Showing papers on "Aphididae published in 2017"

Evidence for Soybean Aphid (Hemiptera: Aphididae) Resistance to Pyrethroid Insecticides in the Upper Midwestern United States.

Abstract: Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a damaging invasive pest of soybean in the upper Midwest. Threshold-based insecticide applications are the primary control method for soybean aphid, but few insecticide groups are available (i.e., pyrethroids, organophosphates, and neonicotinoids). To quantify current levels of soybean aphid susceptibility to pyrethroids in the upper Midwest and monitor for insecticide resistance, leaf-dip bioassays were performed with λ-cyhalothrin in 2013-2015, and glass-vial bioassays were performed with λ-cyhalothrin and bifenthrin in 2015 and 2016. Soybean aphids were collected from 27 population-years in Minnesota and northern Iowa, and were compared with a susceptible laboratory colony with no known insecticide exposure since discovery of soybean aphid in North America in 2000. Field-collected aphids from some locations in leaf-dip and glass-vial bioassays had significantly lower rates of insecticide-induced mortality compared with the laboratory population, although field population susceptibility varied by year. In response to sublethal concentrations of λ-cyhalothrin, adult aphids from some locations required higher concentrations of insecticide to reduce nymph production compared with the laboratory population. The most resistant field population demonstrated 39-fold decreased mortality compared with the laboratory population. The resistance documented in this study, although relatively low for most field populations, indicates that there has been repeated selection pressure for pyrethroid resistance in some soybean aphid populations. Integrated pest management and insecticide resistance management should be practiced to slow further development of soybean aphid resistance to pyrethroids.

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

Abstract: 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.

Microsatellite Markers Reveal a Predominant Sugarcane Aphid (Homoptera: Aphididae) Clone is Found on Sorghum in Seven States and One Territory of the USA

Abstract: The sugarcane aphid (Melanaphis sacchari) has become a serious pest causing severe economic losses to sorghum [Sorghum bicolor (L.) Moench] grown in the southern United States. Since its original detection in four states in 2013, M. sacchari on sorghum has now, in 2016, spread to 19 states. The presence of one or multiple genotypes on sorghum in the United States has not yet been established. In this study, genome sequencing of M. sacchari was used to develop microsatellite markers. A total of 8,665,267 reads and 1.44 Gb of nucleotide sequences were generated, and 79.6% of the reads were from M. sacchari. Melanaphis sacchari DNA from 46 samples from 17 locations across seven states and one US territory was polymerase chain reaction (PCR) amplified using 38 newly created microsatellite markers, as well as 14 published microsatellite markers. Genotyping with the 52 microsatellite markers indicated that the samples of M. sacchari on sorghum were all one genotype, with the exception of a single sample collected from Sinton, TX, which had the predominant genotype as well as another genotype. Genotyping of the aphid samples with 12 microsatellite markers for Buchnera aphidicola, the obligate aphid symbiont, had nearly identical results. The invasive M. sacchari on sorghum appears to be spreading in the United States on sorghum as primarily one asexual clone. K. Harris-Shultz, X. Ni, and H. Wang, USDA-ARS, Crop Genetics and Breeding Research Unit, 115 Coastal Way, Tifton, GA 31793; P.A. Wadl, USDA-ARS, US Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414; X. Wang, USDA-ARS, Southern Plains Agricultural Research Center, 2881 F&B Rd., College Station, TX 77845; F. Huang, Louisiana State Univ. AgCenter, 404 Life Science Building, Baton Rouge, LA 70803; K. Flanders, Auburn Univ., 201 Extension Hall, Auburn Univ., AL 36849; N. Seiter, Univ. of Arkansas System Division of Agriculture, Southeast Research and Extension Center, PO Box 3508, Monticello, AR 71656; D. Kerns, Louisiana State Univ., Macon Ridge Research Station, 212A Macon Ridge Rd., Winnsboro, LA 71295; R. Meagher, USDA-ARS, Insect Behavior and Biocontrol Research Unit, 1600-1700 SW 23rd Dr., Gainesville, FL 32608; Q. Xue, Texas A&M AgriLife Research, 6500 Amarillo Blvd W., Amarillo, TX 79106; D. Reisig, North Carolina State Univ., The Vernon James Research & Extension Center, 207 Research Station Rd., Plymouth, NC 27962; D. Buntin, Univ. of Georgia Griffin Campus, 1109 Experiment St., Griffin, GA 30223; H.E. Cuevas, USDA-ARS, Tropical Agriculture and Research Station, 2200 P.A. Campos Ave Suite 201, Mayaguez, PR 00680; M.J. Brewer, Texas AgriLife Research–Corpus Christi, 10345 Hwy 44, Corpus Christi, TX 78406; X. Yang, Univ. of California Davis, 1636 E. Alisal St., Salinas, CA 93905. Received 20 Dec. 2016. Accepted 4 Apr. 2017. *Corresponding author (Karen.Harris@ars. usda.gov). Assigned to Associate Editor Tejinder Mall. Abbreviations: GC, guanine-cytosine; MLL, multilocus lineages; PCR, polymerase chain reaction; SSR, simple sequence repeat; UPGMA, unweighted pair group method with arithmetic mean. Published in Crop Sci. 57:2064–2072 (2017). doi: 10.2135/cropsci2016.12.1010 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Published May 18, 2017

Identification of Conditions for Successful Aphid Control by Ladybirds in Greenhouses.

Abstract: 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.

The Cuticle Protein Gene MPCP4 of Myzus persicae (Homoptera: Aphididae) Plays a Critical Role in Cucumber Mosaic Virus Acquisition.

Abstract: Myzus persicae (Sulzer) (Homoptera: Aphididae) is one of the most important agricultural pests worldwide In addition to sucking phloem sap, M persicae also transmits Cucumber mosaic virus (CMV) as a vector in a nonpersistent manner At present, the infection mechanism remains unclear, especially the process of aphid virus acquisition In this study, we isolated four M persicae cuticle protein genes (MPCP1, MPCP2, MPCP4, and MPCP5) from M persicae The relative amount of the gene encoding Cucumber mosaic virus capsid protein (CMV CP) and the transcript levels of these four cuticle protein genes were investigated in aphid virus acquisition by feeding the tobacco preinfested by CMV The relative expression of MPCP1, MPCP2, and MPCP4 were significantly higher than MPCP5 at 24 h after aphids feeding on virus-infested tobacco Yeast two-hybrid assays demonstrated that the protein encoded by MPCP4 gene was closely associated with the CMV CP through the direct interaction Moreover, the ability of M persicae to acquire CMV was suppressed by RNA interference of MPCP4 All these lines of evidence indicate that MPCP4, as a viral putative receptor in the stylet of aphid, plays an important role in aphid acquisition of CMV

Selection of fungal isolates for virulence against three aphid pest species of crucifers and okra

Abstract: Aphids are regarded as important pest problems of vegetable crops worldwide. Most vegetable growers in sub-Saharan Africa heavily rely on synthetic chemical insecticides for aphids’ control. Fungus-based biopesticides are being considered as alternatives to chemical insecticides. This study evaluates virulence of five isolates of Metarhizium anisopliae and three of Beauveria bassiana against Brevicoryne brassicae, Lipaphis pseudobrassicae, and Aphis gossypii, and their thermotolerance and conidial yield as a prerequisite for strain selection. The study also evaluates performance of the best isolate in screenhouse experiment against target aphid species. Three isolates of M. anisopliae ICIPE30, ICIPE62, and ICIPE69 outperformed the others, causing mortality of 85–98 %, 83–97 %, and 73–77 %, in B. brassicae, L. pseudobrassicae, and A. gossypii, respectively, 7 days post-inoculation. Isolate ICIPE62 had the shortest LT50 values of 3.4, 2.5, and 2.6 days at 1 × 108 conidia ml−1, and the lowest LC50 values of 7.3 × 105, 9.3 × 104, and 3.0 × 104 conidia ml−1 on day 7 against A. gossypii, B. brassicae, and L. pseudobrassicae, respectively. Furthermore, ICIPE62 produced more conidia on the surface of aphid cadavers than ICIPE30 and ICIPE69 and showed wider thermotolerance with optimum ranges between 25 and 30 °C. Application of conidia of ICIPE62 formulated in aqueous and emulsifiable formulations negatively affected aphid population growth rate on kale and okra plants compared to controls in screenhouse experiments. These results have demonstrated the potential of M. anisopliae isolate ICIPE62 in suppression of A. gossypii, B. brassicae, and L. pseudobrassicae populations and could therefore be considered as biopesticide candidate for the control of these target aphids.

Symbiont Diversity of Aphis ( Toxoptera ) citricidus (Hemiptera: Aphididae) as Influenced by Host Plants

Abstract: Aphids are well known for their association with endosymbiont bacteria. Almost all aphids harbor Buchnera aphidicola as an obligate symbiont and several other bacteria as facultative symbionts. Associations of facultative symbionts and aphids are quite variable in terms of diversity and prevalence across aphid species. Facultative symbionts can have a major impact on aphid bioecological traits. A number of factors shape the outcome of the facultative symbiont-aphid association, including aphid clone, bacterial genotype, geography, and host plant association. The effects of host plant on aphid-facultative symbiont associations are the least understood. We performed deep sequencing of the bacterial community associated with field populations of the oligophagous aphid Aphis (Toxoptera) citricidus collected from different host plants. We demonstrate that (i) A. citricidus has low symbiont diversity, (ii) symbiont diversity is affected by host plant, and (iii) host plants affect the relative abundance of the obligate symbiont Buchnera and an unknown genus of Enterobacteriaceae.

Genetic population structure of sugarcane aphid, Melanaphis sacchari, in sorghum, sugarcane, and Johnsongrass in the continental USA

Abstract: In 2013, an outbreak of Melanaphis sacchari Zehntner (Hemiptera: Aphididae) was reported in sorghum in Texas, USA. Although this aphid has been reported in the continental USA for nearly a century, its occurrence was limited to Florida and Louisiana sugarcane. After 2013 and within just 3 years M. sacchari was reported in almost all sorghum growing regions from south central to southeastern states in the USA. Sorghum fields in affected areas have sustained considerable losses. This aphid has also been reported on Johnsongrass and other feral grasses. The speed at which this aphid has spread raises serious concerns about future infestations. Many aphid species present genetically distinct populations when feeding on different host plants. Thus, it was hypothesized that the recent outbreak in sorghum could be explained by a recent introduction of a sorghum‐specialized genotype. In this study, we genetically characterized M. sacchari in three of its most common host plants – sorghum, sugarcane, and Johnsongrass – across its geographic distribution in the continental USA. Although M. sacchari specimens were grouped within three genetically distinct clusters, we did not find evidence of host plant or geographic population structure. Our characterization of the genetic structure of this pest provides baseline data aimed to help explain its recent outbreak in sorghum, as well as information that may aid in the design of sustainable control strategies.

Searching for wheat resistance to aphids and wheat bulb fly in the historical Watkins and Gediflux wheat collections

Abstract: Insect pests can reduce wheat yield by direct feeding and transmission of plant viruses. Here we report results from laboratory and field phenotyping studies on a wide range of wheat, including landraces from the Watkins collection deriving from before the green revolution, more modern cultivars from the Gediflux collection (north-western Europe) and modern UK Elite varieties, for resistance to the bird cherry-oat aphid, Rhopalosiphum padi (Homoptera: Aphididae) and the English grain aphid, Sitobion avenae (Homoptera: Aphididae). A total of 338 lines were screened for R. padi and 340 lines for S. avenae. Field trials were also conducted on 122 Watkins lines to identify wheat bulb fly, Delia coarctata, preference on these landraces. Considerable variation was shown in insect performance among and within different wheat collections, with reduced susceptibility in a number of varieties, but phenotyping did not identify strong resistance to aphids or wheat bulb fly. Field trials showed within collection differences in aphid performance, with fewer aphids populating lines from the Watkins collection. This differs from development data in laboratory bioassays and suggests that there is a pre-alighting cue deterring aphid settlement and demonstrates differences in aphid preference and performance on older plants in the field compared with seedlings in the laboratory, highlighting the need for phenotyping for aphid resistance at different plant growth stages. No association was identified between performance of the different insect species on individual varieties, potentially suggesting different nutritional requirements or resistance mechanisms.

Toxicity of three aphicides to the generalist predators Chrysoperla carnea (Neuroptera: Chrysopidae) and Orius insidiosus (Hemiptera: Anthocoridae).

Abstract: Recent widespread infestations of the invasive sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), in sorghum fields in the southern USA have created demand for insecticides that will provide effective control of sugarcane aphid, while conserving those beneficial species that contribute to biological control of the pest. We tested the susceptibility of both adult and immature stages of two aphid predators, the green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), to three aphicides, flonicamid, sulfoxaflor and flupyradifurone. Flonicamid was innocuous to both species regardless of life stage or route of exposure. Lacewing adults were more susceptible to sulfoxaflor and flupyradifurone than were larvae, and had higher mortality when fed contaminated honey solution than when contacting residues on an inert surface. When laid in sunflower stems treated with these two materials, eggs of O. insidiosus hatched successfully, but nymphs experienced significant mortality when exposed to treated stems, likely due to phytophagous behavior that resulted in some insecticide ingestion. Despite these impacts, we conclude that both sulfoxaflor and flupyradifurone are likely to be relatively innocuous in comparison to more broad-spectrum insecticides and are thus potentially compatible with biological control and overall management of M. sacchari in grain sorghum.

Complete mitochondrial genome of the aphid Hormaphis betulae (Mordvilko) (Hemiptera: Aphididae: Hormaphidinae).

Abstract: The complete mitochondrial genome of Hormaphis betulae has been sequenced and annotated, which is the first representation from the aphid subfamily Hormaphidinae. This mitogenome is 15 088 bp long with an A + T content of 82.2%, containing 37 genes arranged in the same order as the putative ancestral arrangement of insects and a control region. All protein-coding genes start with an ATN codon and terminate with a TAA codon or a single T residue. All the 22 tRNAs, ranging from 61 to 78 bp, have the typical clover-leaf structure except for trnS (AGN). The lengths of rrnL and rrnS genes are 1275 and 776 bp, respectively. The control region is 509 bp long and located between rrnS and trnI, including three domains: an AT-rich zone, a poly-thymidine stretch, and a stem-loop region. The phylogenetic tree supports H. betulae as the basal lineage within Aphididae.

Food plant records of Aphidini (Aphidinae: Aphididae: Hemiptera) in India

Abstract: The Aphidini is one of the 2 tribes of the subfamily Aphidinae (Aphididae: Hemiptera) containing about 830 species/subspecies assigned to 33 genera. Out of these, only 9 genera and 70 species/subspecies were recorded from India infesting 940 plant species belonging to 138 families, out of which only 19 families are monocot. Indian Aphidini are recorded mostly on the plant family Asteraceae (102 plant species), followed by Fabaceae (96 plant species), Poaceae (92 plant species), Lamiaceae (46 plant species), Rosaceae (38 plant species), Solanaceae (34 plant species), Apocyanaceae (28 plant species), Rubiaceae (26 plant species), Malvaceae (25 plant species), Rutaceae (22 plant species), Cucurbitaceae (22 plant species), Polygonaceae (21 plant species), etc. Out of 70 described species of Aphidini from India, 14 species are monophagous; 40 species are oligophagous infesting 2 to 20 plant species; and 8 species are moderately polyphagous infesting 21 to 55 plant species while 8 species are highly polyphagous feeding on 55 upto 569 plant species. The present contribution provides updated checklist of Indian Aphidini with the valid scientific name of the aphids as well as their food plants.

Brassica aphid (Hemiptera: Aphididae) populations are conditioned by climatic variables and parasitism level: a study case of Triângulo Mineiro, Brazil.

Abstract: Cosmopolitan pests such as Brevicoryne brassicae, Lipaphis pseudobrassicae, and Myzus persicae (Aphididae) cause significant damage to Brassicaceae crops. Assessment of the important biotic and abiotic factors that regulate these pests is an essential step in the development of effective Integrated Pest Management programs for these aphids. This study evaluated the influence of leaf position, precipitation, temperature, and parasitism on populations of L. pseudobrassicae, M. persicae, and B. brassicae in collard greens fields in the Triângulo Mineiro region (Minas Gerais state), Brazil. Similar numbers of B. brassicae were found on all parts of the collard green plants, whereas M. persicae and L. pseudobrassicae were found in greatest numbers on the middle and lower parts of the plant. While temperature and precipitation were positively related to aphid population size, their effects were not accumulative, as indicated by a negative interaction term. Although Diaeretiella rapae was the main parasitoid of these aphids, hyperparasitism was dominant; the main hyperparasitoid species recovered from plant samples was Alloxysta fuscicornis. Parasitoids seem to have similar distributions on plants as their hosts. These results may help predict aphid outbreaks and gives clues for specific intra-plant locations when searching for and monitoring aphid populations.

Updated Checklist of Food Plants of Macrosiphini (Aphididae: Hemiptera) in India-1

Abstract: The Macrosiphini is one of the 2 tribes of the subfamily Aphidinae (Aphididae: Hemiptera) containing about 2166 species/subspecies assigned to 242 genera. Out of these, only 96 genera and 374 species are recorded from India infesting hundreds of plant species belonging to several families. The food plants of Indian Macrosiphini is catalogued alphabetically (aphid species-wise) in three parts. In this contribution, food plants of only 25 genera and 109 species of aphids belonging to the tribe Macrosiphini (Acutosiphon to Dysaphis) are catalogued. These aphids feeds on 400 plant species belonging to 79 families. Most suffered families are Asteraceae (81 species) followed by Rosaceae (35 species), Fabaceae (27 species), Brassicaceae (22 species), Lamiaceae (18 species) and Solanaceae (17 species). Among them, several species are crops of agricultural and horticultural importance. The update checklist of food plants of rest of Macrosiphini will be dealt in successive articles.

Plant-mediated species networks : The modulating role of herbivore density

Abstract: 1. When herbivores of distinct feeding guilds, such as phloem feeders and leaf chewers, interact, the outcome of these interactions often shows facilitation. However, whether this facilitation turns into competition at stronger herbivory pressure remains unknown. 2. Using an integrative approach that links ecological processes (behavioural choices of insects) with physiological plant mechanisms (nutrient and phytohormone levels) for the wild crucifer Brassica nigra (L.) Koch., this study evaluates preferences of leaf chewers for plants previously infested with several densities of the specialist aphid Brevicoryne brassicae L. (Hemiptera, Aphididae). As leaf chewers, four species of caterpillars (Lepidoptera) were selected that differ in their degree of specialisation in crucifers. 3. These results show that, whereas at low and medium aphid densities caterpillars displayed a preference for aphid-infested plants or no preference, at high aphid infestation density, all four species of caterpillar preferred uninfested plants, with a significant difference for Pieris rapae and Mamestra brassicae. 4. In contrast to our expectation, the consistent preference for uninfested plants at a high aphid density could not be associated with a decrease in plant nutrition. However, while jasmonate concentrations [i.e. 12-oxo-phytodienoic acid and jasmonic acid (JA)] at medium aphid-density infestation decreased compared with low levels of infestation, at high infestation level, the jasmonates JA as well as JA conjugated with the amino acid isoleucine were present at higher levels compared with low-infestation treatments. 5. This work provides evidence that positive interactions observed in herbivore communities can be transient, leading to negative interactions mediated by changes in plant defences rather than in plant nutrition.

Intraguild predation on the aphid parasitoid Aphelinus asychis by the ladybird Harmonia axyridis

Abstract: We investigated intraguild predation (IGP) on an aphid parasitoid, Aphelinus asychis Walker (Hymenoptera: Aphelinidae), by the multicolored Asian ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), and used the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) as the prey/host in the laboratory. The ladybirds reared on artificial diet and on aphids consumed more aphids than mummies, while those reared on parasitized aphids consumed similar numbers of aphids and mummies. The ladybirds chose more mummies in treatments when mummies were more abundant, and more aphids when numbers of aphids and mummies were equal, or when aphids were more abundant. However, at all density treatments, rejection rates of mummies (36%) were much greater than of aphids (2%). H. axyridis prey on more aphids than A. asychis mummies, which enhances biological control by the two species. However, prior feeding experience affected subsequent choice, increasing the competition between natural enemies which would reduce their combined effectiveness for biological control.

The Effects of Bean Leafroll Virus on Life History Traits and Host Selection Behavior of Specialized Pea Aphid (Acyrthosiphon pisum, Hemiptera: Aphididae) Genotypes.

Abstract: 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.

Susceptibility of Macrosiphum euphorbiae to the parasitoid Aphidius ervi: larval development depends on host aphid genotype

Abstract: The potato aphid, Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae: Macrosiphini), is a common polyphagous aphid in Europe and North America. However, the factors influencing potato aphid dynamics and susceptibility to natural enemies are largely undescribed, particularly in relation to facultative endosymbiotic bacteria, which can provide protection against parasitism and disease in some aphid species. This study investigated whether potato aphid susceptibility to one of its principal natural enemies, the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), varied in relation to aphid genotype and/or endosymbiont presence. Parasitism and aphid fitness assays were conducted on clonal lineages of aphids, harbouring their natural endosymbiont infections, collected over 3 years from separate geographic locations. Parasitized aphids were dissected to quantify parasitoid oviposition, larval development, and mummification. Amongst the 19 clonal lines of M. euphorbiae tested, seven aphid genotypes were identified, and 11 lines harboured one or both of the facultative endosymbionts Hamiltonella defensa Moran et al. and Regiella insecticola Moran et al.; H. defensa infections were associated exclusively with two of the seven M. euphorbiae genotypes. Parasitism resistance was detected in clonal lines belonging to a single aphid genotype and resulted from failure of parasitoid eggs to develop into larvae rather than failure of the parasitoid to oviposit. Contrary with studies of several other aphid species, there was little evidence that H. defensa provided strong protection to M. euphorbiae from parasitism by A. ervi. Furthermore, there were no clear fitness costs to the aphid associated with parasitism resistance or with H. defensa infection. The two M. euphorbiae genotypes in which H. defensa occurred, which included the resistant genotype, exhibited faster development, higher survival, and greater fecundity than the other five aphid genotypes. These findings suggest that biological control of M. euphorbiae using A. ervi alone could exacerbate pest problems by selecting for the fittest parasitism‐resistant genotypes.

Updated check-list of Indian Eriosomatinae (Aphidinae: Aphididae: Hemiptera) and their food plants

Abstract: The articles provides updated checklist of Indian aphids (Aphididae: Hemiptera) belonging to the subfamily Eriosomatinae and their food plants Out of 470 valid species of world Eriosomatinae assigned to 53 genera, in India only 64 species assigned to 19 genera were recorded so far, out of which 22 species are endemic Some of them are pestiferous These aphids feed on 130 valid plant species belonging to 30 plant families Tetraneura (Tetraneurella) nigriabdominalis was observed highly polyphagous infesting 64 plant species followed by Geoica lucifuga (22 plant species), Tetraneura (Tetraneura) radicicola (17 plant species), Tetraneura (Indotetraneura) basui (13 plant species), and Forda orientalis (12 plant species) The most preferred plants for these aphids belong to family Poaceae (76 plant species), followed by family Rosaceae (17 species), Saliaceae (9 species), Anacardiaceae (6 species) and Asteraceae (6 species) The host plant of Ceratopemphigella delhiensis is still not known as it was only light trapped

Genome of Russian wheat aphid an economically important cereal aphid

Abstract: Although the hemipterans ( Aphididae ) are comprised of roughly 50,000 extant insect species, only four have sequenced genomes that are publically available, namely (pea aphid), (Kissing bug), (Green peach aphid) and (Russian wheat aphid). As a significant proportion of agricultural pests are phloem feeding aphids, it is crucial for sustained global food security that a greater understanding of the genomic and molecular functioning of this family be elucidated. Recently, the genome of US D. noxia biotype US2 was sequenced but its assembly only incorporated ~ 32% of produced reads and contained a surprisingly low gene count when compared to that of the model/first sequenced aphid, . To this end, we present here the genomes of two South African (Kurdjumov, Hemiptera : Aphididae ) biotypes (SA1 and SAM), obtained after sequencing the genomes of the only two D. noxia biotypes with documented linked genealogy. To better understand overall targets and patterns of heterozygosity, we also sequenced a pooled sample of 9 geographically separated D. noxia populations (MixIX). We assembled a 399 Mb reference genome ( PRJNA297165 , representing 64% of the projected genome size 623 Mb) using ± 28 Gb of 101 bp paired-end HiSeq2000 reads from the D. noxia biotype SAM, whilst ± 13 Gb 101 bp paired-end HiSeq2000 reads from the D. noxia biotype SA1 were generated to facilitate genomic comparisons between the two biotypes. Sequencing the MixIX sample yielded ±26 Gb 50 bp paired-end SOLiD reads which facilitated SNP detection when compared to the D. noxia biotype SAM assembly. Ab initio gene calling produced a total of 31,885 protein coding genes from the assembled contigs spanning ~ 399 Mb (GCA_001465515.1).

Updated checklist of host plants of calaphidinae (aphididae : hemiptera) in india

Abstract: Background: The aphids (Aphididae: Hemiptera) are plant sap sucking insects and are major pests of crops, vegetables and fruit trees. Earlier food plant catalogue of Indian aphids dates back almost four decades. The researches on aphid taxonomy as well as their host plants is continued with the description of new taxa, the modified status of others, and the publication of other nomenclatural decisions. The family Aphididae consists of 24 subfamilies and their (subfamilywise) food plant catalogue is being initiated by us. It is the 6th in series of cataloguing the aphids belonging to subfamily Calaphidinae. The work will help to solve some needs pertaining to studies on Indian aphids, such as synonymic handling and their food plant checklist, as well as the lack of a complete and up-todate listing of the species.Materials & Methods: In preparing of this checklist, recent world literatures (published up to January, 2017) were scrutinized for synonymy of the species of aphids as well as their host plants along with the information available at websites: http://Aphid.SpeciesFile.org (version 5.0/5.0) for aphids, and http://www.ars-grin.gov and http://www.theplantlist.org (version 1.1) for plants accessed on January, 2017.   Results: The aphids are a group of over 5000 species of plant sap sucking insects distributed throughout the world, from the rainforest to the desert ground. Currently, the family Aphididae comprises 24 subfamilies, out of which the food plant catalogue of Indian  aphids belonging to subfamily Calaphidinae is provided in this compilation.Calaphidinae consists of 2 tribes: Calaphini and Panaphidini and each tribe consists of 2 subtribes: Calaphidina and Monophidina (Calaphidini), and Myzocallidina and Panaphidina (Panaphidini). In India, Calaphidina is represented by 5 genera and 14 species, while no species of Monaphidina was reported so far. Myzocallidina is represented by only 4 genera and 9 species, while Panaphidina is more diversed containing 16 genera and 25 species. All these 48 species feed on 62 plant species belonging mainly to Betulaceae, Fagaceae, Rosaceae, Juglandaceae, Fabaceae, Poaceae, and Ulmaceae.Conclusion: All members of Calaphidinae are monoecious, oligophagous and mostly associated with trees of Betulaceae (17 aphid species), Fagaceae (13 aphid species), Ulmaceae (2 aphid species), Anacardiaceae (4 aphid species), and Juglandaceae (6 aphid species) and herbaceous plants like Fabaceae (6 aphid species), Poaceae (8 aphid species) and Rosaceae (11 aphid species). Monoecious habit is considered a primitive character in this group and host plant alternation has apparently never or less evolved. The group is distributed mostly from east to west Himalayas. Keywords: Aphids, Callaphidinae, Panaphidini, Myzocallidina, food plant catalogue, checklist.Â

Genetic Structure of the Aphis craccivora (Hemiptera: Aphididae) From Thailand Inferred From Mitochondrial COI Gene Sequence.

Abstract: The cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is one of the most destructive insect pests of legume plants worldwide. Although outbreaks of this pest occur annually in Thailand causing heavy damage, its genetic structure and demographic history are poorly understood. In order to determine genetic structure and genetic relationship of the geographic populations of this species, we examined sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene of 51 individuals collected from 32 localities throughout Thailand. Within the sequences of these geographic populations, 32 polymorphic sites defined 17 haplotypes, ranging in sequence divergence from 0.2% (1 nucleotide) to 2.7% (16 nucleotides). A relatively high haplotype diversity but low nucleotide diversity was detected in the populations of A. craccivora, a finding that is typical for migratory species. Phylogenetic analysis revealed a weak phylogeographic structuring among the geographic populations and among the haplotypes, indicating their close relationship. Considering the distance between the sampling sites, the occurrence of identical haplotypes over wide areas is noteworthy. Moreover, the low genetic distance (FST ranging from -0.0460 to 0.3263) and high rate of per-generation female migration (Nm ranging from 1.0323 to 20.3333) suggested population exchange and gene flow between the A. craccivora populations in Thailand.

Economic Injury Levels for Aphis glycines Matsumura (Hemiptera: Aphididae) on the Soybean Aphid Tolerant KS4202 Soybean.

Abstract: The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an invasive species from Asia that has been the major economic insect pest of soybeans, Glycine max (L.) Merrill, since 2000. While use of soybeans expressing antibiosis and antixenosis is a well-studied strategy to manage this pest, aphid-tolerant soybeans remain underexplored. This study examined the relationship between cumulative aphid-days (CAD) and yield loss in the tolerant soybean KS4202 during two growing seasons to determine the economic injury levels (EILs) for soybean aphids on KS4202. Soybean aphid infestations were initiated during the soybean reproductive stages. A range of CAD treatments (3,000-45,000 CADs) were applied during the growing seasons. Aphid populations reached 45,000 CAD in 2011 and 38,000 CAD in 2013 in plots that were not treated with insecticides. It was estimated that the population doubling time was 9.4 d. In infested plots, soybean yield was reduced by 1.4-13.3%, equivalent to a 3.1% yield loss for every 10,000 CAD. Overall, most CAD treatments did not affect yield parameters, although CAD > 39,000 caused a significant reduction in most yield parameters. The EILs calculated for KS4202 ranged from 526 to 2,050 aphids/plant, which were approximately 2.5-fold higher when compared to EILs previously calculated for susceptible soybean. The adoption of soybean aphid tolerant soybean with higher EILs may help mitigate treatment delay problems by lengthening the treatment lead-time and possibly reduce the number of insecticide applications.

Species composition and richness of aphid parasitoid wasps in cotton fields in northern China.

Abstract: The cotton aphid, Aphis gossypii (Hemiptera: Aphididae), is a serious pest of cotton across the globe, particularly in the cotton agroecosystems of northern China. Parasitic wasps are deemed to be important natural enemies of A. gossypii, but limited information exists about their species composition, richness and seasonal dynamics in northern China. In this study, we combine sampling over a broad geographical area with intensive field trials over the course of three cropping seasons to describe parasitoid-hyperparasitoid communities in cotton crops. We delineate a speciose complex of primary parasitoids and hyperparasitoids associated with A. gossypii. Over 90% of the primary parasitoids were Binodoxys communis. Syrphophagus sp. and Pachyneuron aphidis made up most of the hyperparasitoids. Parasitism rates changed in a similar way following the fluctuation of the aphid population. Early in the growing period, there were more hyperparasitoids, while later, the primary parasitoids provided control of A. gossypii. The first systematic report of this cotton aphid parasitoid complex and their population dynamics in association with their hosts presented a comprehensive assessment of cotton parasitoid species and provided important information for the establishment and promotion of their biological control of cotton aphids.

Laboratory Bioassays to Determine Susceptibility of Woolly Apple Aphid, Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae), to Entomopathogenic Nematodes

Abstract: Woolly apple aphid (WAA), Eriosoma lanigerum, is an important pest of apples, occurring throughout the apple-growing regions of the world. Entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae have generated intensive interest as inundative biocontrol agents of pest insects. Considering resistance of WAA against certain insecticides and the inability of parasitoids to control the aphid successfully early in the season, EPNs offer an alternative biocontrol option. The susceptibility of WAA to seven indigenous EPN species was tested in laboratory bioassays in which Steinernema yirgalemense and Heterorhabditis zealandica were identified as being the most effective against the subterranean adult females of the WAA, with infection rates of 39%and 28 %, respectively. The effect of E. lanigerum size showed that the last instar is most susceptible to infection, whereas none of the crawlers were infected. Increasing the exposure time of the aphids and nematode concentration had no positive effect on the WAA infection rate. On evaluating the ability of infective juveniles of S. yirgalemense and H. zealandica to tolerate exposure to imidacloprid, both nematode species were found to be compatible at the recommended dosage, with no significant nematode mortality having occurred. Neither did imidacloprid affect the ability of the nematodes to infect their hosts after 24 h exposure. The associated bacteria, isolated from 12 EPN isolates, showed a visual inhibitory growth effect, when they were exposed to the haemolymph of WAA. From these results, it is concluded that, although S. yirgalemense showed some infection of WAA, its low mortality and inability to complete its life cycle within the host, limits its effectiveness as a biological control agent against the subterranean stages of WAA in apple orchards.

Identification and virulence characterization of entomopathogenic fungus Lecanicillium attenuatum against the pea aphid Acyrthosiphon pisum (Hemiptera: Aphididae)

Abstract: An entomopathogenic fungal strain was originally isolated on artificial medium from the corpse of a pea aphid (Acyrthosiphon pisum Harris) collected at Jingzhou, China (N30°21′18.15″, E112°08′41.63″). Based on tests of the morphological, physiological and biochemical characteristics and analysis of internal transcribed spacer (ITS) sequences, it was considered to be a strain of Lecanicillium attenuatum Zare & W. Gams. Therefore, the strain was designated L. attenuatum YZU 151121. The activity of the biological agents under study was determined at 26 °C and 90% relative humidity. The number of A. pisum killed was increased by increasing the concentration of L. attenuatum. The results demonstrated that L. attenuatum YZU 151121 showed a high efficacy against 3rd-instar nymphs (LC50 = 2.91 ± 0.365 × 105 conidia/ml) and adults (LC50 = 3.12 ± 0.398 × 106 conidia/ml) after 6 days of exposure. Crude extract from this strain was tested for contact toxicity and showed high activity in 3rd-instar nymphs and adults, with LC50 values of 251.34 ± 49.54 and 315.46 ± 87.66 mg/l, respectively. In addition, crude extract at a concentration of 200 mg/l could significantly reduce fecundity in adults. These results revealed that the strain YZU 151121 may be useful in biopesticides for controlling pea aphid.