Myzus Persicae Research Articles

First monitoring of resistance and corresponding mechanisms in the green peach aphid, Myzus persicae (Sulzer), to registered and unregistered insecticides in Saudi Arabia

Insecticides are widely used as the primary management strategy for controlling Myzus persicae, the devastating pest ravaging various vegetables, fruits, crops, and ornamentals. This study examined the susceptibility of M. persicae field populations to bifenthrin, fosthiazate, acetamiprid, spirotetramat, afidopyropen, and flonicamid while exploring the possible metabolic mechanisms of resistance. The study findings revealed that M. persicae field populations exhibited susceptible-to-moderate resistance to bifenthrin (resistance ratio (RR) = 0.94–19.65) and acetamiprid (RR = 1.73–12.91), low-to-moderate resistance to fosthiazate (RR = 3.67–17.00), and susceptible-to-low resistance to spirotetramat (RR = 0.70–6.68). However, all M. persicae field populations were susceptible to afidopyropen (RR = 0.44–2.25) and flonicamid (RR = 0.40–2.08). As determined by the biochemical assays, carboxylesterases were involved in the resistance cases to bifenthrin and fosthiazate, whereas cytochrome P450 monooxygenases were implicated in the resistance cases to acetamiprid. However, glutathione S-transferases were not implicated in the documented resistance of M. persicae field populations. Overall, the susceptibility of M. persicae field populations to flonicamid and afidopyropen—two unregistered insecticides in Saudi Arabia—suggests their potential as promising chemicals that can expand the various alternatives available for controlling this devastating pest. Although the detected moderate levels of resistance to bifenthrin, fosthiazate, and acetamiprid indicate a shift in the selection pressure of insecticides for M. persicae due to Saudi regulations, which have resulted in eventual obsolescence of conventional insecticides in favor of novel insecticides. Finally, rotational use of aforementioned insecticides can help in managing insecticide resistance in M. persicae.

Synthesis, Bioactivity and Molecular Docking of Nereistoxin Derivatives Containing Phosphonate.

Novel nereistoxin derivatives containing phosphonate were synthesized and characterized via 31P, 1H and 13C NMR and HRMS. The anticholinesterase activity of the synthesized compounds was evaluated on human acetylcholinesterase (AChE) using the in vitro Ellman method. Most of the compounds exhibited good inhibition of acetylcholinesterase. All of these compounds were selected to assess their insecticidal activity (in vivo) against Mythimna separata Walker, Myzus persicae Sulzer and Rhopalosiphum padi. Most of the tested compounds displayed potent insecticidal activity against these three species. Compound 7f displayed good activity against all three insect species, showing LC50 values of 136.86 μg/mL for M. separata, 138.37 μg/mL for M. persicae and 131.64 μg/mL for R. padi. Compound 7b had the highest activity against M. persicae and R. padi, with LC50 values of 42.93 μg/mL and 58.19 μg/mL, respectively. Docking studies were performed to speculate the possible binding sites of the compounds and explain the reasons for the activity of the compounds. The results showed that the compounds had lower binding energies with AChE than with the acetylcholine receptor (AchR), suggesting that compounds are more easily bound with AChE.

Population modeling of oilseed brassica aphids and their biocontrol agents with weather parameters in the north-west Himalayan region of India.

We studied the impact of weather parameters on the population build-up of Brevicoryne brassicae (L.) (Cabbage aphid), Lipaphis erysimi (Kalt.) (Mustard aphid), Myzus persicae (Sulzer) (Green peach aphid) and their biocontrol agents (coccinellids, syrphids, and a parasitoid, Diaeretiella rapae M'Intosh) on oilseed brassicas in Himachal Pradesh, India, during winters from 2016-2017 to 2018-2019. The temperature and sunshine resulted in the build-up of B. brassicae and their biocontrol agents' population, while rainfall and relative humidity caused a negative influence at surveyed locations. The L. erysimi and M. persicae populations showed an inverse correlation with the density-independent factors at most locations. Correlation coefficients indicated a negative correlation of the coccinellids population with the build-up of L. erysimi and M. persicae, while the predator population was positively related to the B. brassicae population at maximum locations. Parasitization by D. rapae showed a negative relationship with the aphid population. Stepwise regression analysis showed that minimum temperature and rainfall had a significant effect on the variability in the population of aphids. The predictive model could interpret more than 90% variation by minimum temperature in the coccinellid population at the surveyed locations. Further, regression analysis with temperature could explain up to 94% variability in parasitization by D. rapae. This study will contribute to predicting the changes that may occur in a population of aphids concerning the weather.

Effects of intercropping marigold, cowpea and an insecticidal soap on whiteflies and aphids in organic squash

AbstractThe silverleaf whitefly MEAM1 (Bemisia tabaci) Gennadius (Hemiptera: Aleyrodidae), the cowpea aphid (Aphis craccivora Koch), the green peach aphid (Myzus persicae Sulzer) and the melon aphid (Aphis gossypii Glover) Hemiptera: Aphididae are major insect pests of squash (Cucurbita pepo L.), causing significant yield losses of up to 80% in Florida. We hypothesized that intercropping African marigold (Tagetes erecta L.) and cowpea (Vigna unguiculata L. Walp.) with zucchini squash will encourage an abundance of beneficial arthropods and increase cultural and biological control against these key insect pests by significantly reducing their populations and consequently improve yields. In a 2‐year field experiment, five treatments were evaluated in a randomized complete block design consisting of four replicates. Three diversified cropping treatments were implemented: (1) intercropping squash with marigold, (2) intercropping squash with cowpea, (3) intercropping squash with marigold and cowpea (mixed). These treatments were compared with an organic grower standard insecticide, (4) M‐Pede (potassium salts of naturally derived fatty acids) sprayed on monocropped squash and (5) monocropped squash with no pest management (control). Results indicated that squash intercropped with marigolds accounted for the highest marketable yields. Squash intercropped with cowpea had marginally high yields but attracted the highest densities of aphids. M‐Pede did not increase squash yields, but reduced aphids, whiteflies and associated squash silverleaf (SSL) disorder ratings and showed no deleterious effect on populations of natural enemies. We conclude that a mixture of marigold and cowpea could be used to suppress pests by increasing beneficial arthropod diversity while enhancing marketable yields of organic squash. M‐Pede could be used as a last resort when experiencing high hemipteran pressure.

Synergism of a mixed diet of Myzus persicae and egg of Ephestia kuehniella on fitness of the predator Nabis stenoferus

Nabis stenoferus is a zoophytophagous predator that lives in grasslands around agricultural fields. It is a candidate biological control agent for use via augmentation or conservation. To find a suitable food source for mass-rearing and to better understand this predator’s biology, we compared the life history characteristics of N. stenoferus under the three different diets: aphids only (Myzus persicae), moth eggs only (Ephestia kuehniella), or a mixed diet of aphids and moth eggs. Interestingly, when only aphids were supplied, N. stenoferus developed to the adult stage but lacked normal levels of fecundity. There was a significant synergism of the mixed diet on N. stenoferus fitness in both the immature and adult stages, i.e., a 13% reduction in the nymphal developmental period and an 87.3-fold increase in fecundity, compared to aphid-only diet. Furthermore, the intrinsic rate of increase was significantly higher for the mixed diet (0.139) than either aphids only (0.022) or moth eggs only (0.097). These results show that M. persicae alone is not a complete diet for the mass-rearing of N. stenoferus, whereas this aphid can be a supplementary food when combined with E. kuehniella eggs. Implications and applications of these findings for biological control are discussed.

An Efficient Breeding Method for Eupeodes corollae (Diptera: Syrphidae), a Pollinator and Insect Natural Enemy in Facility-Horticulture Crops

Facility horticulture plays a crucial role in modern agriculture by utilizing the environment efficiently and ensuring food supply. The hoverfly Eupeodes corollae (Fabricius) (Diptera: Syrphidae) performs a dual ecological function in facility agriculture as larvae prey on aphids and adults pollinate, but it is not widely applied in agriculture due to the lack of a large-scale breeding technology. In this study, we investigated the effects of different factors on the development and reproduction of the prey (i.e., aphids), eggs, larvae, pupae and adults of E. corollae, and determined its propagation techniques. We transferred five pairs of newly emerging E. corollae adults and 40 broad bean plantlets infested with Aphis craccivora Koch to an insect cage. Aphid-infested broad bean seedlings were replaced each day to encourage E. corollae reproduction. Following hatching, we fed the E. corollae larvae with mixed populations of Myzus persicae (Sulzer), Megour japonica Matsumura and A. craccivora in insect boxes, and covered E. corollae pupae with fresh broad bean leaves. Based on the experiment results, an average female E. corollae produced 584.9 eggs. Survival, pupation and emergence rates were 91.1%, 100% and 96.3%, respectively. In conclusion, each pair of E. corollae adults produced 391 adult offspring (58.8% females). This research supplies an optimized mass-breeding technique for commercial production of the hoverfly, which will be helpful to promote its application in the production of green fruits and vegetables.

New binding sites of nicotinic acetylcholine receptors from Myzus persicae

New binding sites of nicotinic acetylcholine receptors from Myzus persicae

Smelling danger: Lady beetle odors affect aphid population abundance and feeding, but not movement between plants

Predator-prey interactions are complex ecological interactions that influence community structure and function. Predators affect prey density directly by consuming and removing prey from the environment. Additionally, predators can elicit non-consumptive effects in prey which influence prey survival by altering prey behavior and physiology. Key to understanding the consequences of non-consumptive effects for prey populations is determining mechanisms of detection of predation risk. With insects, olfactory cues are commonly used to convey information. It has been shown that insect prey may eavesdrop on predator odor cues as a means to determine predation risk. Herein, we assessed whether the volatile odors of the predatory insect Harmonia axyridis (multicolored Asian lady beetle) affect the behavior (feeding and dispersal behaviors) and performance (population abundance) of aphids (Myzus persicae). Aphids reduced phloem ingestion when feeding in close proximity to lady beetle cues, however, predator odors did not drive aphids to relocate on plants or to disperse across plants away from the odor source. The lack of dispersal we observed is in contrast to studies that show increased aphid movement in the presence of predators that can make physical contact with the aphids. We also found that lady beetle odor cues had a population-level effect on aphids, with 25% reduction in aphid population abundance in the presence of the odor cues. This study highlights that anti-predator strategies may differ depending on the mechanism of detection of predation risk (i.e. olfactory versus physical stimuli), or the context in which they experience them, and raises the question of whether anti-predator responses observed are maladaptive or beneficial to aphid survival. These conclusions are critical for both our basic understanding of the mechanisms driving predator-prey interactions as well as providing insight into pest-natural enemy interactions within agricultural landscapes.

Host-induced silencing of MpPar6 confers Myzus persicae resistance in transgenic rape plants

Plant-mediated RNA interference (RNAi) has emerged as a promising technology for insect control. The green peach aphid, Myzus persicae, feeds on over 400 species of host plants. Brassica napus (rape) is the second most important oilseed crop worldwide. Myzus persicae is highly reproductive and causes severe damage to the rape plants due to its quite flexible life cycle. In this study, we tested the RNAi effects of transgenic rape plants on M. persicae. By in vitro feeding M. persicae with artificial diets containing double-stranded RNAs (dsRNAs) targeting seven aphid genes, we identified a new gene encoding the partitioning-defective protein 6 (Par6) as the most potent RNAi target. Tissue- and stage-expression analysis of Par6 suggested this gene is highly expressed in the embryo and adult stage of M. persicae. We next generated transgenic rape plants expressing dsPar6 by Agrobacterium-mediated transformation and obtained nine independent transgenic lines. Compared to wild-type control plants, transgenic rape lines expressing dsPar6 showed strong resistance to M. persicae. Feeding assays revealed that feeding transgenic rape plants to M. persicae significantly decreased MpPar6 expression and survival rate and impaired fecundity. Furthermore, we showed that the resistance levels to M. persicae are positively correlated with dsPar6 expression levels in transgenic rape plants. Our study demonstrates that transgenic rape plants expressing dsPar6 are efficiently protected from M. persicae. Interfering with the genes involved in embryo development could be the effective RNAi targets for controlling aphids and potentially other insect pests.

Metabolic engineering of a 1,8-cineole synthase enhances aphid repellence and increases trichome density in transgenic tobacco (Nicotiana tabacum L.).

The green peach aphid (Myzus persicae Sulzer) is a harmful agricultural pest that causes severe crop damage by directly feeding or indirectly vectoring viruses. 1,8-cineole synthase (CINS) is a multiproduct enzyme that synthesizes monoterpenes, with 1,8-cineole dominating the volatile organic compound profile. However, the relationship between aphid preference and CINS remains elusive. Here, we present evidence that SoCINS, a protein from garden sage (Salvia officinalis), enhanced aphid repellence and increased trichome density in transgenic tobacco. Our results demonstrated that overexpression of SoCINS (SoCINS-OE) led to the emission of 1,8-cineole at a level of up to 181.5 ng per g fresh leaf. Subcellular localization assay showed that SoCINS localized to chloroplasts. A Y-tube olfactometer assay and free-choice assays revealed that SoCINS-OE plants had a repellent effect on aphids, without incurring developmental or fecundity-related penalties. Intriguingly, the SoCINS-OE plants displayed an altered trichome morphology, showing increases in trichome density and in the relative proportion of glandular trichomes, as well as enlarged glandular cells. We also found that SoCINS-OE plants had significantly higher jasmonic acid (JA) levels than wild-type plants. Furthermore, application of 1,8-cineole elicited increased JA content and trichome density. Our results demonstrate that SoCINS-OE plants have a repellent effect on aphids, and suggest an apparent link between 1,8-cineole, JA and trichome density. This study presents a viable and sustainable approach for aphid management by engineering the expression of 1,8-cineole synthase gene in plants, and underscores the potential usefulness of monoterpene synthase for pest control. © 2023 Society of Chemical Industry.

Hydrogel as an alternative to agar for laboratory rearing of the green peach aphid Myzus persicae

BackgroundRearing methodologies are critical for successful insect production. In this context, standard laboratory rearing of aphid species, like the green peach aphid Myzus persicae, uses plant leaf disks floating on an agar layer. However, agar is costly and its use in insect rearing is not always cost-effective. Here, the synthetic polymer hydrogel was tested as an affordable alternative for laboratory rearing of the green peach aphid.MethodsInitially, the effects of three concentrations of hydrogel (0.3, 0.6, and 0.9 g per 100 ml) and agar (1 g per 100 ml) on the ability of aphids to complete their life cycle were compared. Then, using age-stage, two-sex life tables, the suitability of the hydrogel (0.6 g) as a substrate for two different host plants (e.i; Brassica oleraceae and Nicandra physalodes) under two different temperatures in aphids’ production was assessed. Subsequently, the response of the produced aphids in toxicological bioassays was tested.ResultsThe hydrogel concentration of 0.6 g allowed the production of aphids in high numbers, similarly to the agar (1 g), without affecting their life cycle parameters or their reproductive outputs. Furthermore, the most significant differences between the evaluated treatments resulted mostly from the combined effects of the host plants and the temperatures. Therefore, colonies of M. persicae can be maintained over time producing sufficient offspring using N. physalodes leaves on a layer of hydrogel (0.6 g) at 20 °C. Moreover, in toxicological bioassays, the use of higher hydrogel concentrations (0.9 g) is recommended.ConclusionsThe hydrogel can be adopted as a viable alternative to replacing the widely used agar-based methodology for the green peach aphid rearing.

Characterizing the vector competence of Aphis gossypii, Myzus persicae and Aphis craccivora (Hemiptera: Aphididae) to transmit cotton leafroll dwarf virus to cotton in the United States.

Cotton leafroll dwarf virus (CLRDV) is a yield-limiting, aphid-transmitted virus that was identified in cotton, Gossypium hirsutum L., in the United States of America in 2017. CLRDV is currently classified in the genus Polerovirus, family Solemoviridae. Although 8 species of aphids (Hemiptera: Aphididae) are reported to infest cotton, Aphis gossypii Glover is the only known vector of CLRDV to this crop. Aphis gossypii transmits CLRDV in a persistent and nonpropagative manner, but acquisition and retention times have only been partially characterized in Brazil. The main objectives of this study were to characterize the acquisition access period, the inoculation access period, and retention times for a U.S. strain of CLRDV and A. gossypii population. A sub-objective was to test the vector competence of Myzus persicae Sulzer and Aphis craccivora Koch. In our study, A. gossypii apterous and alate morphs were able to acquire CLRDV in 30 min and 24 h, inoculate CLRDV in 45 and 15 min, and retain CLRDV for 15 and 23 days, respectively. Neither M. persicae nor A. craccivora acquired or transmitted CLRDV to cotton.

Temperature-Driven Selection of Predatory Mirid Bugs for Improving Aphid Control in Sweet Pepper Crops

Recent studies have suggested that predatory mirid bugs may be an effective alternative for controlling aphids in sweet pepper greenhouses. This study examined the effect of three constant temperatures (18, 24, and 30 °C) on the life history traits of predatory mirid species Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus bolivari, preying on the aphid Myzus persicae nicotianae in sweet pepper plants. As the temperature increased, the survival rate decreased for M. pygmaeus and D. bolivari, while for N. tenuis, it was the opposite, and their survival increased. When considering all the biological traits studied together, the estimated intrinsic rate of increase (rm) decreased as the temperature increased for M. pygmaeus and D. bolivari. In contrast, the rate increased as the temperature increased for N. tenuis. These results suggest that M. pygmaeus and D. bolivari are better adapted to lower temperatures than N. tenuis, which is more adapted to warm temperatures. The implications of these results for improving the biological control of aphids in sweet pepper greenhouses through the use of mirid bugs are discussed in relation to different temperature regimes.

Importin β1 Mediates Nuclear Entry of EIN2C to Confer the Phloem-Based Defense against Aphids.

Ethylene Insensitive 2 (EIN2) is an integral membrane protein that regulates ethylene signaling towards plant development and immunity by release of its carboxy-terminal functional portion (EIN2C) into the nucleus. The present study elucidates that the nuclear trafficking of EIN2C is induced by importin β1, which triggers the phloem-based defense (PBD) against aphid infestations in Arabidopsis. In plants, IMPβ1 interacts with EIN2C to facilitate EIN2C trafficking into the nucleus, either by ethylene treatment or by green peach aphid infestation, to confer EIN2-dependent PBD responses, which, in turn, impede the phloem-feeding activity and massive infestation by the aphid. In Arabidopsis, moreover, constitutively expressed EIN2C can complement the impβ1 mutant regarding EIN2C localization to the plant nucleus and the subsequent PBD development in the concomitant presence of IMPβ1 and ethylene. As a result, the phloem-feeding activity and massive infestation by green peach aphid were highly inhibited, indicating the potential value of EIN2C in protecting plants from insect attacks.

Assessing the impact of piercing-sucking pests on greenhouse-grown industrial hemp (Cannabis sativa L.).

Cannabis sativa or hemp, defined as <0.3% total tetrahydrocannabinol (THC), is a specialty crop in the United States, of particular interest among growers in the southeastern United States to replace tobacco production. Tetranychus urticae (twospotted spider mite), Aculops cannabicola (hemp russet mite), Polyphagotarsonemus latus (broad mites), and Phorodon cannabis (cannabis aphids) are considered the most significant pests in greenhouse grown hemp. Mite and aphid injury can cause cupping and yellowing of leaves, resulting in leaf drop, and reduced flower and resin production. We sought to understand the effects of feeding by T. urticae and Myzus persicae (green peach aphid), as a proxy for P. cannabis, on the concentration of economically significant cannabinoids through a series of experiments on greenhouse grown plants. First, we compared the variability of chemical concentrations in samples collected from individual plants versus pooled samples from 5 plants, and found that chemical concentrations in single plants were similar to those in pooled plant samples. Next, we compared chemical concentrations prior to arthropod infestation and post infestation. When evaluating the mite feeding damage in 2020, cannabinoids in plants infested with high densities of T. urticae increased more slowly than in uninfested control plants or plants infested with low T. urticae densities. In 2021, the concentration of tetrahydrocannabinol did not differ significantly between treatments. Cannabidiol increased more slowly in plants with low T. urticae densities when compared to uninfested controls but did not differ from the high T. urticae densities 14 days after infestation.

Colonization and endophytic effect of Beauveria bassiana (Bals.-Criv.) Vuill. UHSB-END1 against Myzus persicae (Sulzer) and Plutella xylostella (L.) in cabbage

BackgroundFungal microbial biocontrol agent playing an important role in sustainable pest management with low cost. Conidial contact with cuticle is sufficient to cause disease in insects by entomopathogenic fungi (EPF) compared to bacteria and viruses which required ingestion of contaminated food. The field level application of fungi resulted inconsistent in their efficacy against insects as they withstand in the agroecosystem with adverse environmental conditions. To overcome this bottleneck, endophytic EPF, Beauveria bassiana (Bals.-Criv.) Vuill. (Cordycipitaceae: Hypocreales), is well-studied for the management of insects of cultivated crops and got promising results. The colonization of endophytic isolates varied from one host plant to another and virulence against insects too. Hence, the study was undertaken to know the colonization of indigenous B. bassiana UHSB-END1 isolate in cabbage plant and its efficacy against major insects of cabbage.ResultsThe indigenous isolate of B. bassiana UHSB-END1 was able to colonize cabbage in all the methods of inoculations (seed treatment, seedling root dip, soil drenching, foliar spray and combination treatment) at 30, 45 and 60 days of post-inoculation (dpi). However, the colonization of the fungus inside the cabbage was restricted to tissues of inoculation, and movement from the site of inoculation to other parts of the plant was poor. In the present study, colonization was the highest at 30 dpi in all methods of colonization with restricted colonization to the site of exposure of fungus. Further, in vivo and in planta assay confirmed the effectiveness of B. bassiana UHSB-END1 colonized cabbage against Myzus persicae (Sulzer) and Plutella xylostella (Linnaeus). Under in vivo conditions the maximum mortality of M. persicae and P. xylostella was recorded at 30 dpi. It was decreased slightly at 45 dpi, and the lowest morality was recorded at 60 dpi. In planta experiment also proved better efficacy against both the test insects. Wherein mortality of M. persicae ranged from 22 to 36% five days after release (DAR), it was increased to 48–68% at 10 DAR and reached highest mortality rate at 15DAR (72–96%). Similarly, mortality of P. xylostella ranged from 14 to 24% after five DAR, and it was 27–44% at 10 DAR, and maximum mortality rate of larvae were recorded at 15 DAR (64–96%).ConclusionThe present study reported 100% colonization of cabbage plant by indigenous B. bassiana UHSB-END1 at 30 dpi in combination of treatment and showed a maximum efficacy in managing the population of major insects of cabbage. Introducing this indigenous isolate will pave a ray of hope in managing the both key insects (P. xylostella and M. persicae) in cabbage agroecosystem without disturbing the environment and further helps in production of cabbage with minimum pesticide residue for consumers.

Analysis of Volatile Metabolites from Papaya Seeds as Potential Organic Insecticides against Myzus persicae Sulz

Myzus persicae is a toxic pest that acts as a limiting factor in increasing chili production in Indonesia. Symptoms of leaf curl are always found in every chili growing season along with the presence of these pests. In the field M.persicae controlled with chemical insecticides that trigger pest resistance. The aim of the study was to determine the effectiveness of papaya seed extract in controlling M. persicae , its effect on chili yields, and the content of volatile toxic compounds in papaya seeds which have potential as organic insecticides. Efficacy test in the form of 7 treatments, 5 replicates, namely application of papaya seed 10, 30, 50, 70, and 90 g/l. Analyzed data using analysis of variance with the F test and Duncan Multiple Range Test to determine the best treatment. Analysis of volatile metabolites was performed using Gas Chromatography-Mass Spectrometry to obtain specific metabolites. Papaya seed extract contains several volatile metabolites that act as organic insecticides, namely Heptasiloxane, 1,1,3,3, 5,5,7,7,9,9,11,11,13,13 tetradecamethyl compounds. The efficacy test in the field showed that papaya seed extract with a concentration of 50-70 g/l was able to suppress Myzus persicae attacks to the low attack category level, and increase chili production up to 2 times (100%). The use of papaya seed waste as an organic insecticide is in accordance with the concept of sustainable agriculture because it is environmentally friendly and improves food safety.

Population parameters and growth of Myzus persicae Sulzer (Hemiptera: Aphididae) under elevated CO2 concentrations in the air

AbstractThe effects of three different CO2 concentrations (400, 600, and 1000 ppm) on the population parameters and growth of the green peach aphid, Myzus persicae, were examined. Raw life history data from M. persicae were analyzed using an age‐stage, two‐sex life table to take into account the viable development rate among individuals. The population projections of M. persicae indicate the stage structure and variability of the population growth under different CO2 concentrations based on an age‐stage, two‐sex life table analysis. Significantly longer oviposition duration and higher fecundity were observed under elevated CO2 (600 and 1000 ppm) than those under ambient CO2 (400 ppm). Furthermore, the M. persicae population reared under elevated CO2 concentrations showed higher intrinsic and finite rates of population increase than under ambient CO2 concentrations. These results indicate that the population parameters and growth of M. persicae were positively influenced in the fecundity by elevated CO2 concentrations relative to the ambient CO2. These findings indicate that it is basically remained to understand the direct effects of CO2 elevation on the host plants, and the interaction between the host plants and M. persicae in the same CO2 concentration for establishing more realistic population growth model systems for M. persicae in the aerial environment rising CO2 concentration level.

Genome-wide identification and characterization of the chemosensory relative protein genes in Rhus gall aphid Schlechtendalia chinensis

BackgroundThe Rhus gall aphid Schlechtendalia chinensis specially uses the only species Rhus chinensis and certain moss species (Mniaceae) as its primary host plant and secondary host plants, respectively. Rhus galls are formed on the primary host by the sucking of aphids, and used in traditional medicine as well as other various areas due to their high tannin contents. Chemoreception is critical for insect behaviors such as host searching, location and identification of mates and reproductive behavior. The process of chemoreception is mediated by a series of protein gene families, including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), olfactory receptors (ORs), gustatory receptors (GRs), ionotropic receptors (IRs), and sensory neuron membrane proteins (SNMPs). However, there have been no reports on the analysis of molecular components related to the chemoreception system of S. chinensis at the genome level.ResultsWe examined the genes of eight OBPs, nine CSPs, 24 ORs, 16 GRs, 22 IRs, and five SNMPs in the S. chinensis genome using homological searches, and these chemosensory genes appeared mostly on chromosome 1. Phylogenetic and gene number analysis revealed that the gene families, e.g., ORs, GRs, CSPs and SNMPs in S. chinensis, have experienced major contractions by comparing to Myzus persicae, while the two gene families OBPs and IRs had slight expansion. The current results might be related to the broader host range of M. persicae versus the specialization of S. chinensis on only a host plant. There were 28 gene pairs between genomes of S. chinensis and Acyrthosiphon pisum in the chemoreceptor gene families by collinear comparison. Ka/Ks ratios (< 1) indicated that the genes of S. chinensis were mainly affected by purification selection during evolution. We also found the lower number and expression level of chemoreception genes in S. chinensis than in other 11 aphid species, such as ORs, GRs and IRs, which play an important role in host search.ConclusionOur study firstly identified the genes of the different chemosensory protein gene families in the S. chinensis genome, and analyzed their general features and expression profile, demonstrating the importance of chemoreception in the aphid and providing new information for further functional research.

Exogenous Application of Methyl Salicylate Induces Defence in Brassica against Peach Potato Aphid Myzus persicae.

Plants use a variety of secondary metabolites to defend themselves against herbivore insects. Methyl salicylate (MeSA) is a natural plant-derived compound that has been used as a plant defence elicitor and a herbivore repellent on several crop plants. The aim of this study was to investigate the effect of MeSA treatment of Brassica rapa subsp. chinensis ('Hanakan' pak choi) on its interactions with peach potato aphids, Myzus persicae, and their natural enemy, Diaeretiella rapae. For this, we selected two concentrations of MeSA (75 mg/L and 100 mg/L). Our results showed that aphid performance was significantly reduced on plants treated with MeSA (100 mg/L). In a cage bioassay, the MeSA (100 mg/L)-treated plants showed lower adult survival and larviposition. Similarly, the MeSA (100 mg/L)-treated plants had a significantly lower aphid settlement in a settlement bioassay. In contrast, the M. persicae aphids did not show any significant difference between the MeSA (75 mg/L)-treated and control plants. In a parasitoid foraging bioassay, the parasitoid D. rapae also did not show any significant difference in the time spent on MeSA-treated and control plants. A volatile analysis showed that the MeSA treatment induced a significant change in volatile emissions, as high numbers of volatile compounds were detected from the MeSA-treated plants. Our results showed that MeSA has potential to induce defence in Brassica against M. persicae and can be utilised in developing sustainable approaches for the management of peach potato aphids.