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The green peach aphid, Myzus persicae, is a notorious pest worldwide. We collected a field population of the pest (FZQ-F) that exhibited high resistance to neonicotinoids. Exposure to neonicotinoids can induce oxidative damage in animals; however, it remains unclear whether antioxidant enzymes contribute to the innate immune response of neonicotinoid-resistant pests against high doses of insecticides. Treatment with sublethal doses of thiacloprid (LC10 and LC25) for 3, 6, 12, 24, 48, and 72 h resulted in significantly increased reactive oxygen species (ROS), including H2O2 content, in FZQ-F adults, indicating insecticide-induced oxidative stress. Additionally, the peroxidase activity in FZQ-F adults increased after thiacloprid exposure. Using comparative genomics, we identified 31 heme peroxidases in M. persicae with a typical “2Cys” structure, and phylogenetic analyses divided them into five groups. Comparative transcriptomes revealed that MpPxd2 and MpPxd4 were significantly upregulated in thiacloprid-treated aphids. Thiacloprid exposure significantly induced MpPxd2 and MpPxd4 expression levels, consistent with high H2O2 content and peroxidase activity. The knockdown of MpPxd2 or MpPxd4 in FZQ-F increased their susceptibility to imidacloprid, thiacloprid, and thiamethoxam, verifying the protective role of the heme peroxidases against neonicotinoids in aphids. The knockdown of MpPxd2 or MpPxd4 also led to shorter longevity and a low fecundity of adult aphids at 31 °C compared to controls. The results show that MpPxd2 or MpPxd4 is important in how cells respond to oxidative stress and may help resistant M. persicae pests to handle neonicotinoids.

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.

Plants in the genus Erysimum produce both glucosinolates and cardenolides as a defense mechanism against herbivory. Two natural isolates of Erysimum cheiranthoides (wormseed wallflower) differed in their glucosinolate content, cardenolide content, and their resistance to Myzus persicae (green peach aphid), a broad generalist herbivore. Both classes of defensive metabolites were produced constitutively and were not further induced by aphid feeding. To investigate the relative importance of glucosinolates and cardenolides in E. cheiranthoides defense, we generated an improved genome assembly, genetic map, and segregating F2 population. The genotypic and phenotypic analysis of the F2 plants identified quantitative trait loci, which affected glucosinolates and cardenolides, but not the aphid resistance. The abundance of most glucosinolates and cardenolides was positively correlated in the F2 population, indicating that similar processes regulate their biosynthesis and accumulation. Aphid reproduction was positively correlated with glucosinolate content. Although the overall cardenolide content had little effect on aphid growth and survival, there was a negative correlation between aphid reproduction and helveticoside abundance. However, this variation in defensive metabolites could not explain the differences in aphid growth on the two parental lines, suggesting that processes other than the abundance of glucosinolates and cardenolides have a predominant effect on aphid resistance in E. cheiranthoides.

Despite the known benefits of integrated pest management, adoption in Australian broadacre crops has been slow, in part due to the lack of understanding about how pests and natural enemies interact. We use a previously developed process-based model to predict seasonal patterns in the population dynamics of a canola pest, the green peach aphid (Myzus persicae), and an associated common primary parasitic wasp (Diaeretiella rapae), found in this cropping landscape. The model predicted aphid population outbreaks in autumn and spring. Diaeretiella rapae was able to suppress these outbreaks, but only in scenarios with a sufficiently high number of female wasps in the field (a simulated aphid:wasp density ratio of at least 5:1 was required). Model simulations of aphid-specific foliar pesticide applications facilitated biological control. However, a broad-spectrum pesticide negated the control provided by D. rapae, in one case leading to a predicted 15% increase in aphid densities compared to simulations in which no pesticide was applied. Biological and chemical control could therefore be used in combination for the successful management of the aphid while conserving the wasp. This modelling framework provides a versatile tool for further exploring how chemical applications can impact pests and candidate species for biological control.

An in vivo dual choice bioassay with white cabbage as a host plant was used to determine the repellent effect of three different accessions of caraway (Carum carvi L.) essential oils (EOs) against the green peach aphid Myzus persicae (Sulzer). The dominant components of the EO were D-Carvone (47.3–74.4%) and D-limonene (25.2–51.9%), which accounted for 99.2–99.5% of the EOs determined by GC/MS. The EO with the highest D-limonene content (51.9%) showed the highest repellence (Repellency Index (RI) = +41%), which was stable up to 330 min. The incorporation of several surfactants with different hydrophilic-lipophilic balance values (from 12.4 to 16.7) with caraway EO caused a general inhibition of the repellent effect during the testing period (RI from +41% to −19%). Overall, the findings indicate that caraway EO could be used as a green peach aphid repellent, but more work is needed to formulate the EO into a ready-to-use product.

The green peach aphid, Myzus persicae , is a notorious pest worldwide. We collected a field population of the pest (FZQ-F) that exhibited high resistance to neonicotinoids. Exposure to neonicotinoids can induce oxidative damage in animals; however, it remains unclear whether antioxidant enzymes contribute to the innate immune response of neonicotinoid-resistant pests against high doses of insecticides. Treatment with sublethal doses of thiacloprid (LC 10 and LC 25 ) for 3, 6, 12, 24, 48, and 72 h resulted in significantly increased reactive oxygen species (ROS), including H 2 O 2 content, in FZQ-F adults, indicating insecticide-induced oxidative stress. Additionally, the peroxidase activity in FZQ-F adults increased after thiacloprid exposure. Using comparative genomics, we identified 31 heme peroxidases in M. persicae with a typical "2Cys" structure, and phylogenetic analyses divided them into five groups. Comparative transcriptomes revealed that MpPxd2 and MpPxd4 were significantly upregulated in thiacloprid-treated aphids. Thiacloprid exposure significantly induced MpPxd2 and MpPxd4 expression levels, consistent with high H 2 O 2 content and peroxidase activity. The knockdown of MpPxd2 or MpPxd4 in FZQ-F increased their susceptibility to imidacloprid, thiacloprid, and thiamethoxam, verifying the protective role of the heme peroxidases against neonicotinoids in aphids. The knockdown of MpPxd2 or MpPxd4 also led to shorter longevity and a low fecundity of adult aphids at 31 °C compared to controls. The results show that MpPxd2 or MpPxd4 is important in how cells respond to oxidative stress and may help resistant M. persicae pests to handle neonicotinoids.

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is an economically devastating crop pest worldwide. The M. persicae (SEF-R) population of a cabbage field in China was tested for susceptibilities to 13 insecticides. Compared with the susceptible population (FFJ-S), extremely high and high resistance to beta-cypermethrin (324-fold) and imidacloprid (106.9-fold) was detected in SEF-R. More importantly, this is the first report of resistance in the field M. persicae population to sulfoxaflor (32.4-fold), flupyradifurone (9.5-fold), pymetrozine (34.8-fold), spirotetramat (8.1-fold), flonicamid (5.8-fold), and broflanilide (15.8-fold) in China when compared with FFJ-S. The resistance factor decayed to a low level to sulfoxaflor and pymetrozine after 15 generations without any selection pressure. The resistance-related mutations (R81T and kdr) detected in SEF indicated target-site resistance to neonicotinoids and pyrethroids, respectively. Biochemical assays revealed the involvement of monooxygenase, carboxylesterase, superoxide dismutase, and peroxidase in a multi-insecticide resistance mechanism. The overexpression of P450s, esterases, and a UDP-glycosyltransferase might be responsible for the multi-insecticide resistance in SEF-R. The knockdown of CYP6CY3 in SEF-R increased its susceptibility to imidacloprid, thiacloprid, and thiamethoxam, which verified that P450s play vital roles in neonicotinoid metabolism. Our findings provide guidance for the rational use of insecticides to delay resistance development in GPA.

Osthole, the dominant bioactive constituent in the Cnidium monnieri, has shown acute pesticidal activities. However, its detailed toxicity, antifeedant, and oviposition preference effects against agricultural pests have not been fully understood, limiting its practical use. This study aimed to investigate the contact toxicity, antifeedant activity, and oviposition preference of osthole against three agricultural pests (Tetranychus urticae, Myzus persicae, and Bactrocera dorsalis). Our results showed that the Cnidium monnieri (L.) Cusson (CMC) has a high osthole content of 11.4 mg/g. Osthole exhibited a higher level of acute toxicity against the T. urticae to four other coumarins found in CMC. It showed significant pesticidal activity against T. urticae and M. persicae first-instar nymphs and adults in a dose-dependent manner but not against B. dorsalis adults. Osthole exposure reduced the fecundity and prolonged the developmental time of the T. urticae and M. persicae. Leaf choice bioassays revealed potent antifeedant activity in the T. urticae and M. persicae. Furthermore, the female B. dorsalis showed a distinct preference for laying eggs in mango juice with 0.02 mg/mL osthole at 48 h, a preference that persisted at 96 h. These results provide valuable insights into the toxicity, repellent activity, and attractant activity of osthole, thereby providing valuable insights into its potential efficacy in pest control.

Viruses in the genus Polerovirus infect a wide range of crop plants and cause severe economic crop losses. BrYV belongs to the genus Polerovirus and is transmitted by Myzus persicae. However, the changes in transcriptome and proteome profiles of M. persicae during viral infection are unclear. Here, RNA-Seq and TMT-based quantitative proteomic analysis were performed to compare the differences between viruliferous and nonviruliferous aphids. In total, 1266 DEGs were identified at the level of transcription with 980 DEGs being upregulated and 286 downregulated in viruliferous aphids. At the protein level, among the 18 DEPs identified, the number of upregulated proteins in viruliferous aphids was twice that of the downregulated DEPs. Enrichment analysis indicated that these DEGs and DEPs were mainly involved in epidermal protein synthesis, phosphorylation, and various metabolic processes. Interestingly, the expressions of a number of cuticle proteins and tubulins were upregulated in viruliferous aphids. Taken together, our study revealed the complex regulatory network between BrYV and its vector M. persicae from the perspective of omics. These findings should be of great benefit to screening key factors involved in the process of virus circulation in aphids and provide new insights for BrYV prevention via vector control in the field.

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.

The insect Toll receptor is one of the key members of the Toll signaling pathway, which plays an indispensable role in insect resistance to pathogen infection. Herein, we cloned and characterized five Toll receptor genes from Myzus persicae (Sulzer), which were found to be highly expressed in the first-instar nymphs and adults (both wingless and winged) at different developmental stages. Expressions of MpToll genes were highest in the head, followed by the epidermis. High transcription levels were also found in embryos. Expressions of these genes showed different degrees of positive responses to infection by Escherichia coli and Staphylococcus aureus. The expression of MpToll6-1 and MpToll7 significantly increased after infection with E. coli, whereas the expression of MpToll, MpToll6, MpToll6-1, and MpTollo continuously increased after infection with S. aureus. RNA interference-mediated suppressed expression of these genes resulted in a significant increase in the mortality of M. persicae after infection with the two bacterial species compared with that in the control group. These results suggest that MpToll genes play vital roles in the defense response of M. persicae against bacteria.

Assessing the oviposition preferences of predatory hoverflies is a key factor in the prediction of the success of these biological control agents against aphids in greenhouses, especially when using banker plant systems or in mixed-crop contexts. In this study, two aspects of the oviposition preferences of the American hoverfly, Eupeodes americanus (Wiedemann, 1830) (Diptera: Syrphidae), were evaluated. Firstly, the preference between the banker plant and the target crop was evaluated for three banker plant species (barley, finger millet, or corn) and two target crops (cucumber or pepper). Secondly, the preference between the same two target crops was assessed. Female oviposition preferences were evaluated via two-choice experiments using different plant/aphid systems. The results showed that, for the cucumber crops, the species of banker plant used drastically influenced the oviposition preference of the hoverfly, with a preference for barley over cucumber, cucumber over finger millet, and no preference between corn and cucumber. Unlike cucumber, when used with pepper, barley engendered a preference for the target crop. We conclude that the barley banker plant could be adequate for aphid control in pepper but not in cucumber crops. In a mixed-crop context, the American hoverfly had no preference between cucumber and pepper, which means it has the potential to protect both crops in a mixed-crop greenhouse context. This study shows that the banker plant system should be carefully chosen according to the crops/aphids present in the greenhouse to optimize the impact of the hoverfly as a biocontrol agent. Further work is required to confirm this choice of banker plant in semifield or field testing.

The green peach aphid, Myzus persicae, is globally distributed and an important pest of many economically valuable food crops, largely due to its ability to transmit plant viruses. Almost all aphids, including M. persicae, carry the obligate symbiont Buchnera aphidicola, which provides essential amino acids that aphids cannot obtain from the phloem of plants themselves. Many aphids also harbor facultative (secondary) endosymbionts, which provide benefits under specific ecological conditions. In this study, we screened for secondary endosymbionts in M. persicae, with a particular focus on Australian populations where this species is growing in status as a major agricultural pest. We compared 37 Australian M. persicae populations with other populations, including 21 field populations from China and 15 clones from the UK, France, Italy, Greece, USA, Spain, South Korea, Chile, Japan and Zimbabwe. No secondary endosymbionts were identified in M. persicae samples outside of China, despite samples covering a wide geographic range and being collected from several host plant families. We detected two secondary endosymbionts (Rickettsia, Spiroplasma) in Chinese samples, although diversity appeared lower than detected in a recent study. We also found very high clonal diversity in Chinese samples based on DNA microsatellite markers in comparison with lower clonal diversity from Australia. These patterns may indicate a higher diversity of secondary endosymbionts (and clonal diversity) in the native range of M. persicae when compared to its invasive range.

Fusarium equiseti (JMF-01), as an entomopathogenic fungus, can effectively control agricultural pests and has the potential to be a biocontrol agent. To promote mycelial growth and sporulation, we investigated the optimal submerged culture conditions for F. equiseti. In this study, we used the single-factor method and Box–Behnken design and determined the virulence of the submerged culture against Myzus persicae after optimization. As a result, the highly significant factors affecting the spore concentration of strain JMF-01 were the primary inoculum density and the initial pH, and the highly significant factor affecting the mycelial biomass was the medium-to-flask ratio. The highest mycelial biomass value was 0.35 g when the incubation time was 5.68 days, the initial pH was 5.11, the medium-to-flask ratio was 0.43, and 1 mL of the primary inoculum with spore density of 0.97 × 107 conidia/mL was added. When the incubation time was 6.32 days, the initial pH was 4.46, the medium-to-flask ratio was 0.35, the primary inoculum density was 1.32 × 107 conidia/mL of 1 mL, and the highest spore concentration of 6.49 × 108 blastospores/mL was obtained. Compared with the unoptimized medium conditions, the optimized submerged culture had the highest mycelial biomass and spore concentration, which were 3.46 and 2.06 times higher, respectively. The optimized submerged culture was highly pathogenic toward M. persicae, reaching a 95% mortality rate. Our results provide optimal submerged culture conditions for F. equiseti and lay the basis for later research to expand production for pest control.

Piercing–sucking insects are prominent phloem-feeding insect pests and understanding their feeding behavior and life characteristics plays a crucial role in studying insect host adaptability. The green peach aphid, Myzus persicae (Hemiptera: Aphididae), is one of the most prominent pests in tobacco-growing areas around the world. This study evaluated the adaptability of M. persicae to five host plants: tobacco, radish, Chinese cabbage, Brassica oleracea, and rape using the electropenetrography, age-stage, two-sex life table and population dynamics. The results demonstrated that the feeding behavior of M. persicae differed significantly according to the target hosts. M. persicae exhibited reduced pathway activities and increased phloem sap ingestion on radish, whereas the opposite was observed on Chinese cabbage. Additionally, the mechanical difficulties of M. persicae mouthparts in the probe pathway phase were significantly lower on tobacco and radish than on other host plants. Life table parameters indicated that for M. persicae reared on radish, preadult duration, longevity, and total preoviposition increased significantly and the fecundity was the highest. Furthermore, the net reproductive rate (R0) increased significantly. The population number of M. persicae on radish after 15 days was significantly higher than that on other hosts, except for tobacco. Although M. persicae can successfully survive on the five plants, our results demonstrated that radish is the optimal host. These results provide significant information for understanding the population dynamics of M. persicae and on different host crops integrated management strategy.

Banker plant systems have the advantages of introducing natural enemies preventively and maintaining by providing alternative prey, thus controlling the pests sustainably. Banker plant systems are usually composed of three factors: a banker (secondary) plant, an alternative prey, and a shared predator (attacking an alternative prey on the secondary plant, and the targeted pest on the crop). However, for most banker plant systems, there is a lack of understanding regarding the dynamic relationship among these elements, with detrimental effects on practical applications. Therefore, in this study, the control of Myzus persicae on Capsicum annum by the Coccinella septempunctata–Megoura japonica–Vicia faba banker plant system was used as the research system. The effects of different release time of predators, different initial numbers of alternative prey (Me. japonica) and different initial ratios of target pests/alternative prey on the indirect interaction of two aphids and the biological control effect of shared predators were tested. The occurrence of indirect interactions between the two aphid preys, the impact on population dynamics, and biological control effectiveness of the shared predator C. septempunctata were investigated. When the initial numbers of both species of aphids were equal (200 each), the delay between aphid and C. septempunctata introduction in the cage had no effect on My. persicae, but Me. japonica showed lower numbers when testing the least time between predatory introductions. When the numbers of the two aphids were manipulated, the My. persicae population was significantly reduced by the predator only at a ratio of My. persicae to Me. japonica < 1, while initial ratios ≥ 1 enabled My. persicae population growth. In 1–6 days, the control effect of C. septempunctata was the best. Principal component analysis showed that the experimental time, initial numbers of Me. japonica, and relative numbers of Me. japonica affected the predation of My. persicae by C. septempunctata. In addition, when the initial aphid ratio was greater than 1/4, C. septempunctata was able to effectively control My. persicae. Overall, our study confirmed the number-mediated indirect interaction (apparent competition) relationship and its impact on prey population dynamics. We provide useful information for optimizing banker plant systems, to boost biocontrol of aphid pests.

The indirect interaction between viruses and their insect vectors via the host plants can mediate viral transmission. Thus, elucidating these tripartite interactions is crucial for controlling the occurrence of viral diseases. This study examined the feeding behavior and life table parameters of the green peach aphid, Myzus persicae, using electropenetrography and an age-stage, two-sex life table on PVY-infected and uninfected tobacco plants. Furthermore, the amino acid and soluble sugar contents in tobacco tissue at different stages of PVY infection were determined. The results showed that PVY-infected plants exerted remarkable effects on the feeding activities of M. persicae. Aphids exhibited a reduced non-probing duration and increased phloem sap ingestion on infected plants. Although the nymph development time on the PVY-infected plants was significantly shorter than that of uninfected plants, M. persicae reared on infected plants had reduced fecundity and significantly shortened adult longevity. On day 12, the sugar: amino acid ratio of the PVY-infected plants was significantly higher than that of uninfected plants, whereas the opposite was observed on day 24. Our results demonstrated that PVY could alter the adaptability of M. persicae by modifying the nutritional quality of tobacco plants. In addition, divergent effects on aphids were observed at different infection stages, which are crucial to consider while exploring the interactions between viruses, insect vectors, and host plants. These results provided significant information for comprehending PVY spread and outbreaks.

Arbuscular mycorrhizal fungi (AMF) and ultraviolet-B radiation (UV-B) play important roles in plant–insect interactions by altering plant physiology and histology. We hypothesized that UV-B-induced oxidative stress was mitigated by AMF symbiosis. In this study, we conducted a multifactorial experiment to explore lettuce plant response to AMF inoculation and UV-B exposure (0.4 W m−2; 16 h d−1; 2 weeks), either together or individually, as well as the interaction with the polyphagous insect pest Myzus persicae (Sulzer). Lettuce plants subjected to UV-B radiation showed an increase in callose and oxidative stress indicators, as well as a decrease in stomatal density. Mycorrhizal colonization cancelled out the effect of UV-B on stomatal density, while the symbiosis was not affected by UV-B treatment. The plant volatile emission was significantly altered by UV-B treatment. Specifically, the non-terpene 1-undecene abundance (+M/+UVB: 48.0 ± 7.78%; −M/+UVB: 56.6 ± 14.90%) was increased, whereas the content of the non-terpene aldehydes decanal (+M/+UVB: 8.50 ± 3.90%; −M/+UVB: 8.0 ± 4.87%) and undecanal (+M/+UVB: 2.1 ± 0.65%; −M/+UVB: 1.20 ± 1.18%) and the sesquiterpene hydrocarbons (+M/+UVB: 18.0 ± 9.62 %; −M/+UVB: 19.2 ± 5.90%) was decreased. Mycorrhization, on the other hand, had no significant effect on the plant volatilome, regardless of UV-B treatment. Aphid population was unaffected by any of the treatments, implying a neutral plant response. Overall, this study provides new insights about the interactions among plants, UV-B, and AMF, outlining their limited impact on a polyphagous insect pest.

Neonicotinoid-based real control of aphids in sugar beet permitted the effective management of associated phytoviruses. However, the prohibition on their usage has prompted an urgent search for viable replacements. The development of sugar beet varieties with aphid and/or virus resistance and/or tolerance has a huge potential to reduce aphids and the harm caused by transmitted viruses. Semiochemicals also play a significant part in determining intra- and inter-specific interactions, which directly affect aphid fitness, feeding activity, and ultimately their capacity to spread viruses. Another method of aphid management involves the use of plant volatile organic compounds (VOCs) in conjunction with an attract and kill strategy. Entomopathogenic fungi could also be used to manage aphids without endangering helpful entomofauna. Finally, soil bacteria are particularly effective biocontrol agents because they induce systemic resistance (ISR) as plant growth promoting rhizobacteria (PGPR). The sugar beet-aphid virus model would be a perfect place to test these microbial players. The adoption of complementing eco-compatible techniques in the sugar beet crop will be ensured by the application of a variety of biocontrol opportunities connected to creative aphid control strategies. This should make it possible to create technical itineraries for a comprehensive approach to controlling aphids and related viruses depending on the situation.

Massive outbreaks of virus yellows (VY) and syndrome “basses richesses” (SBR) are thought to be responsible for the major loss of sugar beet yields in 2020 in western cantons of Switzerland. Typical yellowing symptoms were visible during field inspections, and control measures were reportedly ineffective or even absent. Both diseases induce yellowing but have distinct etiologies; while VY is caused by aphid-transmitted RNA viruses, SBR is caused by the cixiid-transmitted γ-proteobacterium Candidatus Arsenophonus phytopathogenicus. To clarify the situation, samples from diseased plants across the country were screened for the causal agents of VY and SBR at the end of the season. Beet yellows virus (BYV) and Beet chlorosis virus (BChV) showed high incidence nationwide, and were frequently found together in SBR-infected fields in the West. Beet mild yellowing virus (BMYV) was detected in two sites in the West, while there was no detection of Beet western yellows virus or Beet mosaic virus. The nucleotide diversity of the detected viruses was then investigated using classic and high-throughput sequencing. For both diseases, outbreaks were analyzed in light of monitoring of the respective vectors, and symptoms were reproduced in greenhouse conditions by means of insect-mediated inoculations. Novel quantification tools were designed for BYV, BChV and Ca. A. phytopathogenicus, leading to the identification of specific tissues tropism for these pathogens.

Plant performance in any one generation is affected not only by the prevailing environmental conditions, but also by the conditions experienced by the parental generation of those plants. These maternal effects have been recorded in a many plant species, but the influence of external biotic (as opposed to abiotic) factors on shaping maternal effects have been rarely examined. Furthermore, almost all previous studies have taken place over one plant generation, rather than across multiple generations. Here, we studied the influence of insect herbivory and arbuscular mycorrhizal (AM) fungal colonisation on the shaping of maternal effects in the annual forb Senecio vulgaris. We grew plants with and without aphids (Myzus persicae) and AM fungi (hereafter termed ‘induction events’) over four successive generations, wherein seeds from plants in any one treatment were used to grow plants of the same treatment in the next generation, all in identical environmental conditions. We found strong evidence of maternal effects in the second plant generation, i.e., after one induction event. These plants took longer to germinate, flowered in a shorter time, produced lighter seeds and were shorter and of lower biomass than their parents. Aphid attack tended to enhance these effects, whereas AM fungi had little influence. However, thereafter there was a gradual recovery in these parameters, so that plants experiencing three inductions showed similar life history parameters to those in the original generation. We conclude that experiments investigating maternal effects need to be performed over multiple plant generations and that biotic factors such as insects and mycorrhizas must also be taken into account, along with abiotic factors, such as nutrient and water availability.

Effective biological control agents that can provide sustainable pest control need to be researched in further detail; functional plants (or non-crop insectary plants), in particular, are garnering increased research interest. Much remains to be learned as to how non-crop plants can augment biological control in greenhouse systems. In this study, we combined laboratory and greenhouse assays to assess the extent to which basil (Ocimum basilicum L.) (Lamiales: Lamiaceae) affected the biological control of aphids by the predatory lacewing Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae). In the presence of the target prey (peach aphid; Myzus persicae (Sulzer)), both the vegetative and flowering stages of basil enhanced C. pallens longevity and (early-age) fecundity as compared to a control treatment. When basil plants were established near aphid infested eggplants (Solanum melongena L.), the C. pallens colonization rate improved by 72–92% in the short-term. Lacewing colonization patterns were modulated by the basil planting density and spatial arrangement (i.e., perimeter planting vs. intercropping). Under high density intercrop arrangements, C. pallens colonization rates were highest, its populations persisted longer in the crop, and the aphid numbers declined more rapidly. Our work shows how basil enhanced the key fitness attributes of a generalist predatory lacewing and benefitted aphid biological control in a greenhouse setting.

Plants have evolved a number of different chemical defenses, covering nearly all classes of (secondary) metabolites, that represent a major barrier to herbivory: some are constitutive; others are induced after attacks from herbivores (HIPVs) and may elicit the attraction of predators and parasitoids. Here, we studied how the female solitary endoparasitoid Aphelinus varipes responds to plant and host aphid volatiles in a series of experiments on five commercially important vegetables that were either healthy or infested with the aphid Myzus persicae: chili pepper, eggplant, crown daisy, Chinese cabbage and cabbage. The results for the olfactory responses of A. varipes showed that the presence of M. persicae increased the attraction of the endoparasitoid to the infested plants. In a second experiment, volatiles from highly attractive and repellent plants were obtained via headspace collection to investigate volatiles from healthy and aphid-damaged plants. The results for the differences in volatile profiles in response to aphid infestation in chili pepper cultivar were dominated by the volatile blends, including α-pinene, decanal and phthalic acid, while in cabbage they were dominated by isophorone. Moreover, when HIPVs with different concentrations were compared, α-pinene at a dose rate of 100 ng/μL attracted more parasitoids, and the comparison was useful to understand the mechanisms of plant secondary volatiles during aphid infestation and to provide new resources to control this insect pest. Overall our study shows how HIPVs can bolster tritrophic interactions by enhancing the attractiveness of parasitoids.

Feeding on mixed, alternating, or changing diets often favor insect development. With the aim to optimize mass rearing and use for the biological control of insect pests, we investigated the effects of various combinations of high-quality (the green peach aphid Myzus persicae ) and low-quality (eggs of the grain moth Sitotroga cerealella ) foods on the larval development of a predatory ladybird Cheilomenes propinqua. In the first experiment, eggs and aphids were mixed in different proportions; in the second experiment, larvae switched from feeding on aphids to feeding on eggs. Although the beneficial additive effect of mixed foods was detected in some treatments with limited diets, feeding on various combinations of eggs with aphids never resulted in higher survival, faster development, or a larger size of emerging adults than those observed for feeding on unlimited amounts of aphids. For the practice of biological control, we conclude that, if necessary (for example, in the case of temporary shortage or a lack of aphids in mass rearing facilities or in the case of preventing release of C. propinqua adults in greenhouses), C. propinqua larvae can be fed with grain moth eggs by replacing, mixing, or alternating with aphids, although this will inevitably result in a proportional decrease in pre-adult survival, rate of development, weight, and size of the emerging adults. On the other hand, even a minimal addition of aphids can have a substantial positive effect on larvae fed with grain moth eggs.

The extensive use of synthetic pesticides has created considerable concern for both human health and the environment, which has prompted the search for safer alternatives, such as the resin of guayule (Parthenium argentatum). Thus, in the present study, we aimed to test the biopesticide activity of crude guayule resin and three derived fractions and compare them to reference products that act against four of the most economically significant plant pests: Tetranychus urticae, Bemisia tabaci, Myzus persicae and Frankliniella occidentalis. None of the guayule products caused plant damage. The crude guayule resin and the hexane and ethyl acetate fractions displayed moderate to high contact mortality against T. urticae and B. tabaci, as well as moderate to high antifeedant activity against T. urticae, B. tabaci and M. persicae. No significant activity was observed against F. occidentalis. A correlation analysis of the activity and fraction composition revealed that guayulins C and D, isoargentatins A and B, argentatins A, B and D and an unknown compound C6 were likely responsible for the contact mortality. By contrast, the antifeedant activity appeared to be caused by guayulins A and B against T. urticae and B. tabaci and by guayulins C and D and argentatin B against M. persicae. The feeding reduction in F. occidentalis was associated with an unknown compound C2 and argentatin C. Therefore, guayule appears to be a promising novel biopesticide.

Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) is a cosmopolitan, highly polyphagous agricultural pest, which has the capacity to displace other native insect herbivores. Here, equipped with an integrated approach, the effect of developmental stages and feeding density of whiteflies on Myzus persicae performance in tobacco plants are investigated. Bioassay results showed that B. tabaci nymphs, but not adult, pre-infestation significantly reduced survival and fecundity of M. persicae, and the strongest resistance to M. persicae was detected at the medium density (9–10 nymphs/cm2). Neither low nor high feeding density of B. tabaci nymphs triggered visible resistance to aphids. However, no significant results were detected in salicylate-deficient NahG plants after B. tabaci nymph infestation. In addition to performance distinctions, hormone quantification and qPCR results revealed very different effects for nymph and adult whitefly stages on the defense responses in tobacco. B. tabaci nymph infestation significantly increased SA accumulation and SA-responsive genes (PR-1a, PR-2a) expression but suppressed JA-regulated responses. In contrast, tobacco plants responded to adult infestation by slightly increasing in both SA- and JA-regulated defenses. Furthermore, higher transcription level of Bt56, coding gene of a secretory salivary effector, was recorded in nymphs vs. adults, while silencing of Bt56 by virus-induced gene silencing (VIGS) partly impaired the aphid resistance induced by B. tabaci nymphs. These results proved that the induction of tobacco defense responses varied with the feeding stages of whiteflies: nymphs of B. tabaci, but not adults, induced a defense response against aphids, with a density threshold for this induced resistance.

The green peach aphid Myzus persicae (Hemiptera: Aphididae) relies heavily on its olfactory system to locate plant hosts, find mates, and avoid parasitoids or predators. The insect odorant receptors (ORs) have been proven to play a critical role in the perception of odorants from the environment. In the present study, 33 odorant receptor candidate genes including the Orco gene were identified from the antennal, head, legs and body transcriptomes of M. persicae. Phylogenetic analysis of ORs from seven different orders of insect species suggests that ORs from different insect species are highly divergent and most ORs from the same species formed monophyletic groups. In addition, the aphid ORs were clustered into six different sub-clades in the same clade. Furthermore, the genomic structure of the OR genes also tends to be consistent, suggesting that ORs from the family Aphididae have a relatively close evolutionary relationship. Reads per kilobase per million (RPKM) and tissue expression profiles analyses revealed that 27 out of the 33 MperORs were uniquely or primarily expressed in the antennae, indicating their putative roles in chemoreception. This work provides a foundation to further investigate the molecular and ecological functions of MperORs in the aphid–aphid, aphid–plant and aphid–natural enemy interactions.

Neonicotinoids are widely used to protect fields against aphid-borne viral diseases. The recent ban of these chemical compounds in the European Union has strongly impacted rapeseed and sugar beet growing practices. The poor sustainability of other insecticide families and the low efficiency of prophylactic methods to control aphid populations and pathogen introduction strengthen the need to characterize the efficiency of new plant protection products targeting aphids. In this study, the impact of Movento® (Bayer S.A.S., Leverkusen, Germany), a tetrameric acid derivative of spirotetramat, on Myzus persicae and on viral transmission was analyzed under different growing temperatures. The results show (i) the high efficiency of Movento® to protect rapeseed and sugar beet plants against the establishment of aphid colonies, (ii) the impact of temperature on the persistence of the Movento® aphicid properties and (iii) a decrease of approximately 10% of the viral transmission on treated plants. These observations suggest a beneficial effect of Movento® on the sanitary quality of treated crops by directly reducing primary infections and indirectly altering, through aphid mortality, secondary infections on which the spread of disease within field depends. These data constitute important elements for the future development of management strategies to protect crops against aphid-transmitted viruses.

Peach orchards are intensively sprayed crops, and alternative methods must be found to replace pesticides. We intend here to evaluate if limiting water and nitrogen (N) supply could be effective in controlling aphid infestation in commercial orchards. N and water supply were therefore either unrestricted or restricted by 30% only for water, or for both water and N, in 2018 and 2019 on trees of two contrasting varieties. Natural infestations (green peach aphid, mealy plum aphid, leaf curl aphid) were monitored regularly at tree and shoot level. Infested and control shoots were compared for their development during the infestation period, their apex concentrations of total N, amino acids, non-structural carbohydrates, and polyphenols at infestation peak. At tree level, limiting both water and N supplies decreased the proportion of infested shoots by 30%, and the number of trees hosting the most harmful specie by 20 to 50%. Limiting only N supplies had almost no effect on infestation severity. At shoot level, the apex N concentration of infested shoots was stable (around 3.2% dry weight) and was found to be independent of treatment, variety, and year. The remaining biochemical variables were not affected by infestation status but by variety and year. Shoot development was only slightly affected by treatment. Aphids colonized the most vigorous shoots, being those with longer apical ramifications in 2018 and higher growth rates in 2019, in comparison with the controls. The differences were, respectively, 40 and 55%. It was concluded that a double restriction in water and N could limit, but not control, aphid infestations in commercial orchards.

Beneficial soil microbes have long been recognized for their ability to improve plant growth, to antagonize pathogens and to prime plants against biotic stressors. Nevertheless, their ability to enhance plant resistance against arthropod pests remains largely unexplored, especially in crop plants such as pepper. Herein, we assessed the effects of several fungal and bacterial species/strains applied in the soil on the performance of key pests of pepper plants. Specifically, we recorded the impact of pepper inoculation with commercial strains of beneficial bacteria (Bacillus amyloliquefaciens and Pseudomonas spp.) as well as fungi (Trichoderma spp. and Cordyceps fumosorosea) on the population growth of the green peach aphid, Myzus persicae, and the two-spotted spider mite, Tetranychus urticae. Furthermore, we recorded the effects of microbial inoculation on plant growth parameters, such as stem and root weight. We found that both pests can be negatively affected by microbial inoculation: spider mites laid up to 40% fewer eggs, and the number of aphids were up to 50% less on pepper-inoculated plants, depending on the microbe. We also recorded a variation among the tested microbes in their impact on herbivore performance, but no significant effects were found on plant biomass. Our results add to the growing literature that beneficial soil microbes may be capable of exerting biocontrol capabilities against aboveground herbivorous pests possibly, among other means, via the elicitation of plant defense responses.

Excessive insecticide application has posed a threat to pollinators and has also increased insecticide resistance of Myzus persicae Sulzer. Therefore, it is urgent to develop an economical and effective strategy, especially for greenhouse vegetables. Firstly, we selected a neonicotinoid insecticide that is specifically fatal to M. persicae but relatively safe to predators and bumblebees by laboratory toxicity tests and risk assessments. Then, we tested the effectiveness of the neonicotinoid insecticide under different temperature conditions. According to the LC50 values and the hazard quotients, thiacloprid met the requirements. Greenhouse trails indicated that thiacloprid was quite efficient, while control dropped to 80% without the application of thiacloprid. As for biological control, Harmonia axyridis effectively controlled 90% of aphids with thiacloprid or not. However, Aphidoletes aphidimyza performed better above 20 °C. Our results indicated that it is cost-effective to control M. persicae with A. aphidimyza in suitable temperature conditions and H. axyridis was more effective at low temperatures. Practically, thiacloprid could be used either as an emergency option to control aphids’ abundance alone or in combination with natural enemies.

Brassica yellows virus (BrYV) is a tentative species of the genus Polerovirus, which occurs widely, and mostly damages Brassicaceae plants in East Asia. Because BrYV cannot be transmitted mechanically, an insect-based transmission method is required for further virus research. Here, a reliable and unrestricted method is described, in which non-viruliferous aphids (Myzus persicae) acquired BrYV from transgenic Arabidopsis thaliana, harboring the full-length viral genome germinated from seeds and its frozen leaves. The aphids then transmitted the virus to healthy plants. There was no significant difference in acquisition rates between fresh and frozen infected leaves, although the transmission rate from frozen infected leaves was lower compared to fresh infected leaves. This simple novel method may be used to preserve viral inocula, evaluate host varietal resistance to BrYV, and investigate interactions among BrYV, aphids, and hosts.

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.

Plants in the genus Erysimum produce both glucosinolates and cardenolides as a defense mechanism against herbivory. Two natural isolates of Erysimum cheiranthoides (wormseed wallflower) differed in their glucosinolate content, cardenolide content, and their resistance to Myzus persicae (green peach aphid), a broad generalist herbivore. Both classes of defensive metabolites were produced constitutively and were not further induced by aphid feeding. To investigate the relative importance of glucosinolates and cardenolides in E. cheiranthoides defense, we generated an improved genome assembly, genetic map, and segregating F2 population. The genotypic and phenotypic analysis of the F2 plants identified quantitative trait loci, which affected glucosinolates and cardenolides, but not the aphid resistance. The abundance of most glucosinolates and cardenolides was positively correlated in the F2 population, indicating that similar processes regulate their biosynthesis and accumulation. Aphid reproduction was positively correlated with glucosinolate content. Although the overall cardenolide content had little effect on aphid growth and survival, there was a negative correlation between aphid reproduction and helveticoside abundance. However, this variation in defensive metabolites could not explain the differences in aphid growth on the two parental lines, suggesting that processes other than the abundance of glucosinolates and cardenolides have a predominant effect on aphid resistance in E. cheiranthoides .

Dicyphine mirids are important biological control agents (BCAs) in horticultural crops. Dicyphus cerastii Wagner can be found in protected tomato crops in Portugal, and has been observed feeding on several tomato pests. However, the predation capacity of this species is poorly studied. In order to investigate the predation capacity of D. cerastii, and how it is affected by prey size and mobility, we evaluated the functional response (FR) and predation rate of female predators on different densities of four prey species: Myzus persicae 1st instar nymphs (large mobile prey), Bemisia tabaci 4th instar nymphs, Ephestia kuehniella eggs (large immobile prey) and Tuta absoluta eggs (small immobile prey). Experiments were performed on tomato leaflets in Petri dish arenas for 24 h. Dicyphus cerastii exhibited type II FR for all prey tested. The predator effectively preyed upon all prey, consuming an average of 88.8 B. tabaci nymphs, 134.4 E. kuehniella eggs, 37.3 M. persicae nymphs and 172.3 T. absoluta eggs. Differences in the FR parameters, attack rate and handling time, suggested that prey size and mobility affected predation capacity. Considering the very high predation rates found for all prey species, D. cerastii proved to be an interesting candidate BCA for tomato crops.

Endophytic entomopathogens have growth promoting, nutrient fortifying, and anti-insect properties that could improve the yield and quality of lettuce (Lactuca sativa L.). Lactuca sativa is a vegetable crop with high demand; however, it is susceptible to aphid infestations. This study’s objectives were to assess the pathogenicity of Beauveria bassiana (strain: SM3) (Bals.) Vuil. (Hypocreales) against Myzus persicae Sulzer, tissue colonization of lettuce by conidia of B. bassiana, as well as the effects of fungal inoculation on growth, tissue nutrient content, and proximate composition of the lettuce plants. Furthermore, the involvement of tissue nutrients in mediating the influence of endophytic fungus on the plant traits was examined. Insects and plants were exposed to four fungal conidial concentrations: 0, 1 × 106, 1 × 107 and 1 × 108 conidia mL−1 in an anti-insect bioassay and a greenhouse experiment, respectively. The B. bassiana strain was pathogenic against M. persicae, inducing mean insect mortality of 78% at the highest concentration (1 × 108 conidia mL−1). The B. bassiana endophytically colonized up to 76% of plants exposed to 1 × 108 conidia mL−1. Crown size and plant height varied significantly among treatments. However, the plant fresh and dry weights and nutrient elements N, P, K, Ca, and Mg did not vary significantly among treatments. Among the plant macronutrients assessed, only tissue carbon content was significantly (p < 0.01) affected by conidial treatments. The tissue C and Cu contents significantly correlated with the antioxidant capacity of the lettuce plants. Most of the micronutrients, viz. Mn, Fe, Cu, and B were remarkably higher (p < 0.05) in the fungus-treated plants than in the control plants. The antioxidant capacity (FRAP and TEAC) of plant extracts varied significantly (p < 0.001) among treatments, with the highest conidial treatment yielding the most increased antioxidant activity. In conclusion, the B. bassiana strain was endophytic to lettuce, pathogenic against M. persicae, and induced increased micro-nutrient tissue contents and antioxidant activities. This study demonstrated that B. bassiana could be potentially used in the biofortification of nutritive and medicinal qualities of plants.

This study investigated the toxicity of essential oils (EOs) from Santolina chamaecyparissus (L.) and Tagetes patula (L.) towards the green peach aphid Myzus persicae (Sulzer) and the bird cherry-oat aphid Rhopalosiphum padi (L.). The effects of the EOs on aphid population parameters and levels of biochemical markers of oxidative stress within insect tissues were analyzed. In laboratory bioassays, application of the studied EOs at sublethal concentrations reduced daily fecundity and led to a decrease in the intrinsic rate of natural increase in both aphid species. Treatment with EOs also induced generation of reactive oxygen species (ROS) within aphid tissues. The highest levels of superoxide anion and hydrogen peroxide were noted after 24 and 48 h of exposure. Moreover, a significant increase in lipid peroxidation was shown in treated aphids, especially between 48 and 72 h after exposure. The increase was more pronounced after treatment with the essential oil of S. chamaecyparissus, which also exhibited higher aphicidal activity in toxicity tests. The activities of antioxidant enzymes—superoxide dismutase (SOD) and catalase (CAT)—were significantly elevated in both aphid species in response to the tested EOs. The obtained results suggest that oxidative stress evoked by treatment with the studied EOs may be an important factor determining their toxicity towards aphids.

Aphids transmit CMV (cucumber mosaic virus) in a non-persistent manner. However, little is known about the mechanism of CMV transmission. In this study, an integrated analysis of the mRNA and protein was performed to identify important putative regulators involved in the transmission of CMV by aphids. At the level of transcription, a total of 20,550 genes (≥2-fold expression difference) were identified as being differentially expressed genes (DEGs) 24 h after healthy aphid transfer to infected tobacco plants using the RNA-seq approach. At the protein level, 744 proteins were classified as being differentially abundant between virus-treated and control M. persicae using iTRAQ (isobaric tags for relative and absolute quantitation) analysis. The combined mRNA and protein analysis enabled the identification of some viral putative regulators, such as cuticle proteins, ribosomal proteins, and cytochrome P450 enzymes. The results show that most of the key putative regulators were highly accumulated at the protein level. Based on those findings, we can speculate that the process by which aphids spread CMV is mainly related to post-translational regulation rather than transcription.

The green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), a polyphagous insect pest is a major threat to a wide range of crops worldwide. Aiming to evaluate the life history traits of M. persicae, feeding on different host plants, we used five vegetables: cabbage, Brassica oleracea (Brassicaceae); chinese cabbage, B. rapa (Brassicaceae); chili pepper, Capsicum annum (Solanaceae); crown daisy, Chrysanthemum coronarium (Asteraceae); and eggplant, Solanum melongena (Solanaceae). TWOSEX-MSchart software was used for the statistical analysis about the age-stage, two-sex life table theory. The highest fecundity (69.65 individuals) rate of M. persicae, intrinsic rate of increase (r = 0.425 d−1), finite rate of increase (λ = 1.531 d−1), net reproductive rate (R0 = 69.65 offspring), and shortest mean generation time (T = 9.964 d) were recorded on the chili pepper plant. Whereas, lower fitness occurred on cabbage. The findings attained from population growth parameters indicate that chili pepper is the most susceptible plant, while cabbage is resistant to aphids. Population projection results also supported this statement, as the final total population size on cabbage was significantly lower than other plants. The reported information would be useful for devising integrated pest management programs, particularly those involving M. persicae. This information also suggests the adaptability of M. persicae causing economic damage to these vegetable cultivars.

The green peach aphid Myzus persicae Sulzer is the main vector of the semipersistently transmitted and phloem-limited Beet yellows virus (BYV, Closterovirus). Studies monitoring the M. persicae probing behavior by using the Electrical penetration graphs (EPG) technique revealed that inoculation of BYV occurs during unique brief intracellular punctures (phloem-pds) produced in companion and/or sieve element cells. Intracellular stylet punctures (or pds) are subdivided in three subphases (II-1, II-2 and II-3), which have been related to the delivery or uptake of non-phloem limited viruses transmitted in a non-persistent or semipersistent manner. As opposed to non-phloem limited viruses, the specific pd subphase(s) involved in the successful delivery of phloem limited viruses by aphids remain unknown. Therefore, we monitored the feeding process of BYV-carrying M. persicae individuals in sugar beet plants by the EPG technique and the feeding process was artificially terminated at each phloem-pd subphase. Results revealed that aphids that only performed the subphase II-1 of the phloem-pd transmitted BYV at similar efficiency than those allowed to perform subphase II-2 or the complete phloem-pd. This result suggests that BYV inoculation occurs during the first subphase of the phloem-pd. The specific transmission mechanisms involved in BYV delivery in phloem cells are discussed.

Mixed infection of plant viruses is ubiquitous in nature and can affect virus–plant–vector interactions differently than single virus infection. While several studies have examined virus–virus interactions involving mixed virus infection, relatively few have examined effects of mixed virus infection on vector preference and fitness, especially when multiple vectors are involved. This study explored how single and mixed viral infection of a non-persistently transmitted cucumber mosaic virus (CMV) and propagative and persistently-transmitted tomato spotted wilt orthotospovirus (TSWV) in pepper, Capsicum annum L., influenced the preference and fitness of their vectors, the green peach aphid, Myzus persicae (Sulzer), and the tobacco thrips, Frankliniella fusca (Hinds), respectively. In general, mixed infected plants exhibited severe symptoms compared with individually infected plants. An antagonistic interaction between the two viruses was observed when CMV titer was reduced following mixed infection with TSWV in comparison with the single infection. TSWV titer did not differ between single and mixed infection. Myzus persicae settling preference and median developmental were not significantly different between CMV and/or TSWV-infected and non-infected plants. Moreover, M. persicae fecundity did not differ between CMV-infected and non-infected pepper plants. However, M. persicae fecundity was substantially greater on TSWV-infected plants than non-infected plants. Myzus persicae fecundity on mixed-infected plants was significantly lower than on singly-infected and non-infected plants. Frankliniella fusca fecundity was higher on CMV and/or TSWV-infected pepper plants than non-infected pepper plants. Furthermore, F. fusca-induced feeding damage was higher on TSWV-infected than on CMV-infected, mixed-infected, or non-infected pepper plants. Overall, our results indicate that the effects of mixed virus infection on vectors were not different from those observed following single virus infection. Virus-induced host phenotype-modulated effects were realized on both specific and non-specific vectors, suggesting crosstalk involving all vectors and viruses in this pathosystem. The driving forces of these interactions need to be further examined. The effects of interactions between two viruses and two vectors towards epidemics of one or both viruses also need to be examined.

The Cucumber aphid (Myzus persicae), a destructive cucumber aphid usually managed by chemical pesticides, is responsible for enormous annual agricultural losses. A protein elicitor, PeBL1, was investigated in the present work for its ability to induce a defense response against M. persicae in cucumber. The rates of population growth (Intrinsic rate of increase) of M. persicae (second and third generations) decreased with PeBL1-treated cucumber seedlings as compared to positive (water) and negative 70.58 μg mL−1 controls (50 mM Tris-HCl, pH 8.0). In an assay on host selection, M. persicae had a preference for colonizing control plants as compared to the PeBL1-treated cucumber seedlings. The nymphal development time of the aphid was extended with the PeBL1-treated cucumber seedlings. Likewise, fecundity was reduced, with less offspring produced in the PeBL1-treated cucumber seedlings as compared to the positive (water) and negative 70.58 μg mL−1 controls (50 mM Tris-HCl, pH 8.0). The cucumber leaves treated with PeBL1 had a hazardous surface environment for M. persicae, caused by trichomes and wax formation. Jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) levels were significantly higher, exhibiting significant accumulation in the PeBL1-treated cucumber seedlings. The following results showed that PeBL1 considerably altered the height of the cucumber plant and the surface structure of the leaves to minimize M. persicae reproduction, and it prevented colonization. Defensive processes also included the activation of pathways (JA, SA, and ET). This study provides evidence of biocontrol for the use of PeBL1 in cucumber defense against M. persicae.

Botanical and fungal biopesticides, including endophytes, are in high demand given the current restrictive legislations on the use of chemical pesticides. As part of an ongoing search for new biopesticides, a series of fungal endophytes have been isolated from selected medicinal plants including Lauraceae species. In the current study, an extract from the endophytic fungus Trichoderma sp. EFI 671, isolated from the stem parts of the medicinal plant Laurus sp., was screened for bioactivity against plant pathogens (Fusarium graminearum, Rhizoctonia solani, Sclerotinia sclerotiorum and Botrytis cinerea), insect pests (Spodoptera littoralis, Myzus persicae, Rhopalosiphum padi) and plant parasites (Meloidogyne javanica), with positive results against M. persicae. The chemical study of the neutral fraction of the active hexane extract resulted in the isolation of a triglyceride mixture (m1), eburicol (2), β-sitostenone (3), ergosterol (4) and ergosterol peroxide (5). The free fatty acids present in the acid fraction of the extract and in m1 (oleic, linoleic, palmitic and stearic) showed strong dose-dependent antifeedant effects against M. persicae. Liquid (potato dextrose broth, PDB and Sabouraud Broth, SDB) and solid (corn, sorghum, pearl millet and rice) growth media were tested in order to optimize the yield and bioactivity of the fungal extracts. Pearl millet and corn gave the highest extract yields. All the extracts from these solid media had strong effects against M. persicae, with sorghum being the most active. Corn media increased the methyl linoleate content of the extract, pearl millet media increased the oleic acid and sorghum media increased the oleic and linoleic acids compared to rice. The antifeedant effects of these extracts correlated with their content in methyl linoleate and linoleic acid. The phytotoxic effects of these extracts against ryegrass, Lolium perenne, and lettuce, Lactuca sativa, varied with culture media, with sorghum being non- toxic.

This study reports the characterization of protein elicitor PeBb1 derived from entomopathogenic fungus Beauveria bassiana ARSEF-2860 strain and its putative role in induced systemic resistance in Brassica rapa ssp. pekinensis against green peach aphid Myzus persicae. The sequence of purified elicitor protein was matched with the genomic sequence of a hypothetical protein BBA_10269 from B. bassiana ARSEF-2860 (GenBank Accession No. XP_008603588.1). The protein-encoding gene PeBb1 contained 534 bp cDNA encoding a polypeptide of 177 amino acids with a molecular mass of 19 kDa. The recombinant elicitor protein was expressed in Escherichia coli using pET-28a (+) expression vector and induced necrosis in the leaves of tobacco. The effects of elicitor protein on aphid M. persicae was determined by applying three different concentrations of PeBb1 (i.e., 26, 35, 53 μM) on B. rapa plants at 4-leaf stage and the treated plants were exposed to newly emerged (0−6 h old) apterous adult aphids. Bioassay results showed significant (p < 0.05) sub-lethal effects of the exogenous application of PeBb1 elicitor on M. persicae. Moreover, the RT-qPCR gene expression analyses showed a significant up-regulation of most of the key genes linked to ethylene (ET)- and jasmonic acid (JA)-associated plant defense pathways in elicitor-treated plants. These results not only recommend the putative utilization of PeBb1 elicitor protein in future biological pest control strategies against phloem-feeding insect pests such as M. persicae, but also help in better comprehension of the mechanisms through which beneficial fungi trigger the induced plant resistance.

An in vivo dual choice bioassay with white cabbage as a host plant was used to determine the repellent effect of three different accessions of caraway ( Carum carvi L.) essential oils (EOs) against the green peach aphid Myzus persicae (Sulzer). The dominant components of the EO were D-Carvone (47.3-74.4%) and D-limonene (25.2-51.9%), which accounted for 99.2-99.5% of the EOs determined by GC/MS. The EO with the highest D-limonene content (51.9%) showed the highest repellence (Repellency Index (RI) = +41%), which was stable up to 330 min. The incorporation of several surfactants with different hydrophilic-lipophilic balance values (from 12.4 to 16.7) with caraway EO caused a general inhibition of the repellent effect during the testing period (RI from +41% to -19%). Overall, the findings indicate that caraway EO could be used as a green peach aphid repellent, but more work is needed to formulate the EO into a ready-to-use product.

This study describes the insecticidal activity of a novel Bacillus thuringiensis Cry-related protein with a deduced 799 amino acid sequence (~89 kDa) and ~19% pairwise identity to the 95-kDa-aphidicidal protein (sequence number 204) from patent US 8318900 and ~40% pairwise identity to the cancer cell killing Cry proteins (parasporins Cry41Ab1 and Cry41Aa1), respectively. This novel Cry-related protein contained the five conserved amino acid blocks and the three conserved domains commonly found in 3-domain Cry proteins. The protein exhibited toxic activity against the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae) with the lowest mean lethal concentration (LC50 = 32.7 μg/mL) reported to date for a given Cry protein and this insect species, whereas it had no lethal toxicity against the Lepidoptera of the family Noctuidae Helicoverpa armigera (Hübner), Mamestra brassicae (L.), Spodoptera exigua (Hübner), S. frugiperda (J.E. Smith) and S. littoralis (Boisduval), at concentrations as high as ~3.5 μg/cm2. This novel Cry-related protein may become a promising environmentally friendly tool for the biological control of M. persicae and possibly also for other sap sucking insect pests.

The peach potato aphid, Myzus persicae (Sulzer), is a worldwide pest of many crops, and the most important aphid pest of peach and potato crops in Tunisia, mainly due to virus transmission, for which insecticides are frequently applied. We studied the genetic structure of M. persicae populations in Tunisia, in order to further our understanding of the biotic and abiotic factors shaping populations and to predict their evolutionary responses to the present management practices. We monitored peach orchards and seed potato crops in different seasons and regions from 2011−2013 and in 2016 (19 populations), assessing the genetic diversity of M. persicae at six microsatellite loci. Temporal and spatial changes in the frequency and distribution of 397 genotypes in 548 sampled aphids were studied. Only 37 genotypes were found more than once (clonal amplification), as most genotypes were found only once (91.60% in peach; 88.73% in potato crops). A similarly high genetic diversity was observed in aphids sampled from peach (G/N = 0.76; Ho = 0.617) and potato (G/N = 0.70; Ho = 0.641). Only a weak genetic differentiation among populations was found, mainly between geographic locations. Clustering analysis revealed genotypes to be grouped mainly according to host plant. The availability of the primary host, high proportion of unique genotypes, high genetic diversity and lack of structuring suggest that the aphid reproduces mainly through cyclical parthenogenesis in Tunisia. On the other hand, we provide a farm-scale study that shows how easily M. persicae can colonize different areas and hosts, which may have important implications in relation to plant virus vectoring.

Eugenia winzerlingii (Myrtaceae) is an endemic plant from the Yucatan peninsula. Its organic extracts and fractions from leaves have been tested on two phloem-feeding insects, Bemisia tabaci and Myzus persicae, on two plant parasitic nematodes, Meloidogyne incognita and Meloidogyne javanica, and phytotoxicity on Lolium perenne and Solanum lycopersicum. Results showed that both the hexane extract and the ethyl acetate extract, as well as the fractions, have strong antifeedant and nematicidal effects. Gas chromatography-mass spectrometry analyses of methylated active fractions revealed the presence of a mixture of fatty acids. Authentic standards of detected fatty acids and methyl and ethyl derivatives were tested on target organisms. The most active compounds were decanoic, undecanoic, and dodecanoic acids. Methyl and ethyl ester derivatives had lower effects in comparison with free fatty acids. Dose-response experiments showed that undecanoic acid was the most potent compound with EC50 values of 21 and 6 nmol/cm2 for M. persicae and B. tabaci, respectively, and 192 and 64 nmol for M. incognita and M. javanica, respectively. In a phytotoxicity assay, medium-chain fatty acids caused a decrease of 38−52% in root length and 50−60% in leaf length of L. perenne, but no effects were observed on S. lycopersicum. This study highlights the importance of the genus Eugenia as a source of bioactive metabolites for plant pest management.

Thujone is a natural biologically active monoterpene ketone component of essential oils of numerous plants. The aim of the study was to evaluate the effect of β-thujone and β-thujone derivatives bisulfite adduct, lactone, oxime, and lactam application on behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae) during probing and settling. The choice and no-choice tests (aphid settling and Electrical Penetration Graph (EPG), respectively) revealed that stereochemistry of thujone was important for biological activity (β-thujone caused changes in aphid behavior while α-thujone did not) and that cyclopentane ring modifications and functional groups addition gave derivatives that possessed stronger and more durable deterrent effects. The most effective modification was the incorporation of a lactam moiety into the β-thujone molecule. Application of β-thujone lactam limited aphid settling for at least 24 h, caused restlessness in aphids and a delay or failure in reaching phloem phase by M. persicae. β-Thujone lactam can be considered a deterrent of medium potency with activity expressed at preingestive phase of aphid probing. Other compounds did not restrain aphid stylet penetration in non-phloem tissues but slightly limited sap ingestion (lactone, oxime), and restrained aphid settling for a period of less than 24 h (β-Thujone, bisulphite adduct, lactone).

Restricting Turnip yellows virus (TuYV) spread in canola (Brassica napus) crops often relies upon the application of systemic insecticides to protect young vulnerable plants from wide-scale green-peach aphid (GPA; Myzus persicae) colonization and subsequent virus infection. For these to be applied at the optimal time to ensure they prevent epidemics, growers would need to be forewarned of incoming viruliferous aphid migration and colonization. This study was conducted to field validate a loop-mediated isothermal amplification (LAMP) protocol designed to detect TuYV in aphids caught on traps and develop an early warning system for TuYV epidemics. Double-sided yellow sticky traps were deployed at 30 sites sown with canola over a two-year period in the south-west Australian grainbelt. Using LAMP, the percentage (%) of trap sides with TuYV-carrying aphids was measured and related to TuYV infection incidence in the adjacent crop. When TuYV was detected in aphids on >30% trap sides in a six-week period from pre-emergence to GS15 (five-leaf stage), TuYV reached >60% crop incidence by GS30 (beginning of stem elongation). Whereas, TuYV detection in aphids on ≤15% trap sides during this period was associated with ≤6% TuYV incidence by GS30. Furthermore, when large numbers of aphids, including GPA, were caught during this period but no TuYV was detected in them, minimal TuYV spread (≤5%) occurred in the crop by GS30. Therefore, the LAMP TuYV protocol can be used in an early warning system for TuYV epidemics by providing detection of initial viruliferous aphid migration into a canola crop before they establish colonies throughout the crop and spread virus. This would enable proactive, non-prophylactic, and thereby more effective systemic insecticide applications to minimize seed yield and quality losses due to early season TuYV infection.