Myzus Persicae Research Articles

Dual-role regulator of a novel miR-3040 in photoperiod-mediated wing dimorphism and wing development in green peach aphid.

Wing dimorphism is regarded as an important phenotypic plasticity involved in the migration and reproduction of aphids. However, the signal transduction and regulatory mechanism of wing dimorphism in aphids are still unclear. Herein, the optimal environmental conditions were first explored for inducing winged offspring of green peach aphid, and the short photoperiod was the most important environmental cue to regulate wing dimorphism. Compared to 16 L:8 D photoperiod, the proportion of winged offspring increased to 90% under 8 L:16 D photoperiod. Subsequently, 5 differentially expressed microRNAs (miRNAs) in aphids treated with long and short photoperiods were identified using small RNA sequencing, and a novel miR-3040 was identified as a vital miRNA involved in photoperiod-mediated wing dimorphism. More specifically, the inhibition of miR-3040 expression could reduce the proportion of winged offspring induced by short photoperiod, whereas its activation increased the proportion of winged offspring under long photoperiod. Meanwhile, the expression level of miR-3040 in winged aphids was about 2.5 times that of wingless aphids, and the activation or inhibition of miR-3040 expression could cause wing deformity, revealing the dual-role regulator of miR-3040 in wing dimorphism and wing development. In summary, the current study identified the key environmental cue for wing dimorphism in green peach aphid, and the first to demonstrate the dual-role regulator of miR-3040 in photoperiod-mediated wing dimorphism and wing development.

Serine proteinase inhibitors from Nicotiana benthamiana, a nonpreferred host plant, inhibit the growth of Myzus persicae (green peach aphid).

The green peach aphid (Myzus persicae) is a severe agricultural crop pest that has developed resistance to most current control methods, requiring the urgent development of novel strategies. Plant proteinase inhibitors (PINs) are small proteins that protect plants against pathogens and/or herbivores, likely by preventing efficient protein digestion. We identified 67 protease genes in the transcriptomes of three M. persicae lineages (USDA-Red, G002 and G006). Comparison of gene expression levels in aphid guts and whole aphids showed that several proteases, including a highly expressed serine protease, are significantly overexpressed in the guts. Furthermore, we identified three genes encoding serine protease inhibitors (SerPIN-II1, 2 and 3) in Nicotiana benthamiana, which is a nonpreferred host for M. persicae. Using virus-induced gene silencing (VIGS) with a tobacco rattle virus (TRV) vector and overexpression with a turnip mosaic virus (TuMV) vector, we demonstrated that N. benthamiana SerPIN-II1 and SerPIN-II2 cause reduced survival and growth, but do not affect aphid protein content. Likewise, SerPIN-II3 overexpression reduced survival and growth, and serpin-II3 knockout mutations, which we generated using CRISPR/Cas9, increased survival and growth. Protein content was significantly increased in aphids fed on SerPIN-II3 overexpressing plants, yet it was decreased in aphids fed on serpin-II3 mutants. Our results show that three PIN-IIs from N. benthamiana, a nonpreferred host plant, effectively inhibit M. persicae survival and growth, thereby representing a new resource for the development of aphid-resistant crop plants. © 2024 Society of Chemical Industry.

Wheat companion plants reduced aphid and flea beetle infestations in Brassica vegetable crops in a multiple-year field study in central Germany

Alternative pest control systems such as companion plants are increasingly gaining importance owing to a reduced range of available synthetic insecticides and more rigorous regulation of their use in the EU. Therefore, we evaluated the effects of Brassica vegetables grown with wheat companion plants on relevant pests, respective natural enemies and harvest weight. Six trials were conducted in white cabbage and three in Chinese cabbage between 2017 and 2021. We identified an overall aphid-regulating effect for Brevicoryne brassicae (L.) and Myzus persicae (Sulz.) (Hemiptera: Aphididae) in white cabbage and a regulating effect on flea beetles (Phyllotreta spp.) (Coleoptera: Chrysomelidae) in both tested Brassica crops. Feeding by cabbage root fly Delia radicum L. (Diptera: Anthomyiidae) larvae on white cabbage roots was not consistently affected. Natural enemies including ladybirds (Coleoptera: Coccinellidae), hoverfly larvae (Diptera: Syrphidae), spiders (Araneida), ground beetles (Coleoptera: Carabidae), and rove beetles (Coleoptera: Staphylinidae) were assessed on crop plants or in pitfall traps. The activity density of rove beetles was increased by wheat companions in both Brassica crops, while that of ground beetles was reduced in white cabbage. The weight of harvested white cabbage was reduced by wheat companions, varying between a mean reduction of 7.67% and 40.08% in different experiments. In conclusion, wheat companion plants can be an additional tool for regulating pests in Brassica vegetables. However, competition effects on crop yield and the compatibility with other cultivation aspects, e.g. crop rotation, have to be considered.

Deleterious effects of the endosymbiont Rickettsiella viridis in Myzus persicae are environmentally dependent

AbstractEndosymbionts living within insect cells can modify host fitness and could provide new tools for pest control. The endosymbiont Rickettsiella viridis has been transferred experimentally into the green peach aphid, Myzus persicae, a globally important agricultural pest. This Rickettsiella spreads via vertical and horizontal transmission and induces host fitness costs which could potentially suppress pest populations. Endosymbiont prevalence can fluctuate in natural populations, and it is important to identify factors that contribute to their spread or loss. Here, we explore the effects of Rickettsiella infection when aphids are reared on eight different host plants or exposed to thermal, starvation and desiccation stresses. Rickettsiella infection reduced M. persicae fecundity and longevity across all host plants, but the magnitude of costs varied among host plants and generations. Rickettsiella was horizontally transmitted and spread in caged populations at initial ratios of 1:2 Rickettsiella (+): Rickettsiella (−) on all host plants, but with limited long-term persistence under cycling 20–30 °C. We also identified temperature-dependent costs of Rickettsiella infection on heat knockdown time, chill coma recovery, and starvation tolerance. Finally, we present evidence that Rickettsiella infection reduces host activity levels under heat stress. Our results suggest that Rickettsiella infections induce a variety of deleterious effects but with complex environment-dependent interactions. This work helps understand ecological conditions that enhance or limit the spread of these endosymbionts in aphid populations.

Diversity of Culturable Gut Bacteria in Natural Aphid Populations and Their Contribution to Insecticide Degradation

Microorganisms in insects play pivotal roles in various aspects, including nutrition, development, protection, physiology, and behavior. Aphids, a distinct group of insects that feed on plant sap, have been the focus of research exploring the intricate relationships between microbes and insects. While extensive investigations have delved into the obligate endosymbionts in aphids, there remains a gap in understanding the diversity of gut microbes and other associated microorganisms. This study employed culture-dependent methods to isolate microorganisms from diverse aphid species (Aphis gossypii, A. nerii, A. craccivora, Hysteroneura setariae, and Myzus persicae). The results identified three bacterial phyla (Firmicutes, Proteobacteria, Actinobacteria), belonging to families such as Bacillaceae, Corynebacteriaceae, Micrococcaceae, Morganellaceae, Staphylococcaceae, and Xanthomonadaceae. Bacillus emerged as the predominant taxon, with Aphis craccivora exhibiting both high abundance and an even distribution of bacteria. Both A. craccivora and A. gossypii displayed a diverse array of bacterial species, with A. gossypii exhibiting the highest dominance index. Hysteroneura setariae showcased a diverse dominance of bacteria among aphids. Notably, the microorganisms Exiguobacterium indicum MPB-2 and Pseudomonas hibiscicola CCF 2-2 demonstrated the ability to degrade imidacloprid at a rate of 18-22%. This finding emphasizes their capacity to utilize insecticides as sole sources of carbon and nitrogen, ultimately benefiting the fitness of the insects. This study contributes to our understanding of the microorganisms presented in aphids. Highlighting the efficacy of culture-dependent methods in unveiling the diversity of these microscopic organisms.

Comparative Economics of Different Management Tactics by Novel Insecticides against Pest Complex on Capsicum (Capsicum annuum L.) under Protected Conditions

Field experiment was conducted under shade net house at Hi-Tech Horticulture Farm, Rajasthan Agricultural Research Institute, Durgapura (Sri Karan Narendra Agriculture University, Jobner), Jaipur, Rajasthan to work out the economics and cost benefit ratio of different management strategies by three spraying of eleven bio-rationale and newer pesticides against Yellow Mite, Polyphagotarsonemus latus (Banks), thrips, Scirtothrips dorsalis Hood, aphids (Aphis gossypii Glover, Myzus persicae Sulzer), Whitefly, Bemisia tabaci (Gennadius) and Beat army worm, Spodoptera exigua (Hubner) during summer 2014 and 2015 on capsicum (Capsicum annuum L.). The result on the basis of pooled data indicated that maximum net profit of Rs 77185/ha was obtained in the treatment of fipronil 0.005% with the yield of 51.46 q/ha followed by emamectin benzoate 0.002% (Rs 67422/ha) with the yield of 49.77 q/ha. The minimum net profit of Rs 23840/ha was recorded in the treatment of NSKE 5% followed by azadirachtin 0.0003% (Rs 29876). The net profit ranging from Rs 53613/ha to Rs 60263/ha was computed in the treatment of acephate (Rs 53613/ha), spiromesifen (Rs 59971/ha), spinosad (Rs 58262/ha) and indoxacarb (Rs 60263/ha), whereas, Rs 39125/ha to 41476/ha was found in propargite and novaluron. The maximum incremental cost benefit ratio (1:20.23) was found in fipronil (0.005%) followed by 1:17.99 in the treatment of acephate (0.075%). The minimum ICBR (1:4.64) was recorded in the treatments of novaluron followed by spinosad (1:5.96). Study revealed that three spray of fipronil 5 SC @ 1 ml/l or emamectin benzoate 5 SG @ 0.4 g/l can be suggested to the farmers for the management of pest complex on capsicum under shade net house conditions during summer for off season production.

Hesperidin as a Species-Specific Modifier of Aphid Behavior.

Hesperidin is a highly bioactive natural flavonoid whose role in ecological interactions is poorly known. In particular, the effects of hesperidin on herbivores are rarely reported. Flavonoids have been considered as prospective biopesticides; therefore, the aim of the present study was to examine the influence of hesperidin on the host plant selection behavior of three aphid (Hemiptera: Aphididae) species: Acyrthosiphon pisum Harrris, Rhopalosiphum padi (L.), and Myzus persicae (Sulz.). The aphid host plants were treated with 0.1% and 0.5% ethanolic solutions of hesperidin. Aphid probing behavior in the no-choice experiment was monitored using electropenetrography and aphid settling on plants in the choice experiment was recorded. The results demonstrated that hesperidin can be applied as a pre-ingestive, ingestive, and post-ingestive deterrent against A. pisum, as an ingestive deterrent against R. padi, and as a post-ingestive deterrent against M. persicae using the relatively low 0.1% concentration. While in A. pisum the deterrent effects of hesperidin were manifested as early as during aphid probing in peripheral plant tissues, in M. persicae, the avoidance of plants was probably the consequence of consuming the hesperidin-containing phloem sap.

Influence of Alternative Prey on the Functional Response of a Predator in Two Contexts: With and without Intraguild Predation

In biological control, joint releases of predators and parasitoids are standard. However, intraguild predation (IGP) can occur when a predator attacks a parasitoid, potentially affecting pest control dynamics. In addition to the focal prey (FP), Trialeurodes vaporariorum, the intraguild predator (IG-predator) Geocoris punctipes can consume the parasitoid Eretmocerus eremicus (IG-prey). In this IGP context with multiple prey, an alternative prey (AP), like the aphid Myzus persicae, may influence interactions. Theory predicts that, in simple interactions, a predator’s functional response (FR) to the FP changes with the presence of an AP. However, whether this holds in an IGP context is unknown. In this study, we empirically tested that prediction. Our results show that without IGP, G. punctipes exhibits a generalized FR with and without AP. Nevertheless, with IGP, the predator exhibited a Type II FR at low and high AP densities, increasing pressure on the FP and potentially favoring short-term biological control strategies. However, when 25 AP were offered, the predator’s response shifted, underscoring the importance of monitoring AP densities to prevent potential disruptions in FP control. In both contexts, the increase in AP produced a handling time increase and a decrease in consumption rate. These results indicate that the theoretical prediction of the effect of AP on the FR is met only under specific conditions, and the complexity of multitrophic interactions must be considered.

Plant-derived artificial miRNA effectively reduced the proliferation of aphid (Aphidoidea) through spray-induced gene silencing.

Aphids (Hemiptera: Aphididae) are notorious sap-sucking insects that rampantly threaten agricultural production worldwide. Current management against aphids in the field heavily relies on chemical pesticides, which makes economical and eco-friendly methods urgently needed. Spray-induced gene silencing (SIGS) offers a powerful and precise approach to pest management. However, the high costs and instability of double-stranded RNA (dsRNA) regulators applied for downstream RNA interference (RNAi) still limit this strategy. It remains uncertain if RNAi regulators applied in SIGS could extend to small RNA (sRNA), especially miRNA. We chose two sRNA sequences, miR-9b and miR-VgR, whose corresponding targets ABCG4 and VgR are both essential for aphid growth and development. The efficacy of these sequences was initially verified by chemically synthetic single-stranded RNA (syn-ssRNA). Through spray treatment, we observed a significantly decreased survival number and increased abnormality rate of green peach aphids fed on the host under laboratory conditions. Based on our previous study, we generated transgenic plants expressing artificial miR-9b (amiR-9b) and miR-VgR (amiR-VgR). Remarkably, plant-derived amiRNA exerted potent and long-lasting inhibitory efficacy with merely one percent concentration of chemical synthetics. Notably, the simultaneous application of amiR-9b and amiR-VgR exhibited superior inhibitory efficacy. We explored the potential use of sRNA-based biopesticide through SIGS while investigating the dosage requirements. To optimize this strategy, the utilization of plant-derived amiRNA was proposed. The results suggested that attributed to stability and durability, deploying amiRNA in pest management is a potential and promising solution for the field application. © 2024 Society of Chemical Industry.

How aphids fly: Take‐off, free flight and implications for short and long distance migration

Abstract An introduction to high‐speed photography and its entomological impact is provided, emphasizing the importance of high frame rates and high resolution. The take‐off and free flight of Drepanosiphum platanoidis and Myzus persicae were studied in still air using high‐speed photography in HD. The wing tip and body posture were tracked to show how they are displaced during each wingbeat cycle. The important structural elements of the wing are described. The wingbeat is driven by a reinforced leading edge, the pterostigma and costa. The remainder of the coupled fore‐ and hindwing acts as a single aerofoil that deforms during flight, due to sparse venation and a lack of cross veins. During flight, aphids use a ‘near clap and fling’ mechanism with a body pitch close to 90°. Rapid acceleration about the thoracic lateral axis into wing reversal generates enough lift for take‐off, typically within the first or second wingbeat. Unique footage shows that aphids demonstrate a high degree of flight control and manoeuvrability in the lab, occasionally using forward and inverted flight, two flight modes that are otherwise poorly known. While research into the impact of turbulent convection is needed, we posit that the strength of atmospheric forces presents a formidable challenge to aphid migrants. Above the flight boundary layer, migrating aphids may not easily oppose upwardly moving air, although if used, ‘frozen flight’ may cause them to descend on average. We evaluate five devices for insect flight research.

Development of an attenuated potato virus Y mutant carrying multiple mutations in helper-component protease for cross-protection

Tobacco (Nicotiana tabacum) is one of the major cash crops in China. Potato virus Y (PVY), a representative member of the genus Potyvirus, greatly reduces the quality and yield of tobacco leaves by inducing veinal necrosis. Mild strain-mediated cross-protection is an attractive method of controlling diseases caused by PVY. Currently, there is a lack of effective and stable attenuated PVY mutants. Potyviral helper component-protease (HC-Pro) is a likely target for the development of mild strains. Our previous studies showed that the residues lysine at positions 124 and 182 (K124 and K182) in HC-Pro were involved in PVY virulence, and the conserved KITC motif in HC-Pro was involved in aphid transmission. In this study, to improve the stability of PVY mild strains, K at position 50 (K50) in KITC motif, K124, and K182 were separately substituted with glutamic acid (E), leucine (L), and arginine (R), resulting in a triple-mutant PVY-HCELR. The mutant PVY-HCELR had attenuated virulence and did not induce leaf veinal necrosis symptoms in tobacco plants and could not be transmitted by Myzus persicae. Furthermore, PVY-HCELR mutant was genetically stable after six serial passages, and only caused mild mosaic symptoms in tobacco plants even at 90 days post inoculation. The tobacco plants cross-protected by PVY-HCELR mutant showed high resistance to the wild-type PVY. This study showed that PVY-HCELR mutant was a promising mild mutant for cross-protection to control PVY.

Assessment of Balkan Pepper (Capsicum annuum L.) Accessions for Agronomic, Fruit Quality, and Pest Resistance Traits

To maintain the continuous genetic variation and increase the genetic gain, appreciable germplasm diversity and its comprehensive characterization is necessary to further utilize gene sources for pre-breeding. The diversity of pepper forms, cultivation traditions and diverse fruit usages are typical for Balkan countries. Considering this rich diversity, 21 pepper accessions from the Balkan region were evaluated for morphological, biochemical, and insect resistance traits during 2018 and 2019 at Maritsa Vegetable Crops Research Institute, Plovdiv, Bulgaria. Among the studied accessions, the highest productivity was observed in pumpkin shape K1115 and kapia type K1081 accessions, with 0.74 kg and 0.70 kg per plant, respectively. Concerning fruit quality, the highest total polyphenols and ferric reducing antioxidant power (FRAP) were observed in pumpkin shape K712 (203.44 mg GAE/100 g FW) and K1103A (11.49 µmol Fe2+/g FW) accessions, respectively. Concerning insect resistance, 38% of studied accessions showed no infestation of green peach aphid. The kapia type K697 accession was seen as the most reliable resistance source, as it was not infested by aphids and had the least thrips (20% on plants) and cotton bollworm (6.67% on plants and 8.34% on fruit) damage. Based on examined traits, accessions were identified for enhanced fruit quality and promising insect resistance and have been included in further pre-breeding efforts.

Rifampicin synergizes the toxicity of insecticides against the green peach aphid, Myzus persicae

Myzus persicae is an important pest that has developed resistance to nearly all currently used insecticidal products. The employment of insecticide synergists is one of the effective strategies that need to be developed for the management of this resistance. Our study showed that treatment with a combination of the antibiotic, rifampicin, with imidacloprid, cyantraniliprole, or clothianidin significantly increased their toxicities against M. persicae, by 2.72, 3.59, and 2.41 folds, respectively. Rifampicin treatment led to a noteworthy reduction in the activities of multifunctional oxidases (by 32.64%) and esterases (by 23.80%), along with a decrease in the expression of the CYP6CY3 gene (by 58.57%) in M. persicae. It also negatively impacted the fitness of the aphids, including weight, life span, number of offspring, and elongation of developmental duration. In addition, bioassays showed that the combination of rifampicin and a detoxification enzyme inhibitor, piperonyl butoxide, or dsRNA of CYP6CY3 further significantly improved the toxicity of imidacloprid against M. persicae, by 6.19- and 7.55-fold, respectively. The present study suggests that development of active ingredients such as rifampicin as candidate synergists, show promise to overcome metabolic resistance to insecticides in aphids.

Multiple toxins and a protease contribute to the aphid-killing ability of Pseudomonas fluorescens PpR24.

Aphids are globally important pests causing damage to a broad range of crops. Due to insecticide resistance, there is an urgent need to develop alternative control strategies. In our previous work, we found Pseudomonas fluorescens PpR24 can orally infect and kill the insecticide-resistant green-peach aphid (Myzus persicae). However, the genetic basis of the insecticidal capability of PpR24 remains unclear. Genome sequencing of PpR24 confirmed the presence of various insecticidal toxins such as Tc (toxin complexes), Rhs (rearrangement hotspot) elements, and other insect-killing proteases. Upon aphids infection with PpR24, RNA-Seq analysis revealed 193 aphid genes were differentially expressed with down-regulation of 16 detoxification genes. In addition, 1325 PpR24 genes (542 were upregulated and 783 downregulated) were subject to differential expression, including genes responsible for secondary metabolite biosynthesis, the iron-restriction response, oxidative stress resistance, and virulence factors. Single and double deletion of candidate virulence genes encoding a secreted protease (AprX) and four toxin components (two TcA-like; one TcB-like; one TcC-like insecticidal toxins) showed that all five genes contribute significantly to aphid killing, particularly AprX. This comprehensive host-pathogen transcriptomic analysis provides novel insight into the molecular basis of bacteria-mediated aphid mortality and the potential of PpR24 as an effective biocontrol agent.

Molecular mechanisms for selective action of afidopyropen to Myzus persicae and Coccinella septempunctata.

Afidopyropen is a novel insecticide with high selectivity between sucking insects such as the peach aphids Myzus persicae and natural enemies like the seven-spotted lady beetle Coccinella septempunctata. However, the mechanisms of selective action for afidopyropen remain unknown. The LC50 values of afidopyropen to the 1st-4th instar larvae and adult C. septempunctata were 372- to more than 7267-fold higher than that to adult M. persicae. Though the activity of cytochrome P450s in M. persicae was 6.1- to 7.5-fold higher than that in C. septempunctata, the latter has much higher activities of carboxylesterase (CarEs) and glutathione S-transferases (GSTs), and the crude enzyme of C. septempunctata and M. persicae showed similar metabolism efficiency to afidopyropen. Molecular docking results demonstrated that afdopyropen showed higher binding affinity to the vanilloid-type transient receptor potential (TRPV) channel of M. persicae (-9.1 kcal/mol) than to that of C. septempunctata (-8.2 kcal/mol). And the EC50 value of afdopyropen to the TRPV channel of C. septempunctata (41 360 nM) was 19 885-fold higher than that in M. persicae (2.08 nM). Our results demonstrated that the significantly different sensitivity of M. persicae and C. septempunctata TRPV channel to afidopyropen play a key role in the high selectivity of afidopyropen. These findings provide new insights into the selective mechanisms of afidopyropen against insect pests and natural enemies as well as the theory support for coordinated application of chemical control and biological control. © 2024 Society of Chemical Industry.

Neem's promise: The way to a sustainable future and eco-friendly biopesticides

Modern agriculture must include pest management since pests can seriously harm crops and lower yields, resulting in considerable financial losses. Conventional chemical insecticides have been used as the main method of pest management, but their detrimental effects on the environment and human health have inspired the quest for new environmentally friendly options. In this situation, Azadirachta indica showed promise as a sustainable and eco-friendly biopesticide. This research shows many aspects for Azadirachta indica as an environment friendly biopesticide. Neem is well known for having antiviral, antiseptic, and antifungal characteristics, which make it a crucial component in remedies for many illnesses, skin disorders, and mouth care. It is also beneficial to the environment. When added to the soil, its seeds and leaves help increase the fertility of the soil and structure. Additionally, the tree's large root system helps stop soil erosion. Azadirachta indica, is a great asset in the field of pest control and agricultural sustainability due to its repellent and antifeedant qualities. These characteristics are a result of neem's bioactive substances, known as Azadirachtin which has been the subject of in-depth study and use because of its function as a natural repellent and antifeedant Azadirachtin is a potent natural insect growth regulator because it interferes with beetle feeding, molting, and reproduction. Furthermore, the eco-friendliness of azadirachtin and its safety for people and non-target animals highlight its essential function in sustainable pest management techniques, aiding in the advancement of environmentally friendly and healthier agricultural systems. The neem plant is a unique botanical gem that has enormous medicinal, farming, and cultural significance. Its adaptability and environmental friendliness make it an important resource for sustainable agriculture and human well-being. Three commercialized neem-based formulations were tested aphid, Myzus persicae, including Azatrol, Triple Action Neem Oil (70% neem oil), and Pure Neem Oil (100% neem oil) in greenhouse and laboratory settings. A bioassay using a leaf disc choice test indicated that of the established neem-based insecticides tested were effective against the aphid at the recommended concentrations. However, a doubling in the quantity of Azatrol and Triple Action Neem Oil resulted in a 50% decrease in the number of aphids landing on handled leaf tissue compared to untreated leaf tissue.

Substrate-borne vibrations produced during the interaction with natural enemies alter aphids probing behavior

AbstractThe “ecology of fear”, i.e., physiological and behavioral alterations displayed by pests in response to predation risk, has recently been proposed as a sustainable alternative to chemicals for pest control. However, the development of such a strategy requires a detailed understanding of the signals and cues underlying the pest-antagonist interaction and eliciting the prey behavioral alteration. Here, we characterized the substrate-borne vibrations produced during the interaction between the green peach aphid Myzus persicae and its antagonists, the parasitoid wasp Aphidius colemani and the ladybug Adalia bipunctata. Thereafter, coupling the electrical penetration graph (EPG) with a stimulus controller, we evaluated whether the playback of the vibrations, alone and in combination with the alarm pheromone, impacted aphid probing behavior and interaction with the host plant. Aphids responded to vibrations exhibiting longer non-probing, shorter intracellular probes, i.e. the behavior through which the insect evaluates host plant quality, delay in accessing the phloem vessels and decrease of the frequency of phloem salivation events. In contrast, on plants treated with the alarm pheromone, insects displayed longer intracellular probes. We hypothesize that the alarm pheromone, signaling a distant threat, might induce a careful evaluation of the host plant in order to decide the magnitude of the reaction. On the other hand, vibrations might indicate a closely approaching threat pushing the aphid to rush the host evaluation process and the whole feeding process. The possible repercussion of the behavioral alterations observed on the dynamics of aphid-borne plant virus transmission is also discussed.

Hormetic effect induced by Beauveria bassiana in Myzus persicae.

Myzus persicae, a serious sap-sucking pest of a large variety of host plants in agriculture, is traditionally controlled using chemical insecticides but there isinterestin using biopesticides as restrictions are increasingly placed on the use of broad-spectrum pesticides. Here, we show that in Petri dish experiments, high concentrations of the fungal entomopathogen Beauveria bassiana led to rapid mortality of M. persicae, although at a low concentration (1 × 104 conidia mL-1) there is a hormetic effect in which survival and fecundity are enhanced. Hormetic effects persisted across a generation with reduced development time and increased fecundity in the offspring of M. persicae exposed to B. bassiana. The whole-plant experiment points to a hormetic effect being detected in two out of three tested lines. The impact of these effects might also depend on whether M. persicae was transinfected with the endosymbiont Rickettsiella viridis, which decreases fecundity and survival compared with aphids lacking this endosymbiont. This fecundity cost was ameliorated in the generation following exposure to the entomopathogen. Although B. bassiana is effective in controlling M. persicae especially at higher spore concentrations, utilization of this entomopathogen requires careful consideration of hormetic effects at lower spore concentrations, and further research to optimize its application for sustainable agriculture is recommended. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A Long Photoperiod Promoted the Development, Reproduction, and Predation of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) at an Average Greenhouse Temperature during the Winter.

To explore the feasibility of adjusting the photoperiod to regulate the life parameters and predation ability of Harmonia axyridis Pallas in greenhouses during the winter, life tables were constructed for H. axyridis under the three following photoperiods: 9L:15D (light/dark), 12L:12D, and 16L:8D at 15 °C, an average greenhouse temperature during the winter when aphids severely damage vegetables. The effects of photoperiods on predation by this ladybird were tested in both laboratory and greenhouse settings. The results showed that increased illumination promoted the development and reproduction of H. axyridis; under medium and long photoperiods, the pre-adult periods were 3.61 days and 4.34 days shorter than that under the short photoperiod, respectively, and the fecundity increased by 1.78 and 2.41 times. Population parameters r, λ, and R0 increased as illumination time increased, whereas T decreased. Increased illumination also increased the predation by third- and fourth-instar larvae and adults. The amounts of predation by fourth-instar larvae and adults increased by 22.16% and 75.09% under the medium photoperiod, and those under the long photoperiod increased by 71.96% and 89.64%, respectively. The numbers of Myzus persicae Sulzer predated by H. axyridis under the long photoperiod were higher than those under the short photoperiod in a greenhouse, and the predation parameters were influenced.

Efficacy of neonicotinoid and non-neonicotinoid treatments on virus yellows and sugar beet yields

Myzus persicae (Sulzer), commonly known as the green peach aphid, plays a pivotal role in transmitting a range of yellowing viruses, including beet yellows virus, beet mild yellowing virus, beet chlorosis virus, and beet mosaic virus, to sugar beet plants (Beta vulgaris L.). Because of their environmental impacts, three neonicotinoid-based products (imidacloprid, thiamethoxam thiamethoxam, and clothianidine) have faced recent bans in multiple countries and there is thus an increasing need to explore alternative and effective methods for aphid control.In this study, we assess the efficacy of seven conventional aphicides, one neonicotinoid seed treatment, two foliar-applied neonicotinoids, and four companion plants in mitigating the propagation of virus yellows and increasing sugar beet yields. Our analysis is based on data obtained from 64 trials conducted from 2018 to 2022 2023 in France, Belgium, and the Netherlands. These trials were analyzed using linear mixed-effect models in order to estimate the efficacy of neonicotinoid and non-neonicotinoid treatments on the virus yellows and the sugar-beet yields.Our results revealed that the neonicotinoid seed treatment thiamethoxam exhibited strong efficacy in both reducing virus yellows and enhancing yields compared to alternative treatments. However, the most effective treatment for reducing virus yellows was a composite treatment combining barley companion plant, spirotetramat, and flonicamid, which led to an 87.0% reduction in virus yellows incidence compared to the untreated control group [95% confidence interval = (73.3; 93.6)]. In terms of sugar beet yields, spirotetramat at a dosage of 0.75 l/ha proved to be the most effective treatment, resulting in a 15.7% increase in yields compared to the untreated group [95% confidence interval = (9.1; 22.6)]. While companion plants were able to reduce virus yellows, they did not significantly increase yields compared to the untreated treatment. This outcome may be attributed to the competitive interactions between companion plants and sugar beets, in the context of dry seasons. Furthermore, our analysis indicated that the impact of spirotetramat, sulfoxaflor, flonicamid and thiamethoxam on yields tended to increase with higher aphid pressures.