

Field studies of the blackmargined aphid, Monellia caryella (Fitch), were conducted on three cultivars, “Cheyenne,” “Kiowa,” and “Pawnee,” of pecan, Carya illinoinisis (Wang) K. Koch. Aphid and natural enemy (lacewings, ladybird beetles, and spiders) densities were determined twice weekly by direct...

Release of Predators of the Balsam Woolly Aphid in North Carolina

Treesearch

Gene D. Amman; Charles F. Speers

1964-01-01

The balsam woolly aphid, Chermes piceae Ratz. (Homoptera: Chermidae), was accidentally introduced into North America from Europe about 1900 (Balch 1952). The aphid is now a serious pest of Fraser fir, Abies fraseri (Pursh)Poir., in the Southern Appalachians. Since its discovery in Northo-1957 (Speers 1958), the aphid has killed thousands of trees annually. Fraser fir...

Development of a DNA microarray for species identification of quarantine aphids.

PubMed

Lee, Won Sun; Choi, Hwalran; Kang, Jinseok; Kim, Ji-Hoon; Lee, Si Hyeock; Lee, Seunghwan; Hwang, Seung Yong

2013-12-01

Aphid pests are being brought into Korea as a result of increased crop trading. Aphids exist on growth areas of plants, and thus plant growth is seriously affected by aphid pests. However, aphids are very small and have several sexual morphs and life stages, so it is difficult to identify species on the basis of morphological features. This problem was approached using DNA microarray technology. DNA targets of the cytochrome c oxidase subunit I gene were generated with a fluorescent dye-labelled primer and were hybridised onto a DNA microarray consisting of specific probes. After analysing the signal intensity of the specific probes, the unique patterns from the DNA microarray, consisting of 47 species-specific probes, were obtained to identify 23 aphid species. To confirm the accuracy of the developed DNA microarray, ten individual blind samples were used in blind trials, and the identifications were completely consistent with the sequencing data of all individual blind samples. A microarray has been developed to distinguish aphid species. DNA microarray technology provides a rapid, easy, cost-effective and accurate method for identifying aphid species for pest control management. © 2013 Society of Chemical Industry.

Aphid vector population density determines the emergence of necrogenic satellite RNAs in populations of cucumber mosaic virus.

PubMed

Betancourt, Mónica; Fraile, Aurora; Milgroom, Michael G; García-Arenal, Fernando

2016-06-01

The satellite RNAs of cucumber mosaic virus (CMV) that induce systemic necrosis in tomato plants (N-satRNA) multiply to high levels in the infected host while severely depressing CMV accumulation and, hence, its aphid transmission efficiency. As N-satRNAs are transmitted into CMV particles, the conditions for N-satRNA emergence are not obvious. Model analyses with realistic parameter values have predicted that N-satRNAs would invade CMV populations only when transmission rates are high. Here, we tested this hypothesis experimentally by passaging CMV or CMV+N-satRNAs at low or high aphid densities (2 or 8 aphids/plant). As predicted, high aphid densities were required for N-satRNA emergence. The results showed that at low aphid densities, random effects due to population bottlenecks during transmission dominate the epidemiological dynamics of CMV/CMV+N-satRNA. The results suggest that maintaining aphid populations at low density will prevent the emergence of highly virulent CMV+N-satRNA isolates.

Gene discovery in EST sequences from the wheat leaf rust fungus puccinia triticina sexual spores, asexual spores and haustoria, compared to other rust and corn smut fungi

USDA-ARS?s Scientific Manuscript database

Background: Rust fungi are biotrophic basidiomycete plant pathogens that cause major diseases on plants and trees world-wide, affecting agriculture and forestry. Their biotrophic nature precludes many established molecular genetic manipulations and lines of research. The generation of genomic resour...

Assessment of corn and banana leaves as potential standardized substrates for leaf decomposition in streams affected by mountaintop removal coal mining, West Virginia, USA

EPA Science Inventory

Mountaintop removal and valley filling is a method of coal mining that buries Central Appalachian headwater streams. A 2007 federal court ruling highlighted the need for measurement of both ecosystem structure and function when assessing streams for mitigaton. Rapid functional as...

Ants farm subterranean aphids mostly in single clone groups - an example of prudent husbandry for carbohydrates and proteins?

PubMed Central

2012-01-01

Background Mutualistic interactions are wide-spread but the mechanisms underlying their evolutionary stability and ecological dynamics remain poorly understood. Cultivation mutualisms in which hosts consume symbionts occur in phylogenetically diverse groups, but often have symbiont monocultures for each host. This is consistent with the prediction that symbionts should avoid coexistence with other strains so that host services continue to benefit relatives, but it is less clear whether hosts should always favor monocultures and what mechanisms they might have to manipulate symbiont diversity. Few mutualisms have been studied in sufficient genetic detail to address these issues, so we decided to characterize symbiont diversity in the complex mutualism between multiple root aphid species and Lasius flavus ants. After showing elsewhere that three of these aphid species have low dispersal and mostly if not exclusively asexual reproduction, we here investigate aphid diversity within and between ant nest mounds. Results The three focal species (Geoica utricularia, Forda marginata and Tetraneura ulmi) had considerable clonal diversity at the population level. Yet more than half of the ant mounds contained just a single aphid species, a significantly higher percentage than expected from a random distribution. Over 60% of these single-species mounds had a single aphid clone, and clones tended to persist across subsequent years. Whenever multiple species/clones co-occurred in the same mound, they were spatially separated with more than 95% of the aphid chambers containing individuals of a single clone. Conclusions L. flavus “husbandry” is characterized by low aphid “livestock” diversity per colony, especially at the nest-chamber level, but it lacks the exclusive monocultures known from other cultivation mutualisms. The ants appear to eat most of the early instar aphids, so that adult aphids are unlikely to face limited phloem resources and scramble competition with other aphids. We suggest that such culling of carbohydrate-providing symbionts for protein ingestion may maintain maximal host yield per aphid while also benefitting the domesticated aphids as long as their clone-mates reproduce successfully. The cost-benefit logic of this type of polyculture husbandry has striking analogies with human farming practices based on slaughtering young animals for meat to maximize milk-production by a carefully regulated adult livestock population. PMID:22747564

C-band backscattering from corn canopies

NASA Technical Reports Server (NTRS)

Daughtry, C. S. T.; Ranson, K. J.; Biehl, L. L.

1991-01-01

A frequency-modulatad continuous-wave C-band (4.8 GHz) scatterometer was mounted on an aerial lift truck, and backscatter coefficients of corn (Zea mays L.) were acquired as functions of polarizations, view angles, and row directions. As phytomass and green-leaf area index increased, the backscatter also increased. Near anthesis, when the canopies were fully developed, the major scattering elements were located in the upper 1 m of the 2.8 m tall canopy and little backscatter was measured below that level for view angles of 30 deg or greater. C-band backscatter data could provide information to monitor tillage operations at small view zenith angles and vegetation at large view zenith angles.

Identification of Proteins Differentially Regulated in Response to Soybean Aphid Infestation of Soybean Near Isogenic Lines differing in Aphid Resistance

USDA-ARS?s Scientific Manuscript database

The soybean aphid, a plant sap sucking insect, has become an important soybean pest in the USA and infestation of soybean by this insect can lead to significant yield losses. The Rag2 gene of soybean, providing resistance to soybean aphid biotypes I (IL) and II (OH), was identified by researchers in...

A Trio of Viral Proteins Tunes Aphid-Plant Interactions in Arabidopsis thaliana

PubMed Central

Du, Zhiyou; Murphy, Alex M.; Anggoro, Damar Tri; Tungadi, Trisna; Luang-In, Vijitra; Lewsey, Mathew G.; Rossiter, John T.; Powell, Glen; Smith, Alison G.; Carr, John P.

2013-01-01

Background Virus-induced deterrence to aphid feeding is believed to promote plant virus transmission by encouraging migration of virus-bearing insects away from infected plants. We investigated the effects of infection by an aphid-transmitted virus, cucumber mosaic virus (CMV), on the interaction of Arabidopsis thaliana, one of the natural hosts for CMV, with Myzus persicae (common names: ‘peach-potato aphid’, ‘green peach aphid’). Methodology/Principal Findings Infection of Arabidopsis (ecotype Col-0) with CMV strain Fny (Fny-CMV) induced biosynthesis of the aphid feeding-deterrent 4-methoxy-indol-3-yl-methylglucosinolate (4MI3M). 4MI3M inhibited phloem ingestion by aphids and consequently discouraged aphid settling. The CMV 2b protein is a suppressor of antiviral RNA silencing, which has previously been implicated in altering plant-aphid interactions. Its presence in infected hosts enhances the accumulation of CMV and the other four viral proteins. Another viral gene product, the 2a protein (an RNA-dependent RNA polymerase), triggers defensive signaling, leading to increased 4MI3M accumulation. The 2b protein can inhibit ARGONAUTE1 (AGO1), a host factor that both positively-regulates 4MI3M biosynthesis and negatively-regulates accumulation of substance(s) toxic to aphids. However, the 1a replicase protein moderated 2b-mediated inhibition of AGO1, ensuring that aphids were deterred from feeding but not poisoned. The LS strain of CMV did not induce feeding deterrence in Arabidopsis ecotype Col-0. Conclusions/Significance Inhibition of AGO1 by the 2b protein could act as a booby trap since this will trigger antibiosis against aphids. However, for Fny-CMV the interplay of three viral proteins (1a, 2a and 2b) appears to balance the need of the virus to inhibit antiviral silencing, while inducing a mild resistance (antixenosis) that is thought to promote transmission. The strain-specific effects of CMV on Arabidopsis-aphid interactions, and differences between the effects of Fny-CMV on this plant and those seen previously in tobacco (inhibition of resistance to aphids) may have important epidemiological consequences. PMID:24349433

Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid.

PubMed

Margaritopoulos, John T; Kasprowicz, Louise; Malloch, Gaynor L; Fenton, Brian

2009-05-11

Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci. Bayesian clustering and admixture analysis split the aphid genotypes into three genetic clusters: European M. persicae persicae, New Zealand M. persicae persicae and Global M. persicae nicotianae. This partition was supported by FST and genetic distance analyses. The results showed two further points, a possible connection between genotypes found in the UK and New Zealand and globalization of nicotianae associated with colonisation of regions where tobacco is not cultivated. In addition, we report the presence of geographically widespread clones and for the first time the presence of a nicotianae genotype in the Old and New World. Lastly, heterozygote deficiency was detected in some sexual and asexual populations. The study revealed important genetic variation among the aphid populations we examined and this was partitioned according to region and host-plant. Clonal selection and gene flow between sexual and asexual lineages are important factors shaping the genetic structure of the aphid populations. In addition, the results reflected the globalization of two subspecies of M. persicae with successful clones being spread at various scales throughout the world. A subspecies appears to result from direct selection on tobacco plants. This information highlights the ultimate ability of a polyphagous aphid species to generate and maintain ecologically successful gene combinations through clonal propagation and the role of human transportation and global commerce for expanding their range.

Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid

PubMed Central

Margaritopoulos, John T; Kasprowicz, Louise; Malloch, Gaynor L; Fenton, Brian

2009-01-01

Background Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci. Results Bayesian clustering and admixture analysis split the aphid genotypes into three genetic clusters: European M. persicae persicae, New Zealand M. persicae persicae and Global M. persicae nicotianae. This partition was supported by FST and genetic distance analyses. The results showed two further points, a possible connection between genotypes found in the UK and New Zealand and globalization of nicotianae associated with colonisation of regions where tobacco is not cultivated. In addition, we report the presence of geographically widespread clones and for the first time the presence of a nicotianae genotype in the Old and New World. Lastly, heterozygote deficiency was detected in some sexual and asexual populations. Conclusion The study revealed important genetic variation among the aphid populations we examined and this was partitioned according to region and host-plant. Clonal selection and gene flow between sexual and asexual lineages are important factors shaping the genetic structure of the aphid populations. In addition, the results reflected the globalization of two subspecies of M. persicae with successful clones being spread at various scales throughout the world. A subspecies appears to result from direct selection on tobacco plants. This information highlights the ultimate ability of a polyphagous aphid species to generate and maintain ecologically successful gene combinations through clonal propagation and the role of human transportation and global commerce for expanding their range. PMID:19432979

Identifying potential RNAi targets in grain aphid (Sitobion avenae F.) based on transcriptome profiling of its alimentary canal after feeding on wheat plants.

PubMed

Zhang, Min; Zhou, Yuwen; Wang, Hui; Jones, Huw; Gao, Qiang; Wang, Dahai; Ma, Youzhi; Xia, Lanqin

2013-08-16

The grain aphid (Sitobion avenae F.) is a major agricultural pest which causes significant yield losses of wheat in China, Europe and North America annually. Transcriptome profiling of the grain aphid alimentary canal after feeding on wheat plants could provide comprehensive gene expression information involved in feeding, ingestion and digestion. Furthermore, selection of aphid-specific RNAi target genes would be essential for utilizing a plant-mediated RNAi strategy to control aphids via a non-toxic mode of action. However, due to the tiny size of the alimentary canal and lack of genomic information on grain aphid as a whole, selection of the RNAi targets is a challenging task that as far as we are aware, has never been documented previously. In this study, we performed de novo transcriptome assembly and gene expression analyses of the alimentary canals of grain aphids before and after feeding on wheat plants using Illumina RNA sequencing. The transcriptome profiling generated 30,427 unigenes with an average length of 664 bp. Furthermore, comparison of the transcriptomes of alimentary canals of pre- and post feeding grain aphids indicated that 5490 unigenes were differentially expressed, among which, diverse genes and/or pathways were identified and annotated. Based on the RPKM values of these unigenes, 16 of them that were significantly up or down-regulated upon feeding were selected for dsRNA artificial feeding assay. Of these, 5 unigenes led to higher mortality and developmental stunting in an artificial feeding assay due to the down-regulation of the target gene expression. Finally, by adding fluorescently labelled dsRNA into the artificial diet, the spread of fluorescence signal in the whole body tissues of grain aphid was observed. Comparison of the transcriptome profiles of the alimentary canals of pre- and post-feeding grain aphids on wheat plants provided comprehensive gene expression information that could facilitate our understanding of the molecular mechanisms underlying feeding, ingestion and digestion. Furthermore, five novel and effective potential RNAi target genes were identified in grain aphid for the first time. This finding would provide a fundamental basis for aphid control in wheat through plant mediated RNAi strategy.

Population Dynamics of Aphids on Cereals: Digging in the Time-Series Data to Reveal Population Regulation Caused by Temperature

PubMed Central

Brabec, Marek; Honěk, Alois; Pekár, Stano; Martinková, Zdenka

2014-01-01

Aphid populations show periodic fluctuations and many causes are attributed to their dynamic. We investigated the regulation by temperature of the aphid populations composed of Metopolophium dirhodum, Sitobion avenae, and Rhopalosiphum padi on winter wheat using a 24 years long time series data. We computed the sum of daily temperatures above 5°C, the threshold temperature for aphid development, and the sum of daily temperatures within the [0(threshold for wheat development),5] °C interval. Applying Generalised Additive Model framework we tested influences of temperature history expressed via degree days before the start of the aphid immigration on the length of their occurrence. We aimed to estimate the magnitude and direction of this influence, and how far to the past before the start of the aphid season the temperature effect goes and then identify processes responsible for the effect. We fitted four models that differed in the way of correcting for abundance in the previous year and in specification of temperature effects. Abundance in the previous year did not affect the length of period of aphid population growth on wheat. The temperature effect on the period length increased up to 123 days before the start of the current season, i.e. when wheat completed vernalization. Increased sum of daily temperatures above 5°C and the sum of daily temperatures within the [0,5] °C interval both shortened the length of period of aphid population growth. Stronger effect of the latter suggests that wheat can escape from aphid attacks if during winter temperatures range from 0 to 5°C. The temperature influence was not homogeneous in time. The strongest effect of past temperature was about 50 to 80 and 90 to 110 days before the beginning of the current aphid season indicating important role of termination of aphid egg dormancy and egg hatching. PMID:25184219

Overexpression of IRM1 Enhances Resistance to Aphids in Arabidopsis thaliana

PubMed Central

Chen, Xi; Zhang, Zhao; Visser, Richard G. F.; Broekgaarden, Colette; Vosman, Ben

2013-01-01

Aphids are insects that cause direct damage to crops by the removal of phloem sap, but more importantly they spread devastating viruses. Aphids use their sophisticated mouthpart (i.e. stylet) to feed from the phloem sieve elements of the host plant. To identify genes that affect host plant resistance to aphids, we previously screened an Arabidopsis thaliana activation tag mutant collection. In such mutants, tagged genes are overexpressed by a strong 35S enhancer adjacent to the natural promoter, resulting in a dominant gain-of-function phenotype. We previously identified several of these mutants on which the aphid Myzus persicae showed a reduced population development compared with wild type. In the present study we show that the gene responsible for the phenotype of one of the mutants is At5g65040 and named this gene Increased Resistance to Myzus persicae 1 (IRM1). Overexpression of the cloned IRM1 gene conferred a phenotype identical to that of the original mutant. Conversely, an IRM1 knockout mutant promoted aphid population development compared to the wild type. We performed Electrical Penetration Graph analysis to investigate how probing and feeding behaviour of aphids was affected on plants that either overexpressed IRM1 or contained a knockout mutation in this gene. The EPG results indicated that the aphids encounter resistance factors while reaching for the phloem on the overexpressing line. This resistance mechanism also affected other aphid species and is suggested to be of mechanical nature. Interestingly, genetic variation for IRM1 expression in response to aphid attack was observed. Upon aphid attack the expression of IRM1 was initially (after 6 hours) induced in ecotype Wassilewskija followed by suppression. In Columbia-0, IRM1 expression was already suppressed six hours after the start of the infestation. The resistance conferred by the overexpression of IRM1 in A. thaliana trades off with plant growth. PMID:23951039

Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

PubMed

Nebreda, M; Moreno, A; Pérez, N; Palacios, I; Seco-Fernández, V; Fereres, A

2004-03-01

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

Soil pathogen-aphid interactions under differences in soil organic matter and mineral fertilizer.

PubMed

van Gils, Stijn; Tamburini, Giovanni; Marini, Lorenzo; Biere, Arjen; van Agtmaal, Maaike; Tyc, Olaf; Kos, Martine; Kleijn, David; van der Putten, Wim H

2017-01-01

There is increasing evidence showing that microbes can influence plant-insect interactions. In addition, various studies have shown that aboveground pathogens can alter the interactions between plants and insects. However, little is known about the role of soil-borne pathogens in plant-insect interactions. It is also not known how environmental conditions, that steer the performance of soil-borne pathogens, might influence these microbe-plant-insect interactions. Here, we studied effects of the soil-borne pathogen Rhizoctonia solani on aphids (Sitobion avenae) using wheat (Triticum aestivum) as a host. In a greenhouse experiment, we tested how different levels of soil organic matter (SOM) and fertilizer addition influence the interactions between plants and aphids. To examine the influence of the existing soil microbiome on the pathogen effects, we used both unsterilized field soil and sterilized field soil. In unsterilized soil with low SOM content, R. solani addition had a negative effect on aphid biomass, whereas it enhanced aphid biomass in soil with high SOM content. In sterilized soil, however, aphid biomass was enhanced by R. solani addition and by high SOM content. Plant biomass was enhanced by fertilizer addition, but only when SOM content was low, or in the absence of R. solani. We conclude that belowground pathogens influence aphid performance and that the effect of soil pathogens on aphids can be more positive in the absence of a soil microbiome. This implies that experiments studying the effect of pathogens under sterile conditions might not represent realistic interactions. Moreover, pathogen-plant-aphid interactions can be more positive for aphids under high SOM conditions. We recommend that soil conditions should be taken into account in the study of microbe-plant-insect interactions.

Social aggregation in pea aphids: experiment and random walk modeling.

PubMed

Nilsen, Christa; Paige, John; Warner, Olivia; Mayhew, Benjamin; Sutley, Ryan; Lam, Matthew; Bernoff, Andrew J; Topaz, Chad M

2013-01-01

From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control.

Sharing a Host Plant (Wheat [Triticum aestivum]) Increases the Fitness of Fusarium graminearum and the Severity of Fusarium Head Blight but Reduces the Fitness of Grain Aphids (Sitobion avenae)

PubMed Central

Drakulic, Jassy; Caulfield, John; Woodcock, Christine; Jones, Stephen P. T.; Linforth, Robert; Bruce, Toby J. A.

2015-01-01

We hypothesized that interactions between fusarium head blight-causing pathogens and herbivores are likely to occur because they share wheat as a host plant. Our aim was to investigate the interactions between the grain aphid, Sitobion avenae, and Fusarium graminearum on wheat ears and the role that host volatile chemicals play in mediating interactions. Wheat ears were treated with aphids and F. graminearum inoculum, together or separately, and disease progress was monitored by visual assessment and by quantification of pathogen DNA and mycotoxins. Plants exposed to both aphids and F. graminearum inoculum showed accelerated disease progression, with a 2-fold increase in disease severity and 5-fold increase in mycotoxin accumulation over those of plants treated only with F. graminearum. Furthermore, the longer the period of aphid colonization of the host prior to inoculation with F. graminearum, the greater the amount of pathogen DNA that accumulated. Headspace samples of plant volatiles were collected for use in aphid olfactometer assays and were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC-coupled electroantennography. Disease-induced plant volatiles were repellent to aphids, and 2-pentadecanone was the key semiochemical underpinning the repellent effect. We measured aphid survival and fecundity on infected wheat ears and found that both were markedly reduced on infected ears. Thus, interactions between F. graminearum and grain aphids on wheat ears benefit the pathogen at the expense of the pest. Our findings have important consequences for disease epidemiology, because we show increased spread and development of host disease, together with greater disease severity and greater accumulation of pathogen DNA and mycotoxin, when aphids are present. PMID:25769834

Sharing a Host Plant (Wheat [Triticum aestivum]) Increases the Fitness of Fusarium graminearum and the Severity of Fusarium Head Blight but Reduces the Fitness of Grain Aphids (Sitobion avenae).

PubMed

Drakulic, Jassy; Caulfield, John; Woodcock, Christine; Jones, Stephen P T; Linforth, Robert; Bruce, Toby J A; Ray, Rumiana V

2015-05-15

We hypothesized that interactions between fusarium head blight-causing pathogens and herbivores are likely to occur because they share wheat as a host plant. Our aim was to investigate the interactions between the grain aphid, Sitobion avenae, and Fusarium graminearum on wheat ears and the role that host volatile chemicals play in mediating interactions. Wheat ears were treated with aphids and F. graminearum inoculum, together or separately, and disease progress was monitored by visual assessment and by quantification of pathogen DNA and mycotoxins. Plants exposed to both aphids and F. graminearum inoculum showed accelerated disease progression, with a 2-fold increase in disease severity and 5-fold increase in mycotoxin accumulation over those of plants treated only with F. graminearum. Furthermore, the longer the period of aphid colonization of the host prior to inoculation with F. graminearum, the greater the amount of pathogen DNA that accumulated. Headspace samples of plant volatiles were collected for use in aphid olfactometer assays and were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC-coupled electroantennography. Disease-induced plant volatiles were repellent to aphids, and 2-pentadecanone was the key semiochemical underpinning the repellent effect. We measured aphid survival and fecundity on infected wheat ears and found that both were markedly reduced on infected ears. Thus, interactions between F. graminearum and grain aphids on wheat ears benefit the pathogen at the expense of the pest. Our findings have important consequences for disease epidemiology, because we show increased spread and development of host disease, together with greater disease severity and greater accumulation of pathogen DNA and mycotoxin, when aphids are present. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Remote sensing of crop parameters with a polarized, frequency-doubled Nd:YAG laser

NASA Astrophysics Data System (ADS)

Kalshoven, James E., Jr.; Tierney, Michael R., Jr.; Daughtry, Craig S. T.; McMurtrey, James E., III

1995-05-01

Polarized laser remote-sensing measurements that correlate the yield, the normalized difference vegetation index, and the leaf area index with the depolarized backscattered radiation from corn plots grown with eight different nitrogen fertilization dosages are presented. A polarized Nd:YAG laser emitting at 1064 and 532 nm is used. Depolarization increased significantly with increasing fertilization at the infrared wavelength, and there was a decrease in the depolarization at the green wavelength. The depolarization spectral difference index, defined as the absolute difference in the depolarization at the two wavelengths, is introduced as a parameter that is an indicator of the condition of the internal leaf structure.

Prevalence of entomophthoralean fungi (Entomophthoromycota) of aphids in relation to developmental stages.

PubMed

Manfrino, Romina G; Gutierrez, Alejandra C; Rueda Páramo, Manuel E; Salto, César E; López Lastra, Claudia C

2016-08-01

Transmission of fungal pathogens of aphids may be affected by the host developmental stage. Brassica and Lactuca sativa L. crops were sampled in Santa Fe, Argentina, to determine the prevalence of fungal-diseased aphids and investigate the differences between developmental stages of aphids. The fungal pathogens identified were Zoophthora radicans (Bref.) A. Batko, Pandora neoaphidis (Remaud. & Hennebert) Humber and Entomophthora planchoniana Cornu. Their prevalence on each crop was calculated. The numbers of infected aphids were significantly different between the different developmental stages on all crops except B. oleracea var. botrytis L. The entomophthoralean fungi identified are important mortality factors of aphids on horticultural crops in Santa Fe. The numbers of infected nymphs and adults were significantly different, nymphs being the most affected developmental stage. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

(E)-β-farnesene gene reduces Lipaphis erysimi colonization in transgenic Brassica juncea lines

PubMed Central

Verma, Shiv Shankar; Sinha, Rakesh Kumar; Jajoo, Anajna

2015-01-01

Aphids are the major concern that significantly reduces the yield of crops. (E)-β-farnesene (Eβf) is the principal component of the alarm pheromone of many aphids. The results of current research support the direct defense response of (E)-β-farnesene (Eβf) against aphid Lipaphis erysimi (L.) Kaltenbach in Brassica juncea. Eβf gene was isolated from Mentha arvensis and transformed into B. juncea, showed direct repellent against aphid colonization. The seasonal mean population (SMP) recorded under field condition showed significantly higher aphid colonization in wild type in comparison to most of the transgenic lines, and shows positive correlation with the repellency of transgenic plant expressing (E)-β-farnesene. The current research investigation provides direct evidence for aphid control in B. juncea using Eβf, a non-toxic mode of action. PMID:26251882

Relationships Between Aphids (Insecta: Homoptera: Aphididae) and Slugs (Gastropoda: Stylommatophora: Agriolimacidae) Pests of Legumes (Fabaceae: Lupinus)

PubMed Central

Kozłowski, Jan; Strażyński, Przemysław; Jaskulska, Monika; Kozłowska, Maria

2016-01-01

Lupin plants are frequently damaged by various herbivorous invertebrates. Significant among these are slugs and aphids, which sometimes attack the same plants. Relationships between aphids, slugs and food plant are very interesting. Grazing by these pests on young plants can lead to significant yield losses. There is evidence that the alkaloids present in some lupin plants may reduce grazing by slugs, aphids and other invertebrates. In laboratory study was analyzed the relationships between aphid Aphis craccivora and slug Deroceras reticulatum pests of legumes Lupinus angustifolius. It was found that the presence of aphids significantly reduced slug grazing on the plants. The lupin cultivars with high alkaloid content were found to be less heavily damaged by D. reticulatum, and the development of A. craccivora was found to be inhibited on such plants. PMID:27324580

Variable Isotopic Compositions of Host Plant Populations Preclude Assessment of Aphid Overwintering Sites

PubMed Central

Voegtlin, David J.; Hamilton, Krista L.; Hogg, David B.

2017-01-01

Soybean aphid (Aphis glycines Matsumura) is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a regional scale. In this preliminary study, we explored the utility of variation in stable isotopes of carbon and nitrogen to distinguish soybean aphid overwintering origins. We compared variation in bulk 13C and 15N content in buckthorn (Rhamnus cathartica L.) and soybean aphids in Wisconsin, among known overwintering locations in the northern Midwest. Specifically, we looked for associations between buckthorn and environmental variables that could aid in identifying overwintering habitats. We detected significant evidence of correlation between the bulk 13C and 15N signals of soybean aphids and buckthorn, despite high variability in stable isotope composition within and among buckthorn plants. Further, the 15N signal in buckthorn varied predictably with soil composition. However, lack of sufficient differentiation of geographic areas along axes of isotopic and environmental variation appears to preclude the use of carbon and nitrogen isotopic signals as effective predictors of likely aphid overwintering sites. These preliminary data suggest the need for future work that can further account for variability in 13C and 15N within/among buckthorn plants, and that explores the utility of other stable isotopes in assessing likely aphid overwintering sites. PMID:29206134

Identification of an intraspecific alarm pheromone and two conserved odorant-binding proteins associated with (E)-β-farnesene perception in aphid Rhopalosiphum padi.

PubMed

Fan, Jia; Xue, Wenxin; Duan, Hongxia; Jiang, Xin; Zhang, Yong; Yu, Wenjuan; Jiang, Shanshan; Sun, Jingrun; Chen, Julian

2017-08-01

(E)-β-farnesene (EBF) is the common active component of aphid alarm pheromone. Either or both of two orthologs of ordorant-binding proteins (OBPs), OBP3 and OBP7, recently reported in aphids, may be involved in EBF perception. The aim of this study was to investigate the respondence of the aphid Rhopalosiphum padi to its intraspecific alarm pheromone and which OBP is responsible for that response. We tested the olfactory response of the aphid R. padi to EBF and freshly crushed aphids. Then, we extracted the volatiles from crushed aphids using solid phase microextraction (SPME) for analysis with GC×GC-TOF/MS. We also cloned two OBPs cDNAs in R. padi (RpadOBP3 and RpadOBP7) and expressed them in competent Escherichia coli cells. Both recombinant proteins, RpadOBP3 and RpadOBP7, bound EBF well, with RpadOBP7 having specifically stronger affinity for EBF than for other volatiles. Based on the crystal structure of the OBPs with high identity, we performed homology modeling and analyzed the interactions between RpadOBPs and EBF. In conclusion, R. padi was repelled by both EBF and crushed aphids. EBF was identified as the only volatile that acted as the alarm pheromone. Our results indicated that OBP7 is a potential molecular target to control wheat aphids by disturbing their behaviors to the alarm pheromone. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genome Sequence of the Pea Aphid Acyrthosiphon pisum

PubMed Central

2010-01-01

Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. These findings include discovery of extensive gene duplication in more than 2000 gene families as well as loss of evolutionarily conserved genes. Gene family expansions relative to other published genomes include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The pea aphid genome reveals that only a limited number of genes have been acquired from bacteria; thus the reduced gene count of Buchnera does not reflect gene transfer to the host genome. The inventory of metabolic genes in the pea aphid genome suggests that there is extensive metabolite exchange between the aphid and Buchnera, including sharing of amino acid biosynthesis between the aphid and Buchnera. The pea aphid genome provides a foundation for post-genomic studies of fundamental biological questions and applied agricultural problems. PMID:20186266

Soybean Aphid Infestation Induces Changes in Fatty Acid Metabolism in Soybean

PubMed Central

Kanobe, Charles; McCarville, Michael T.; O’Neal, Matthew E.; Tylka, Gregory L.; MacIntosh, Gustavo C.

2015-01-01

The soybean aphid (Aphis glycines Matsumura) is one of the most important insect pests of soybeans in the North-central region of the US. It has been hypothesized that aphids avoid effective defenses by inhibition of jasmonate-regulated plant responses. Given the role fatty acids play in jasmonate-induced plant defenses, we analyzed the fatty acid profile of soybean leaves and seeds from aphid-infested plants. Aphid infestation reduced levels of polyunsaturated fatty acids in leaves with a concomitant increase in palmitic acid. In seeds, a reduction in polyunsaturated fatty acids was associated with an increase in stearic acid and oleic acid. Soybean plants challenged with the brown stem rot fungus or with soybean cyst nematodes did not present changes in fatty acid levels in leaves or seeds, indicating that the changes induced by aphids are not a general response to pests. One of the polyunsaturated fatty acids, linolenic acid, is the precursor of jasmonate; thus, these changes in fatty acid metabolism may be examples of “metabolic hijacking” by the aphid to avoid the induction of effective defenses. Based on the changes in fatty acid levels observed in seeds and leaves, we hypothesize that aphids potentially induce interference in the fatty acid desaturation pathway, likely reducing FAD2 and FAD6 activity that leads to a reduction in polyunsaturated fatty acids. Our data support the idea that aphids block jasmonate-dependent defenses by reduction of the hormone precursor. PMID:26684003

Inheritance patterns of secondary symbionts during sexual reproduction of pea aphid biotypes.

PubMed

Peccoud, Jean; Bonhomme, Joël; Mahéo, Frédérique; de la Huerta, Manon; Cosson, Olivier; Simon, Jean-Christophe

2014-06-01

Herbivorous insects frequently harbor bacterial symbionts that affect their ecology and evolution. Aphids host the obligatory endosymbiont Buchnera, which is required for reproduction, together with facultative symbionts whose frequencies vary across aphid populations. These maternally transmitted secondary symbionts have been particularly studied in the pea aphid, Acyrthosiphon pisum, which harbors at least 8 distinct bacterial species (not counting Buchnera) having environmentally dependent effects on host fitness. In particular, these symbiont species are associated with pea aphid populations feeding on specific plants. Although they are maternally inherited, these bacteria are occasionally transferred across insect lineages. One mechanism of such nonmaternal transfer is paternal transmission to the progeny during sexual reproduction. To date, transmission of secondary symbionts during sexual reproduction of aphids has been investigated in only a handful of aphid lineages and 3 symbiont species. To better characterize this process, we investigated inheritance patterns of 7 symbiont species during sexual reproduction of pea aphids through a crossing experiment involving 49 clones belonging to 9 host-specialized biotypes, and 117 crosses. Symbiont species in the progeny were detected with diagnostic qualitative PCR at the fundatrix stage hatching from eggs and in later parthenogenetic generations. We found no confirmed case of paternal transmission of symbionts to the progeny, and we observed that maternal transmission of a particular symbiont species (Serratia symbiotica) was quite inefficient. We discuss these observations in respect to the ecology of the pea aphid. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Key Transport and Ammonia Recycling Genes Involved in Aphid Symbiosis Respond to Host-Plant Specialization.

PubMed

Kim, Dohyup; Minhas, Bushra F; Li-Byarlay, Hongmei; Hansen, Allison K

2018-05-25

Microbes are known to influence insect-plant interactions; however, it is unclear if host-plant diet influences the regulation of nutritional insect symbioses. The pea aphid, Acyrthosiphon pisum , requires its nutritional endosymbiont, Buchnera , for the production of essential amino acids. We hypothesize that key aphid genes that regulate the nutritional symbioses respond to host-plant diet when aphids feed on a specialized (alfalfa) compared to a universal host-plant diet (fava), which vary in amino acid profiles. Using RNA-Seq and whole genome bisulfite sequencing, we measured gene expression and DNA methylation profiles for such genes when aphids fed on either their specialized or universal host-plant diets. Our results reveal that when aphids feed on their specialized host-plant they significantly up-regulate and/or hypo-methylate key aphid genes in bacteriocytes related to the amino acid metabolism, including glutamine synthetase in the GOGAT cycle that recycles ammonia into glutamine and the glutamine transporter ApGLNT1 Moreover, regardless of what host-plant aphids feed on we observed significant up-regulation and differential methylation of key genes involved in the amino acid metabolism and the glycine/serine metabolism, a metabolic program observed in proliferating cancer cells potentially to combat oxidative stress. Based on our results, we suggest that this regulatory response of key symbiosis genes in bacteriocytes allows aphids to feed on a suboptimal host-plant that they specialize on. Copyright © 2018, G3: Genes, Genomes, Genetics.

How conserved are the bacterial communities associated with aphids? A detailed assessment of the Brevicoryne brassicae (Hemiptera: Aphididae) using 16S rDNA.

PubMed

Clark, E L; Daniell, T J; Wishart, J; Hubbard, S F; Karley, A J

2012-12-01

Aphids harbor a community of bacteria that include obligate and facultative endosymbionts belonging to the Enterobacteriaceae along with opportunistic, commensal, or pathogenic bacteria. This study represents the first detailed analysis of the identity and diversity of the bacterial community associated with the cabbage aphid, Brevicoryne brassicae (L.). 16S rDNA sequence analysis revealed that the community of bacteria associated with B. brassicae was diverse, with at least four different bacterial community types detected among aphid lines, collected from widely dispersed sites in Northern Britain. The bacterial sequence types isolated from B. brassicae showed little similarity to any bacterial endosymbionts characterized in insects; instead, they were closely related to free-living extracellular bacterial species that have been isolated from the aphid gut or that are known to be present in the environment, suggesting that they are opportunistic bacteria transmitted between the aphid gut and the environment. To quantify variation in bacterial community between aphid lines, which was driven largely by differences in the proportions of two dominant bacterial orders, the Pseudomonales and the Enterobacteriales, we developed a novel real-time (Taqman) qPCR assay. By improving our knowledge of aphid microbial ecology, and providing novel molecular tools to examine the presence and function of the microbial community, this study forms the basis of further research to explore the influence of the extracellular bacterial community on aphid fitness, pest status, and susceptibility to control by natural enemies.

Competing Role of Bioactive Constituents in Moringa oleifera Extract and Conventional Nutrition Feed on the Performance of Cobb 500 Broilers

PubMed Central

Karthivashan, Govindarajan; Arulselvan, Palanisamy; Alimon, Abd. Razak; Safinar Ismail, Intan; Fakurazi, Sharida

2015-01-01

The influence of Moringa oleifera (MO) leaf extract as a dietary supplement on the growth performance and antioxidant parameters was evaluated on broiler meat and the compounds responsible for the corresponding antioxidant activity were identified. 0.5%, 1.0%, and 1.5% w/v of MO leaf aqueous extracts (MOLE) were prepared, and nutritional feed supplemented with 0%, 0.5%, 1.0%, and 1.5% w/w of MO leaf meal (MOLM) extracts were also prepared and analysed for their in vitro antioxidant potential. Furthermore, the treated broiler groups (control (T1) and treatment (T2, T3, and T4)) were evaluated for performance, meat quality, and antioxidant status. The results of this study revealed that, among the broilers fed MOLM, the broilers fed 0.5% w/w MOLM (T2) exhibited enhanced meat quality and antioxidant status (P < 0.05). However, the antioxidant activity of the MOLE is greater than that of the MOLM. The LC-MS/MS analysis of MOLM showed high expression of isoflavones and fatty acids from soy and corn source, which antagonistically inhibit the expression of the flavonoids/phenols in the MO leaves thereby masking its antioxidant effects. Thus, altering the soy and corn gradients in conventional nutrition feed with 0.5% w/w MO leaves supplement would provide an efficient and cost-effective feed supplement. PMID:25793214

Gall volatiles defend aphids against a browsing mammal

PubMed Central

2013-01-01

Background Plants have evolved an astonishing array of survival strategies. To defend against insects, for example, damaged plants emit volatile organic compounds that attract the herbivore’s natural enemies. So far, plant volatile responses have been studied extensively in conjunction with leaf chewing and sap sucking insects, yet little is known about the relationship between plant volatiles and gall-inducers, the most sophisticated herbivores. Here we describe a new role for volatiles as gall-insects were found to benefit from this plant defence. Results Chemical analyses of galls triggered by the gregarious aphid Slavum wertheimae on wild pistachio trees showed that these structures contained and emitted considerably higher quantities of plant terpenes than neighbouring leaves and fruits. Behavioural assays using goats as a generalist herbivore confirmed that the accumulated terpenes acted as olfactory signals and feeding deterrents, thus enabling the gall-inducers to escape from inadvertent predation by mammals. Conclusions Increased emission of plant volatiles in response to insect activity is commonly looked upon as a “cry for help” by the plant to attract the insect’s natural enemies. In contrast, we show that such volatiles can serve as a first line of insect defences that extends the ‘extended phenotype’ represented by galls, beyond physical boundaries. Our data support the Enemy hypothesis insofar that high levels of gall secondary metabolites confer protection against natural enemies. PMID:24020365

Abscisic acid deficiency increases defence responses against Myzus persicae in Arabidopsis.

PubMed

Hillwig, Melissa S; Chiozza, Mariana; Casteel, Clare L; Lau, Siau Ting; Hohenstein, Jessica; Hernández, Enrique; Jander, Georg; MacIntosh, Gustavo C

2016-02-01

Comparison of Arabidopsis thaliana (Arabidopsis) gene expression induced by Myzus persicae (green peach aphid) feeding, aphid saliva infiltration and abscisic acid (ABA) treatment showed a significant positive correlation. In particular, ABA-regulated genes are over-represented among genes that are induced by M. persicae saliva infiltration into Arabidopsis leaves. This suggests that the induction of ABA-related gene expression could be an important component of the Arabidopsis-aphid interaction. Consistent with this hypothesis, M. persicae populations induced ABA production in wild-type plants. Furthermore, aphid populations were smaller on Arabidopsis aba1-1 mutants, which cannot synthesize ABA, and showed a significant preference for wild-type plants compared with the mutant. Total free amino acids, which play an important role in aphid nutrition, were not altered in the aba1-1 mutant line, but the levels of isoleucine (Ile) and tryptophan (Trp) were differentially affected by aphids in wild-type and mutant plants. Recently, indole glucosinolates have been shown to promote aphid resistance in Arabidopsis. In this study, 4-methoxyindol-3-ylmethylglucosinolate was more abundant in the aba1-1 mutant than in wild-type Arabidopsis, suggesting that the induction of ABA signals that decrease the accumulation of defence compounds may be beneficial for aphids. © 2015 BSPP AND JOHN WILEY & SONS LTD.

Alteration of intersubunit acid–base pair interactions at the quasi-threefold axis of symmetry of Cucumber mosaic virus disrupts aphid vector transmission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bricault, Christine A.; Perry, Keith L., E-mail: KLP3@cornell.edu

2013-06-05

In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majoritymore » of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility.« less

Protein digestion in cereal aphids (Sitobion avenae) as a target for plant defence by endogenous proteinase inhibitors.

PubMed

Pyati, Prashant; Bandani, Ali R; Fitches, Elaine; Gatehouse, John A

2011-07-01

Gut extracts from cereal aphids (Sitobion avenae) showed significant levels of proteolytic activity, which was inhibited by reagents specific for cysteine proteases and chymotrypsin-like proteases. Gut tissue contained cDNAs encoding cathepsin B-like cysteine proteinases, similar to those identified in the closely related pea aphid (Acyrthosiphon pisum). Analysis of honeydew (liquid excreta) from cereal aphids fed on diet containing ovalbumin showed that digestion of ingested proteins occurred in vivo. Protein could partially substitute for free amino acids in diet, although it could not support complete development. Recombinant wheat proteinase inhibitors (PIs) fed in diet were antimetabolic to cereal aphids, even when normal levels of free amino acids were present. PIs inhibited proteolysis by aphid gut extracts in vitro, and digestion of protein fed to aphids in vivo. Wheat subtilisin/chymotrypsin inhibitor, which was found to inhibit serine and cysteine proteinases, was more effective in both inhibitory and antimetabolic activity than wheat cystatin, which inhibited cysteine proteases only. Digestion of ingested protein is unlikely to contribute significantly to nutritional requirements when aphids are feeding on phloem, and the antimetabolic activity of dietary proteinase inhibitors is suggested to result from effects on proteinases involved in degradation of endogenous proteins. Copyright © 2011 Elsevier Ltd. All rights reserved.

Indirect effect of a transgenic wheat on aphids through enhanced powdery mildew resistance.

PubMed

von Burg, Simone; Álvarez-Alfageme, Fernando; Romeis, Jörg

2012-01-01

In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici) and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM) mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew) became more favourable for another pest (aphids).

Indirect Effect of a Transgenic Wheat on Aphids through Enhanced Powdery Mildew Resistance

PubMed Central

von Burg, Simone; Álvarez-Alfageme, Fernando; Romeis, Jörg

2012-01-01

In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici) and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM) mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew) became more favourable for another pest (aphids). PMID:23056284

A cost of alarm pheromone production in cotton aphids, Aphis gossypii

NASA Astrophysics Data System (ADS)

Byers, John A.

2005-02-01

The sesquiterpene, (E)-β-farnesene, is used by many aphid species as an alarm pheromone to warn related individuals of predation. Disturbed cotton aphids, Aphis gossypii Glover, released (E)-β-farnesene into the air as detected by solid phase microextraction and gas chromatography mass spectrometry (GC MS). Solvent extracts of cotton aphids of various life stages and weights also were analyzed by GC MS for sums of ions 69 and 93, which discriminated (E)-β-farnesene from coeluting compounds. Aphids of all life stages and sizes reared on cotton plants in both an environmental chamber and glasshouse contained (E)-β-farnesene in amounts ranging from 0.1 to 1.5 ng per individual. The quantities of (E)-β-farnesene in aphids increased in relation to increasing body weight, and variation in individual weights explained about 82% of the variation in alarm pheromone. However, the concentrations (ng/mg fresh weight) declined exponentially with increasing body weight. These findings indicate that aphid nymphs try to compensate for their smaller size by producing relatively more pheromone per weight than adults but still cannot approach an evolutionary optimal load, as assumed in adults with the greatest total amounts. This suggests that young aphids need to balance costs of growth and maturation with costs of producing the alarm pheromone.

Wide dispersal of aphid-pathogenic Entomophthorales among aphids relies upon migratory alates.

PubMed

Feng, Ming-Guang; Chen, Chun; Chen, Bin

2004-05-01

Entomophthoralean mycoses are of general importance in the natural control of aphids, but mechanisms involved in their dissemination are poorly understood. Despite several possible means of fungal survival, the dispersal of the mycoses in aphids has never been related to the flight of their migratory alates that are able to locate suitable host plants. In this study, aphid-pathogenic fungi proved to be widely disseminated among various aphids by their alates through migratory flight based on the following findings. First, up to 36.6% of the 7139 migratory alates (including nine species of vegetable or cereal aphids) trapped from air > 30 m above the ground in three provinces of China were found bearing eight species of fungal pathogens. Of those, six were aphid-specific Entomophthorales dominated in individual cases by Pandora neoaphidis, which occurs globally but has no resting spores discovered to date. Secondly, infected alates were confirmed to be able to fly for hours, to initiate colonies on plants after flight and to transmit fungal infection to their offspring in a laboratory experiment, in which 238 Sitobion avenae alates were individually flown in a computer-monitoring flight mill system after exposure to a spore shower of P. neoaphidis and then allowed to colonize host plants.

An alternative pathway to eusociality: Exploring the molecular and functional basis of fortress defense.

PubMed

Lawson, Sarah P; Sigle, Leah T; Lind, Abigail L; Legan, Andrew W; Mezzanotte, Jessica N; Honegger, Hans-Willi; Abbot, Patrick

2017-08-01

Some animals express a form of eusociality known as "fortress defense," in which defense rather than brood care is the primary social act. Aphids are small plant-feeding insects, but like termites, some species express division of labor and castes of aggressive juvenile "soldiers." What is the functional basis of fortress defense eusociality in aphids? Previous work showed that the acquisition of venoms might be a key innovation in aphid social evolution. We show that the lethality of aphid soldiers derives in part from the induction of exaggerated immune responses in insects they attack. Comparisons between closely related social and nonsocial species identified a number of secreted effector molecules that are candidates for immune modulation, including a convergently recruited protease described in unrelated aphid species with venom-like functions. These results suggest that aphids are capable of antagonizing conserved features of the insect immune response, and provide new insights into the mechanisms underlying the evolution of fortress defense eusociality in aphids. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

[An example of research on biological control: Entomophthora fungi pathogenic for aphids].

PubMed

Latgé, J P; Remaudière, G; Papierok, B

1978-01-01

The results obtained in 15 years of research on the Entomophthorales pathogen of aphids showed the importance of the action of these fungi in the regulation of natural aphid populations and their possible use in agriculture as a biological control agent. Recent ecological studies on natural populations of aphids established the seasonal variation of the different fungal species and the diverse degrees of specificity between the species or groups of species of aphid and the various species of Entomophthora. The study of populations dynamics of an aphid species on a cultivated plant permitted the determination of the way a certain number of biotic and abiotic factors, such as temperature, humidity, thresholds of the insect population and of the infecting fungus lead to an epizootic development. If the air propagation of the disease by conidia is understood for a long time, the role of the soil as a reservoir for the infecting fungus has been demonstrated recently. Under favourable climatic conditions, the use of industrially produced resistant resting spores would allow the regulation of aphid populations in nature.

Production and Characterization of Bacillus thuringiensis Cry1Ac-Resistant Cotton Bollworm Helicoverpa zea (Boddie)▿

PubMed Central

Anilkumar, Konasale J.; Rodrigo-Simón, Ana; Ferré, Juan; Pusztai-Carey, Marianne; Sivasupramaniam, Sakuntala; Moar, William J.

2008-01-01

Laboratory-selected Bacillus thuringiensis-resistant colonies are important tools for elucidating B. thuringiensis resistance mechanisms. However, cotton bollworm, Helicoverpa zea, a target pest of transgenic corn and cotton expressing B. thuringiensis Cry1Ac (Bt corn and cotton), has proven difficult to select for stable resistance. Two populations of H. zea (AR and MR), resistant to the B. thuringiensis protein found in all commercial Bt cotton varieties (Cry1Ac), were established by selection with Cry1Ac activated toxin (AR) or MVP II (MR). Cry1Ac toxin reflects the form ingested by H. zea when feeding on Bt cotton, whereas MVP II is a Cry1Ac formulation used for resistance selection and monitoring. The resistance ratio (RR) for AR exceeded 100-fold after 11 generations and has been maintained at this level for nine generations. This is the first report of stable Cry1Ac resistance in H. zea. MR crashed after 11 generations, reaching only an RR of 12. AR was only partially cross-resistant to MVP II, suggesting that MVP II does not have the same Cry1Ac selection pressure as Cry1Ac toxin against H. zea and that proteases may be involved with resistance. AR was highly cross-resistant to Cry1Ab toxin but only slightly cross-resistant to Cry1Ab expressing corn leaf powder. AR was not cross-resistant to Cry2Aa2, Cry2Ab2-expressing corn leaf powder, Vip3A, and cypermethrin. Toxin-binding assays showed no significant differences, indicating that resistance was not linked to a reduction in binding. These results aid in understanding why this pest has not evolved B. thuringiensis resistance, and highlight the need to choose carefully the form of B. thuringiensis protein used in experiments. PMID:18024681

Microorganisms from aphid honeydew attract and enhance the efficacy of natural enemies

PubMed Central

Leroy, Pascal D.; Sabri, Ahmed; Heuskin, Stéphanie; Thonart, Philippe; Lognay, Georges; Verheggen, François J.; Francis, Frédéric; Brostaux, Yves; Felton, Gary W.; Haubruge, Eric

2011-01-01

Aphids are one of the most serious pests of crops worldwide, causing major yield and economic losses. To control aphids, natural enemies could be an option but their efficacy is sometimes limited by their dispersal in natural environment. Here we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which acts as a kairomone enhancing the efficiency of aphid natural enemies. Our findings represent the first case of a host-associated bacterium driving prey location and ovipositional preference for the natural enemy. We show that this bacterium has a key role in tritrophic interactions because it is the direct source of volatiles used to locate prey. Some specific semiochemicals produced by S. sciuri were also identified as significant attractants and ovipositional stimulants. The use of this host-associated bacterium could certainly provide a novel approach to control aphids in field and greenhouse systems. PMID:21673669

Relationships Between Aphids (Insecta: Homoptera: Aphididae) and Slugs (Gastropoda: Stylommatophora: Agriolimacidae) Pests of Legumes (Fabaceae: Lupinus).

PubMed

Kozłowski, Jan; Strażyński, Przemysław; Jaskulska, Monika; Kozłowska, Maria

2016-01-01

Lupin plants are frequently damaged by various herbivorous invertebrates. Significant among these are slugs and aphids, which sometimes attack the same plants. Relationships between aphids, slugs and food plant are very interesting. Grazing by these pests on young plants can lead to significant yield losses. There is evidence that the alkaloids present in some lupin plants may reduce grazing by slugs, aphids and other invertebrates. In laboratory study was analyzed the relationships between aphid Aphis craccivora and slug Deroceras reticulatum pests of legumes Lupinus angustifolius. It was found that the presence of aphids significantly reduced slug grazing on the plants. The lupin cultivars with high alkaloid content were found to be less heavily damaged by D. reticulatum, and the development of A. craccivora was found to be inhibited on such plants. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

Distribution and diversity of Russian wheat aphid (Hemiptera: Aphididae) biotypes in South Africa and Lesotho.

PubMed

Jankielsohn, Astrid

2011-10-01

Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae) was recorded for the first time in South Africa in 1978. In 2005, a second biotype, RWASA2, emerged, and here we report on the emergence of yet another biotype, found for the first time in 2009. The discovery of new Russian wheat aphid biotypes is a significant challenge to the wheat, Triticum aestivum L., industry in South Africa. Russian wheat aphid resistance in wheat, that offered wheat producers a long-term solution to Russian wheat aphid control, may no longer be effective in areas where the new biotypes occur. It is therefore critical to determine the diversity and extent of distribution of biotypes in South Africa to successfully deploy Russian wheat aphid resistance in wheat. Screening of 96 Russian wheat aphid clones resulted in identification of three Russian wheat aphid biotypes. Infestations of RWASA1 caused susceptible damage symptoms only in wheat entries containing the Dn3 gene. Infestations of RWASA2 caused susceptible damage symptoms in wheat entries containing Dn1, Dn2, Dn3, and Dn9 resistant genes. Based on the damage-rating scores for the seven resistance sources, a new biotype, which caused damage rating scores different from those for RWASA1 and RWASA2, was evident among the Russian wheat aphid populations tested. This new biotype is virulent to the same resistance sources as RWASA2 (Dn1, Dn2, Dn3, and Dn9), but it also has added virulence to Dn4, whereas RWASA2 is avirulent to this resistance source.

The price of protection: a defensive endosymbiont impairs nymph growth in the bird cherry-oat aphid, Rhopalosiphum padi.

PubMed

Leybourne, Daniel J; Bos, Jorunn I B; Valentine, Tracy A; Karley, Alison J

2018-05-24

Bacterial endosymbionts have enabled aphids to adapt to a range of stressors, but their effects in many aphid species remain to be established. The bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus), is an important pest of cereals worldwide and has been reported to form symbiotic associations with Serratia symbiotica and Sitobion miscanthi L-type Symbiont endobacteria, although the resulting aphid phenotype has not been described. This study presents the first report of R. padi infection with the facultative bacterial endosymbiont Hamiltonella defensa. Individuals of R. padi were sampled from populations in Eastern Scotland, UK, and shown to represent seven R. padi genotypes based on the size of polymorphic microsatellite markers; two of these genotypes harboured H. defensa. In parasitism assays, survival of H. defensa-infected nymphs following attack by the parasitoid wasp Aphidius colemani (Viereck) was five-fold higher than for uninfected nymphs. Aphid genotype was a major determinant of aphid performance on two Hordeum species, a modern cultivar of barley H. vulgaris and a wild relative H. spontaneum, although aphids infected with H. defensa showed 16% lower nymph mass gain on the partially-resistant wild relative compared with uninfected individuals. These findings suggest that deploying resistance traits in barley will favour the fittest R. padi genotypes, but symbiont-infected individuals will be favoured when parasitoids are abundant, although these aphids will not achieve optimal performance on a poor quality host plant. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Characterization of Arabidopsis Transcriptional Responses to Different Aphid Species Reveals Genes that Contribute to Host Susceptibility and Non-host Resistance

PubMed Central

Jaouannet, Maëlle; Morris, Jenny A.; Hedley, Peter E.; Bos, Jorunn I. B.

2015-01-01

Aphids are economically important pests that display exceptional variation in host range. The determinants of diverse aphid host ranges are not well understood, but it is likely that molecular interactions are involved. With significant progress being made towards understanding host responses upon aphid attack, the mechanisms underlying non-host resistance remain to be elucidated. Here, we investigated and compared Arabidopsis thaliana host and non-host responses to aphids at the transcriptional level using three different aphid species, Myzus persicae, Myzus cerasi and Rhopalosiphum pisum. Gene expression analyses revealed a high level of overlap in the overall gene expression changes during the host and non-host interactions with regards to the sets of genes differentially expressed and the direction of expression changes. Despite this overlap in transcriptional responses across interactions, there was a stronger repression of genes involved in metabolism and oxidative responses specifically during the host interaction with M. persicae. In addition, we identified a set of genes with opposite gene expression patterns during the host versus non-host interactions. Aphid performance assays on Arabidopsis mutants that were selected based on our transcriptome analyses identified novel genes contributing to host susceptibility, host defences during interactions with M. persicae as well to non-host resistance against R. padi. Understanding how plants respond to aphid species that differ in their ability to infest plant species, and identifying the genes and signaling pathways involved, is essential for the development of novel and durable aphid control in crop plants. PMID:25993686

Water Stress and Aphid Feeding Differentially Influence Metabolite Composition in Arabidopsis thaliana (L.)

PubMed Central

Mewis, Inga; Khan, Mohammed A. M.; Glawischnig, Erich; Schreiner, Monika; Ulrichs, Christian

2012-01-01

Little is known about how drought stress influences plant secondary metabolite accumulation and how this affects plant defense against different aphids. We therefore cultivated Arabidopsis thaliana (L.) plants under well-watered, drought, and water-logged conditions. Two aphid species were selected for this study: the generalist Myzus persicae (Sulzer) and the crucifer specialist Brevicoryne brassicae (L.). Metabolite concentrations in the phloem sap, which influence aphid growth, changed particularly under drought stress. Levels of sucrose and several amino acids, such as glutamic acid, proline, isoleucine, and lysine increased, while concentrations of 4-methoxyindol-3-ylmethyl glucosinolate decreased. M. persicae population growth was highest on plants under drought stress conditions. However, B. brassicae did not profit from improved phloem sap quality under drought stress and performed equally in all water treatments. Water stress and aphids generally had an opposite effect on the accumulation of secondary metabolites in the plant rosettes. Drought stress and water-logging led to increased aliphatic glucosinolate and flavonoid levels. Conversely, aphid feeding, especially of M. persicae, reduced levels of flavonoids and glucosinolates in the plants. Correspondingly, transcript levels of aliphatic biosynthetic genes decreased after feeding of both aphid species. Contrary to M. persicae, drought stress did not promote population growth of B. brassicae on these plants. The specialist aphid induced expression of CYP79B2, CYP79B3, and PAD3 with corresponding accumulation of indolyl glucosinolates and camalexin. This was distinct from M. persicae, which did not elicit similarly strong camalexin accumulation, which led to the hypothesis of a specific defense adaptations against the specialist aphid. PMID:23144921

Discovery and Targeted LC-MS/MS of Purified Polerovirus Reveals Differences in the Virus-Host Interactome Associated with Altered Aphid Transmission

PubMed Central

Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J.; Thannhauser, Theodore W.; Gray, Stewart M.

2012-01-01

Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions. PMID:23118947

Discovery and targeted LC-MS/MS of purified polerovirus reveals differences in the virus-host interactome associated with altered aphid transmission.

PubMed

Cilia, Michelle; Peter, Kari A; Bereman, Michael S; Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J; Thannhauser, Theodore W; Gray, Stewart M

2012-01-01

Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions.

Terpenoid biosynthesis in Arabidopsis attacked by caterpillars and aphids: effects of aphid density on the attraction of a caterpillar parasitoid.

PubMed

Kroes, Anneke; Weldegergis, Berhane T; Cappai, Francesco; Dicke, Marcel; van Loon, Joop J A

2017-12-01

One of the responses of plants to insect attack is the production of volatile organic compounds that mediate indirect defence of plants by attracting natural enemies of the attacking herbivores. Herbivore-induced plant volatiles (HIPVs) include terpenoids that play key roles in the attraction of natural enemies. Crosstalk between phytohormonal signalling pathways is well known to affect the regulation of plant defences, including the emission of HIPVs. Thus, simultaneous feeding on the same plant by caterpillars and aphids, can affect the attraction of parasitoids by the plant compared to single insect attack. The role of aphid density in the regulation of HIPV emission by plants under dual attack has not been studied previously. Here, we investigated the attraction of Diadegma semiclausum, a parasitoid of the Diamondback moth Plutella xylostella, to volatiles emitted by Arabidopsis thaliana plants, simultaneously attacked by host caterpillars, and by the non-host aphid Brevicoryne brassicae. Our study shows that the effect of aphid infestation on parasitoid attraction is influenced by the density of the aphids. Biosynthesis and emission of (E,E)-α-farnesene could be linked to the observed preference of D. semiclausum parasitoids for the HIPV blend emitted by plants dually infested by caterpillars and aphids at a high density compared to dually infested plants with a low aphid density. Parasitoids such as D. semiclausum are important enemies of herbivorous insects and a better understanding of how plants express indirect defence mechanisms in response to multiple insect attack will provide important knowledge on plant-herbivore-parasitoid interactions under multiple stress conditions.

The Nerium oleander aphid Aphis nerii is tolerant to a local isolate of Aphid lethal paralysis virus (ALPV).

PubMed

Dombrovsky, Aviv; Luria, Neta

2013-04-01

In a survey that was conducted during the year 2011, a local strain of Aphid lethal paralysis virus (ALPV) was identified and isolated from a wild population of Aphis nerii aphids living on Nerium oleander plants located in northern Israel. The new strain was tentatively named (ALPV-An). RNA extracted from the viral particles allowed the amplification and determination of the complete genome sequence. The virus genome is comprised of 9835 nucleotides. In a BLAST search analysis, the ALPV-An sequence showed 89 % nucleotide sequence identity with the whole genome of a South African ALPV and 96 and 94 % amino acid sequence identity with the ORF1 and ORF2 of that strain, respectively. In preliminary experiments, spray-applied, purified ALPV virions were highly pathogenic to the green peach aphid Myzus persicae; 95 % mortality was recorded 4 days post-infection. These preliminary results demonstrate the potential of ALPV for use as a biologic agent for some aphid control. Surprisingly, no visible ALPV pathogenic effects, such as morphological changes or paralysis, were observed in the A. nerii aphids infected with ALPV-An. The absence of clear ALPV symptoms in A. nerii led to the formulation of two hypotheses, which were partially examined in this study. The first hypothesis suggest that A. nerii is resistant or tolerant of ALPV, while the second hypothesis propose that ALPV-An may be a mild strain of ALPV. Currently, our results is in favor with the first hypothesis since ALPV-An is cryptic in A. nerii aphids and can be lethal for M. persicae aphids.

Expression differences in Aphidius ervi (Hymenoptera: Braconidae) females reared on different aphid host species

PubMed Central

Legeai, Fabrice; Gonzalez-Gonzalez, Angelica; Lavandero, Blas; Simon, Jean-Christophe

2017-01-01

The molecular mechanisms that allow generalist parasitoids to exploit many, often very distinct hosts are practically unknown. The wasp Aphidius ervi, a generalist koinobiont parasitoid of aphids, was introduced from Europe into Chile in the late 1970s to control agriculturally important aphid species. A recent study showed significant differences in host preference and host acceptance (infectivity) depending on the host A. ervi were reared on. In contrast, no genetic differentiation between A. ervi populations parasitizing different aphid species and aphids of the same species reared on different host plants was found in Chile. Additionally, the same study did not find any fitness effects in A. ervi if offspring were reared on a different host as their mothers. Here, we determined the effect of aphid host species (Sitobion avenae versus Acyrthosiphon pisum reared on two different host plants alfalfa and pea) on the transcriptome of adult A. ervi females. We found a large number of differentially expressed genes (between host species: head: 2,765; body: 1,216; within the same aphid host species reared on different host plants: alfalfa versus pea: head 593; body 222). As expected, the transcriptomes from parasitoids reared on the same host species (pea aphid) but originating from different host plants (pea versus alfalfa) were more similar to each other than the transcriptomes of parasitoids reared on a different aphid host and host plant (head: 648 and 1,524 transcripts; body: 566 and 428 transcripts). We found several differentially expressed odorant binding proteins and olfactory receptor proteins in particular, when we compared parasitoids from different host species. Additionally, we found differentially expressed genes involved in neuronal growth and development as well as signaling pathways. These results point towards a significant rewiring of the transcriptome of A. ervi depending on aphid-plant complex where parasitoids develop, even if different biotypes of a certain aphid host species (A. pisum) are reared on the same host plant. This difference seems to persist even after the different wasp populations were reared on the same aphid host in the laboratory for more than 50 generations. This indicates that either the imprinting process is very persistent or there is enough genetic/allelic variation between A. ervi populations. The role of distinct molecular mechanisms is discussed in terms of the formation of host fidelity. PMID:28852588

Identifying potential RNAi targets in grain aphid (Sitobion avenae F.) based on transcriptome profiling of its alimentary canal after feeding on wheat plants

PubMed Central

2013-01-01

Background The grain aphid (Sitobion avenae F.) is a major agricultural pest which causes significant yield losses of wheat in China, Europe and North America annually. Transcriptome profiling of the grain aphid alimentary canal after feeding on wheat plants could provide comprehensive gene expression information involved in feeding, ingestion and digestion. Furthermore, selection of aphid-specific RNAi target genes would be essential for utilizing a plant-mediated RNAi strategy to control aphids via a non-toxic mode of action. However, due to the tiny size of the alimentary canal and lack of genomic information on grain aphid as a whole, selection of the RNAi targets is a challenging task that as far as we are aware, has never been documented previously. Results In this study, we performed de novo transcriptome assembly and gene expression analyses of the alimentary canals of grain aphids before and after feeding on wheat plants using Illumina RNA sequencing. The transcriptome profiling generated 30,427 unigenes with an average length of 664 bp. Furthermore, comparison of the transcriptomes of alimentary canals of pre- and post feeding grain aphids indicated that 5490 unigenes were differentially expressed, among which, diverse genes and/or pathways were identified and annotated. Based on the RPKM values of these unigenes, 16 of them that were significantly up or down-regulated upon feeding were selected for dsRNA artificial feeding assay. Of these, 5 unigenes led to higher mortality and developmental stunting in an artificial feeding assay due to the down-regulation of the target gene expression. Finally, by adding fluorescently labelled dsRNA into the artificial diet, the spread of fluorescence signal in the whole body tissues of grain aphid was observed. Conclusions Comparison of the transcriptome profiles of the alimentary canals of pre- and post-feeding grain aphids on wheat plants provided comprehensive gene expression information that could facilitate our understanding of the molecular mechanisms underlying feeding, ingestion and digestion. Furthermore, five novel and effective potential RNAi target genes were identified in grain aphid for the first time. This finding would provide a fundamental basis for aphid control in wheat through plant mediated RNAi strategy. PMID:23957588

Clues to an evolutionary mystery: the genes for T-toxin, enabler of the devastating 1970 Southern Corn Leaf Blight epidemic, are present in ancestral species, suggesting an ancient origin.

PubMed

Condon, Bradford J; Elliott, Candace E; Gonzalez, Jonathan; Yun, Sung-Hwan; Akagi, Yasunori; Wiesner-Hanks, Tyr; Kodama, Motoichiro; Turgeon, Gillian

2018-05-24

The Southern Corn Leaf Blight epidemic of 1970 devastated fields of T-cytoplasm corn planted in monoculture throughout the eastern US. The epidemic was driven by race T, a previously unseen race of Cochliobolus heterostrophus. A second fungus, Phyllosticta zeae-maydis, with the same biological specificity, appeared coincidentally. Race T produces T-toxin, while P. zeae-maydis produces PM-toxin, both host selective polyketide toxins necessary for supervirulence. Present abundance of genome sequences offers an opportunity to tackle the evolutionary origins of T- and PM- toxin biosynthetic genes, previously thought unique to these species. Using the C. heterostrophus genes as probes, we identified orthologs in six additional Dothideomycete and three Eurotiomycete species. In stark contrast to the genetically fragmented race T Tox1 locus which encodes these genes, all newly found Tox1-like genes in other species reside at a single collinear locus. This compact arrangement, phylogenetic analyses, comparisons of Tox1 protein tree topology to a species tree, and Tox1 gene characteristics suggest that the locus is ancient and that some species, including C. heterostrophus, gained Tox1 by horizontal gene transfer. C. heterostrophus and P. zeae-maydis did not exchange Tox1 DNA at the time of the SCLB epidemic, but how they acquired Tox1 remains uncertain. The presence of additional genes in Tox1-like clusters of other species, but not in C. heterostrophus and P. zeae-maydis, suggests that the metabolites produced differ from T- and PM-toxin.

Effectiveness of a water-saving super-absorbent polymer in soil water conservation for corn (Zea mays L.) based on eco-physiological parameters.

PubMed

Islam, M Robiul; Hu, Yuegao; Mao, Sishuai; Mao, Jinzhu; Eneji, A Egrinya; Xue, Xuzhang

2011-08-30

The objective was to study soil water conservation and physiological growth of corn (Zea mays L.) using water-saving super-absorbent polymer (SAP) at 30 kg ha(-1). The effectiveness of SAP was studied under three irrigation levels (adequate, moderate and deficit) using a new type of negative hydraulic pressure controlled auto-irrigator in the years 2009 and 2010 in a greenhouse at Beijing, P.R. China. Eight weeks after sowing, plant height and leaf area increased significantly by 41.6 and 79.6% under deficit irrigation for SAP treatment. The SAP had little effect on shoot dry mass under adequate and moderate irrigation but increased it significantly by 133.5% under deficit irrigation. Similarly, the efficiency of water use also increased by 97.1%. Leaf water potential under adequate and moderate irrigation differs slightly for SAP application, whereas under deficit irrigation the values were exceeded significantly by 27.8%. The superior growth and water use efficiency of corn treated with SAP under deficit irrigation was ascribed to maintenance of higher relative water contents in leaves as well as intercellular carbon dioxide concentration, net photosynthesis and transpiration rate. Our results suggested that plant growth and different physiological activities are restricted by drought stress and the application of super-absorbent polymer could conserve soil water, making same available to plants for increased growth and biomass accumulation especially under severe water stress. Thus, application of SAP is a suitable soil management practice for the locations characterised by severe water stress. Copyright © 2011 Society of Chemical Industry.

Identification of the prothoracicotropic hormone (Ptth) coding gene and localization of its site of expression in the pea aphid Acyrthosiphon pisum.

PubMed

Barberà, M; Martínez-Torres, D

2017-10-01

Insect hormones control essential aspects of physiology, behaviour and development in insects. The majority of insect hormones are peptide hormones that perform a highly diverse catalogue of functions. Prothoracicotropic hormone (PTTH) is a brain neuropeptide hormone whose main function is to stimulate the secretion of ecdysone (the moulting hormone) by the prothoracic glands in insect larvae thus playing a key role in the control of moulting and metamorphosis. Moreover, both PTTH release or blockade have been reported to act as a switch to terminate or initiate larval and pupal diapauses. In insects, diapause is a prevalent response often regulated by the photoperiod. It has been shown that PTTH participates as an output of the circadian clock and a role in photoperiodic processes is suggested in some insect species. Aphids (Hemiptera: Aphididae) reproduce by cyclical parthenogenesis with a sexual phase, induced by short photoperiods, that leads to the production of diapausing eggs. With the availability of the pea aphid (Acyrthosiphon pisum) genome, efforts to identify and characterize genes relevant to essential aspects of aphid biology have multiplied. In spite of its relevance, several genomic and transcriptomic studies on aphid neuropeptides failed to detect aphid PTTH amongst them. Here we report on the first identification of the aphid PTTH coding gene and the neuroanatomical localization of its expression in the aphid brain. © 2017 The Royal Entomological Society.

Aphids (Hemiptera, Aphididae) on ornamental plants in greenhouses in Bulgaria

PubMed Central

Yovkova, Mariya; Petrović-Obradović, Olivera; Tasheva-Terzieva, Elena; Pencheva, Aneliya

2013-01-01

Abstract Investigations on the species composition and host range of aphids on ornamental greenhouse plants in Bulgaria was conducted over a period of five years, from 2008 to 2012. Twenty greenhouses, growing ornamentals for landscaping, plant collections and other purposes were observed. They were located in the regions of Sofia, Plovdiv, Smolyan, Pavlikeni, Varna and Burgas. The total number of collected aphid samples was 279. Their composition included 33 aphid species and one subspecies from 13 genera and 5 subfamilies. Twenty-eight species were found to belong to subfamily Aphidinae. Almost 70 % of all recorded species were polyphagous. The most widespread aphid species was Myzus persicae, detected in 13 greenhouses all year round, followed by Aulacorthum solani (10 greenhouses) and Aphis gossypii (9 greenhouses). The widest host range was shown by Myzus persicae (43 hosts), Aulacorthum solani (32 hosts) and Aulacorthum circumflexum (23 hosts). The list of host plants includes 114 species from 95 genera and 58 families. The greatest variety of aphid species was detected on Hibiscus (9 species). Out of all aphid samples 12.9 % were collected on Hibiscus and 6.8 %, on Dendranthema. The greatest variety of aphid species was detected on Hibiscus (9 species). Periphyllus californiensis and Aphis (Aphis) fabae mordvilkoi are reported for the first time for Bulgaria. Furthermore, Aphis spiraecola has been found in new localities and has widened its host range in this country. PMID:24039530

Survey of aphid population in a yellow passion fruit crop and its relationship on the spread Cowpea aphid-borne mosaic virus in a subtropical region of Brazil.

PubMed

Garcêz, Renata Maia; Chaves, Alexandre Levi Rodrigues; Eiras, Marcelo; Meletti, Laura Maria Molina; de Azevedo Filho, Joaquim Adelino; da Silva, Leonardo Assis; Colariccio, Addolorata

2015-01-01

Passion fruit woodiness may be caused by Cowpea aphid-borne mosaic virus (CABMV) and is currently the major passion fruit disease in Brazil. To assess the virus-vector-host interactions, a newly introduced golden passion fruit plantation located in eastern region of São Paulo State, Brazil, was monitored. Dissemination of CABMV was determined analyzing golden passion fruit plants monthly for 18 months by PTA-ELISA. Seasonality and aphid fauna diversity was determined by identification of the captured species using yellow sticky, yellow water-pan and green tile traps. Population composition of the aphid species was determined using the descriptive index of occurrence, dominance and general classification and overlap of species in the R program. Analyses of species grouping afforded to recognize 14 aphid species. The genus Aphis represented 55.42 % of the species captured. Aphid species formed two distinct clusters, one of which was characterized by the diversity of polyphagous species that presented high potential to spread CABMV. The low abundance and diversity of aphid species did not interfere negatively in the CABMV epidemiology. The genus Aphis, particularly Aphis fabae/solanella and A. gossypii, was crucial in the spread of CABMV in passion fruit orchards in the eastern State of São Paulo.

Demography of soybean aphid (Homoptera: Aphididae) at summer temperatures.

PubMed

McCornack, B P; Ragsdale, D W; Venette, R C

2004-06-01

Soybean aphid, Aphis glycines Matsumura, is now widely established in soybean, Glycine max L., production areas of the northern United States and southern Canada and is becoming an important economic pest. Temperature effect on soybean aphid fecundity and survivorship is not well understood. We determined the optimal temperature for soybean aphid growth and reproduction on soybean under controlled conditions. We constructed life tables for soybean aphid at 20, 25, 30, and 35 degrees C with a photoperiod of 16:8 (L:D) h. Population growth rates were greatest at 25 degrees C. As temperature increased, net fecundity, gross fecundity, generation time, and life expectancy decreased. The prereproductive period did not differ between 20 and 30 degrees C; however, at 30 degrees C aphids required more degree-days (base 8.6 degrees C) to develop. Nymphs exposed to 35 degrees C did not complete development, and all individuals died within 11 d. Reproductive periods were significantly different at all temperatures, with aphids reproducing longer and producing more progeny at 20 and 25 degrees C than at 30 or 35 degrees C. Using a modification of the nonlinear Logan model, we estimated upper and optimal developmental thresholds to be 34.9 and 27.8 degrees C, respectively. At 25 degrees C, aphid populations doubled in 1.5 d; at 20 and 30 degrees C, populations doubled in 1.9 d.

Bacterial symbionts, Buchnera, and starvation on wing dimorphism in English grain aphid, Sitobion avenae (F.) (Homoptera: Aphididae)

PubMed Central

Zhang, Fangmei; Li, Xiangrui; Zhang, Yunhui; Coates, Brad; Zhou, Xuguo “Joe”; Cheng, Dengfa

2015-01-01

Wing dimorphism in aphids can be affected by multiple cues, including both biotic (nutrition, crowding, interspecific interactions, the presence of natural enemies, maternal and transgenerational effects, and alarm pheromone) and abiotic factors (temperature, humidity, and photoperiod). The majority of the phloem-feeding aphids carry Buchnera, an obligate symbiotic proteobacteria. Buchnera has a highly reduced genome size, but encode key enzymes in the tryptophan biosynthetic pathway and is crucial for nutritional balance, development and reproduction in aphids. In this study, we investigated the impact of two nutritional-based biotic factors, symbionts and starvation, on the wing dimorphism in the English grain aphid, Sitobion avenae, a devastating insect pest of cereal crops (e.g., wheat) worldwide. Elimination of Buchnera using the antibiotic rifampicin significantly reduced the formation of winged morphs, body mass, and fecundity in S. avenae. Furthermore, the absence of this primary endosymbiont may disrupt the nutrient acquisition in aphids and alter transgenerational phenotypic expression. Similarly, both survival rate and the formation of winged morphs were substantially reduced after neonatal (<24 h old) offspring were starved for a period of time. The combined results shed light on the impact of two nutritional-based biotic factors on the phenotypic plasticity in aphids. A better understanding of the wing dimorphism in aphids will provide the theoretical basis for the prediction and integrated management of these phloem-feeding insect pests. PMID:26042046

Aphid Resistance in Medicago truncatula Involves Antixenosis and Phloem-Specific, Inducible Antibiosis, and Maps to a Single Locus Flanked by NBS-LRR Resistance Gene Analogs1

PubMed Central

Klingler, John; Creasy, Robert; Gao, Lingling; Nair, Ramakrishnan M.; Calix, Alonso Suazo; Jacob, Helen Spafford; Edwards, Owain R.; Singh, Karam B.

2005-01-01

Aphids and related insects feed from a single cell type in plants: the phloem sieve element. Genetic resistance to Acyrthosiphon kondoi Shinji (bluegreen aphid or blue alfalfa aphid) has been identified in Medicago truncatula Gaert. (barrel medic) and backcrossed into susceptible cultivars. The status of M. truncatula as a model legume allows an in-depth study of defense against this aphid at physiological, biochemical, and molecular levels. In this study, two closely related resistant and susceptible genotypes were used to characterize the aphid-resistance phenotype. Resistance conditions antixenosis since migratory aphids were deterred from settling on resistant plants within 6 h of release, preferring to settle on susceptible plants. Analysis of feeding behavior revealed the trait affects A. kondoi at the level of the phloem sieve element. Aphid reproduction on excised shoots demonstrated that resistance requires an intact plant. Antibiosis against A. kondoi is enhanced by prior infestation, indicating induction of this phloem-specific defense. Resistance segregates as a single dominant gene, AKR (Acyrthosiphon kondoi resistance), in two mapping populations, which have been used to map the locus to a region flanked by resistance gene analogs predicted to encode the CC-NBS-LRR subfamily of resistance proteins. This work provides the basis for future molecular analysis of defense against phloem parasitism in a plant model system. PMID:15778464

AtWRKY22 promotes susceptibility to aphids and modulates salicylic acid and jasmonic acid signalling

PubMed Central

Kloth, Karen J.; Wiegers, Gerrie L.; Busscher-Lange, Jacqueline; van Haarst, Jan C.; Kruijer, Willem; Bouwmeester, Harro J.; Dicke, Marcel; Jongsma, Maarten A.

2016-01-01

Aphids induce many transcriptional perturbations in their host plants, but the signalling cascades responsible and the effects on plant resistance are largely unknown. Through a genome-wide association (GWA) mapping study in Arabidopsis thaliana, we identified WRKY22 as a candidate gene associated with feeding behaviour of the green peach aphid, Myzus persicae. The transcription factor WRKY22 is known to be involved in pathogen-triggered immunity, and WRKY22 gene expression has been shown to be induced by aphids. Assessment of aphid population development and feeding behaviour on knockout mutants and overexpression lines showed that WRKY22 increases susceptibility to M. persicae via a mesophyll-located mechanism. mRNA sequencing analysis of aphid-infested wrky22 knockout plants revealed the up-regulation of genes involved in salicylic acid (SA) signalling and down-regulation of genes involved in plant growth and cell-wall loosening. In addition, mechanostimulation of knockout plants by clip cages up-regulated jasmonic acid (JA)-responsive genes, resulting in substantial negative JA–SA crosstalk. Based on this and previous studies, WRKY22 is considered to modulate the interplay between the SA and JA pathways in response to a wide range of biotic and abiotic stimuli. Its induction by aphids and its role in suppressing SA and JA signalling make WRKY22 a potential target for aphids to manipulate host plant defences. PMID:27107291

Facultative symbiont infections affect aphid reproduction.

PubMed

Simon, Jean-Christophe; Boutin, Sébastien; Tsuchida, Tsutomu; Koga, Ryuichi; Le Gallic, Jean-François; Frantz, Adrien; Outreman, Yannick; Fukatsu, Takema

2011-01-01

Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproduction alternate within the annual life cycle. Many species, including the pea aphid, also show variation in their reproductive mode at the population level, with some lineages reproducing by cyclical parthenogenesis and others by permanent parthenogenesis. While the role of facultative symbionts has been well studied during the parthenogenetic phase of their aphid hosts, very little is known on their possible influence during the sexual phase. Here we investigated whether facultative symbionts modulate the capacity to produce sexual forms in various genetic backgrounds of the pea aphid with controlled symbiont composition and also in different aphid genotypes from natural populations with previously characterized infection status and reproductive mode. We found that most facultative symbionts exhibited detrimental effects on their hosts fitness under sex-inducing conditions in comparison with the reference lines. We also showed that the loss of sexual phase in permanently parthenogenetic lineages of A. pisum was not explained by facultative symbionts. Finally, we demonstrated that Spiroplasma infection annihilated the production of males in the host progeny by inducing a male-killing phenotype, an unexpected result for organisms such as aphids that reproduce primarily through clonal reproduction.

Differential Expression of Superoxide Dismutase Genes in Aphid-Stressed Maize (Zea mays L.) Seedlings

PubMed Central

Sytykiewicz, Hubert

2014-01-01

The aim of this study was to compare the expression patterns of superoxide dismutase genes (sod2, sod3.4, sod9 and sodB) in seedling leaves of the Zea mays L. Tasty Sweet (susceptible) and Ambrozja (relatively resistant) cultivars infested with one of two hemipteran species, namely monophagous Sitobion avenae F. (grain aphid) or oligophagous Rhopalosiphum padi L. (bird cherry-oat aphid). Secondarily, aphid-elicited alternations in the antioxidative capacity towards DPPH (1,1-diphenyl-2-picrylhydrazyl) radical in insect-stressed plants were evaluated. Comprehensive comparison of expression profiles of the four sod genes showed that both insect species evoked significant upregulation of three genes sod2, sod3.4 and sod9). However, aphid infestation affected non-significant fluctuations in expression of sodB gene in seedlings of both maize genotypes. The highest levels of transcript accumulation occurred at 8 h (sod2 and sod3.4) or 24 h (sod9) post-infestation, and aphid-induced changes in the expression of sod genes were more dramatic in the Ambrozja cultivar than in the Tasty Sweet variety. Furthermore, bird cherry-oat aphid colonization had a more substantial impact on levels of DPPH radical scavenging activity in infested host seedlings than grain aphid colonization. Additionally, Ambrozja plants infested by either hemipteran species showed markedly lower antioxidative capacity compared with attacked Tasty Sweet plants. PMID:24722734

Differential expression of superoxide dismutase genes in aphid-stressed maize (Zea mays L.) seedlings.

PubMed

Sytykiewicz, Hubert

2014-01-01

The aim of this study was to compare the expression patterns of superoxide dismutase genes (sod2, sod3.4, sod9 and sodB) in seedling leaves of the Zea mays L. Tasty Sweet (susceptible) and Ambrozja (relatively resistant) cultivars infested with one of two hemipteran species, namely monophagous Sitobion avenae F. (grain aphid) or oligophagous Rhopalosiphum padi L. (bird cherry-oat aphid). Secondarily, aphid-elicited alternations in the antioxidative capacity towards DPPH (1,1-diphenyl-2-picrylhydrazyl) radical in insect-stressed plants were evaluated. Comprehensive comparison of expression profiles of the four sod genes showed that both insect species evoked significant upregulation of three genes sod2, sod3.4 and sod9). However, aphid infestation affected non-significant fluctuations in expression of sodB gene in seedlings of both maize genotypes. The highest levels of transcript accumulation occurred at 8 h (sod2 and sod3.4) or 24 h (sod9) post-infestation, and aphid-induced changes in the expression of sod genes were more dramatic in the Ambrozja cultivar than in the Tasty Sweet variety. Furthermore, bird cherry-oat aphid colonization had a more substantial impact on levels of DPPH radical scavenging activity in infested host seedlings than grain aphid colonization. Additionally, Ambrozja plants infested by either hemipteran species showed markedly lower antioxidative capacity compared with attacked Tasty Sweet plants.

Aquatic degradation of Cry1Ab protein and decomposition dynamics of transgenic corn leaves under controlled conditions.

PubMed

Böttger, Rita; Schaller, Jörg; Lintow, Sven; Gert Dudel, E

2015-03-01

The increasing cultivation of genetically modified corn plants (Zea mays) during the last decades is suggested as a potential risk to the environment. One of these genetically modified variety expressed the insecticidal Cry1Ab protein originating from Bacillus thuringiensis (Bt), resulting in resistance against Ostrinia nubilalis, the European corn borer. Transgenic litter material is extensively studied regarding the decomposition in soils. However, only a few field studies analyzed the fate of the Cry1Ab protein and the impact of green and senescent leaf litter from corn on the decomposition rate and related ecosystem functions in aquatic environments. Consequently, a microbial litter decomposition experiment was conducted under controlled semi-natural conditions in batch culture using two maize varieties: one variety with Cry1Ab and another one with the appertaining Iso-line as control treatment. The results showed no significant differences between the treatment with Cry1Ab and the Iso-line regarding loss of total mass in dry weight of 43% for Iso-line and 45% for Bt-corn litter, lignin content increased to 137.5% (Iso-line) and 115.7% (Bt-corn), and phenol loss decreased by 53.6% (Iso-line), 62.2% (Bt-corn) during three weeks of the experiment. At the end of the experiment Cry1Ab protein was still detected with 6% of the initial concentration. A slightly but significant lower cellulose content was found for the Cry1Ab treatment compared to the Iso-line litter at the end of the experiment. The significant higher total protein (25%) and nitrogen (25%) content in Bt corn, most likely due to the additionally expression of the transgenic protein, may increase the microbial cellulose degradation and decrease microbial lignin degradation. In conclusion a relevant year by year input of protein and therefore nitrogen rich Bt corn litter into aquatic environments may affect the balanced nutrient turnover in aquatic ecosystems. Copyright © 2014 Elsevier Inc. All rights reserved.

Water Stress Modulates Soybean Aphid Performance, Feeding Behavior, and Virus Transmission in Soybean

PubMed Central

Nachappa, Punya; Culkin, Christopher T.; Saya, Peter M.; Han, Jinlong; Nalam, Vamsi J.

2016-01-01

Little is known about how water stress including drought and flooding modifies the ability of plants to resist simultaneous attack by insect feeding and transmission of insect-vectored pathogen. We analyzed insect population growth, feeding behaviors, virus transmission, and plant amino acid profiles and defense gene expression to characterize mechanisms underlying the interaction between water stress, soybean aphid and aphid-transmitted, Soybean mosaic virus, on soybean plants. Population growth of non-viruliferous aphids was reduced under drought stress and saturation, likely because the aphids spent less time feeding from the sieve element on these plants compared to well-watered plants. Water stress did not impact population growth of viruliferous aphids. However, virus incidence and transmission rate was lowest under drought stress and highest under saturated conditions since viruliferous aphids took the greatest amount time to puncture cells and transmit the virus under saturated conditions and lowest time under drought stress. Petiole exudates from drought-stressed plants had the highest level of total free amino acids including asparagine and valine that are critical for aphid performance. Aphids did not benefit from improved phloem sap quality as indicated by their lower densities on drought-stressed plants. Saturation, on the other hand, resulted in low amino acid content compared to all of the other treatments. Drought and saturation had significant and opposing effects on expression of marker genes involved in abscisic acid (ABA) signaling. Drought alone significantly increased expression of ABA marker genes, which likely led to suppression of salicylic acid (SA)- and jasmonic acid (JA)-related genes. In contrast, ABA marker genes were down-regulated under saturation, while expression of SA- and JA-related genes was up-regulated. We propose that the apparent antagonism between ABA and SA/JA signaling pathways contributed to an increase in aphid densities under drought and their decrease under saturation. Taken together, our findings suggests that plant responses to water stress is complex involving changes in phloem amino acid composition and signaling pathways, which can impact aphid populations and virus transmission. PMID:27200027

Vat, an Amazing Gene Conferring Resistance to Aphids and Viruses They Carry: From Molecular Structure to Field Effects

PubMed Central

Boissot, Nathalie; Schoeny, Alexandra; Vanlerberghe-Masutti, Flavie

2016-01-01

We review half a century of research on Cucumis melo resistance to Aphis gossypii from molecular to field levels. The Vat gene is unique in conferring resistance to both A. gossypii and the viruses it transmits. This double phenotype is aphid clone-dependent and has been observed in 25 melon accessions, mostly from Asia. It is controlled by a cluster of genes including CC-NLR, which has been characterized in detail. Copy-number polymorphisms (for the whole gene and for a domain that stands out in the LLR region) and single-nucleotide polymorphisms have been identified in the Vat cluster. The role of these polymorphisms in plant/aphid interactions remains unclear. The Vat gene structure suggests a functioning with separate recognition and response phases. During the recognition phase, the VAT protein is thought to interact (likely indirectly) with an aphid effector introduced during cell puncture by the aphid. A few hours later, several miRNAs are upregulated in Vat plants. Peroxidase activity increases, and callose and lignin are deposited in the walls of the cells adjacent to the stylet path, disturbing aphid behavior. In aphids feeding on Vat plants, Piwi-interacting RNA-like sequences are abundant and the levels of other miRNAs are modified. At the plant level, resistance to aphids is quantitative (aphids escape the plant and display low rates of reproduction). Resistance to viruses is qualitative and local. Durability of NLR genes is highly variable. A. gossypii clones are adapted to Vat resistance, either by introducing a new effector that interferes with the deployment of plant defenses, or by adapting to the defenses it triggered. Viruses transmitted in a non-persistent manner cannot adapt to Vat resistance. At population level, Vat reduces aphid density and genetic diversity. The durability of Vat resistance to A. gossypii populations depends strongly on the agro-ecosystem, including, in particular, the presence of other cucurbit crops serving as alternative hosts for adapted clones in fall and winter. At the crop level, Vat resistance decreases the intensity of virus epidemics when A. gossypii is the main aphid vector in the crop environment. PMID:27725823

Use of electrical penetration graphs (EPG) and quantitative PCR to evaluate the relationship between feeding behaviour and Pandora neoaphidis infection levels in green peach aphid, Myzus persicae.

PubMed

Chen, Chun; Ye, Sudan; Hu, Huajun; Xue, Chengmei; Yu, Xiaoping

2018-01-01

A real-time qPCR method was developed, validated, and used to quantity the fungal pathogen, P. neoaphidis, within aphids at different times during infection; colonization rate fitted the Gompertz model well (R 2  = 0.9356). Feeding behaviour of P. neoaphidis-infected and uninfected M. persicae were investigated, for the first time, using DC-electrical penetration graphs (DC-EPG) that characterized the waveforms made during different aphid stylet probing periods corresponding to epidermis penetration, salivation and ingestion. In the 6 h following the 12-h incubation period (to achieve infection), there were significant differences in the number of events of Np (non-probing) and C (stylet pathway) between infected and uninfected aphids. However, the difference between total duration of Np and C were not significantly different between infected and uninfected aphids. There were no significant differences in the number of events or total duration of E1 (phloem salivation) or E2 (phloem ingestion) between infected and uninfected aphids. There were significant differences in mean number of events and total duration of the pd waveform (intracellular punctures) in infected and uninfected aphids. In the 16 h prior to death, the same differences in behaviour were observed but they were even more obvious. Furthermore, the total duration time of E2 was significantly greater in uninfected aphids than infected aphids, a change that had not been observed in the first 6 h observation period. In conclusion, qPCR quantification demonstrated 'molecular' colonization levels throughout infection, and EPG data analysis during the two periods (during early infection and then during late infection just prior to death) demonstrated the actual physical effects of fungal infection on feeding behaviour of M. persicae; this has the potential to decrease the aphid's capacity of transmission and dispersal. These studies increase our understanding of the interaction between P. neoaphidis and its host aphid. Copyright © 2017 Elsevier Ltd. All rights reserved.

Change in Biotypic Diversity of Russian Wheat Aphid (Hemiptera: Aphididae) Populations in the United States.

PubMed

Puterka, G J; Giles, K L; Brown, M J; Nicholson, S J; Hammon, R W; Peairs, F B; Randolph, T L; Michaels, G J; Bynum, E D; Springer, T L; Armstrong, J S; Mornhinweg, D W

2015-04-01

A key component of Russian wheat aphid, Diuraphis noxia (Kurdjumov), management has been through planting resistant wheat cultivars. A new biotype, RWA2, appeared in 2003 which caused widespread damage to wheat cultivars containing the Dn4 gene. Biotypic diversity in Russian wheat aphid populations has not been addressed since 2005 when RWA2 dominated the biotype complex. Our objectives were to determine the biotypic diversity in the Central Great Plains and Colorado Plateau at regional (2010, 2011, 2013) and local (2012) levels and detect the presence of new Russian wheat aphid biotypes. Regional and within-field aphid collections were screened against Russian wheat aphid-resistant wheat genotypes containing genes Dn3, Dn4, Dn6, Dn7, Dn9, CI2401; and resistant barley STARS 9301B. In 2010, all aphid collections from Texas were avirulent to the Dn4 resistance gene in wheat. Regional results revealed Dn4 avirulent RWA6 was widespread (55-84%) in populations infesting wheat in both regions. Biotypes RWA1, 2, and 3/7 were equally represented with percentages<20% each while RWA8 was rarely detected. Combining percentages of RWA1, 6, and 8 across regions to estimate avirulence to Dn4 gene revealed high percentages for both 2011 (64-80%) and 2013 (69-90%). In contrast, the biotype structure at the local level differed where biotype percentages varied up to ≥2-fold between fields. No new biotypes were detected; therefore, Dn7, CI2401, and STARS9301B remained resistant to all known Russian wheat aphid biotypes. This study documents a shift to Dn4 avirulent biotypes and serves as a valuable baseline for biotypic diversity in Russian wheat aphid populations prior to the deployment of new Russian wheat aphid-resistant wheat cultivars. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

Bacterial Communities Associated with Host-Adapted Populations of Pea Aphids Revealed by Deep Sequencing of 16S Ribosomal DNA

PubMed Central

Gauthier, Jean-Pierre; Outreman, Yannick; Mieuzet, Lucie; Simon, Jean-Christophe

2015-01-01

Associations between microbes and animals are ubiquitous and hosts may benefit from harbouring microbial communities through improved resource exploitation or resistance to environmental stress. The pea aphid, Acyrthosiphon pisum, is the host of heritable bacterial symbionts, including the obligate endosymbiont Buchnera aphidicola and several facultative symbionts. While obligate symbionts supply aphids with key nutrients, facultative symbionts influence their hosts in many ways such as protection against natural enemies, heat tolerance, color change and reproduction alteration. The pea aphid also encompasses multiple plant-specialized biotypes, each adapted to one or a few legume species. Facultative symbiont communities differ strongly between biotypes, although bacterial involvement in plant specialization is uncertain. Here, we analyse the diversity of bacterial communities associated with nine biotypes of the pea aphid complex using amplicon pyrosequencing of 16S rRNA genes. Combined clustering and phylogenetic analyses of 16S sequences allowed identifying 21 bacterial OTUs (Operational Taxonomic Unit). More than 98% of the sequencing reads were assigned to known pea aphid symbionts. The presence of Wolbachia was confirmed in A. pisum while Erwinia and Pantoea, two gut associates, were detected in multiple samples. The diversity of bacterial communities harboured by pea aphid biotypes was very low, ranging from 3 to 11 OTUs across samples. Bacterial communities differed more between than within biotypes but this difference did not correlate with the genetic divergence between biotypes. Altogether, these results confirm that the aphid microbiota is dominated by a few heritable symbionts and that plant specialization is an important structuring factor of bacterial communities associated with the pea aphid complex. However, since we examined the microbiota of aphid samples kept a few generations in controlled conditions, it may be that bacterial diversity was underestimated due to the possible loss of environmental or transient taxa. PMID:25807173

Evaluation of late vegetative and reproductive stage soybeans for resistance to soybean aphid (Hemiptera: Aphididae).

PubMed

Prochaska, T J; Pierson, L M; Baldin, E L L; Hunt, T E; Heng-Moss, T M; Reese, J C

2013-04-01

The soybean aphid, Aphis glycines Matsumura, has become the most significant soybean [Glycine max (L.) Merrill] insect pest in the north central soybean production region of North America. The objectives of this research were to measure selected genotypes for resistance to the soybean aphid in the later vegetative and reproductive stages under field conditions, and confirm the presence of tolerance in KS4202. The results from 2007 to 2011 indicate that KS4202 can support aphid populations with minimal yield loss at levels where significant yield loss would be expected in most other genotypes. The common Nebraska cultivar, 'Asgrow 2703', appears to show signs of tolerance as well. None of the yield parameters were significantly different between the aphid infested and noninfested treatments. Based on our results, genotypes may compensate for aphid feeding in different ways. Asgrow 2703 appears to produce a similar number of seeds as its noninfested counterpart, although the seeds produced are slightly smaller. Field evaluation of tolerance in KS4202 indicated a yield loss of only 13% at 34,585-53,508 cumulative aphid-days, when 24-36% yield loss would have been expected.

DNA barcoding reveals a mysterious high species diversity of conifer-feeding aphids in the mountains of southwest China

PubMed Central

Chen, Rui; Jiang, Li-Yun; Chen, Jing; Qiao, Ge-Xia

2016-01-01

The mountains of southwest China are one of the hot spots of biodiversity in the world. However, the high-altitude fauna that inhabit these mountains remain a mystery. In this study, the species diversity of the aphids of the genus Cinara from the high-altitude coniferous forests was first assessed, and then the processes and the mechanisms of speciation were discussed. Three hundreds and four aphid samples that contained 3040 individuals were collected during fourteen field surveys. The molecular clusters derived from the DNA barcodes were used to explore the species diversity. Notably, the aphid alpha-diversity was high, with as many as 94 candidate species, and furthermore, 86.2% of the species collected had not been previously recorded. The centers of aphid species richness corresponded to the distributional pattern of the diversity of the host conifer plant species. The divergence time revealed that following the uplift of the Qinghai-Tibetan Plateau during the Pleistocene, the changes in the climate, ecology and host habitats were likely the most important factors that drove the rapid process of evolutionary radiation in the aphids. Our findings revealed the high species diversity of the aphids with DNA barcoding. PMID:26838797

Shallot Aphids, Myzus ascalonicus, in Strawberry: Biocontrol Potential of Three Predators and Three Parasitoids

PubMed Central

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 predation (34.62 ± 3.45, 25.25 ± 3.18, and 13.34 ± 1.45, respectively). Further studies on A. bipunctata revealed that the larvae maintained their daily predation capacity (32.0 ± 6.3) on strawberry plants. About 60% of already ovipositing A. bipunctata refrained from laying any eggs on the first day after transfer to set-ups with combinations of shallot or peach-potato aphids, Myzus persicae (Sulzer) (Homoptera: Aphididae), and strawberry or sweet pepper leaves. The aphid species and the plant species did not, however, have a significant influence on the number of females laying eggs, the average number of eggs laid during the first day being 6.37±1.28 per female. Adult lady beetles had a significant preference for odor from controls without plants over odors from uninfested strawberry or pepper plants, but they showed no preference for either of the plant species, whether infested with aphids or not. The predation capacity of A. bipunctata on shallot aphids holds promise for its use in inundative biocontrol, and the results on egg laying cues suggests that inoculative biocontrol may be possible, although further studies will be needed for a complete evaluation. PMID:24224712

Preparing soft-bodied arthropods for microscope examination: Aphids (Insecta: Hemiptera: Aphididae)

USDA-ARS?s Scientific Manuscript database

Proper identification of aphids (Hemiptera: Aphididae) require preparation of the specimen on a microscope slide. This training video provides visual instruction on how to prepare aphid specimens on microscope slides for examination and indentification. Steps ranging from collection, specimen clear...

Spatial and temporal spread of Citrus tristeza virus and its aphid vectors in the North western area of Morocco.

PubMed

Elhaddad, Abdesslam; ElAmrani, Amal; Fereres, Alberto; Moreno, Aranzazu

2016-12-01

First report of Citrus tristeza virus (CTV,Closterovirus) in Morocco datesback to 1961 in collections of citrus varieties. An exhaustive survey of citrus in the north of the country in 2009 revealed that CTV was spread all over the citrus production area. We attempted to evaluate the relative contribution of different aphid species in the spread of CTV disease in a Citrus reticulata orchard at the Loukkous region during 2 years (2012 and 2013). The overall CTV incidence estimated in the experimental site increased from 17.8% in 2012 to 31.15% in 2013. The most abundant aphid species colonising clementine trees was Aphis spiraecola and A. gossypii. Both aphid species reached their maximum peaks during the spring season. The rate of viruliferous aphids, estimated by real-time RT-PCR of single aphid, revealed that 35.4% of winged A. gossypii and 28.8% of winged A. spiraecola were viruliferous, confirming a high inoculum pressure in the area surrounding the experimental site. The aphid species Toxoptera citricida, which is able to transmit the aggressive isolates of CTV, was not found in the Loukkous region. The study of the spatial distribution of the CTV showed that in general, the disease was randomly distributed in the field. Overall, the results seem to indicate that A. spiraecola may be considered as the major aphid species contributing to CTV spread in our experimental conditions. The prevalence of mild strains in the region and the high level of aphid flight activity could explain the rapid evolution of CTV incidence in the experimental area. © 2015 Institute of Zoology, Chinese Academy of Sciences.

Rag Virulence Among Soybean Aphids (Hemiptera: Aphididae) in Wisconsin.

PubMed

Crossley, Michael S; Hogg, David B

2015-02-01

Soybean aphid, Aphis glycines Matsumura, a pest of soybean, Glycine max (L.) Merr., and native of Asia, invaded North America sometime before 2000 and rapidly became the most significant insect pest of soybean in the upper Midwest. Plant resistance, a key component of integrated pest management, has received significant attention in the past decade, and several resistance (Rag) genes have been identified. However, the efficacy of Rag (Resistance to Aphis glycines) genes in suppressing aphid abundance has been challenged by the occurrence of soybean aphids capable of overcoming Rag gene-mediated resistance. Although the occurrence of these Rag virulent biotypes poses a serious threat to effective and sustainable management of soybean aphid, little is known about the current abundance of biotypes in North America. The objective of this research was to determine the distribution of Rag virulent soybean aphids in Wisconsin. Soybean aphids were collected from Wisconsin during the summers of 2012 and 2013, and assayed for Rag1, Rag2, and Rag1+2 virulence using no-choice tests in a greenhouse. One clone from Monroe County in 2012 reacted like biotype 4, three clones in different counties in 2013 responded like biotype 2, and eight others expressed varying degrees of Rag virulence. Rag virulence in 2013 was observed in aphids from 33% of the sampled sites and was accounted for by just 4.5% of sampled clones, although this is likely a conservative estimate. No-choice test results are discussed in light of current questions on the biology, ecology, and population genetics of soybean aphid. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Biological and genetic features of introduced aphid populations in agroecosystems.

PubMed

Figueroa, Christian C; Fuentes-Contreras, Eduardo; Molina-Montenegro, Marco A; Ramírez, Claudio C

2018-04-01

In agroecosystems, introduced aphids that reproduce by obligate parthenogenesis (OP) show strong biased representation of a few genotypes (superclones), whereas species with cyclical parthenogenesis (CP) exhibit the opposite trend with many unique genotypes. We analyzed the biological and genetic features of 23 different aphid species introduced in different geographic areas and climates, finding putative superclones in about 60% of them. We have examined the proximal causes for aphid establishment and spread after their introduction, and found that OP, host availability, and phenotypic plasticity are among the main variables underpinning the ability of aphids to succeed in new geographic areas, which may explain the high potential for invasion in this group of pest insects. Copyright © 2018 Elsevier Inc. All rights reserved.

Agronomy of strip intercropping broccoli with alyssum for biological control of aphids

USDA-ARS?s Scientific Manuscript database

Organic broccoli growers in California typically control aphids by intercropping broccoli with strips of alyssum (Lobularia maritima (L.) Desv.) which attracts hoverflies (Diptera: Syrphidae) that are important predators of aphids. A three year study with transplanted organic broccoli in Salinas, ...

Rise and fall of cotton aphid (Hemiptera: Aphididae) populations in southeastern cotton production systems.

PubMed

Abney, Mark R; Ruberson, John R; Herzog, Gary A; Kring, Timothy J; Steinkraus, Donald C; Roberts, Phillip M

2008-02-01

The impact of natural enemies on cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), populations in cotton, Gossypium hirsutum L., production systems in the southeastern United States was evaluated over 3 yr in irrigated commercial cotton fields. Fungal epizootics caused by the entomopathogen Neozygites fresenii (Nowakowski) Batko reduced aphid numbers to subthreshold levels in 1999, 2000, and 2001 and occurred consistently in early to mid-July in all 3 yr. Scymnus spp. were the most abundant aphidophagous predators, although other coccinellid species and generalist predators such as spiders, fire ants, heteropterans, and neuropterans also were present. Studies using arthropod exclusion cages demonstrated little impact of predators or parasitoids on aphid populations before fungal epizootics. Arthropod natural enemies were most abundant after epizootics and may have suppressed aphid populations late in the season. Seed cotton yield, and lint quality were not affected by aphicide applications in any year of the study. Implications of these findings for aphid management in the southeastern United States are discussed.

Elevated CO2 increases R gene-dependent resistance of Medicago truncatula against the pea aphid by up-regulating a heat shock gene.

PubMed

Sun, Yucheng; Guo, Huijuan; Yuan, Erliang; Ge, Feng

2018-03-01

Resistance against pathogens and herbivorous insects in many plant results from the expression of resistance (R) genes. Few reports, however, have considered the effects of elevated CO 2 on R gene-based resistance in plants. The current study determined the responses of two near isogenic Medicago truncatula genotypes (Jester has an R gene and A17 does not) to the pea aphid and elevated CO 2 in open-top chambers in the field. Aphid abundance, mean relative growth rate and feeding efficiency were increased by elevated CO 2 on A17 plants but were reduced on Jester plants. According to proteomic and gene expression data, elevated CO 2 enhanced pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) but decreased the effector-triggered immunity (ETI) in aphid-infested A17 plants. For aphid-infested Jester plants, by contrast, elevated CO 2 enhanced the ETI-related heat shock protein (HSP) 90 and its co-chaperones, the jasmonic acid (JA) signaling pathway, and ubiquitin-mediated proteolysis. In a loss-of-function experiment, silencing of the HSP90 gene in Jester plants impaired the JA signaling pathway and ubiquitin-mediated proteolysis against the aphid under ambient CO 2 , and negated the increased resistance against the aphid under elevated CO 2 . Our results suggest that increases in expression of HSP90 are responsible for the enhanced resistance against the aphid under elevated CO 2 . © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

AtWRKY22 promotes susceptibility to aphids and modulates salicylic acid and jasmonic acid signalling.

PubMed

Kloth, Karen J; Wiegers, Gerrie L; Busscher-Lange, Jacqueline; van Haarst, Jan C; Kruijer, Willem; Bouwmeester, Harro J; Dicke, Marcel; Jongsma, Maarten A

2016-05-01

Aphids induce many transcriptional perturbations in their host plants, but the signalling cascades responsible and the effects on plant resistance are largely unknown. Through a genome-wide association (GWA) mapping study in Arabidopsis thaliana, we identified WRKY22 as a candidate gene associated with feeding behaviour of the green peach aphid, Myzus persicae The transcription factor WRKY22 is known to be involved in pathogen-triggered immunity, and WRKY22 gene expression has been shown to be induced by aphids. Assessment of aphid population development and feeding behaviour on knockout mutants and overexpression lines showed that WRKY22 increases susceptibility to M. persicae via a mesophyll-located mechanism. mRNA sequencing analysis of aphid-infested wrky22 knockout plants revealed the up-regulation of genes involved in salicylic acid (SA) signalling and down-regulation of genes involved in plant growth and cell-wall loosening. In addition, mechanostimulation of knockout plants by clip cages up-regulated jasmonic acid (JA)-responsive genes, resulting in substantial negative JA-SA crosstalk. Based on this and previous studies, WRKY22 is considered to modulate the interplay between the SA and JA pathways in response to a wide range of biotic and abiotic stimuli. Its induction by aphids and its role in suppressing SA and JA signalling make WRKY22 a potential target for aphids to manipulate host plant defences. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Activation of defence in sweet pepper, Capsicum annum, by cis-jasmone, and its impact on aphid and aphid parasitoid behaviour.

PubMed

Dewhirst, Sarah Y; Birkett, Michael A; Loza-Reyes, Elisa; Martin, Janet L; Pye, Barry J; Smart, Lesley E; Hardie, Jim; Pickett, John A

2012-10-01

Two important pests of the sweet pepper, Capsicum annuum, are the peach potato aphid, Myzus persicae, and the glasshouse potato aphid, Aulacorthum solani. Current aphid control measures include the use of biological control agents, i.e., parasitic wasps, but with varying levels of success. One option to increase parasitoid efficiency is to activate plant defence. Therefore, sweet pepper plants were treated with the naturally occurring plant defence activator cis-jasmone, and its impact upon the behaviour and development of aphids and aphid parasitoids was investigated. Growth rate studies revealed that the intrinsic rate of population increase of A. solani and M. persicae on sweet pepper plants treated with cis-jasmone (cJSP) was not affected compared with untreated plants (UnSP), but the positive behavioural response of alate M. persicae towards the volatile organic compounds (VOCs) from UnSP was eliminated by cis-jasmone treatment 48 h previously (cJSP48). In addition, the aphid parasitoid Aphidius ervi preferred VOCs from cJSP48 compared with UnSP, and a significant increase in foraging time was also observed on cJSP. Analysis of VOCs collected from cJSP48 revealed differences compared with UnSP. There is evidence that treatment with cis-jasmone has the potential to improve protection of sweet pepper against insect pests. © Crown copyright 2012. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

Screening of sorghum lines for resistance against sugarcane aphid, Melanaphis sacchari (Zehnter)

USDA-ARS?s Scientific Manuscript database

The sugarcane aphid Melanaphis sacchari (Zehnter) has emerged as the most significant threat to sorghum (Sorghum bicolor (L.) Moench) production in the United States. Since 2013, discovery of aphid resistant germplasm has been a priority all stakeholders involved. We screened twenty three differen...

Towards efficient multi-scale methods for monitoring sugarcane aphid infestations in sorghum

USDA-ARS?s Scientific Manuscript database

We discuss approaches and issues involved with developing optimal monitoring methods for sugarcane aphid infestations (SCA) in grain sorghum. We discuss development of sequential sampling methods that allow for estimation of the number of aphids per sample unit, and statistical decision making rela...

National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Cerataphis brasiliensis

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the palm aphid, Cerataphis brasiliensis, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures...

NDVI to detect sugarcane aphid injury to grain sorghum

USDA-ARS?s Scientific Manuscript database

Multispectral remote sensing has potential to provide quick and inexpensive information on sugarcane aphid, Melanaphis sacchari (Zehntner), pest status in sorghum fields. The purpose of this report is to describe a study conducted to determine if injury caused by sugarcane aphid to sorghum plants i...

Estimating the Relative Water Content of Single Leaves from Optical Polarization Measurements

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2016-01-01

Remotely sensing the water status of plants and the water content of canopies remain long-term goals of remote sensing research. For monitoring canopy water status, existing approaches such as the Crop Water Stress Index and the Equivalent Water Thickness have limitations. The CWSI does not work well in humid regions, requires estimates of the vapor pressure deficit near the canopy during the remote sensing over-flight and, once stomata close, provides little information regarding the canopy water status. The EWI is based upon the physics of water-light interaction, not plant physiology. In this research, we applied optical polarization techniques to monitor the VISNIR light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both changed nonlinearly as each leaf dried, R increasing and T decreasing. Our results tie changes in the VISNIR R and T to leaf physiological changes linking the light scattered out of the drying leaf interior to its relative water content and to changes in leaf cellular structure and pigments. Our results suggest remotely sensing the physiological water status of a single leaf and perhaps of a plant canopy might be possible in the future. However, using our approach to estimate the water status of a leaf does not appear possible at present, because our results display too much variability that we do not yet understand.

Estimating the Relative Water Content of Single Leaves from Optical Polarization Measurements.

NASA Astrophysics Data System (ADS)

Vanderbilt, V. C.; Daughtry, C. S. T.; Dahlgren, R. P.

2016-12-01

Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. For monitoring canopy water status, existing approaches such as the Crop Water Stress Index and the Equivalent Water Thickness have limitations. The CWSI does not work well in humid regions, requires estimates of the vapor pressure deficit near the canopy during the remote sensing over-flight and, once stomata close, provides little information regarding the canopy water status. The EWI is based upon the physics of water-light interaction, not plant physiology. In this research, we applied optical polarization techniques to monitor the VIS/NIR light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both changed nonlinearly as each leaf dried, R increasing and T decreasing. Our results tie changes in the VIS/NIR R and T to leaf physiological changes - linking the light scattered out of the drying leaf interior to its relative water content and to changes in leaf cellular structure and pigments. Our results suggest remotely sensing the physiological water status of a single leaf - and perhaps of a plant canopy - might be possible in the future. However, using our approach to estimate the water status of a leaf does not appear possible at present, because our results display too much variability that we do not yet understand.

Comparative transcriptome analysis of Gossypium hirsutum L. in response to sap sucking insects: aphid and whitefly

PubMed Central

2013-01-01

Background Cotton (Gossypium hirsutum L.) is a major fiber crop that is grown worldwide; it faces extensive damage from sap-sucking insects, including aphids and whiteflies. Genome-wide transcriptome analysis was performed to understand the molecular details of interaction between Gossypium hirsutum L. and sap-sucking pests, namely Aphis gossypii (Aphid) and Bemisia tabacci (Whiteflies). Roche’s GS-Titanium was used to sequence transcriptomes of cotton infested with aphids and whiteflies for 2 h and 24 h. Results A total of 100935 contigs were produced with an average length of 529 bp after an assembly in all five selected conditions. The Blastn of the non-redundant (nr) cotton EST database resulted in the identification of 580 novel contigs in the cotton plant. It should be noted that in spite of minimal physical damage caused by the sap-sucking insects, they can change the gene expression of plants in 2 h of infestation; further change in gene expression due to whiteflies is quicker than due to aphids. The impact of the whitefly 24 h after infestation was more or less similar to that of the aphid 2 h after infestation. Aphids and whiteflies affect many genes that are regulated by various phytohormones and in response to microbial infection, indicating the involvement of complex crosstalk between these pathways. The KOBAS analysis of differentially regulated transcripts in response to aphids and whiteflies indicated that both the insects induce the metabolism of amino acids biosynthesis specially in case of whiteflies infestation at later phase. Further we also observed that expression of transcript related to photosynthesis specially carbon fixation were significantly influenced by infestation of Aphids and Whiteflies. Conclusions A comparison of different transcriptomes leads to the identification of differentially and temporally regulated transcripts in response to infestation by aphids and whiteflies. Most of these differentially expressed contigs were related to genes involved in biotic, abiotic stresses and enzymatic activities related to hydrolases, transferases, and kinases. The expression of some marker genes such as the overexpressors of cationic peroxidase 3, lipoxygenase I, TGA2, and non-specific lipase, which are involved in phytohormonal-mediated plant resistance development, was suppressed after infestation by aphids and whiteflies, indicating that insects suppressed plant resistance in order to facilitate their infestation. We also concluded that cotton shares several pathways such as phagosomes, RNA transport, and amino acid metabolism with Arabidopsis in response to the infestation by aphids and whiteflies. PMID:23577705

Defensive changes in maize leaves induced by feeding of Mediterranean corn borer larvae.

PubMed

Santiago, Rogelio; Cao, Ana; Butrón, Ana; López-Malvar, Ana; Rodríguez, Víctor M; Sandoya, Germán V; Malvar, Rosa A

2017-02-15

Plants can respond to insect attack via defense mechanisms that reduce insect performance. In this study, we examined the effects of several treatments applied to two maize genotypes (one resistant, one susceptible) on the subsequent growth and survival of Sesamia nonagrioides Lef. (Mediterranean corn borer, MCB) larvae. The treatments were infestation with MCB larvae, application of MCB regurgitant upon wounding, wounding alone, or exposure to methyl jasmonate, and they were applied at the V6-V8 stage of maize development. We also monitored changes in the concentrations of compounds known to be involved in constitutive resistance, such as cell wall-bound hydroxycinnamates and benzoxazinoids. In both maize genotypes, the leaves of plants pre-infested with MCB larvae were less suitable for larval development than those from untreated plants. Application of MCB regurgitant upon wounding, and wounding itself, resulted in leaf tissues becoming less suitable for larval growth than those of pre-infested plants, suggesting that there could be herbivore-associated effector molecules that suppress some wounding responses. A single application of MCB regurgitant did not seem to mimic feeding by MCB larvae, although the results suggested that regurgitant deposited during feeding may have enhanced ferulates and diferulates synthesis in infested vs. control plants. Jasmonic acid may play a role in mediating the maize response to MCB attack, but it did not trigger hydroxycinnamate accumulation in the leaves to a level comparable to that induced by larval leaf feeding. The EP39 maize genotype showed an increase in leaf cell wall strength by increasing hemicellulose cross-linking in response to MCB attack, while induced defenses in the EP42 plants appeared to reflect a broader array of resistance mechanisms. The results indicated that leaf feeding by MCB larvae can increase leaf antibiosis against MCB in two maize genotypes with contrasting levels of resistance against this borer. Also, the larval regurgitant played a positive role in eliciting a defense response. We determined the effects of the plant response on larval growth, and detected defense compounds related to borer resistance.

Newly identified resistance to soybean aphid (Aphis glycines) in soybean plant introduction lines

USDA-ARS?s Scientific Manuscript database

Host-plant resistance is potentially efficacious in managing the soybean aphid (SA, Aphis glycines Matsumura), a major invasive pest in northern soybean-production regions of North America. However, development of aphid-resistant soybean has been complicated by the presence of virulent SA biotypes,...

Mind your elders: wild soybean’s contribution to soybean aphid resistance

USDA-ARS?s Scientific Manuscript database

Currently, biotype 4 soybean aphid (Aphis glycines Matsamura, SBA) is the most virulent SBA biotype. Overcoming the most aphid resistant genes, SBA biotype 4 has become the greatest challenge in utilizing plant resistance in soybean [Glycine max (L.) Merr.]. Soybean’s wild ancestor Glycine soja (Sie...

Utilization of ladybird beetles to curb aphids in strawberry high tunnels: preliminary results

USDA-ARS?s Scientific Manuscript database

Native and exotic aphid species continue to pose a threat to the successful cultivation of small fruits in greenhouses, glasshouses, and high tunnels throughout the World. There is considerable interest in using biological controls (predators and parasitoids) to manage aphids in lieu of synthetic in...

Risk to native Uroleucon aphids (Hemiptera: Aphididae) from non-native lady beetles (Coleoptera: Coccinellidae)

USDA-ARS?s Scientific Manuscript database

Aphids in the genus Uroleucon Mordvilko (Hemiptera: Aphididae) are native herbivores that feed on goldenrod (Solidago spp.) and other Asteraceae in North America. The aphids are potential prey for a wide variety of natural enemies, including native and non-native species of lady beetles (Coleoptera...

Aphid population fluctuations and patterns of species dominance in Puerto Rico

USDA-ARS?s Scientific Manuscript database

Technical Abstract: Papaya ringspot virus (PRSV) is a non-persistently transmitted virus affecting papaya and cucurbit production worldwide. Papaya is not known to be colonized by any species of aphid, but multiple species can transmit the virus. That means that transmission depends on aphid populat...

Transparency Master: The Annual Aphid Cycle.

ERIC Educational Resources Information Center

Sessions, Mary Lynne

1983-01-01

Aphids, often referred to as plant lice, can be found in great numbers on stems, leaves, and flowers of many plants. In many cases these organisms are potentially harmful to their plant hosts. Provided is a description of the annual life cycle of the aphid and an accompanying transparency master. (Author/JN)

Preceding crop affects soybean aphid abundance and predator-prey dynamics in soybean

USDA-ARS?s Scientific Manuscript database

Crop rotations alter the soil environment and physiology of the subsequent crop in ways that may affect herbivore abundance. Soybean aphids are a consistent pest of soybean throughout North America, but little work has focused on how preceding crops may affect aphid populations. In a replicated expe...

Virus-induced gene silencing of WRKY53 and an inducible phenylalanine ammonia-lyase in wheat reduces aphid resistance

USDA-ARS?s Scientific Manuscript database

Although several wheat genes differentially expressed during the Russian wheat aphid resistance response have recently been identified, their requirement for and specific role in resistance remain unclear. Progress in wheat-aphid interaction research is hampered by inadequate collections of mutant g...

Identification of conditions for successful aphid control by ladybirds in greenhouses

USDA-ARS?s Scientific Manuscript database

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...

Prey foraging by Hippodamia convergens for cereal aphids on wheat

USDA-ARS?s Scientific Manuscript database

We investigated predation by adult convergent lady beetle, Hippodamia convergens Guerin-Meneville, on English grain aphid, Sitobion avenae L., on wheat, Triticum aestivum L., plants in a laboratory arena, and developed a functional response model for the number of aphids eaten by an adult female con...

Detection of novel QTLs for foxglove aphid resistance in soybean

USDA-ARS?s Scientific Manuscript database

Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The objective of this study was to identify the putative QTL for foxglove aphid resistance in wild soybean, PI 366121, (Glycine soja Sieb...

National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Myzus persicae

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the green peach aphid, Myzus persicae, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures t...

National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Aphis gossypii

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the cotton aphid, Aphis gossypii, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures that ca...

Role of Soybean mosaic virus-encoded proteins in seed and aphid transmission in soybean

USDA-ARS?s Scientific Manuscript database

Soybean mosaic virus (SMV) is seed and aphid transmitted and can cause significant reductions in yield and seed quality in soybean, Glycine max. The roles in seed and aphid transmission of selected SMV-encoded proteins were investigated by constructing chimeric recombinants between SMV 413 (efficien...

Invertebrate communities in spring wheat and the identification of cereal aphid predators through molecular gut content analysis

USDA-ARS?s Scientific Manuscript database

Cereal aphid complexes are responsible for reducing wheat production worldwide; however, management against these species is rare in North America. Generalist predators may contribute to reducing cereal aphid numbers and preventing significant damage to crops. A two-year survey identifying the arth...

Large-scale gene discovery in the pea aphid Acyrthosiphon pisum (Hemiptera)

PubMed Central

Sabater-Muñoz, Beatriz; Legeai, Fabrice; Rispe, Claude; Bonhomme, Joël; Dearden, Peter; Dossat, Carole; Duclert, Aymeric; Gauthier, Jean-Pierre; Ducray, Danièle Giblot; Hunter, Wayne; Dang, Phat; Kambhampati, Srini; Martinez-Torres, David; Cortes, Teresa; Moya, Andrès; Nakabachi, Atsushi; Philippe, Cathy; Prunier-Leterme, Nathalie; Rahbé, Yvan; Simon, Jean-Christophe; Stern, David L; Wincker, Patrick; Tagu, Denis

2006-01-01

Aphids are the leading pests in agricultural crops. A large-scale sequencing of 40,904 ESTs from the pea aphid Acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. A strong AT bias was found, indicating a compositional shift between Drosophila melanogaster and A. pisum. An in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). This project is the first to address the genetics of the Hemiptera and of a hemimetabolous insect. PMID:16542494

Neozygites osornensis sp. nov., a fungal species causing mortality to the cypress aphid Cinara cupressi in Chile.

PubMed

Retamal, Cristian Montalva; Barta, Marek; Pérez, Eladio Rojas; Flores, Eduardo Valenzuela

2013-01-01

An entomophthoralean fungus causing epizootics in populations of the cypress aphid, Cinara cupressi Buckton, in Chile is described as a new species, Neozygites osornensis Montalva et Barta. The aphid pathogen is described based on morphological characters. An exhaustive description, illustrations and a comparison with closely related species are provided. The fungus differs from similar Neozygites species by smaller hyphal bodies, nuclei, primary conidia, capilliconidia and capilliphores and by noticeably different shape of capilliconidia. A key to aphid-pathogenic species of Neozygites is also included.

Large-scale label-free quantitative proteomics of the pea aphid-Buchnera symbiosis.

PubMed

Poliakov, Anton; Russell, Calum W; Ponnala, Lalit; Hoops, Harold J; Sun, Qi; Douglas, Angela E; van Wijk, Klaas J

2011-06-01

Many insects are nutritionally dependent on symbiotic microorganisms that have tiny genomes and are housed in specialized host cells called bacteriocytes. The obligate symbiosis between the pea aphid Acyrthosiphon pisum and the γ-proteobacterium Buchnera aphidicola (only 584 predicted proteins) is particularly amenable for molecular analysis because the genomes of both partners have been sequenced. To better define the symbiotic relationship between this aphid and Buchnera, we used large-scale, high accuracy tandem mass spectrometry (nanoLC-LTQ-Orbtrap) to identify aphid and Buchnera proteins in the whole aphid body, purified bacteriocytes, isolated Buchnera cells and the residual bacteriocyte fraction. More than 1900 aphid and 400 Buchnera proteins were identified. All enzymes in amino acid metabolism annotated in the Buchnera genome were detected, reflecting the high (68%) coverage of the proteome and supporting the core function of Buchnera in the aphid symbiosis. Transporters mediating the transport of predicted metabolites were present in the bacteriocyte. Label-free spectral counting combined with hierarchical clustering, allowed to define the quantitative distribution of a subset of these proteins across both symbiotic partners, yielding no evidence for the selective transfer of protein among the partners in either direction. This is the first quantitative proteome analysis of bacteriocyte symbiosis, providing a wealth of information about molecular function of both the host cell and bacterial symbiont.

Population dynamics of Aphis gossypii Glover and in sole and intercropping systems of cotton and cowpea.

PubMed

Fernandes, Francisco S; Godoy, Wesley A C; Ramalho, Francisco S; Garcia, Adriano G; Santos, Bárbara D B; Malaquias, José B

2018-01-01

Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with two aphid species and were evaluated at 7, 14, 28, 35, 42, and 49 days after the infestations. Mathematical models were used to fit the population dynamics of two aphid species. There were good fits for aphid dynamics by mathematical model over time. The highest population peak of both species A. gossypii and A. craccivora was found in the sole crops, and the lowest population peak was found in crop system t2. These results are important for integrated management programs of aphids in cotton and cowpea.

Identification of differentially expressed genes related to aphid resistance in cucumber (Cucumis sativus L.)

PubMed Central

Liang, Danna; Liu, Min; Hu, Qijing; He, Min; Qi, Xiaohua; Xu, Qiang; Zhou, Fucai; Chen, Xuehao

2015-01-01

Cucumber, a very important vegetable crop worldwide, is easily damaged by pests. Aphids (Aphis gossypii Glover) are among the most serious pests in cucumber production and often cause severe loss of yield and make fruit quality get worse. Identifying genes that render cucumbers resistant to aphid-induced damage and breeding aphid-resistant cucumber varieties have become the most promising control strategies. In this study, a Illumina Genome Analyzer platform was applied to monitor changes in gene expression in the whole genome of the cucumber cultivar ‘EP6392’ which is resistant to aphids. Nine DGE libraries were constructed from infected and uninfected leaves. In total, 49 differentially expressed genes related to cucumber aphid resistance were screened during the treatment period. These genes are mainly associated with signal transduction, plant-pathogen interactions, flavonoid biosynthesis, amino acid metabolism and sugar metabolism pathways. Eight of the 49 genes may be associated with aphid resistance. Finally, expression of 9 randomly selected genes was evaluated by qRT-PCR to verify the results for the tag-mapped genes. With the exception of 1-aminocyclopropane-1-carboxylate oxidase homolog 6, the expression of the chosen genes was in agreement with the results of the tag-sequencing analysis patterns. PMID:25959296

Effects of imidacloprid and clothianidin seed treatments on wheat aphids and their natural enemies on winter wheat.

PubMed

Zhang, Peng; Zhang, Xuefeng; Zhao, Yunhe; Wei, Yan; Mu, Wei; Liu, Feng

2016-06-01

Wheat aphid (Hemiptera: Aphididae) is one of the major pests of winter wheat and has posed a significant threat to winter wheat production in China. Although neonicotinoid insecticidal seed treatments have been suggested to be a control method, the season-long efficacy on pests and the impact on their natural enemies are still uncertain. Experiments were conducted to determine the efficacy of imidacloprid and clothianidin on the control of aphids, the number of their natural enemies and the emergence rate and yield of wheat during 2011-2014. Imidacloprid and clothianidin seed treatments had no effect on the emergence rate of winter wheat and could prevent yield losses and wheat aphid infestations throughout the winter wheat growing season. Furthermore, their active ingredients were detected in winter wheat leaves up to 200 days after sowing. Imidacloprid and clothianidin seed treatments had no adverse effects on ladybirds, hoverflies or parasitoids, and instead increased the spider-aphid ratios. Wheat seeds treated with imidacloprid and clothianidin were effective against wheat aphids throughout the winter wheat growing season and reduced the yield loss under field conditions. Imidacloprid and clothianidin seed treatments may be an important component of the integrated management of wheat aphids on winter wheat. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

The green peach aphid Myzus persicae perform better on pre-infested Chinese cabbage Brassica pekinensis by enhancing host plant nutritional quality

PubMed Central

Cao, He-He; Liu, Hui-Ru; Zhang, Zhan-Feng; Liu, Tong-Xian

2016-01-01

The green peach aphid, Myzus persicae Sulzer, is a notorious pest on vegetables, which often aggregates in high densities on crop leaves. In this study, we investigated whether M. persicae could suppress the resistance level of Chinese cabbage Brassica pekinensis. M. persicae performed better in terms of weight gain (~33% increase) and population growth (~110% increase) when feeding on previously infested (pre-infested) Chinese cabbage compared with those on non-infested plants. However, when given a choice, 64% of the aphids preferred to settle on non-infested leaves, while 29% of aphids chose pre-infested leaves that had a 2.9 times higher concentration of glucosinolates. Aphid feeding significantly enhanced the amino acid:sugar ratio of phloem sap and the absolute amino acid concentration in plant leaves. Aphid infestation significantly increased the expression levels of salicylic acid (SA) marker genes, while it had marginal effects on the expression of jasmonate marker genes. Exogenously applied SA or methyl jasmonate had no significant effects on M. persicae performance, although these chemicals increased glucosinolates concentration in plant leaves. M. persicae infestation increase amino acid:sugar ratio and activate plant defenses, but aphid performed better on pre-infested plants, suggesting that both nutrition and toxics should be considered in insect-plant interaction. PMID:26905564

The impacts of climate change and belowground herbivory on aphids via primary metabolites

NASA Astrophysics Data System (ADS)

Ryalls, James M. W.

Global climate and atmospheric change (summarised as climate change for brevity) may alter patterns of crop damage by insect herbivores, but little is known about how multiple climate change factors, acting in tandem, shape such interactions. Crucially, the specific plant-mediated mechanisms underpinning these effects remain largely unknown. Moreover, research into the effects of climate change on leguminous plant species, which have the ability to fix atmospheric nitrogen (N2) via their association with root nodule-dwelling rhizobial bacteria, and their associated insect herbivores, is surprisingly scarce considering their increasing importance in terrestrial ecosystems worldwide. Using a model legume, lucerne, otherwise known as alfalfa, Medicago sativa (Fabaceae), and a model pest species, the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae), this work addresses how predicted changes in carbon dioxide (CO2) concentrations, temperature and rainfall patterns as well as interactions with other organisms, including the root-feeding weevil Sitona discoideus (Coleoptera: Curculionidae), might shape legume-feeding aphid populations in the future. Recent literature on the impacts of climate change on aphids and the biology and trophic interactions of lucerne aphids specifically were synthesised in chapters one and two, respectively. These chapters highlighted the importance of the interactions between multiple abiotic and biotic variables in shaping aphid population dynamics. Empirical research chapters three to six, using up to five lucerne genotypes (i.e. cultivars) in glasshouse and field experiments, addressed how A. pisum responded to the isolated and combined effects of climate change and root herbivory. In particular, chapter three determined the effects of elevated temperatures (eT) and elevated atmospheric CO2 concentrations (eCO2) on root-feeding S. discoideus larvae and their interaction with A. pisum. Chapter four addressed whether the effects of eT, eCO2 and simulated root damage on aphids could be explained by changes in plant amino acid concentrations. Chapter five built on the mechanistic findings from chapter four to determine whether specific groups of amino acids were responsible for driving the effects of eT and eCO2 on aphid fecundity, longevity and intrinsic rate of increase (rm). Chapter six extended this research to the field to determine the plant-mediated effects of water stress and root herbivory on aphids in a mixed grass-legume system. Lucerne demonstrated an over compensatory growth response to root herbivory by S. discoideus larvae by increasing net root biomass and nodulation by 31% and 45%, respectively. eT negated the positive effects of eCO2 on weevil larval development, as well as on a number of lucerne characteristics (e.g. nodulation and amino acid concentrations) and aphid performance parameters (e.g. population growth, fecundity and rm). Root herbivory by S. discoideus negatively impacted aphids in general, although effects were dependent on feeding duration and herbivore arrival sequence (i.e. whether aphids fed on the plant before or after root herbivory). While drought negatively impacted aphid abundance, potentially via reduced phloem turgor and sap viscosity, the effects of eT, eCO2 and root herbivory on aphids were often driven by concentrations of specific amino acid groups. Nitrogen (N) leached from lacerated lucerne root nodules by S. discoideus led to increased concentrations of N in a neighbouring grass, Phalaris aquatica (Poaceae), with knock-on effects on plant competition and community dynamics. The opposing effects of eT and eCO2 on plant characteristics and both aboveground and belowground herbivores demonstrates the importance of combining trophic complexity with multiple climatic factors as a means of gaining realistic insights into how insect and plant communities will respond under future conditions. Identifying the specific amino acid changes underpinning aphid responses to climate change and root herbivory offers the potential for breeding aphid resistance traits into lucerne cultivars and informing adaptation strategies against future threats. Changes in precipitation patterns and plant-mediated indirect aboveground-belowground herbivore interactions can alter the outcome of competition between N-fixing legumes and non-N-fixing grasses, with important implications for plant community structure and productivity. Avenues for future research are explored and other causal agents of changes in aphid performance are discussed, which may further elucidate the mechanisms underpinning climate change and belowground herbivory impacts on aphid pests.

Assessing the value and pest management window provided by neonicotinoid seed treatments for management of soybean aphid (Aphis glycines Matsumura) in the Upper Midwestern United States.

PubMed

Krupke, Christian H; Alford, Adam M; Cullen, Eileen M; Hodgson, Erin W; Knodel, Janet J; McCornack, Brian; Potter, Bruce D; Spigler, Madeline I; Tilmon, Kelley; Welch, Kelton

2017-10-01

A 2-year, multi-state study was conducted to assess the benefits of using soybean seed treated with the neonicotinoid thiamethoxam to manage soybean aphid in the upper Midwestern USA and compare this approach with an integrated pest management (IPM) approach that included monitoring soybean aphids and treating with foliar-applied insecticide only when the economic threshold was reached. Concentrations of thiamethoxam in soybean foliage were also quantified throughout the growing season to estimate the pest management window afforded by insecticidal seed treatments. Both the IPM treatment and thiamethoxam-treated seed resulted in significant reductions in cumulative aphid days when soybean aphid populations reached threshold levels. However, only the IPM treatment resulted in significant yield increases. Analysis of soybean foliage from thiamethoxam-treated seeds indicated that tissue concentrations of thiamethoxam were statistically similar to plants grown from untreated seeds beginning at the V2 growth stage, indicating that the period of pest suppression for soybean aphid is likely to be relatively short. These data demonstrate that an IPM approach, combining scouting and foliar-applied insecticide where necessary, remains the best option for treatment of soybean aphids, both in terms of protecting the yield potential of the crop and of break-even probability for producers. Furthermore, we found that thiamethoxam concentrations in foliage are unlikely to effectively manage soybean aphids for most of the pests' activity period across the region. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Aphid Transmission of the Ontario Isolate of Plum Pox Virus.

PubMed

Lowery, D Thomas; Vickers, Patricia M; Bittner, Lori A; Stobbs, Lorne W; Foottit, Robert G

2015-10-01

Utilization of timed virus acquisition access probes in studies of plum pox virus (PPV) transmission by aphids demonstrated that endemic species transmitted the virus readily from plum, Prunus domestica (L.) Batsch; peach, P. persica (L.); or dwarf flowering almond, P. glandulosa Thunberg., to peach seedlings. The green peach aphid, Myzus persicae (Sulzer), was shown to be the most efficient vector. Acquisition of virus by green peach aphids from infected peach leaves resulted in 18-28% infected peach seedlings, while aphids previously fed on infected leaves of plum transferred virus to 36% of peach seedlings. Although the spirea aphid, Aphis spiraecola (Patch), was a less efficient vector than M. persicae it is perhaps more important for the spread of PPV due to its greater abundance and occurrence earlier in the season when peach trees are thought to be more susceptible to infection. Virus transmission rates varied depending on the virus source and healthy test plant species. In contrast to many previous studies, aphid inoculation of the experimental host Nicotiana benthamiana Domin occurred at a low rate, never exceeding 4%. Acquisition of PPV by M. persicae from infected peach fruit was greatly reduced compared with acquisition from leaves. The results of this research indicate that the Ontario isolate of PPV-D is readily transmissible by aphids to peach and natural spread of the virus needs to be considered in future management or eradication programs. © Her Majesty in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada. Published by Oxford University Press on behalf of Entomological Society of America.

A Genetic Survey of Pyrethroid Insecticide Resistance in Aphids in New Brunswick, Canada, with Particular Emphasis on Aphids as Vectors of Potato virus Y.

PubMed

MacKenzie, Tyler D B; Arju, Irin; Poirier, René; Singh, Mathuresh

2018-05-28

Aphids are viral vectors in potatoes, most importantly of Potato virus Y (PVY), and insecticides are frequently used to reduce viral spread during the crop season. Aphids collected from the potato belt of New Brunswick, Canada, in 2015 and 2016 were surveyed for known and novel mutations in the Na-channel (para) gene, coding for the target of synthetic pyrethroid insecticides. Specific genetic mutations known to confer resistance (kdr and skdr) were found in great abundance in Myzus persicae (Sulzer) (Hemiptera: Aphididae), which rose from 76% in 2015 to 96% in 2016. Aphids other than M. persicae showed lower frequency of resistance. In 2015, 3% of individuals contained the resistance mutation skdr, rising to 13% in 2016 (of 45 species). Several novel resistance mutations or mutations not before reported in aphids were identified in this gene target. One of these mutations, I936V, is known to confer pyrethroid resistance in another unrelated insect, and three others occur immediately adjacent and prompt similar chemical shifts in the primary protein structure, to previously characterized mutations associated with pyrethroid resistance. Most novel mutations were found in species other than M. persicae or others currently tracked individually by the provincial aphid monitoring program, which were determined by cytochrome C oxidase I (cox1) sequencing. Through our cox1 DNA barcoding survey, at least 45 species of aphids were discovered in NB potato fields in 2015 and 2016, many of which are known carriers of PVY.

Identificatoin and confirmation of resistance against soybean aphid (Aphis glycines) in eight wild soybean lines

USDA-ARS?s Scientific Manuscript database

The development and use of aphid-resistant soybean (Glycine max) cultivars has been complicated by the presence of multiple virulent biotypes of the soybean aphid (SA, Aphis glycines Matsumura). Ultimately, a variety of unique resistance sources may be needed to develop cultivars with a broad spectr...

Status of Imported and Native Predators of the Balsam Woolly Aphid on Mt. Mitchell, North Carolina

Treesearch

Gerhard F. Fedde

1972-01-01

On the Mt. Mitchell area during the summer of 1968, 20 stands of Fraser fir, Abies fraseri (Pursh) Poir., infested by the balsam woolly aphid, Adelges piceae (Ratzeburg), were examined for native and previously imported predators of the aphid. Laricobius erichsonii Bosenhauer (Coleoptera: Derodontidae) was...

Expression of Russian Wheat Aphid (Homoptera: Aphididae) Resistance in Genotypes of Tall Fescue Harboring Different Isolates of Acremonium Endophyte

Treesearch

S.L. Clement; D.G. Lester; A. Dan Wilson; R.C. Johnson; J.H. Bouton

1996-01-01

Experiments were conducted to compare the expression of Russian wheat aphid, Diurnphis noxia (Mordvilko), resistance in 2 genotypes of tall fescue grass, Festucn arundinacea Schreb., harboring different isolates of the endophytic fungus Acremonium coenophialum Morgan-Jones & cams. Aphids did not select...

Insect and plant-derived miRNAs in greenbug (schizaphis graminum) and yellow sugarcane aphid (sipha flava) revealed by deep sequencing

USDA-ARS?s Scientific Manuscript database

Schizaphis graminum (green bug; GB) and Sipha flava yellow sugarcane aphid; YSA) are two cereal aphid species with broad host ranges capable of establishing on sorghum (Sorghum bicolor) and several switchgrass (Panicum virgatum) cultivars. Switchgrass and sorghum are staple renewable bioenergy crops...

Life history and morphological plasticity of three biotypes of soybean aphid (Aphis glycines)

USDA-ARS?s Scientific Manuscript database

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a pest of soybean, Glycine max (L.) Merr. (Fabaceae), from eastern Asia that was first reported in North America in 2000. The influence of temperature on plasticity of life history and morphological traits of the soybean aphid ha...

Genetics coupled to quantitative intact proteomics links heritable aphid and endosymbiont protein isoform expression to polerovirus transmission

USDA-ARS?s Scientific Manuscript database

Yellow dwarf viruses in the family Luteoviridae, such as Cereal yellow dwarf virus-RPV (CYDV-RPV), are vectored by aphids and cause the most economically important virus disease of cereal crops worldwide. The identification of aphid proteins mediating virus transmission will better define transmiss...

Transcriptome profilng of defense responses to aphid feeding in wheat

USDA-ARS?s Scientific Manuscript database

Greenbug (Schizaphis graminum) is a serious aphid pest in small grain crops in the southern Great Plains of the US. We are trying to understand the molecular mechanisms of host resistance against aphid infestation in the grass genome using wheat-greenbug as a model system. In the present study, a mi...

Characterization and genetics of multiple soybean aphid biotype resistance in five soybean plant introductions

USDA-ARS?s Scientific Manuscript database

Soybean aphid (Aphis glycines Matsumura) is the most important soybean [Glycine max (L.) Merr.] insect pest in the USA. The objectives of this study were to characterize the resistance expressed in the five plant introductions (PIs) to four soybean aphid biotypes, determine the mode of resistance in...

Resistance to lettuce aphid (Nasonovia ribisnigri) biotype 0 in wild lettuce accessions PI 491093 and PI 274378

USDA-ARS?s Scientific Manuscript database

Lettuce aphid, Nasonovia ribisnigri Mosley (Homoptera : Aphididae), is a major insect pest of lettuce, Lactuca sativa L, in many commercial lettuce productions areas around the world. Resistance to lettuce aphid was first reported in Lactuca virosa L. accession IVT 280 and characterized as complete,...

Management of Sugarcane Aphid in Sorghum

ERIC Educational Resources Information Center

Zerger, Sarah

2017-01-01

Sugarcane aphids are becoming a more prevalent pest in sorghum in the United States, especially in the south and are making their way north. There are many management practices that can be used on sugarcane aphids, the most important being scouting and maintaining populations. The most common mistake once a pest has been found is to immediately…

Association mapping of aphid resistance in USDA cowpea (Vigna unguiculata L. Walp.) core collection using SNPs

USDA-ARS?s Scientific Manuscript database

Cowpea aphid (CPA; Aphis craccivora) is a destructive insect pest of cowpea, as well as other legume crops including alfalfa, beans, chickpea, lentils, lupins and peanuts. The utilization of aphid resistance in cowpea breeding is one of the most efficient and environmental friendly methods to contro...

Outbreak of sorghum/sugarcane aphid on sorghum: First detections, distribution, and notes on management

USDA-ARS?s Scientific Manuscript database

An outbreak of an invasive aphid was discovered damaging grain sorghum in Texas and neighboring states in 2013. It may be a new variant of sugarcane aphid, Melanaphis sacchari, that has a high preference for sorghum, or a very closely related species (M. sorghi). We designate it sorghum/sugarcane ...

Indirect multi-trophic interactions mediated by induced plant resistance: impact of caterpillar feeding on aphid parasitoids

PubMed Central

Hagenbucher, Steffen; Wäckers, Felix L.; Romeis, Jörg

2014-01-01

Cotton produces insecticidal terpenoids that are induced by tissue-feeding herbivores. Damage by Heliothis virescens caterpillars increases the terpenoid content, which reduces the abundance of aphids. This effect is not evident in Bt-transgenic cotton, which is resistant to H. virescens. We determined whether induction of terpenoids by caterpillars influences the host quality of Aphis gossypii for the parasitoid Lysiphlebus testaceipes and whether this interaction is influenced by Bt cotton. The exposure of parasitoids to terpenoids was determined by quantifying terpenoids in the aphids. We detected several terpenoids in aphids and found a positive relationship between their concentrations in plants and aphids. When L. testaceipes was allowed to parasitize aphids on Bt and non-Bt cotton that was infested or uninfested with H. virescens, fewer parasitoid mummies were found on infested non-Bt than on Bt cotton. Important parasitoid life-table parameters, however, were not influenced by induced resistance following H. virescens infestation, or the Bt trait. Our study provides an example of a tritrophic indirect interaction web, where organisms are indirectly linked through changes in plant metabolites. PMID:24522627

Stress response and tolerance of Zea mays to CeO2 nanoparticles: cross talk among H2O2, heat shock protein, and lipid peroxidation.

PubMed

Zhao, Lijuan; Peng, Bo; Hernandez-Viezcas, Jose A; Rico, Cyren; Sun, Youping; Peralta-Videa, Jose R; Tang, Xiaolei; Niu, Genhua; Jin, Lixin; Varela-Ramirez, Armando; Zhang, Jian-ying; Gardea-Torresdey, Jorge L

2012-11-27

The rapid development of nanotechnology will inevitably release nanoparticles (NPs) into the environment with unidentified consequences. In addition, the potential toxicity of CeO(2) NPs to plants and the possible transfer into the food chain are still unknown. Corn plants (Zea mays) were germinated and grown in soil treated with CeO(2) NPs at 400 or 800 mg/kg. Stress-related parameters, such as H(2)O(2), catalase (CAT), and ascorbate peroxidase (APX) activity, heat shock protein 70 (HSP70), lipid peroxidation, cell death, and leaf gas exchange were analyzed at 10, 15, and 20 days post-germination. Confocal laser scanning microscopy was used to image H(2)O(2) distribution in corn leaves. Results showed that the CeO(2) NP treatments increased accumulation of H(2)O(2), up to day 15, in phloem, xylem, bundle sheath cells and epidermal cells of shoots. The CAT and APX activities were also increased in the corn shoot, concomitant with the H(2)O(2) levels. Both 400 and 800 mg/kg CeO(2) NPs triggered the up-regulation of the HSP70 in roots, indicating a systemic stress response. None of the CeO(2) NPs increased the level of thiobarbituric acid reacting substances, indicating that no lipid peroxidation occurred. CeO(2) NPs, at both concentrations, did not induce ion leakage in either roots or shoots, suggesting that membrane integrity was not compromised. Leaf net photosynthetic rate, transpiration, and stomatal conductance were not affected by CeO(2) NPs. Our results suggest that the CAT, APX, and HSP70 might help the plants defend against CeO(2) NP-induced oxidative injury and survive NP exposure.

Stress Response and Tolerance of Zea mays to CeO2 Nanoparticles: Cross Talk among H2O2, Heat Shock Protein and Lipid Peroxidation

PubMed Central

Zhao, Lijuan; Peng, Bo; Hernandez-Viezcas, Jose A.; Rico, Cyren; Sun, Youping; Peralta-Videa, Jose R.; Tang, Xiaolei; Niu, Genhua; Jin, Lixin; Varela-Ramirez, Armando; Zhang, Jian-ying; Gardea-Torresdey, Jorge L.

2014-01-01

The rapid development of nanotechnology will inevitably release nanoparticles (NPs) into the environment with unidentified consequences. In addition, the potential toxicity of CeO2 NPs to plants, and the possible transfer into the food chain, are still unknown. Corn plants (Zea mays) were germinated and grown in soil treated with CeO2 NPs at 400 or 800 mg/kg. Stress related parameters, such as: H2O2, catalase (CAT) and ascorbate peroxidase (APX) activity, heat shock protein 70 (HSP 70), lipid peroxidation, cell death and leaf gas exchange were analyzed at 10, 15, and 20 days post germination. Confocal laser scanning microscopy was used to image H2O2 distribution in corn leaves. Results showed that the CeO2 NP treatments increased accumulation of H2O2, up to day 15, in phloem, xylem, bundle sheath cells, and epidermal cells of shoots. The CAT and APX activities were also increased in the corn shoot, concomitant with the H2O2 levels. Both 400 and 800 mg/kg CeO2 NPs triggered the up regulation of the HSP 70 in roots, indicating a systemic stress response. None of the CeO2 NPs increased the level of thiobarbituric acid reacting substances, indicating that no lipid peroxidation occurred. CeO2 NPs, at both concentrations, did not induce ion leakage in either roots or shoots, suggesting membrane integrity was not compromised. Leaf net photosynthetic rate, transpiration, and stomatal conductance were not affected by CeO2 NPs. Our results suggest that the CAT, APX and HSP 70 might help the plants defend against CeO2 NPs induced oxidative injury and survive NP exposure. PMID:23050848

Aphid Species and Population Dynamics Associated with Strawberry.

PubMed

Bernardi, D; Araujo, E S; Zawadneak, M A C; Botton, M; Mogor, A F; Garcia, M S

2013-12-01

Aphids are among the major pests associated with strawberries in Southern Brasil. In this study, we identified the main species that occur in strawberry fields in the states of Paraná and Rio Grande do Sul, Brasil. We also compared the effectiveness of different sampling methods and studied the population dynamics of aphid species during two strawberry crop cycles in the municipality of Pinhais, state of Paraná, Brasil. Chaetosiphon fragaefolii (Cockerell) and Aphis forbesi Weed were the main species associated with strawberry. The method of hit plant and the Möericke trap showed equal effectiveness to capture wingless and winged insects. The peak population of aphids in the state of Paraná occurred from September to November. This information can help producers to implement strategies to monitor and control the major aphid species that occur in strawberry culture.

An invasive herbivore structures plant competitive dynamics.

PubMed

Wong, Lydia; Grainger, Tess Nahanni; Start, Denon; Gilbert, Benjamin

2017-11-01

Species interactions are central to our understanding of ecological communities, but may change rapidly with the introduction of invasive species. Invasive species can alter species interactions and community dynamics directly by having larger detrimental effects on some species than others, or indirectly by changing the ways in which native species compete among themselves. We tested the direct and indirect effects of an invasive aphid herbivore on a native aphid species and two host milkweed species. The invasive aphid caused a 10-fold decrease in native aphid populations, and a 30% increase in plant mortality (direct effects). The invasive aphid also increased the strength of interspecific competition between the two native plant hosts (indirect effects). By investigating the role that indirect effects play in shaping species interactions in native communities, our study highlights an understudied component of species invasions. © 2017 The Author(s).

Complex Effects of Fertilization on Plant and Herbivore Performance in the Presence of a Plant Competitor and Activated Carbon

PubMed Central

Mahdavi-Arab, Nafiseh; Meyer, Sebastian T.; Mehrparvar, Mohsen; Weisser, Wolfgang W.

2014-01-01

Plant-herbivore interactions are influenced by host plant quality which in turn is affected by plant growth conditions. Competition is the major biotic and nutrient availability a major abiotic component of a plant’s growth environment. Yet, surprisingly few studies have investigated impacts of competition and nutrient availability on herbivore performance and reciprocal herbivore effects on plants. We studied growth of the specialist aphid, Macrosiphoniella tanacetaria, and its host plant tansy, Tanacetum vulgare, under experimental addition of inorganic and organic fertilizer crossed with competition by goldenrod, Solidago canadensis. Because of evidence that competition by goldenrod is mediated by allelopathic compounds, we also added a treatment with activated carbon. Results showed that fertilization increased, and competition with goldenrod decreased, plant biomass, but this was likely mediated by resource competition. There was no evidence from the activated carbon treatment that allelopathy played a role which instead had a fertilizing effect. Aphid performance increased with higher plant biomass and depended on plant growth conditions, with fertilization and AC increasing, and plant competition decreasing aphid numbers. Feedbacks of aphids on plant performance interacted with plant growth conditions in complex ways depending on the relative magnitude of the effects on plant biomass and aphid numbers. In the basic fertilization treatment, tansy plants profited from increased nutrient availability by accumulating more biomass than they lost due to an increased number of aphids under fertilization. When adding additional fertilizer, aphid numbers increased so high that tansy plants suffered and showed reduced biomass compared with controls without aphids. Thus, the ecological cost of an infestation with aphids depends on the balance of effects of growth conditions on plant and herbivore performance. These results emphasize the importance to investigate both perspectives in plant herbivore interactions and characterize the effects of growth conditions on plant and herbivore performance and their respective feedbacks. PMID:25078980

Contribution of Chlorophyll Fluorescence to the Reflectance of Corn Foliage

NASA Technical Reports Server (NTRS)

Campbell, Petya K. Entcheva; Middleton, Elizabeth M.; Corp, L. A.; McMurtrey, J. E.; Kim, M. S.; Chappelle, E. W.; Butcher, L. M.; Ranson, K. Jon (Technical Monitor)

2002-01-01

To assess the contribution of chlorophyll fluorescence (ChlF) to apparent reflectance (Ra) in the red/far-red, spectra were collected on a C4 agricultural species (corn, Zea Mays L.) under conditions ranging from nitrogen deficiency to excess. A significant contribution of ChlF to Ra was observed, with on average 10-25% at 685nm and 2-6% at 740nm of Ra being due to ChlF. Higher ChlF was consistently measured from the abaxial leaf surface as compared to the adaxial. Using 350-665nm excitation, the study confirms the trends in three ChlF ratios established previously by active F technology, suggesting that the ChlF utility this technology has developed for monitoring vegetation physiological status is likely applicable also under natural solar illumination.

Comparative Transcriptional Analysis of Asexual and Sexual Morphs Reveals Possible Mechanisms in Reproductive Polyphenism of the Cotton Aphid

PubMed Central

Jiang, Feng; Guo, Wei; Zhou, Shu-Tang

2014-01-01

Aphids, the destructive insect pests in the agriculture, horticulture and forestry, are capable of reproducing asexually and sexually upon environmental change. However, the molecular basis of aphid reproductive mode switch remains an enigma. Here we report a comparative analysis of differential gene expression profiling among parthenogenetic females, gynoparae and sexual females of the cotton aphid Aphis gossypii, using the RNA-seq approach with next-generation sequencing platforms, followed by RT-qPCR. At the cutoff criteria of fold change ≥2 and P<0.01, we identified 741 up- and 879 down-regulated genes in gynoparae versus parthenogenetic females, 2,101 up- and 2,210 down-regulated genes in sexual females compared to gynoparae, and 1,614 up- and 2,238 down-regulated genes in sexual females relative to parthenogenetic females. Gene ontology category and KEGG pathway analysis suggest the involvement of differentially expressed genes in multiple cellular signaling pathways into the reproductive mode transition, including phototransduction, cuticle composition, progesterone-mediated oocyte maturation and endocrine regulation. This study forms a basis for deciphering the molecular mechanisms underlying the shift from asexual to sexual reproduction in the cotton aphid. It also provides valuable resources for future studies on this host-alternating aphid species, and the insight into the understanding of reproductive mode plasticity in different aphid species. PMID:24915491

Aphid (Myzus persicae) feeding on the parasitic plant dodder (Cuscuta australis) activates defense responses in both the parasite and soybean host.

PubMed

Zhuang, Huifu; Li, Juan; Song, Juan; Hettenhausen, Christian; Schuman, Meredith C; Sun, Guiling; Zhang, Cuiping; Li, Jing; Song, Dunlun; Wu, Jianqiang

2018-06-01

Dodders (Cuscuta spp.) are shoot holoparasites, whose haustoria penetrate host tissues to enable fusion between the parasite and host vascular systems, allowing Cuscuta to extract water, nutrients and other molecules from hosts. Aphids are piercing-sucking herbivores that use specialized stylets to feed on phloem sap. Aphids are known to feed on Cuscuta, but how Cuscuta and its host plant respond to aphids attacking the parasite was unknown. Phytohormone quantification, transcriptomic analysis and bioassays were performed to determine the responses of Cuscuta australis and its soybean (Glycine max) hosts to the feeding of green peach aphid (GPA; Myzus persicae) on C. australis. Decreased salicylic acid levels and 172 differentially expressed genes (DEGs) were found in GPA-attacked C. australis, and the soybean hosts exhibited increased jasmonic acid contents and 1015 DEGs, including > 100 transcription factor genes. Importantly, GPA feeding on C. australis increased the resistance of the soybean host to subsequent feeding by the leafworm Spodoptera litura and soybean aphid Aphis glycines, resulting in 21% decreased leafworm mass and 41% reduced aphid survival rate. These data strongly suggest that GPA feeding on Cuscuta induces a systemic signal, which is translocated to hosts and activates defense against herbivores. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Virulent Diuraphis noxia Aphids Over-Express Calcium Signaling Proteins to Overcome Defenses of Aphid-Resistant Wheat Plants

PubMed Central

Sinha, Deepak K.; Chandran, Predeesh; Timm, Alicia E.; Aguirre-Rojas, Lina; Smith, C. Michael

2016-01-01

The Russian wheat aphid, Diuraphis noxia, an invasive phytotoxic pest of wheat, Triticum aestivum, and barley, Hordeum vulgare, causes huge economic losses in Africa, South America, and North America. Most acceptable and ecologically beneficial aphid management strategies include selection and breeding of D. noxia-resistant varieties, and numerous D. noxia resistance genes have been identified in T. aestivum and H. vulgare. North American D. noxia biotype 1 is avirulent to T. aestivum varieties possessing Dn4 or Dn7 genes, while biotype 2 is virulent to Dn4 and avirulent to Dn7. The current investigation utilized next-generation RNAseq technology to reveal that biotype 2 over expresses proteins involved in calcium signaling, which activates phosphoinositide (PI) metabolism. Calcium signaling proteins comprised 36% of all transcripts identified in the two D. noxia biotypes. Depending on plant resistance gene-aphid biotype interaction, additional transcript groups included those involved in tissue growth; defense and stress response; zinc ion and related cofactor binding; and apoptosis. Activation of enzymes involved in PI metabolism by D. noxia biotype 2 aphids allows depletion of plant calcium that normally blocks aphid feeding sites in phloem sieve elements and enables successful, continuous feeding on plants resistant to avirulent biotype 1. Inhibition of the key enzyme phospholipase C significantly reduced biotype 2 salivation into phloem and phloem sap ingestion. PMID:26815857

Aggressive mimicry coexists with mutualism in an aphid

PubMed Central

Salazar, Adrián; Fürstenau, Benjamin; Quero, Carmen; Pérez-Hidalgo, Nicolás; Carazo, Pau; Font, Enrique; Martínez-Torres, David

2015-01-01

Understanding the evolutionary transition from interspecific exploitation to cooperation is a major challenge in evolutionary biology. Ant–aphid relationships represent an ideal system to this end because they encompass a coevolutionary continuum of interactions ranging from mutualism to antagonism. In this study, we report an unprecedented interaction along this continuum: aggressive mimicry in aphids. We show that two morphs clonally produced by the aphid Paracletus cimiciformis during its root-dwelling phase establish relationships with ants at opposite sides of the mutualism–antagonism continuum. Although one of these morphs exhibits the conventional trophobiotic (mutualistic) relationship with ants of the genus Tetramorium, aphids of the alternative morph are transported by the ants to their brood chamber and cared for as if they were true ant larvae. Gas chromatography-mass spectrometry analyses reveal that the innate cuticular hydrocarbon profile of the mimic morph resembles the profile of ant larvae more than that of the alternative, genetically identical nonmimic morph. Furthermore, we show that, once in the brood chamber, mimic aphids suck on ant larva hemolymph. These results not only add aphids to the limited list of arthropods known to biosynthesize the cuticular chemicals of their deceived hosts to exploit their resources but describe a remarkable case of plastic aggressive mimicry. The present work adds a previously unidentified dimension to the classical textbook paradigm of aphid–ant relationships by showcasing a complex system at the evolutionary interface between cooperation and exploitation. PMID:25583474

Expression profiling of selected glutathione transferase genes in Zea mays (L.) seedlings infested with cereal aphids.

PubMed

Sytykiewicz, Hubert; Chrzanowski, Grzegorz; Czerniewicz, Paweł; Sprawka, Iwona; Łukasik, Iwona; Goławska, Sylwia; Sempruch, Cezary

2014-01-01

The purpose of this report was to evaluate the expression patterns of selected glutathione transferase genes (gst1, gst18, gst23 and gst24) in the tissues of two maize (Zea mays L.) varieties (relatively resistant Ambrozja and susceptible Tasty Sweet) that were colonized with oligophagous bird cherry-oat aphid (Rhopalosiphum padi L.) or monophagous grain aphid (Sitobion avenae L.). Simultaneously, insect-triggered generation of superoxide anion radicals (O2•-) in infested Z. mays plants was monitored. Quantified parameters were measured at 1, 2, 4, 8, 24, 48 and 72 h post-initial aphid infestation (hpi) in relation to the non-infested control seedlings. Significant increases in gst transcript amounts were recorded in aphid-stressed plants in comparison to the control seedlings. Maximal enhancement in the expression of the gst genes in aphid-attacked maize plants was found at 8 hpi (gst23) or 24 hpi (gst1, gst18 and gst24) compared to the control. Investigated Z. mays cultivars formed excessive superoxide anion radicals in response to insect treatments, and the highest overproduction of O2•- was noted 4 or 8 h after infestation, depending on the aphid treatment and maize genotype. Importantly, the Ambrozja variety could be characterized as having more profound increments in the levels of gst transcript abundance and O2•- generation in comparison with the Tasty Sweet genotype.

Plant resistance in sorghums to the sugarcane aphid Melanaphis sacchari (Hemiptera: Aphididae)

USDA-ARS?s Scientific Manuscript database

We evaluated ten sorghum lines that were near or in commercial release with the intent of identifying phenotypic expression of host-plant resistance to the sugarcane aphid. Two of the ten entries OL2042 and SP7715 expressed a high degree of resistance to the sugarcane aphid with damage ratings <3.0...

Using multispectral imagery to compare the spatial pattern of injury to wheat caused by Russian wheat aphid and greenbug

USDA-ARS?s Scientific Manuscript database

The Russian wheat aphid, Diuraphis noxia (Mordvilko), and greenbug, Schizaphis graminum (Rondani), are important aphid pests of wheat. Outbreaks of both pests in commercial wheat fields occur almost every year in the Great Plains of the United States. Infestations of both pests in wheat fields are...

Safeguarding world wheat and barley production against Russian wheat aphid: An international pre-breeding initiative

USDA-ARS?s Scientific Manuscript database

The Russian wheat aphid (RWA), Diuraphis noxia, is one of the most damaging insect pests of wheat and barley throughout the World. This aphid, although is not yet present in Australia, is extremely damaging with up to 70% yield loses in wheat and barley producing lands, causing significant financia...

77 FR 46373 - Field Release of Aphelinus glycinis for the Biological Control of the Soybean Aphid in the...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-03

... Inspection Service [Docket No APHIS-2012-0061] Field Release of Aphelinus glycinis for the Biological Control... for the biological control of the soybean aphid, Aphis glycines, in the continental United States. We... glycinis for the Biological Control of the Soybean Aphid in the Continental United States'' (March 2012...

Registration of Tx3410 through Tx3428 sorghum germplasm resistant to sugarcane aphid [Melanaphis sacchari (Zehntner)

USDA-ARS?s Scientific Manuscript database

The sugarcane aphid [Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae)] became virulent on sorghum in the United States in 2013. By 2015 the aphid was identified in 400 counties in 17 states accounting for 97% of hectares and 98% of production in the U.S. In 2014 and 2015, the estimated econom...

Mutualistic and antagonistic trophic interactions in canola: the role of aphids in shaping pest and predator populations

USDA-ARS?s Scientific Manuscript database

Aphids have important effects on the abundance and occurrence of tending ants, predators, and pests in agronomic systems, and DNA-based gut content analysis can aid in establishing predator-prey interactions. The purpose of this study was to determine how the presence of aphids, ants, and pest indiv...

Aphid specialization on different summer hosts is associated with strong genetic differentiation and unequal symbiont communities despite a common mating habitat.

PubMed

Vorburger, C; Herzog, J; Rouchet, R

2017-04-01

Specialization on different host plants can promote evolutionary diversification of herbivorous insects. Work on pea aphids (Acyrthosiphon pisum) has contributed significantly to the understanding of this process, demonstrating that populations associated with different host plants exhibit performance trade-offs across hosts, show adaptive host choice and genetic differentiation and possess different communities of bacterial endosymbionts. Populations specialized on different secondary host plants during the parthenogenetic summer generations are also described for the black bean aphid (Aphis fabae complex) and are usually treated as different (morphologically cryptic) subspecies. In contrast to pea aphids, however, host choice and mate choice are decoupled in black bean aphids, because populations from different summer hosts return to the same primary host plant to mate and lay overwintering eggs. This could counteract evolutionary divergence, and it is currently unknown to what extent black bean aphids using different summer hosts are indeed differentiated. We addressed this question by microsatellite genotyping and endosymbiont screening of black bean aphids collected in summer from the goosefoot Chenopodium album (subspecies A. f. fabae) and from thistles of the genus Cirsium (subspecies A. f. cirsiiacanthoides) across numerous sites in Switzerland and France. Our results show clearly that aphids from Cirsium and Chenopodium exhibit strong and geographically consistent genetic differentiation and that they differ in their frequencies of infection with particular endosymbionts. The dependence on a joint winter host has thus not prevented the evolutionary divergence into summer host-adapted populations that appear to have evolved mechanisms of reproductive isolation within a common mating habitat. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Identification of the main venom protein components of Aphidius ervi, a parasitoid wasp of the aphid model Acyrthosiphon pisum.

PubMed

Colinet, Dominique; Anselme, Caroline; Deleury, Emeline; Mancini, Donato; Poulain, Julie; Azéma-Dossat, Carole; Belghazi, Maya; Tares, Sophie; Pennacchio, Francesco; Poirié, Marylène; Gatti, Jean-Luc

2014-05-06

Endoparasitoid wasps are important natural enemies of the widely distributed aphid pests and are mainly used as biological control agents. However, despite the increased interest on aphid interaction networks, only sparse information is available on the factors used by parasitoids to modulate the aphid physiology. Our aim was here to identify the major protein components of the venom injected at oviposition by Aphidius ervi to ensure successful development in its aphid host, Acyrthosiphon pisum. A combined large-scale transcriptomic and proteomic approach allowed us to identify 16 putative venom proteins among which three γ-glutamyl transpeptidases (γ-GTs) were by far the most abundant. Two of the γ-GTs most likely correspond to alleles of the same gene, with one of these alleles previously described as involved in host castration. The third γ-GT was only distantly related to the others and may not be functional owing to the presence of mutations in the active site. Among the other abundant proteins in the venom, several were unique to A. ervi such as the molecular chaperone endoplasmin possibly involved in protecting proteins during their secretion and transport in the host. Abundant transcripts encoding three secreted cystein-rich toxin-like peptides whose function remains to be explored were also identified. Our data further support the role of γ-GTs as key players in A. ervi success on aphid hosts. However, they also evidence that this wasp venom is a complex fluid that contains diverse, more or less specific, protein components. Their characterization will undoubtedly help deciphering parasitoid-aphid and parasitoid-aphid-symbiont interactions. Finally, this study also shed light on the quick evolution of venom components through processes such as duplication and convergent recruitment of virulence factors between unrelated organisms.

The Effect of Temperature and Host Plant Resistance on Population Growth of the Soybean Aphid Biotype 1 (Hemiptera: Aphididae).

PubMed

Hough, Ashley R; Nechols, James R; McCornack, Brian P; Margolies, David C; Sandercock, Brett K; Yan, Donglin; Murray, Leigh

2017-02-01

A laboratory experiment was conducted to evaluate direct and indirect effects of temperature on demographic traits and population growth of biotype 1 of the soybean aphid, Aphis glycines Matsumura. Our objectives were to better understand how temperature influences the expression of host plant resistance, quantify the individual and interactive effects of plant resistance and temperature on soybean aphid population growth, and generate thermal constants for predicting temperature-dependent development on both susceptible and resistant soybeans. To assess indirect (plant-mediated) effects, soybean aphids were reared under a range of temperatures (15-30 °C) on soybean seedlings from a line expressing a Rag1 gene for resistance, and life history traits were quantified and compared to those obtained for soybean aphids on a susceptible soybean line. Direct effects of temperature were obtained by comparing relative differences in the magnitude of life-history traits among temperatures on susceptible soybeans. We predicted that temperature and host plant resistance would have a combined, but asymmetrical, effect on soybean aphid fitness and population growth. Results showed that temperature and plant resistance influenced preimaginal development and survival, progeny produced, and adult longevity. There also appeared to be a complex interaction between temperature and plant resistance for survival and developmental rate. Evidence suggested that the level of plant resistance increased at higher, but not lower, temperature. Soybean aphids required about the same number of degree-days to develop on resistant and susceptible plants. Our results will be useful for making predictions of soybean aphid population growth on resistant plants under different seasonal temperatures. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A single gene, AIN, in Medicago truncatula mediates a hypersensitive response to both bluegreen aphid and pea aphid, but confers resistance only to bluegreen aphid

PubMed Central

Klingler, John P.; Nair, Ramakrishnan M.; Edwards, Owain R.; Singh, Karam B.

2009-01-01

Biotic stress in plants frequently induces a hypersensitive response (HR). This distinctive reaction has been studied intensively in several pathosystems and has shed light on the biology of defence signalling. Compared with microbial pathogens, relatively little is known about the role of the HR in defence against insects. Reference genotype A17 of Medicago truncatula Gaertn., a model legume, responds to aphids of the genus Acyrthosiphon with necrotic lesions resembling a HR. In this study, the biochemical nature of this response, its mode of inheritance, and its relationship with defence against aphids were investigated. The necrotic lesion phenotype and resistance to the bluegreen aphid (BGA, Acyrthosiphon kondoi Shinji) and the pea aphid (PA, Acyrthosiphon pisum (Harris)) were analysed using reference genotypes A17 and A20, their F2 progeny and recombinant inbred lines. BGA-induced necrotic lesions co-localized with the production of H2O2, consistent with an oxidative burst widely associated with hypersensitivity. This HR correlated with stronger resistance to BGA in A17 than in A20; these phenotypes cosegregated as a semi-dominant gene, AIN (Acyrthosiphon-induced necrosis). In contrast to BGA, stronger resistance to PA in A17, compared with A20, did not cosegregate with a PA-induced HR. The AIN locus resides in a cluster of sequences predicted to encode the CC-NBS-LRR subfamily of resistance proteins. AIN-mediated resistance presents a novel opportunity to use a model plant and model aphid to study the role of the HR in defence responses to phloem-feeding insects. PMID:19690018

Effect of an alternate weed host, hairy nightshade, Solanum sarrachoides, on the biology of the two most important potato leafroll virus (Luteoviridae: Polerovirus) vectors, Myzus persicae and Macrosiphum euphorbiae (Aphididae: Homoptera).

PubMed

Srinivasan, Rajagopalbabu; Alvarez, Juan M; Bosque-Pérez, Nilsa A; Eigenbrode, Sanford D; Novy, Richard G

2008-04-01

Hairy nightshade, Solanum sarrachoides (Sendtner), is a ubiquitous weed in potato agro-ecosystems and nonagricultural lands of southeastern Idaho and the Pacific Northwest. This weed increases the complexity of the Potato leafroll virus (PLRV) (Luteoviridae: Polervirus)-potato pathosystem by serving as aphid and virus reservoir. Previous field studies showed higher densities of green peach aphid, Myzus persicae (Sulzer), and potato aphid, Macrosiphum euphorbiae (Thomas), the two most important vectors of PLRV, on S. sarrachoides compared with potato plants in the same fields. Some of the S. sarrachoides plants sampled in these surveys tested positive for PLRV. Viral infections can alter the physiology of plant hosts and aphid performance on such plants. To understand better the potential effects of S. sarrachoides on the PLRV-potato-aphid pathosystem, the life histories of M. persicae and M. euphorbiae were compared on virus-free and PLRV-infected S. sarrachoides and potato. Individual nymphs of each aphid species were held in clip cages on plants from each treatment to monitor their development, survival, and reproductive output. Nymphal survival for both aphids across plant species was higher on S. sarrachoides than on potato, and, within plant species, it was higher on PLRV-infected plants than on noninfected plants. With a few exceptions, similar patterns occurred for fecundity, reproductive periods, adult longevity, and intrinsic rate of increase. The enhanced performance of aphids on S. sarrachoides and on PLRV-infected plants could alter the vector population dynamics and thus the PLRV-disease epidemiology in fields infested with this weed.

The phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) is a pathogen of the pea aphid.

PubMed

Grenier, Anne-Marie; Duport, Gabrielle; Pagès, Sylvie; Condemine, Guy; Rahbé, Yvan

2006-03-01

Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

The Effects of Bean Leafroll Virus on Life History Traits and Host Selection Behavior of Specialized Pea Aphid (Acyrthosiphon pisum, Hemiptera: Aphididae) Genotypes.

PubMed

Davis, T S; Wu, Y; Eigenbrode, S D

2017-02-01

Intraspecific specialization by insect herbivores on different host plant species contributes to the formation of genetically distinct "host races," but the effects of plant virus infection on interactions between specialized herbivores and their host plants have barely been investigated. Using three genetically and phenotypically divergent pea aphid clones (Acyrthosiphon pisum L.) adapted to either pea (Pisum sativum L.) or alfalfa (Medicago sativa L.), we tested how infection of these hosts by an insect-borne phytovirus (Bean leafroll virus; BLRV) affects aphid performance and preference. Four important findings emerged: 1) mean aphid survival rate and intrinsic rate of population growth (Rm) were increased by 15% and 14%, respectively, for aphids feeding on plants infected with BLRV; 2) 34% of variance in survival rate was attributable to clone × host plant interactions; 3) a three-way aphid clone × host plant species × virus treatment significantly affected intrinsic rates of population growth; and 4) each clone exhibited a preference for either pea or alfalfa when choosing between noninfected host plants, but for two of the three clones tested these preferences were modestly reduced when selecting among virus-infected host plants. Our studies show that colonizing BLRV-infected hosts increased A. pisum survival and rates of population growth, confirming that the virus benefits A. pisum. BLRV transmission affected aphid discrimination of host plant species in a genotype-specific fashion, and we detected three unique "virus-association phenotypes," with potential consequences for patterns of host plant use by aphid populations and crop virus epidemiology. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Plant domestication slows pest evolution.

PubMed

Turcotte, Martin M; Lochab, Amaneet K; Turley, Nash E; Johnson, Marc T J

2015-09-01

Agricultural practices such as breeding resistant varieties and pesticide use can cause rapid evolution of pest species, but it remains unknown how plant domestication itself impacts pest contemporary evolution. Using experimental evolution on a comparative phylogenetic scale, we compared the evolutionary dynamics of a globally important economic pest - the green peach aphid (Myzus persicae) - growing on 34 plant taxa, represented by 17 crop species and their wild relatives. Domestication slowed aphid evolution by 13.5%, maintained 10.4% greater aphid genotypic diversity and 5.6% higher genotypic richness. The direction of evolution (i.e. which genotypes increased in frequency) differed among independent domestication events but was correlated with specific plant traits. Individual-based simulation models suggested that domestication affects aphid evolution directly by reducing the strength of selection and indirectly by increasing aphid density and thus weakening genetic drift. Our results suggest that phenotypic changes during domestication can alter pest evolutionary dynamics. © 2015 John Wiley & Sons Ltd/CNRS.