Showing papers on "Aphididae published in 2015"
TL;DR: Overall, 9 of 20 parental sorghum entries tested for phenotypic damage in the field resulted in good resistance to the sugarcane aphid and should be utilized in breeding programs that develop agronomically acceptable sorghums for the southern regions of the United States.
Abstract: The graminous host range and sources of sorghum [Sorghum bicolor (L.) Moench.] plant resistance, including cross-resistance from greenbug, Schizaphis graminum (Rondani), were studied for the newly emerging sugarcane aphid, Melanaphis sacchari (Zehntner), in greenhouse no-choice experiments and field evaluations. The sugarcane aphid could not survive on field corn, Zea mays (L.), Teff grass, Eragrostis tef (Zucc.), proso millet, Panicum miliaceum L., barley, Hordeum vulgare L., and rye, Secale cereale L. Only sorghum genotypes served as hosts including Johnsongrass, Sorghum halepense (L.), a highly suitable noncrop host that generates high numbers of sugarcane aphid and maintains moderate phenotypic injury. The greenbug-resistant parental line RTx2783 that is resistant to greenbug biotypes C and E was resistant to sugarcane aphid in both greenhouse and field tests, while PI 55607 greenbug resistant to biotypes B, C, and E was highly susceptible. PI 55610 that is greenbug resistant to biotypes B, C, and E maintained moderate resistance to the sugarcane aphid, while greenbug-resistant PI 264453 was highly susceptible to sugarcane aphid. Two lines and two hybrids from the Texas A&M breeding program B11070, B11070, AB11055-WF1-CS1/RTx436, and AB11055-WF1-CS1/RTx437 were highly resistant to sugarcane aphid, as were parental types SC110, SC170, and South African lines Ent62/SADC, (Macia/TAM428)-LL9, (SV1*Sima/IS23250)-LG15. Tam428, a parental line that previously showed moderate resistance in South Africa and India, also showed moderate resistance in these evaluations. Overall, 9 of 20 parental sorghum entries tested for phenotypic damage in the field resulted in good resistance to the sugarcane aphid and should be utilized in breeding programs that develop agronomically acceptable sorghums for the southern regions of the United States.
106 citations
56 citations
TL;DR: The findings suggest that the capacity of indigenous aphidophagous guilds to respond to, and ultimately control, invasive aphid species may be underestimated.
54 citations
TL;DR: A DNA-based approach is developed to untangle the structure of the aphid-parasitoid food web in citrus, where Aphis spiraecola Patch is a key pest and Binodoxys angelicae Haliday, its dominant primary parasitoid, is attacked by a complex of hyper parasitoids.
51 citations
TL;DR: All the predators studied are preadapted to utilize sugarcane aphid as prey and have excellent potential to provide sustainable biological control of this newly invasive pest.
Abstract: The performance of four aphid predators, Hippodamia convergens Guerin-Meneville, Coleomegilla maculata DeGeer, Chrysoperla carnea Stephens and Orius insidiosus Say was compared on three prey species: Schizaphis graminum Rondani, Melanaphis sacchari (Zehntner), and Ephestia kuehniella Zeller eggs. Species predatory in both life stages (all except Ch. carnea) were reared on E. kuehniella eggs and switched to aphid prey for assessment of reproduction. Differences were greater between the E. kuehniella and aphid diets than between the two aphid species. Juvenile survival was high for all predators on all prey, except for O. insidiosus, which had survival on E. kuehniella > S. graminum > M. sacchari. The fastest development of Ch. carnea and O. insidiosus was obtained on E. kuehniella, whereas H. convergens developed fastest on S. graminum, and C. maculata did not differ among diets. S. graminum also yielded the largest H. convergens adults, whereas the largest adults of other predators were obtained on E. kuehniella. Female fecundity and egg viability were similarly high on both aphid diets for H. convergens and C. maculata, whereas, on E. kuehniella, 50% of the former entered reproductive diapause and the latter species had reduced fecundity. Reproductive success of Ch. carnea was S. graminum = M. sacchari > E. kuehniella, but it was similar among treatments for O. insidiosus, although female infertility ranged from 25 to 37.5%. We concluded that all the predators studied are preadapted to utilize sugarcane aphid as prey and have excellent potential to provide sustainable biological control of this newly invasive pest.
51 citations
TL;DR: Results suggest a hormesis induced by lower concentration of sulfoxaflor in M. persicae, an important insect pest of many crops around the world, may be an alternative mechanism for pest resurgence.
Abstract: The green peach aphid, Myzus persicae (Sulzer), is an important insect pest of many crops around the world. Pesticide-induced hormesis may be an alternative mechanism for pest resurgence. In this study, life table parameters were applied to the estimation of sulfoxaflor-induced hormesis of adult M. persicae following 2-d LC25 concentration exposure. Leaf-dip bioassays showed that the sulfoxaflor possessed high toxicity against M. persicae, with an LC50 of 0.059 mg/liter. The results indicated that the exposure of the parent generation of M. persicae to sublethal sulfoxaflor induced increase in reproduction and prolongation of immature development duration in the first progeny generation. Both R0 and GRR of aphids for treatment group were significantly higher than for the control in F1 generation, and the mean generation time was significantly postponed in treated group. These results suggest a hormesis induced by lower concentration of sulfoxaflor in M. persicae. It would be useful for assessing the overall effects of sulfoxaflor on M. persicae.
49 citations
TL;DR: B.bassiana significantly affected the rate of nymph production by the lettuce aphid, with the highest effect seen when the alatoid fourth instar of N. ribisnigri was inoculated with B. bassiana .
37 citations
TL;DR: The aphid responses to changes in plant volatile profiles induced by neighboring plants may facilitate refinement of habitat manipulation strategies (e.g., intercropping) for integrated pest management to reduce aphid occurrence in crops.
Abstract: Olfactory orientation by aphids is guided by specific volatile blends released from their hosts. Host plants that co-exist with other plants may be less attractive for aphids due to volatile interactions between neighboring plants which can lead to changes in their volatile emissions. These changes in host plant volatile profiles induced by interactions between undamaged plants could be used to manage aphid populations in crops. When potato plants are exposed to volatiles from onion plants, the volatile profile of potato changes in relation to that of unexposed plants with consistently greater quantities of two terpenoids released. We examined the host plant searching behavior of aphids and showed that induced changes in plant volatile emissions affect aphid behavior. We assessed olfactory responses of winged and wingless aphids, Myzus persicae Sulzer (Hemiptera: Aphididae) to the changed volatile emissions. Both morphs were significantly less attracted to odors of potato plants that had been exposed to volatiles from onion than to odors of unexposed potato plants. Further, both morphs were significantly less attracted to synthetic blends mimicking volatiles emitted by onion-exposed potato plants than to blends mimicking non-exposed controls, and to single compounds emitted in greater quantities by exposed potato. Aphid morphs were repelled differently depending on the concentration of odor sources; winged aphids responded to higher doses than did wingless aphids. The aphid responses to changes in plant volatile profiles induced by neighboring plants may facilitate refinement of habitat manipulation strategies (e.g., intercropping) for integrated pest management to reduce aphid occurrence in crops.
34 citations
TL;DR: Three morphologically different species groups "agilis", "brevipilosus" and "cembrae" were proposed due to the differences in head, antennae, legs and dorsal chaetotaxy as well as dorsal sclerotization.
33 citations
TL;DR: The aphids’ feeding behavior on the cultivar Kalya, with a low alkaloid content but reduced susceptibility, indicates that not only the total alkaloids content influences the feeding behavior but additional plant factors have an impact.
Abstract: Since the beginning of breeding narrow-leafed lupins [Lupinus angustifolius L. (Fabaceae)] with a low alkaloid content, susceptibility to several aphid species has increased. Therefore, the probing and feeding behavior of Aphis fabae Scopoli, Aphis craccivora Koch, Acyrthosiphon pisum (Harris), Myzus persicae (Sulzer), and the well-adapted Macrosiphum albifrons Essig (all Hemiptera: Aphididae) was studied over 12 h on narrow-leafed lupin genotypes containing varying amounts and compositions of alkaloids. We used the electrical penetration graph (EPG) technique to obtain information on the influence of alkaloid content and composition on the susceptibility to various aphid species. Results indicated that the total time of probing of A. fabae, A. craccivora, A. pisum, and M. persicae increased with a reduced alkaloid content, whereas the alkaloid content had no influence on M. albifrons. Almost all of the individuals (>93%) conducted sieve element phases on the highly susceptible genotype Bo083521AR (low alkaloid content). A reduced occurrence of phloem phases was observed during the 12-h recording on the alkaloid-rich cultivar Azuro, especially for A. pisum (37.5%) and A. fabae (55.0%). Furthermore, aphids feeding on genotypes with low alkaloid content had in most cases significantly longer sieve element phases than when feeding on resistant genotypes (Kalya: low alkaloid content, yet resistant; Azuro: high alkaloid content, resistant), whereas M. albifrons showed the longest phloem phase on the alkaloid-rich cultivar Azuro. As most significant differences were found in phloem-related parameters, it is likely that the most important plant factors influencing aphid probing and feeding behavior are localized in the sieve elements. The aphids’ feeding behavior on the cultivar Kalya, with a low alkaloid content but reduced susceptibility, indicates that not only the total alkaloid content influences the feeding behavior but additional plant factors have an impact.
32 citations
TL;DR: The present study provides the first documentation that remote sensing holds potential for detecting changes in plant spectral reflectance induced by soybean aphid, and may assist future IPM programs to reduce sampling costs and prevent prophylactic insecticide sprays.
Abstract: Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is the most economically important insect pest of soybean in the north central United States. Scouting-based integrated pest management (IPM) programs could become more efficient and more widely adopted by using plant spectral reflectance to estimate soybean aphid injury. Our objective was to determine whether plant spectral reflectance is affected by soybean aphid feeding. Field trials were conducted in 2013 and 2014 using caged plots. Early-, late-, and noninfested treatments were established to create a gradient of soybean aphid pressure. Whole-plant soybean aphid densities were recorded weekly. Measurements of plant spectral reflectance occurred on two sample dates per year. Simple linear regression models were used to test the effect of cumulative aphid-days (CAD) on plant spectral reflectance at 680 nm (RED) and 800 nm (NIR), normalized difference vegetation index (NDVI), and relative chlorophyll content. Data indicated that CAD had no effect on canopy-level RED reflectance, but CAD decreased canopy-level NIR reflectance and NDVI. Canopy- and leaf-level measurements typically indicated similar plant spectral response to increasing CAD. CAD generally had no effect on relative chlorophyll content. The present study provides the first documentation that remote sensing holds potential for detecting changes in plant spectral reflectance induced by soybean aphid. The use of plant spectral reflectance in soybean aphid management may assist future IPM programs to reduce sampling costs and prevent prophylactic insecticide sprays.
TL;DR: It was found that aphid virulence on Rag soybean was not dependent on Arsenophonus: virulent aphid biotypes performed well on Rag Soybean, and avirulent aphids performed poorly on rag soybean, regardless of whether Arsenophoneus was present or not.
Abstract: Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), invokes substantial chemical treatment and economic cost in North America. Resistant soybean genotypes hold promise as a low-impact control methodology, but soybean aphid "biotypes" capable of development on resistant soy cast doubt on the durability of soy resistance. We hypothesized that variation in soybean aphid ability to colonize resistant soy is partially attributable to a bacterial symbiont of soybean aphid, Arsenophonus. We used microinjection to manipulate Arsenophonus infection in both virulent and avirulent aphid biotypes, resulting in five pairs of infected versus uninfected isolines. These isolines were subjected to various population growth rate assays on resistant Rag versus susceptible soybean. We found that aphid virulence on Rag soybean was not dependent on Arsenophonus: virulent aphid biotypes performed well on Rag soybean, and avirulent aphid biotypes performed poorly on Rag soybean, regardless of whether Arsenophonus was present or not. However, we did find that Arsenophonus-infected clones on average performed significantly better than their paired uninfected isolines. This pattern was not consistently evident on every date for every clone, either in the population assays nor when we compared lifetime fecundity of individual aphids in a separate experiment. Nevertheless, this overall benefit for infected aphids may be sufficient to explain the high frequency of Arsenophonus infection in soybean aphids.
TL;DR: 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 overwintered locations.
Abstract: 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.
TL;DR: It is suggested that a refuge may prevent virulent A. glycines biotypes from overcoming Rag genes if this aphid-resistance were used commercially in North America.
Abstract: Sustainable use of insect resistance in crops require insect resistance management plans that may include a refuge to limit the spread of virulence to this resistance. However, without a loss of fitness associated with virulence, a refuge may not prevent virulence from becoming fixed within a population of parthenogenetically reproducing insects like aphids. Aphid-resistance in soybeans (i.e., Rag genes) prevent outbreaks of soybean aphid (Aphis glycines), yet four biotypes defined by their capacity to survive on aphid-resistant soybeans (e.g., biotype-2 survives on Rag1 soybean) are found in North America. Although fitness costs are reported for biotype-3 on aphid susceptible and Rag1 soybean, it is not clear if virulence to aphid resistance in general is associated with a decrease in fitness on aphid susceptible soybeans. In laboratory assays, we measured fitness costs for biotype 2, 3 and 4 on an aphid-susceptible soybean cultivar. In addition, we also observed negative cross-resistance for biotype-2 on Rag3, and biotype-3 on Rag1 soybean. We utilized a simple deterministic, single-locus, four compartment genetic model to account for the impact of these findings on the frequency of virulence alleles. When a refuge of aphid susceptible was included within this model, fitness costs and negative cross-resistance delayed the increase of virulence alleles when virulence was inherited recessively or additively. If virulence were inherited additively, fitness costs decreased the frequency of virulence. Combined, these results suggest that a refuge may prevent virulent A. glycines biotypes from overcoming Rag genes if this aphid-resistance were used commercially in North America.
TL;DR: The findings indicate the potential of both Orius spp.
TL;DR: The similarity in abundance patterns in different fields of a region in a given year suggests the existence of a mechanism allowing a rapid synchronisation of the relative abundance patterns at an intra-regional scale that could be useful in predicting host-parasitoid communities and bear important consequences for the ecosystem service provided by parasitoids.
Abstract: Understanding the stability of communities is fundamental in theoretical and applied ecology. Organisms atop trophic chains are particularly sensitive to disturbance, especially when they are dependent on a specific trophic resource subject to strong fluctuations in density and quality, which is the case of parasitoids. We investigated the (1) variability in spatiotemporal relative abundance patterns of a cereal aphid parasitoid community, determining at what scales such patterns vary in agrosystems. We also investigated whether (2) parasitoid relative abundances are strongly influenced by host relative abundances and if (3) different host species are exploited at distinct rates. Aphid parasitoid populations were monitored in three remote agricultural regions in France between 2010 and 2012. Five parasitoid species (Hymenoptera: Braconidae: Aphidiinae) and three aphid species (Hemiptera: Aphididae) were identified in each of those three regions. Fields sampled in one region in a single year exhibited similar relative abundance patterns, with aphid parasitoid communities varying across regions and years. All parasitoid species were able to exploit each monitored host species. Metopolophium dirhodum Wlk was consistently a more frequent species among parasitized aphids than among living aphids, indicating that this aphid species was exploited at a higher rate than the other two aphid species found (Sitobion avenae F and Rhopalosiphum padi L). Those findings suggest the cereal aphid-parasitoid network is not strictly determined by the intrinsic permanent environmental characteristics but partially varies from one year to another. The similarity in abundance patterns in different fields of a region in a given year suggests the existence of a mechanism allowing a rapid synchronisation of the relative abundance patterns at an intra-regional scale. This phenomenon could be useful in predicting host-parasitoid communities and bear important consequences for the ecosystem service provided by parasitoids.
TL;DR: The aphids’ walking abilities may have strong implications for their spatial distribution in natural habitats, for their levels of infestation and damage and for virus epidemiology in agricultural fields, and should be incorporated in models of aphid and virus dispersal.
TL;DR: It is revealed that flight capacity is clearly influenced by temperature, and that A. colemani is more suitable than A. matricariae for the biological control of A. gossypii in Mediterranean environments.
Abstract: The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae) is one of the major pests of many greenhouse crops. The aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Braconidae: Aphidiinae) have been considered good agents for the biological control of A. gossypii. In Mediterranean area, these parasitoids can currently be released under elevated temperature conditions. However, few findings on their behavior changes with temperature are available. In this study, we analyze the consequence of constant temperatures ranging from 20 to 32 °C on the flight, walking and oviposition capacities of Aphidius colemani and Aphidius matricariae. Our results revealed that flight capacity is clearly influenced by temperature. The optimal temperatures for flying are 20 and 25 °C for A. colemani and A. matricariae, respectively. For both species, we observed an increase in the walking capacity but a decrease in the reproductive potential at higher temperatures. Furthermore, regardless of the tested temperature, the mummy production rate was always higher in A. colemani than in A. matricariae. These results indicate that A. colemani is more suitable than A. matricariae for the biological control of A. gossypii in Mediterranean environments. © 2015, Springer Science+Business Media New York.
TL;DR: 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 worldwide is investigated.
Abstract: 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.
TL;DR: It is found that fecundity was significantly correlated with mean relative growth rate (MRGR), weight gain, and development time, and that the faster aphid develops the greater body and feces, depending on aphid species, wheat accession, and analyses level.
Abstract: The fecundity advantage hypothesis suggests that females with a large body size produce more offspring than smaller females. We tested this hypothesis by exploring the correlations between life-history traits of three aphid species feeding on ten wheat accessions at three levels of analysis with respect to the host plant: overall, inter-accession, and intra-accession. We found that fecundity was significantly correlated with mean relative growth rate (MRGR), weight gain, and development time, and that the faster aphid develops the greater body and fecundity, depending on aphid species, wheat accession, and analyses level. Larger aphids of all three species produced more offspring overall; this held true for Sitobion avenae and Schizaphis graminum at the inter-accession level, and for S. avenae, Rhopalosiphum padi, and S. graminum for three, five, and eight accessions respectively at the intra-accession level. Only one correlation, between intrinsic rates of natural increase (rm) and MRGR, was significant for all aphid species at all three analysis levels. A more accurate statement of the fecundity advantage hypothesis is that cereal aphids with greater MRGR generally maintain higher rm on wheat. Our results also provide a method for exploring relationships between individual life-history traits and population dynamics for insects on host plants.
TL;DR: Potential for flonicamid and the mixture of pyrethrins and azadirachtin to increase compatibility between chemical and biological controls is indicated.
Abstract: The invasive soybean aphid, Aphis glycines Matsumura, is an important pest in North American soybean production. Predators can play an important role in suppressing A. glycines. However, current A. glycines management practices rely primarily on broad-spectrum insecticides, which can adversely affect natural enemy populations. An alternative is the use of selective insecticides that control the targeted pest species, while having a reduced impact on natural enemies. In greenhouse and laboratory assays, we tested the effects of lambda-cyhalothrin, two rates of flonicamid, which is currently not registered for use in soybean, and a formulated mixture of pyrthrins and azadirachtin on A. glycines and its natural enemies, Chrysoperla rufilabris (Burmeister), Orius insidiosus (Say) and Hippodamia convergens (Guerin-Meneville). All insecticides significantly reduced A. glycines populations. Lambda-cyhalothrin was highly toxic to the natural enemies tested. Flonicamid showed the lowest toxicity to natural enemies...
TL;DR: In this article, the authors measured the effect of constant temperature on the adult pre-reproductive period and the life table fertility parameters (infinitesimal increase ratio, gross reproduction rate, net reproduction rate (R0), finite increase ratio (λ), generation time, and the time required for the population to double in the number of individuals (DT), and the reproduction value (RVx)) of the fennel pest H. foeniculi.
Abstract: Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae) is a cosmopolitan species and the main pest of fennel in northeastern Brazil. Understanding the relationship between temperature variations and the population growth rates of H. foeniculi is essential to predict the population dynamics of this aphid in the fennel crop. The aim of this study was to measure the effect of constant temperature on the adult prereproductive period and the life table fertility parameters (infinitesimal increase ratio (rm), gross reproduction rate (GRR), net reproduction rate (R0), finite increase ratio (λ), generation time (GT), the time required for the population to double in the number of individuals (DT), and the reproduction value (RVx)) of the fennel pest H. foeniculi. The values of lx (survival of nymphs at age x) increased as the temperature rose from 15 to 28°C and fell at 30°C, whereas mx (number of nymphs produced by each nymph of age x) increased from 15 to 25°C and fell at 28 and 30°C. The net reproduction rates (R0) of populations of H. foeniculi increased with temperature and ranged from 1.9 at 15°C to 12.23 at 28°C for each generation. The highest population increase occurred with the apterous aphids at 28°C. The rate of population increase per unit time (rm) (day) ranged from 0.0033 (15°C) to 0.1995 (28°C). The highest values of rm were recorded at temperatures of 28°C and 30°C. The rm values were a good fit to the models tested, with R2 > 0.91 and R2adj > 0.88. The models tested (Davidson, Sharpe and DeMichele modified by Schoolfield et al., Logan et al., Lamb, and Briere et al.) were very good fits for the rm values observed, with R2 > 0.91 and R2adj > 0.88. The only exception was the Davidson model. Of the parameters studied, the reproductive capacity was higher in the apterous aphids, with the unique exception of daily fecundity at 28°C, which was higher in the alate aphids of H. foeniculi. Parameters relating to the age-specific fertility table for H. foeniculi were heavily influenced by temperature, with the highest biotic potential and population growth capacity found at 34°C. Therefore, the results obtained in this study could be of practical significance for predicting outbreaks of fennel aphids and improving the management of this aphid in fennel crops.
TL;DR: The results confirmed that the limitation in aphid feeding from plant phloem in wheat cultivar XY22 was related to antibiosis but not antixenosis, which caused XY22 tolerance to S. avenae.
Abstract: Continuous ingestion of the phloem sap of plants by aphids can remove a significant amount of photoassimilates. Based on our earlier works, we hypothesized that due to the reduced aphid feeding time caused by antibiosis, wheat plants may achieve growth tolerance to aphids. We tested this hypothesis using three wheat cultivars, XY22 (Xiaoyan22), AK58 (Bainongaikang58) and XN979 (Xinong979) and the grain aphid, Sitobion avenae. In the choice test, S. avenae did not show any preference among the three wheat cultivars. However, S. avenae had a lower body weight and a lower intrinsic rate of increase when feeding on XY22 than on AK58 and XN979. The electrical penetration graph results indicated that S. avenae had significantly shorter mean and total phloem ingestion periods on XY22 than on AK58 or XN979. The aphids required a similar time to reach the phloem sap on the three wheat cultivars, but required more time to establish sustained phloem ingestion on XY22. These results suggest that the resistance factors of XY22 may be phloem based. Moreover, XY22 suffered less biomass loss in response to aphid infestation compared with XN979, suggesting that XY22 also had a better growth tolerance to S. avenae than XN979. Wheat resistance level to S. avenae was partially correlated with plant photosynthetic rates, and peroxidase activities. These results confirmed that the limitation in aphid feeding from plant phloem in wheat cultivar XY22 was related to antibiosis but not antixenosis, which caused XY22 tolerance to S. avenae.
TL;DR: Results indicate that although common winter canola aphids were suitable prey for H. convergens and C. carnea, qualitative differences in nutritional suitability exist between Brassica-specialist aphids and the generalist M. persicae, and these differences appear to be influenced by levels of sequestered plant compounds that are toxic to aphid predators.
Abstract: In the southern plains of the United States, winter-adapted canola (Brassica napus L.) is a recently introduced annual oilseed crop that has rapidly increased in hectares during the past 10 yr. Winter canola fields are infested annually with populations of Brevicoryne brassicae (L.) and Lipaphis erysimi (Kaltenbach), and these Brassica specialists are known to sequester plant volatiles from host plants, producing a chemical defense system against predators. Myzus persicae (Sulzer) is also common in winter canola fields, but as a generalist herbivore, does not sequester plant compounds. These three aphid species are expected to affect predator survival and development in very different ways. We conducted laboratory studies to 1) determine whether Hippodamia convergens (Guerin-Meneville) and Chrysoperla carnea (Stephens) larvae demonstrate feeding preferences among winter canola aphids and 2) describe the suitability of these prey species. Predators demonstrated no significant preference among prey, and each aphid species was suitable for predator survival to the adult stage. However, prey species significantly affected development times and adult weights of each predator species. Overall, predator development was delayed and surviving adults weighed less when provided with L. erysimi or B. brassicae, which sequestered high levels of indole glucosinolates from their host plants. Our results indicate that although common winter canola aphids were suitable prey for H. convergens and C. carnea, qualitative differences in nutritional suitability exist between Brassica-specialist aphids and the generalist M. persicae. These differences appear to be influenced by levels of sequestered plant compounds that are toxic to aphid predators.
TL;DR: Results suggest that while the host-finding mechanism of D. rapae has not evolved to allow this parasitoid a discrimination between herbivore-infested and previously infested plants, the Herbivore seems able to suppress emission of a key volatile, thereby reducing its own olfactory detectability to its specialised natural antagonist.
Abstract: In response to insect herbivory, plants release volatile blends that differ quantitatively, and in many cases also qualitatively, from those of undamaged plants. These altered blends can attract the herbivore’s natural antagonists, and such herbivore-induced volatile blends have often been interpreted as co-evolved plant–insect antagonist signals. When comparing volatile profiles of infested Brassica oleracea var. gemmifera L. plants (Brassicales: Brassicaceae), on which Brevicoryne brassicae L. (Hemiptera: Aphididae) aphids are feeding, with previously infested plants (i.e., deprived of aphids four hours prior to volatile collection), we found that the emission of a particular volatile compound, the glucosinolate breakdown product allyl isothiocyanate, was significantly higher in the latter. We used dual choice olfactometry to evaluate attractiveness of plants and aphids to Diaeretiella rapae (M’Intosh 1855) (Hymenoptera: Braconidae), a parasitoid of B. brassicae. Previously infested plants deprived of the herbivore attracted significantly more parasitoids than infested plants, although aphid odours per se proved to be attractive. Mechanical damage approximating aphid stylet insertion remained without effect on emission of allyl isothiocyanate and on parasitoid response. The unexpected higher parasitoid attraction to previously infested than infested plants is discussed here from the perspective of the plant and the parasitoid, as well as from the herbivore. Results suggest that while the host-finding mechanism of D. rapae has not evolved to allow this parasitoid a discrimination between herbivore-infested and previously infested plants, the herbivore seems able to suppress emission of a key volatile, thereby reducing its own olfactory detectability to its specialised natural antagonist.
TL;DR: 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.
Abstract: 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.
TL;DR: The objective of this research was to determine the distribution of Rag virulent soybean aphids in Wisconsin using no-choice tests in a greenhouse and to discuss in light of current questions on the biology, ecology, and population genetics of soy bean aphid.
Abstract: 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.
TL;DR: By subjecting the green peach aphid Myzus persicae Sulzer to well‐watered and drought‐stressed plants of both susceptible and resistant peach, the effects of both stressors on aphid performance and proteomics are tested.
Abstract: Little is known about the simultaneous effects of drought stress and plant resistance on herbivorous insects. By subjecting the green peach aphid Myzus persicae Sulzer to well-watered and drought-stressed plants of both susceptible and resistant peach (Prunus persica), the effects of both stressors on aphid performance and proteomics are tested. Overall, the influence of the water treatment on aphid performance is less pronounced than the effect of host plant genetic resistance. On the susceptible cultivar, aphid survival, host acceptance and ability to colonize the plant do not depend on water treatment. On the resistant cultivar, aphid survival and ability to colonize are higher on drought-stressed than on well-watered plants. A study examining the pattern of protein expression aiming to explain the variation in aphid performance finds higher protein expression in aphids on the drought-stressed susceptible cultivars compared with the well-watered ones. In the susceptible cultivar, the regulated proteins are related to energy metabolism and exoskeleton functionality, whereas, in the resistant cultivar, the proteins are involved with the cytoskeleton. Comparison of the protein expression ratios for resistant versus susceptible plants reveals that four proteins are down-regulated in well-watered plants and 15 proteins are down-regulated in drought-stressed plants. Drought stress applied to the susceptible cultivar induces the regulation of proteins in M. persicae that enable physiological adaptation to maintain an almost unaltered aphid performance. By contrast, for aphids on the resistant cultivar subjected to drought stress, the down-regulation of proteins responds to an induced host susceptibility effect.
02 Nov 2015
TL;DR: Bu calismada, 2011 yilinda Kahramanmaras ve Istanbul illerinden toplanan yaprak biti turleri vedagilimlarini ortaya koymaktadir (Aphididae familyasi), DNA eksraksiyon, PCRamplifikasyon ve siralama protokolleri kullanilmistir.
Abstract: Bu calismada, 2011 yilinda Kahramanmaras ve Istanbul illerinden toplanan yaprak biti turleri vedagilimlarini ortaya koymaktadir (Aphididae familyasi, 9 cinse bagli 16 tur). DNA eksraksiyon, PCRamplifikasyon ve siralama protokolleri kullanilmistir. Hyalopterus persikonus, Rhopalosiphum nymphaeae,Dysaphis (Pomaphis) reaumuri ve Myzus (Myzus) varians yaprakbiti turleri Kahramanmaras bolgesi icin ilk kezrapor edilmistir. Brachycaudus divaricatae ve Hyalopterus yaprak biti turlerinin biyolojik karakterleri ve dagilimtanilamalari bu calismada verilmistir
TL;DR: Results suggest that resistance factors in Kanlow are located in the phloem tissue, although Kanlow plants were significantly enriched for oxalic acid.
Abstract: Two choice studies were performed to evaluate greenbug, Schizaphis graminum (Rondani), and yellow sugarcane aphid, Sipha flava (Forbes), preference for two tetraploid switchgrass populations, Summer and Kanlow, and one experimental hybrid, K × S, derived by crossing Kanlow (male) × Summer (female) plants. Additionally, an assessment of S. graminum feeding behavior was performed on the same switchgrass populations, by using the electrical penetration graph (EPG) technique. Choice studies for S. flava indicated a lack of antixenosis, with no preference by aphids among any of the switchgrass populations at any time point. However, choice studies with S. graminum indicated a preference for the K × S plants at 24 h after aphid introduction. No obvious differences were observed for the leaf surfaces between the three populations. Feeding behavior studies for S. graminum on switchgrasses indicated no differences for the time to first probe or time to first sieve element phase among switchgrass populations. However, duration of sieve element phases for S. graminum was significantly less on Kanlow compared to K × S and Summer. S. graminum also had a significantly lower potential phloem ingestion index (PPII) and few aphids showing sustained phloem ingestion on Kanlow as compared to K × S and Summer plants. These results suggest that resistance factors (chemical or mechanical) in Kanlow are located in the phloem tissue. At the whole leaf level, some differences were observed for a subset of polar metabolites, although Kanlow plants were significantly enriched for oxalic acid.