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Once introduced in a new range, alien plants likely escape specialist natural enemies of their native range, but still have to cope with resident generalist enemies in the invaded habitats. Here we designed a suite of lab experiments to assess whether the generalist aphid pest Aphis fabae was able to feed, survive, reproduce and establish colonies on five vascular plant species invasive to Europe: Erigeron canadensis, Solidago canadensis, Galinsoga quadriradiata, Senecio inaequidens and Reynoutria japonica. We specifically monitored (1) aphids probing behavior using the Electrical Penetration Graph technique, (2) their short-term survival and fecundity rate in clip-cages, and (3) their ability to settle and establish colonies over a period of five weeks. Our results revealed a gradient in the suitability of invasive plants for A. fabae. Senecio inaequidens was the only species with immediate palatability, allowing reproduction and durable colonization. Galinsoga quadriradiata and R. japonica were not immediately palatable but did allow reproduction of the insect. Erigeron canadensis and S. canadensis both appeared as unsuitable hosts for A. fabae. Our results further supported the “Behavioural Constraint Hypothesis” and the high plasticity in generalist herbivore insects by demonstrating that the time needed for A. fabae to recognize G. quadriradiata as a suitable food source under lab conditions was very short. From an agronomical point of view, this study suggests that some alien plants could serve as reservoirs for crop pests, while others could act as lethal traps. [ABSTRACT FROM AUTHOR]

The electrical penetration graph (EPG) technique is of great significance in elucidating the mechanisms of virus transmission by piercing-sucking insects and crop resistance to these insects. The traditional method of manually processing EPG signals encounters the drawbacks of inefficiency and subjectivity. This study investigated the data augmentation and automatic identification of various EPG signals, including A, B, C, PD, E1, E2, and G, which correspond to distinct behaviors exhibited by the Asian citrus psyllid. Specifically, a data augmentation method based on an improved deep convolutional generative adversarial network (DCGAN) was proposed to address the challenge of insufficient E1 waveforms. A multi-criteria evaluation framework was constructed, leveraging maximum mean discrepancy (MMD) to evaluate the similarity between the generated and real data, and singular value decomposition (SVD) was incorporated to optimize the training iterations of DCGAN and ensure data diversity. Four models, convolutional neural network (CNN), K-nearest neighbors (KNN), decision tree (DT), and support vector machine (SVM), were established based on DCGAN to classify the EPG waveforms. The results showed that the parameter-optimized DCGAN strategy significantly improved the model accuracies by 5.8%, 6.9%, 7.1%, and 7.9% for DT, SVM, KNN, and CNN, respectively. Notably, DCGAN-CNN effectively addressed the skewed distribution of EPG waveforms, achieving an optimal classification accuracy of 94.13%. The multi-criteria optimized DCGAN-CNN model proposed in this study enables reliable augmentation and precise automatic identification of EPG waveforms, holding significant practical implications for understanding psyllid behavior and controlling citrus huanglongbing. [ABSTRACT FROM AUTHOR]

This study investigates the settling preferences and feeding behavior of the Bemisia tabaci whitefly on six cassava cultivars using electrical penetration graph techniques. Six distinct electrical penetration graph waveforms—non-probing, stylet pathway, phloem salivation, phloem ingestion, intracellular puncture, and xylem feeding—were identified and analyzed. Significant differences in the frequency and duration of these waveforms were observed among the cassava cultivars. The whiteflies spent the majority of their time in the non-probing phase, particularly on the Huaybong 80, Kasetsart 50, Rayong 9, and Rayong 72 cultivars. CMR-89 cultivar exhibited higher total probe durations in the phloem salivation and ingestion waveforms, suggesting a greater potential for transmission of the Sri Lankan cassava mosaic virus. The study also examined trichome density and size across the cassava cultivars, revealing that CMR-89 had the highest density and small trichomes, while Huaybong 80 had the lowest density. Trichome characteristics significantly impacted whitefly behavior: larger trichomes were negatively correlated with whitefly settling, whereas higher trichome density was positively correlated with longer settling durations. These findings indicate that trichome-based resistance mechanisms are crucial in whitefly deterrence. Overall, the results suggest that cultivars with lower trichome density and larger trichomes are more resistant to whitefly infestation and subsequent Sri Lankan cassava mosaic virus transmission. These insights are valuable for cassava breeding programs focused on enhancing pest resistance, highlighting the importance of trichome characteristics in developing more resilient cassava varieties. [ABSTRACT FROM AUTHOR]

Rice is one of the essential daily commodity for most of Asian. However, the brown plant hopper (BPH; Nilaparvata lugens) infestation had been threatening the increasing demand of rice production. Evaluating resistance level of rice cultivars against BPH will help in managing BPH infestation. The feeding behavior monitoring of brown plant hopper (BPH; Nilaparvata lugens) by using an electrical penetration graph (EPG) was conducted to evaluate the resistance level of several rice cultivars against BPH, including pigmented rice (black rice cv. Sembada hitam; red rice cv. Sembada merah); and the commonly consumed white rice (cv. Ciherang). The EPG instrument allowed the monitoring of BPH feeding behaviors by quantifying three unique waveforms, namely, N3, N4, and N5, which represent BPH feeding activities in areas near phloem tissues, in phloem tissues, and in xylem tissues, respectively. EPG monitoring of BPH feeding activities in black rice revealed the absence of the N3 and N4 waveforms. Red rice showed the N3 waveform but not the N4 waveform. White rice showed all three waveforms occurring with high numbers and long total durations. The absence of the N4 waveform in the two pigmented rice cultivars indicated the failure of BPH to access phloem tissues. Overall, the results revealed that the resistance of rice against BPH based on feeding activity could be ordered as follows: black rice > red rice > white rice. This report provides essential information on the resistance mechanism of pigmented rice cultivars against BPH.

Simple Summary: Endophytic fungi in pasture grasses help the plant resist unfavourable biotic and abiotic conditions. Despite some well-documented aspects of how these fungi confer resistance to insects, some mechanisms are not well known. In this work, we measured the effects of such endophytes on aphids, an important pest group. We measured aphid feeding activity and life-history effects to further understand the mode of action of endophyte–perennial ryegrass systems. We were able to demonstrate that, in some cases, fungal endophytes significantly deterred feeding, but in other cases, feeding was not affected, and yet high mortality was observed. This suggests a complex scenario of interactions between compounds in the endophyte–perennial-ryegrass–aphid system. Our study shows that fungal endophytes have the potential to improve sustainable aphid control by decreasing the use of insecticide sprays. The bird cherry-oat aphid, Rhopalosiphum padi (L.), is an economically significant pest of pasture grasses, the latter being capable of hosting several fungal endophyte–perennial ryegrass symbiota rich in alkaloids and toxic to vertebrates and invertebrates. Measuring aphid feeding behaviour can provide insights into the effectiveness and mode of action of different fungal endophytes. This study investigated the effects of different Epichloë–perennial ryegrass symbiota on the feeding behaviour of R. padi using the electrical penetration graph technique while also assessing the aphid life history. In most cases, endophytes had significant feeding deterrence and paired fecundity and mortality effects. But, in some instances, endophytes with the highest aphid mortality did not significantly deter feeding, suggesting a more complicated scenario of interactions between the relative concentration of metabolites, e.g., host plant defence response metabolites and alkaloids, and/or physical changes to leaf morphology. Overall, this study sheds light on the mode of action of Epichloë endophytes against aphids and highlights the importance of Epichloë–perennial ryegrass symbiota in the management of insect pests such as aphids in pasture-based grazing systems. [ABSTRACT FROM AUTHOR]

The sweet potato whitefly, Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae), is highly harmful to solanaceous crops. The use of essential oils (EOs) is promising for the management of several insect pests, promoting both lethal and sublethal effects. This study aimed to evaluate the effects of sublethal concentrations of Pelargonium graveolens L'Her (Geraniaceae) EO on the feeding behavior of B. tabaci MED on tomato plants (Solanum lycopersicum L., Solanaceae). For this research, the electrical penetration graph (EPG) technique was used to monitor whitefly stylet activities on their host plants. Two sets of plants were previously sprayed with two concentrations of EO (the LC25 and LC50, which were determined in a mortality test), a third set was treated with the insecticide cyantraniliprole, and a fourth set received a control treatment. Our results indicate that the insecticide cyantraniliprole and the EO could both reduce the stylet feeding activity of B. tabaci MED, as well as reduce the number and duration of phloem sap ingestion events (waveform E2), which could avoid or reduce the transmission of viruses. Thus, the application of sublethal concentrations of P. graveolens EO, as well as exposure to cyantraniliprole, negatively affected the feeding behavior of B. tabaci MED. This information may contribute to the management of this pest and the reduction of the incidence of viruses in tomato production. [ABSTRACT FROM AUTHOR]

Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid, Diaphorina citri Kuwayama, which serves as vector of phytopathogens causing citrus greening. However, development of resistance to neonicotinoids among populations of D. citri has coincided with occasional control failures in the field. The objectives of this research were to (1) survey current levels of imidacloprid resistance in Florida citrus; (2) compare feeding behavior between imidacloprid‐resistant and susceptible D. citri using electrical penetration graph recordings, and (3) investigate the possible amplification of insecticide hormoligosis associated with resistance. Field surveys confirmed that the susceptibility of D. citri populations to imidacloprid has decreased in commercial Florida citrus groves compared with a laboratory‐susceptible population. Following 12 generations of selection, resistance to imidacloprid increased by 438 fold compared with the susceptible strain. Imidacloprid‐susceptible D. citri feeding on citrus exhibited significantly more bouts associated with intercellular pathway (C), phloem penetration (D), phloem salivation (E1), and nonprobing (Np) activities than imidacloprid‐resistant counterparts. However, there were no differences observed in the frequency or duration of phloem ingestion or xylem feeding between susceptible and resistant D. citri. There was no statistical difference in fecundity between resistant and susceptible strains. However, the fecundity of imidacloprid‐susceptible female D. citri treated with a sublethal concentration of imidacloprid (LC25) increased significantly compared with controls, while such hormoligosis was less pronounced among imidacloprid‐resistant psyllids. Our results suggest that imidacloprid‐resistant psyllids may cease feeding sooner than susceptible counterparts following sublethal exposure to this insecticide, indicative of a behavioral resistance mechanism. [ABSTRACT FROM AUTHOR]

Culex tarsalis Coquillett (Diptera: Culicidae) mosquitoes are capable of vectoring numerous pathogens affecting public and animal health. Unfortunately, the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues. Electropenetrography (EPG) has the potential to elucidate these behaviors by recording the electrical signals generated during probing. We used an AC–DC EPG with variable input resistors (Ri levels) to construct a waveform library for Cx. tarsalis feeding on human hands. Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types. The optimal settings for EPG recordings of Cx. tarsalis probing on human hands was an Ri level of 107 Ohms using an applied signal of 150 millivolts alternating current. Waveforms for Cx. tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti L. (Diptera: Culicidae): waveform families J (surface salivation), K (stylet penetration through the skin), L (types 1 and 2, search for a blood vessel/ingestion site), M (types 1 and 2, ingestion), N (type 1, an unknown behavior which may be a resting and digestion phase), and W (withdrawal). However, we also observed variations in the waveforms not described in Ae. aegypti, which we named types L3, M3, M4, and N2. This investigation enhances our understanding of mosquito probing behaviors. It also provides a new tool for the automated calculation of peak frequency. This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets. [ABSTRACT FROM AUTHOR]

Cowpea (Vigna unguiculata) is one of the most important crops in semiarid areas of the world, where it thrives in hot, dry conditions. While cowpea is able to withstand abiotic stresses, it suffers serious losses from biotic antagonists, including infestation by the cowpea aphid (Aphis craccivora). Cowpea aphid infestations are highly destructive, especially on young plants. However, it is unclear whether cowpea aphid damage is the result of aphids having phytotoxic effects on their hosts, or simple density effects. To better understand cowpea aphid damage and the potential for resistance traits to mitigate aphid impacts, we evaluated phenotypic changes in cowpea in response to variable aphid densities and systemic versus local infestations. Low aphid densities induced leaf distortions and pseudogalling, suggesting that cowpea aphids are phytotoxic to cowpea. Resistance to the cowpea aphid has been previously identified in an African cowpea germplasm, and near isogenic lines (NILs) containing resistance quantitative trait loci (QTL) were generated in the California blackeye cultivar background. Using a series of performance assays, we determined that resistance conferred by the two QTL counteracts aphid phytotoxicity and severely limits aphid growth and fecundity. Using choice assays, a preference by cowpea aphids for the susceptible NIL was observed. Electrical penetration graph analysis revealed that the resistance phenotype includes weak surface level deterrence and strong phloem-based resistance that manifests during the sap ingestion phase. Our study provides evidence of phytotoxic traits in A. craccivora while identifying a viable means of counteracting aphid damage and reproductive potential through resistance.

Bemisia tabaci New World (NW) (Gennadius) (Hemiptera: Aleyrodidae), a whitefly in the B. tabaci species complex, is polyphagous on many plant species. Yet, it has been displaced, albeit not entirely, by other whitefly species. Potential causes could include issues with adaptation, feeding, and the colonization of new-hosts; however, insights that would help clarify these possibilities are lacking. Here, we sought to address these gaps by performing electropenetrography (EPG) recordings of NW whiteflies, designated "Napus" and "Rapa," reared on 2 colony hosts, Brassica napus and B. rapa , respectively. Analysis of 17 probing and pathway (pw) phase-related EPG variables revealed that the whiteflies exhibited unique probing behaviors on their respective colony hosts, with some deterrence being encountered on B. rapa. Upon switching to B. rapa and B. napus , the probing patterns of Napus and Rapa whiteflies, respectively, adapted quickly to these new-hosts to resemble that of whiteflies feeding on their colony hosts. Results for 3 of the EPG variables suggested that B. rapa 's deterrence against Napus whitefly was significant prior to the phloem phase. This also suggested that adaptation by Rapa whitefly improved its pw probing on B. rapa. Based on analysis of 24 phloem phase-related EPG variables, Napus and Rapa whiteflies performed equally well once they entered phloem phase and exhibited comparable phloem acceptability on both the colony- and new-hosts. These findings demonstrate that NW whiteflies reared on a colony host are highly adaptable to feeding on a new host despite encountering some deterrence during the nonphloem phases in B. rapa plant. [ABSTRACT FROM AUTHOR]

Plant pathogens can alter the behavior of their insect vectors as well as their survival and reproduction. The African psyllid, Trioza erytreae, is one of the vectors of Huanglongbing, a citrus disease caused mainly by "Candidatus Liberibacter asiaticus" (CLas). The purpose of this study was to characterize the effects of CLas on the psyllid, T. erytreae using Citrus volkamerina plants as the study system. The study focused more specifically on the CLas effects prior to and after its acquisition by the psyllid T. erytreae. Our results did not support the hypothesis that CLas effects psyllid probing behavior prior to acquisition; few differences were observed between uninfected T. erytrea feeding on CLas‐infected versus control plants. On the other hand, compared to psyllids that had completed their development on control plants, the ones that had completed their development on a CLas‐infected plant exhibited changes in their behavior (greater velocity), physiology (smaller mass) and biochemistry (lower water and lipid content). Altogether, our results confirm the existence of a marked postacquisition effect on the vector locomotor behavior and a minor preacquisition effect of CLas on the vector behavior, which can be partially explained by physiological and biochemical changes. [ABSTRACT FROM AUTHOR]

Simple Summary: Historically, the pesticidal Bacillus thuringiensis proteins in transgenic cotton cultivars have shown no activity on mirid pests such as the cotton fleahopper. Therefore, control options are limited to foliar applied insecticides, which are often not optimized for reducing potential yield losses. With the inclusion of the Mpp51Aa2 protein, termed ThryvOn, damage from cotton fleahopper feeding can be mitigated. While the effect of the protein has been observed in field studies, there is a limited understanding of the interaction of the protein and the insect. Therefore, the focus of this study was the use of electropenetrography to monitor the feeding behaviors of the cotton fleahopper on both ThryvOn and a non-ThryvOn cotton cultivars. We found that although attempts were made by insects to feed on ThryvOn cotton, they exhibited shorter durations of plant fluid ingestion when feeding. Additionally, the percentage of ingestion events per insect that were sustained was lower. These findings indicate potential damage to the insect gut, consistent with the known symptoms associated with the activity of Bt proteins. Prior to the recent implementation of the Mpp51Aa2 pesticidal protein (ThryvOn), transgenic cotton cultivars have historically offered no control of the cotton fleahopper (Pseudatomocelis seriatus (Reuter)). To evaluate the feeding behavior of cotton fleahoppers on ThryvOn cotton, electropenetrography (EPG) using a Giga-8 DC instrument was used to monitor the probing activity of fourth- and fifth-instar cotton fleahopper nymphs on both ThryvOn and non-ThryvOn cotton squares. Nymphs were individually placed on an excised cotton square for 8 h of EPG recording, after which resulting waveforms were classified as non-probing, cell rupturing, or ingestion. Although there were significantly more cell rupturing events per insect on ThryvOn (mean ± SEM, 14.8 ± 1.7) than on non-ThryvOn squares (mean ± SEM, 10.3 ± 1.6), there was no difference attributable to ThryvOn in the average number of ingestion events per insect. However, the average duration of ingestion events was significantly shorter on squares with ThryvOn (mean ± SEM, 509 ± 148 s) than on squares without (mean ± SEM, 914 ± 135 s). This suggests that cotton fleahoppers continued to probe despite their inability to sustain ingestion. These results provide conclusive evidence that the Mpp51Aa2 pesticidal protein affects the feeding behavior of cotton fleahopper nymphs. [ABSTRACT FROM AUTHOR]

The electrical penetration graph (EPG) technique is of great significance in elucidating the mechanisms of virus transmission by piercing-sucking insects and crop resistance to these insects. The traditional method of manually processing EPG signals encounters the drawbacks of inefficiency and subjectivity. This study investigated the data augmentation and automatic identification of various EPG signals, including A, B, C, PD, E1, E2, and G, which correspond to distinct behaviors exhibited by the Asian citrus psyllid. Specifically, a data augmentation method based on an improved deep convolutional generative adversarial network (DCGAN) was proposed to address the challenge of insufficient E1 waveforms. A multi-criteria evaluation framework was constructed, leveraging maximum mean discrepancy (MMD) to evaluate the similarity between the generated and real data, and singular value decomposition (SVD) was incorporated to optimize the training iterations of DCGAN and ensure data diversity. Four models, convolutional neural network (CNN), K-nearest neighbors (KNN), decision tree (DT), and support vector machine (SVM), were established based on DCGAN to classify the EPG waveforms. The results showed that the parameter-optimized DCGAN strategy significantly improved the model accuracies by 5.8%, 6.9%, 7.1%, and 7.9% for DT, SVM, KNN, and CNN, respectively. Notably, DCGAN-CNN effectively addressed the skewed distribution of EPG waveforms, achieving an optimal classification accuracy of 94.13%. The multi-criteria optimized DCGAN-CNN model proposed in this study enables reliable augmentation and precise automatic identification of EPG waveforms, holding significant practical implications for understanding psyllid behavior and controlling citrus huanglongbing.

This study investigates the settling preferences and feeding behavior of the Bemisia tabaci whitefly on six cassava cultivars using electrical penetration graph techniques. Six distinct electrical penetration graph waveforms—non-probing, stylet pathway, phloem salivation, phloem ingestion, intracellular puncture, and xylem feeding—were identified and analyzed. Significant differences in the frequency and duration of these waveforms were observed among the cassava cultivars. The whiteflies spent the majority of their time in the non-probing phase, particularly on the Huaybong 80, Kasetsart 50, Rayong 9, and Rayong 72 cultivars. CMR-89 cultivar exhibited higher total probe durations in the phloem salivation and ingestion waveforms, suggesting a greater potential for transmission of the Sri Lankan cassava mosaic virus. The study also examined trichome density and size across the cassava cultivars, revealing that CMR-89 had the highest density and small trichomes, while Huaybong 80 had the lowest density. Trichome characteristics significantly impacted whitefly behavior: larger trichomes were negatively correlated with whitefly settling, whereas higher trichome density was positively correlated with longer settling durations. These findings indicate that trichome-based resistance mechanisms are crucial in whitefly deterrence. Overall, the results suggest that cultivars with lower trichome density and larger trichomes are more resistant to whitefly infestation and subsequent Sri Lankan cassava mosaic virus transmission. These insights are valuable for cassava breeding programs focused on enhancing pest resistance, highlighting the importance of trichome characteristics in developing more resilient cassava varieties.

The onion aphid, Neotoxoptera formosana , poses a significant threat to Allium crops worldwide, causing considerable economic losses and quality degradation. To develop effective pest management strategies, it is crucial to understand the feeding behavior and life history of this pest on different Allium crops. In this study, the electrical penetration graph (EPG) technique was used to monitor the thorn-feeding behavior of the onion aphid on 4 Allium crops: leek, chive, garlic, and shallot. The EPG data revealed distinct feeding patterns, with garlic and shallots being more preferred hosts than chives. Additionally, the aphids primarily fed on the phloem in garlic and shallots. Analysis of life history trait showed that chives provided the most favorable conditions for aphid development and reproduction, while leek exhibited relatively unfavorable conditions. Examination of leaf histology also revealed differences among the crops, which may influence aphid feeding behavior. This study provides valuable insights into the interaction between the onion aphid and different Allium crops, aiding in the development of comprehensive pest control strategies to minimize crop damage and economic losses. The use of advanced techniques like EPG contributes to a more detailed understanding of aphid behavior and shows promise for improving pest management in other plant-pest interactions. [ABSTRACT FROM AUTHOR]

Among insect pests of field crops, sap-sucking insects are a major threat to all agricultural commodities. The sucking insect pests damage the crops by sucking the sap thereby weakening the plants, and transmitting several bacterial, fungal and viral pathogens. The electrical penetration graph (EPG) has emerged as a highly valuable tool for analyzing the feeding behavior of sap-sucking insects on a broad range of host plants, examining pathogen transmission, evaluating the efficacy of feeding-restricting insecticides, plant responses to insect attack, and insect morphology and physiology. The EPG generates waveforms that facilitate the observation of probing behavior of the insects, enabling them to gain insights into the mechanisms and extent of underlying feeding. The integration of multiple complementary techniques, including histological analysis, video tracking, electron microscopy, elicitor proteins, and gene editing, has yielded significant advancements in the management of sap-sucking insects. These techniques have provided a deeper understanding of the underlying mechanisms and interactions involved in insect feeding behaviors, offering new opportunities for targeted interventions and improved pest control strategies. The EPG has been employed since the last five decades, yet needs to be investigated at higher levels with modernization. In spite of having a wide application, it still faces certain limitations, challenges, and research gaps that require addressing for enabling the scientists in novel findings. This review paper provides a historical prospect, the applications and technical intricacies of EPG. [ABSTRACT FROM AUTHOR]

Aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is a polyphagous insect species that migrates into the upper Midwest of the United States and the Western Canadian Prairies. Populations of this insect are associated with the transmission of a plant pathogen (Candidatus Phytoplasma asteris, 16SrI) to several annual crops and perennial plant species. Previous studies suggest that aster leafhoppers can sometimes prefer less suitable hosts for their development and survival, yet it is unclear if this lower performance on certain plant species is associated with reduced or impaired probing behaviors due to characteristics of the plants. To characterize the probing behaviors of aster leafhoppers, direct current electropenetrography recordings of male and female adults on barley (Polaes: Poaceae: Hordeum vulgare L.) were combined with plant histology, allowing the identification of nine waveforms and their proposed biological meanings. For each waveform, the number of waveform events per insect (NWEI), the waveform duration per insect (WDI), the waveform duration per event per insect (WDEI), and the percentage of recording time were calculated and statistically compared between sexes. Male and female aster leafhoppers exhibited similar behavioral responses for most of these variables, except for the NWEI for waveforms associated with nonprobing activities and the pathway phase. In these cases, male aster leafhoppers exhibited a higher number of events than females. Comparison of the proposed waveforms in this study with previous work on other hemipteran species provided additional support to the interpretation of the biological activities associated with each waveform. [ABSTRACT FROM AUTHOR]

Sap‐sucking insects often transmit plant viruses but also carry insect viruses, which infect insects but not plants. The impact of such insect viruses on insect host biology and ecology is largely unknown. Here, we identified a novel insect‐specific virus carried by brown citrus aphid (Aphis citricidus), which we tentatively named Aphis citricidus picornavirus (AcPV). Phylogenetic analysis discovered a monophyletic cluster with AcPV and other unassigned viruses, suggesting that these viruses represent a new family in order Picornavirales. Systemic infection with AcPV triggered aphid antiviral immunity mediated by RNA interference, resulting in asymptomatic tolerance. Importantly, we found that AcPV was transmitted horizontally by secretion of the salivary gland into the feeding sites of plants. AcPV influenced aphid stylet behavior during feeding and increased the time required for intercellular penetration, thus promoting its transmission among aphids with plants as an intermediate site. The gene expression results suggested that this mechanism was linked with transcription of salivary protein genes and plant defense hormone signaling. Together, our results show that the horizontal transmission of AcPV in brown citrus aphids evolved in a manner similar to that of the circulative transmission of plant viruses by insect vectors, thus providing a new ecological perspective on the activity of insect‐specific viruses found in aphids and improving the understanding of insect virus ecology. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sugar beet (Beta vulgaris ssp. vulgaris), a key crop for sugar production, faces significant yield losses caused by the black bean aphid Aphis fabae (Scop.) and the green peach aphid Myzus persicae (Sulzer), which also transmits viruses. The restriction on neonicotinoid usage in Europe has intensified this problem, emphasizing the urgent need for breeding resistant crop varieties. This study evaluated 26 sugar beet germplasms for resistance against both aphid species by using performance and feeding behavior assays. Additionally, whole plant bioassays and semi‐field experiments were carried out with Myzus persicae. RESULTS: Our findings demonstrate the presence of temporal resistance against both aphid species in the primary sugar beet gene pool. Beet yellows virus (BYV) carrying aphids showed enhanced performance. Different levels of plant defense mechanisms were involved including resistance against Myzus persicae before reaching the phloem, particularly in sugar beet line G3. In contrast, resistance against Aphis fabae turned out to be predominately phloem‐located. Furthermore, a high incidence of black inclusion bodies inside the stomach of Myzus persicae was observed for approximately 85% of the plant genotypes tested, indicating a general and strong incompatibility between sugar beet and Myzus persicae in an initial phase of interaction. CONCLUSION: Sugar beet resistance against aphids involved different mechanisms and is species‐specific. The identification of these mechanisms and interactions represents a crucial milestone in advancing the breeding of sugar beet varieties with improved resistance. © 2023 Julius Kühn‐Institut and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The bird cherry-oat aphid, Rhopalosiphum padi (L.), is an economically significant pest of pasture grasses, the latter being capable of hosting several fungal endophyte–perennial ryegrass symbiota rich in alkaloids and toxic to vertebrates and invertebrates. Measuring aphid feeding behaviour can provide insights into the effectiveness and mode of action of different fungal endophytes. This study investigated the effects of different Epichloë–perennial ryegrass symbiota on the feeding behaviour of R. padi using the electrical penetration graph technique while also assessing the aphid life history. In most cases, endophytes had significant feeding deterrence and paired fecundity and mortality effects. But, in some instances, endophytes with the highest aphid mortality did not significantly deter feeding, suggesting a more complicated scenario of interactions between the relative concentration of metabolites, e.g., host plant defence response metabolites and alkaloids, and/or physical changes to leaf morphology. Overall, this study sheds light on the mode of action of Epichloë endophytes against aphids and highlights the importance of Epichloë–perennial ryegrass symbiota in the management of insect pests such as aphids in pasture-based grazing systems.

BACKGROUND: Sexual dimorphism exists in most insects; however, less is known about sexual dimorphism in aphids. In this study, we identified sexually dimorphic differences in morphology, feeding behavior and gene expression between sexual females and males of the cotton aphid through electron microscopy, electrical penetration graph techniques and RNA sequencing. RESULTS: All males were alate with a slender reddish‐yellow body and abdominal yellow–black stripes, whereas all sexual females were apterous with a pudgy green body. Sensillum types on the antennae were identical between the two sexes, although males had more sensilla, possibly because the antennae are significantly longer in males compared with sexual females. In terms of feeding behavior, males spent more time probing mesophyll cells and the phloem sieve, and salivating into the phloem sieve. By contrast, sexual females spent more time ingesting xylem sap. In total, 510 and 724 genes were specifically expressed in sexual females and males, respectively, and were significantly enriched in signaling pathways related to reproduction for sexual females (e.g. ovarian steroidogenesis, oxytocin signaling pathway) and energy and flight for males (e.g. thermogenesis, insulin signaling pathway). Moreover, 8551 differentially expressed genes were identified between the two sexes, of which the 3720 upregulated genes in sexual females were mostly enriched in signaling pathways of metabolism and energy, such as thermogenesis and the citrate cycle. CONCLUSION: This study provides insight into sexual dimorphism in aphids and lays a foundation for revealing the molecular mechanism underlying differences between the two sexes in cotton aphid. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The adaptability of phytophagous insects to different host plants is a key determinant of their population propagation. Understanding the feeding behaviour and population dynamics of insects is crucial for elucidating host adaptability and screening for insect-resistant germplasms. Here, we investigated Toxoptera aurantii (Hemiptera: Aphididae) adaptability using electropenetrography and assessed its population growth on seven tea cultivars: Huangjinya (HJY), Qianmei601 (QM601), Fudingdabaicha (FD), Longjing43 (LJ43), Qiancha1 (QC1), Qiancha8 (QC8) and Qiancha10 (QC10). The results showed that the feeding behaviour of T. aurantii differed significantly depending on the tea cultivars. The initial probing of T. aurantii on HJY was the earliest among the seven host plants. Aphids on QC1 and QC10 displayed an increased duration of stylet probing and decreased ingestion of phloem sap, whereas a contrasting trend was observed for aphids on HJY. In addition, the mechanical resistance of T. aurantii fed on HJY and QM601 during the probing phase was significantly lower than that of aphids fed on other cultivars. Population dynamic parameters revealed that the growth rate of T. aurantii reared on HJY was the fastest, and its population quantity within 15 days was markedly higher than that of aphids fed on other cultivars. These findings demonstrate that HJY is the most suitable host plant, whereas QC1 and QC10 are less suitable hosts for T. aurantii, although the aphids successfully survived on all the selected tea cultivars. Our results provide valuable information for the biological control of T. aurantii using resistant tea varieties. [ABSTRACT FROM AUTHOR]

Over the past few decades, inadvertent consequences have stemmed from the intensified use of neonicotinoids in agroecosystems. Neonicotinoid applications can result in both positive (e.g. reduced persistent virus transmission) and negative (e.g. increased host susceptibility) repercussions exhibiting ambiguity for their use in crop production. In soybean, aspects of neonicotinoid usage such as the impact on nonpersistent virus transmission and efficacy against nontarget herbivores have not been addressed. This study evaluated the interaction between the neonicotinoid thiamethoxam and soybean variety and the impact on different pest feeding guilds. Feeding and behavioral bioassays were conducted in the laboratory to assess the effect of thiamethoxam on the mortality and weight gain of the defoliator, Chrysodeixis includens (Walker). Bioassays evaluated impacts dependent and independent of soybean tissue, in addition to both localized and systemic efficacy within the soybean plant. Additionally, using the electrical penetration graph technique (EPG), the probing behavior of 2 piercing-sucking pests, Aphis gossypii Glover and Myzus persicae (Sulzer), was observed. Results from defoliator bioassays revealed thiamethoxam had insecticidal activity against C. includens. Distinctions in thiamethoxam-related mortality between bioassays dependent and independent of soybean tissue (~98% versus ~30% mortality) indicate a contribution of the plant towards defoliator-related toxicity. Observations of defoliator feeding behavior showed a preference for untreated soybean tissue relative to thiamethoxam-treated tissue, suggesting a deterrent effect of thiamethoxam. EPG monitoring of probing behavior exhibited a minimal effect of thiamethoxam on piercing-sucking herbivores. Findings from this study suggest neonicotinoids like thiamethoxam may provide some benefit via insecticidal activity against nontarget defoliators. [ABSTRACT FROM AUTHOR]

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This study aimed to characterize and correlate the stylet penetration behaviors of nymphs of the Neotropical brown stink bug, Euschistus heros (F.), on immature soybean pods. Waveforms were obtained using electropenetrography (EPG). The findings revealed that the nymphs exploited the xylem vessels and the seed tegument or endosperm. Primarily 4 phases were characterized: nonfeeding, pathway, salivation, and ingestion. The waveforms of each phase were similar in appearance across instars. The biological meanings of waveforms were based on visual observations, comparison with waveforms of adults, and histological studies. Np represents the insect resting or walking on soybean pod surface. Eh1 represents the first contact between the mouthparts (stylets) and plant tissue. Eh2 represents xylem sap ingestion, and Eh3 represents seed activities (including tegument and endosperm). The number of waveform events did not differ among instars for all waveforms. However, for Eh3, fifth instars performed more activities than other instars. The second instars had the smallest value, and third and fourth instars had intermediate values. For total duration, all waveforms differed among instars. Np duration was shorter for third compared with second and fourth instars and intermediate for fifth instar. For Eh1, second and third instars had the longest duration (1.5× to 2× greater) compared with fourth and fifth instars. For Eh2 and Eh3, the second-instar showed the longest (~2× greater) and shortest durations, respectively. Overall, this study provides important insights into the feeding behavior of E. heros nymphs so that effective pest management programs can be developed to contain this pest. [ABSTRACT FROM AUTHOR]

Prior to feeding on phloem, aphids perform a preamble of brief intracellular punctures of the cortical parenchyma, ingesting a small amount of cytoplasm from each cell. Given the length of time aphids spend puncturing parenchyma cells before and after phloem feeding, we propose that they are not just testing for potential hosts or mobilizing phloem nutrients, but are actively engaged in 'cytoplasmic feeding'. We combine the electrical penetration graph (EPG) technique to monitor feeding behavior of Myzus persicae (Sulzer) (Hemiptera: Aphididae) with confocal fluorescence microscopy to determine the uptake of parenchyma cytoplasm in the model plant Arabidopsis thaliana (L.) Heynh. (Brassicaceae). Aphids repetitively punctured parenchyma cells throughout the monitoring period, both before and after phloem feeding. As aphids puncture parenchyma cells of A. thaliana expressing cytoplasmic yellow fluorescent protein, the protein is ingested, increasing the intensity in the aphid stylet. The extended time of high‐frequency punctures of parenchyma cells prior to phloem sap ingestion avoids the dilution of the intestinal content resulting from immediate phloem feeding. The enriched nutrient content of parenchyma cytoplasm has time to be absorbed by the intestine into the hemocoel without dilution and excretion in the honeydew. [ABSTRACT FROM AUTHOR]

Tripartite plant–pathogen–phytophagous insect interactions have been widely studied. However, the effect of pathogens on phytophagous insects remains uncertain. Although alfalfa is a widely cultivated forage legume, Peronospora aestivalis and Therioaphis trifolii often co-occur in alfalfa, reducing quality and yields. To explore the relationships between alfalfa Zhongcao No. 3, P. aestivalis, and T. trifolii, an electrical penetration graph and four-arm olfactometer were used to determine T. trifolii behavior on infected and uninfected alfalfa. The physicochemical properties of infected alfalfa leaves were determined. The effects of volatiles on the selection behavior of T. trifolii were analyzed, and the effect of substance content on host selection behavior was determined. Peronosporaaestivalis altered the nutrient composition of alfalfa, and T. trifolii preferentially fed on moderately infected alfalfa (P2) rather than severely infected alfalfa (P3). The E1 and E2 waveform durations were the shortest (11.87 min) and the longest in P2 (122.82 min), respectively. Therioaphistrifolii mostly chose moderately (25.71%) and severely (37.14%) infected alfalfa plants via olfaction. The analysis of volatile components revealed 53 substances in 8 categories. Among them, decanal (1×) and naphthalene (1000× and 10,000×) had a strong repellent effect on T. trifolii, whereas naphthalene (1×), cedrol (100×), 2,6,10,14,18,22-tetracosahexaene, 2,6,10,15,19,23- (1000× and 10,000×) attracted T. trifolii. Our results provide new insights into plant disease and insect pest control and prevention. [ABSTRACT FROM AUTHOR]

Does Xylella fastidiosa , a bacterial plant pathogen with noncirculative foregut-borne transmission, manipulate behavior of its sharpshooter vector to facilitate its own inoculation? To answer this question, blue-green sharpshooters, Graphocephala atropunctata (Signoret), were reared on basil to clean their foreguts, then removed from the colony and given one of four pre-electropenetrography (EPG) treatments: i) old colony adults on basil, ii) young colony adults on basil, iii) young colony adults held on healthy grapevine for 4 days, and iv) young colony adults held on Xf -infected (symptomatic) grapevine for 4 days. After treatments, stylet probing behaviors were recorded on healthy grapevine via AC-DC electropenetrography. Waveforms representing putative Xf inoculation (XB1 [salivation and rinsing egestion] and XC1 [discharging egestion]) and other behaviors were statistically compared among treatments. Mean number of events per insect and 'total' duration per insect of XB1 and XC1 were highest for insects from healthy grape, lowest for basil (regardless of insect age), and intermediate for Xf -infected grape. The surprising results showed that prior exposure to healthy grapevines had a stronger effect on subsequent performance of inoculation behaviors on healthy grapevine than did prior exposure to Xf -infected grapevine. It is hypothesized that non- Xf microbes were acquired from healthy grapevine, causing greater clogging of the precibarium, leading to more performance of inoculation behaviors. This study shows for the first time that presence of noncirculative, foregut-borne microbes can directly manipulate a vector's behavior to increase inoculation. Also, EPG can uniquely visualize the dynamic interactions between vectors and the microbes they carry. [ABSTRACT FROM AUTHOR]

Simple Summary: Diaphorina citri Kuwayama is a phloem-feeding insect that uses piercing–sucking mouthparts to ingest phloem sap from plants. It is the most common citrus pest because it spreads the bacteria that causes huanglongbing during the probing and feeding process. Nowadays, eco-friendly methods such as soil amendment with vermicompost are gaining popularity in the integrated management of D. citri. Here, we investigated why vermicompost amendments cause negative effects to D. citri. We observed that vermicompost disrupted D. citri feeding behavior, particularly for the variables related to phloem sap ingestion, with a significant reduction in the duration of phloem sap ingestion as well as a longer time spent to reach and gain access to phloem sap. Additionally, we demonstrated that vermicompost amendments increased plant defense-associated enzyme activities. We speculate that vermicompost amendments enhance plant resistance against D. citri, which disrupts the insect feeding and eventually impairs the performance of D. citri. Furthermore, we showed how vermicompost amendments affect the feeding behavior of piercing–sucking insects for the first time, and the feeding behavior (decreased efficiency of phloem sap ingestion) suggests vermicompost may suppress the transmission of huanglongbing bacteria by D. citri, yet it still needs to be further studied. Plants grown with vermicompost amendments are known to be harmful to sap-sucking insects, but the underlying mechanism remains to be determined. Here we investigated the feeding behavior of Diaphorina citri Kuwayama on Citrus limon (L.) Burm. F using the electrical penetration graph technique. Plants were grown in soil with different vermicompost rates (0%, 20%, 40%, and 60% w/w). Additionally, plants were tested for the activity of salicylic acid (SA) and jasmonic acid (JA) pathway-related enzymes. When compared to the control, vermicompost treatments (40% and 60%) decreased duration of phloem sap feeding and increased duration of the pathway phase of D. citri, and the 60% vermicompost made it more difficult for D. citri to reach and gain access to phloem sap. Enzymatic assays indicated that the 40% amendment rate increased phenylalanine ammonia lyase (involved in the SA pathway) and polyphenol oxidase (involved in the JA pathway), while the 60% amendment rate increased -1,3-glucanases (involved in the SA pathway) and lipoxygenase (involved in the JA pathway). The 20% amendment rate had no effect on feeding or enzyme activities. This study revealed that vermicompost amendments can reduce the efficiency of D. citri feeding, which may result from increased plant resistance via the SA and JA pathway. [ABSTRACT FROM AUTHOR]

Simple Summary: This study compared the feeding behavior of Riptortus pedestris and Halyomorpha halys on six soybean cultivars. In addition, the damage caused by R. pedestris and H. halys was field-surveyed. The non-penetration waveform was the shortest in Pungsannamul and the longest in Daepung-2ho. In the case of feeding waveforms of the xylem and phloem, it was the longest in Pungsannamul and the shortest in Daepung-2ho, respectively. When six soybean cultivars were planted in two fields, and the seed damage caused by hemipterans was investigated; in both fields, the proportions of damage type B and damage type C were the highest in Pungsannamul and the lowest in Daepung-2ho. The above results will be used as basic information in the control of hemipteran insect pests. Riptortus pedestris (Fabricius) and Halyomorpha halys (Stål) are the major pests that feed on soybean pods, seeds, and fruits. Higher populations and damage occur during the soybean maturity stages (podding to harvest). To compare the feeding behavior of R. pedestris and H. halys, we used the six most cultivated cultivars (Daepung-2ho, Daechan, Pungsannamul, Daewon, Seonpung, and Seoritae) in Korea using the electropenetrography (EPG) technique. Both R. pedestris and H. halys, the NP (non-penetration), a non-probing waveform, was the shortest in the Pungsannamul (298 and 268 min) and the longest in the Daepung-2ho (334 and 339 min), respectively. The feeding waveforms Pb (phloem feeding: E1-Salivation and E2-Sap feeding) and G (xylem feeding) were the longest in Pungsannamul and the shortest in Daepung-2ho. In addition, as a result of investigating the damage rate by planting six cultivars of beans in the field, as expected, the proportions of damage types B and C were highest in Pungsannamul and lowest in Daepung-2ho. These results reveal that both bug species ingest xylem sap from leaflets and stems using a salivary sheath strategy to acquire water and nutrients from soybean pods/seeds with cell-rupture tactics. This study provides perceptive information to understand the feeding behavior, field occurrence, and damage patterns of R. pedestris and H. halys, which may have key implications for the management of hemipteran pests by determining the specificity and susceptibility of host plants. [ABSTRACT FROM AUTHOR]

Apples and pears are among the most widely cultivated fruit species in the world. Pesticides are commonly applied using ground sprayers in conventional orchards; however, most of it will not reach the target plant, increasing the contamination of nontarget organisms such as natural predators, pollinators, and decomposers. Trunk injection is an alternative method of pesticide application that could reduce risks to beneficials and workers. Essential oils represent a 'green' alternative to pesticides due to their reported insecticidal, antimicrobial, antiviral, nematicidal, and antifungal properties. The aim of this study was, therefore, to evaluate the impact that the injection of a cinnamon essential oil solution into the trunk of apple and pear trees could have on their respective pests, Dysaphis plantaginea and Cacopsylla pyri, respectively. The feeding behavior (preference), the life history traits (performance), and the timing of this effect were measured. The injection of an essential oil emulsion in trees impacted hemipteran host-plant colonization, as for both species a modification of their preference and of their performance was observed. The feeding behavior of D. plantaginea was altered as a significantly lower proportion of aphids ingested phloem sap on injected trees, suggesting that the aphids starved to death. On the contrary, the feeding behavior of the psyllids was little changed compared to the control condition, implying that the observed mortality was due to intoxication. The results presented here could theoretically be used to control these two orchard hemipteran pests, although the effectiveness in real conditions still has to be demonstrated. [ABSTRACT FROM AUTHOR]

Most insect herbivores are adapted to feed on a few host plants only, but the mechanisms underlying plant specialization are poorly understood. One of the dominant hypotheses is that insects inject an oral secretion into the plant that manipulates the plant's defences resulting in induced susceptibility. This hypothesis was tested on the pea aphid (Acyrthosiphon pisum), which forms multiple biotypes, each specialized on specific legume hosts. In particular, the hypothesis that a pea-adapted biotype can induce host susceptibility on pea and increase the fitness of a non-pea-adapted biotype was tested. Survival and fecundity of an alfalfa-adapted biotype on peas were enhanced by co-infestation but not by pre-infestation with a pea-adapted biotype. The electrical penetration graph (EPG) method was then used to dissect the components of the alfalfa biotype feeding behaviour on peas with and without co-infestation by the pea biotype. While probing time did not differ between these two conditions, differences were observed in most other EPG parameters. When co-infested with the pea-adapted biotype, the alfalfa-adapted biotype was more likely to establish a phloem feeding and exhibited a longer ingestion time on peas. Our results indicated that the pea-adapted biotype induced pea susceptibility by increasing the accessibility of non-pea-adapted aphids to the host phloem sap. As a result, the alfalfa biotype increased its survival and fecundity. These results contribute to understanding how aphids manipulate their specific host plants. [ABSTRACT FROM AUTHOR]

'Candidatus Liberibacter solanacearum' (Lso) is a bacterial pathogen that causes 'zebra chip' disease in potato. Vectored by the potato psyllid Bactericera cockerelli, Lso inflicts severe economic losses annually in solanaceous and other crops. Conventional management strategies have been insufficient to control the pathogen. As an environmentally friendly phytosanitary technique, electron beam (eBeam) irradiation has been shown to drastically suppress psyllid growth and development. However, whether this chemical-free technology negatively impacts the pathogen transmission remains to be investigated. In this study, we irradiated newly emerged adult psyllids and measured abundance of Lso they carried. An eBeam dose of 100 Gy significantly suppressed Lso in irradiated psyllids, although a rebound was detected on day 7 post irradiation. This resumed bacterial growth was not observed in psyllids irradiated at 250 or 500 Gy. Electrical penetration graphs revealed that eBeam substantially impacted psyllid feeding activity. No significant difference was detected in actin cytoskeleton structure and nucleus integrity of its midgut cells 1 or 7 days post eBeam irradiation at 500 Gy. Furthermore, infection of tomato plants was drastically reduced when fed upon by psyllids exposed to 250 Gy and undetectable at 500 Gy. Thus, eBeam significantly lowered psyllid's transmission efficiency and even abolished this capacity. Taken together, eBeam irradiation curtailed Lso titers in potato psyllids and impaired its bacterial transmission. Our results have demonstrated the real potential of irradiation technology in management of insect-vectored diseases. [ABSTRACT FROM AUTHOR]

The combination of a companion plant with a cultivated plant is considered an interesting strategy to reduce pest pressure and, hence, the use of pesticides. Although several plants from the Alliaceae and Lamiaceae families are known to be efficient companion plants against aphid pests, only a few plants of the Geraniaceae family have been studied so far. The aim of this work was to investigate the potential effects of Geranium macrorrhizum as a companion plant on the colonization of sweet pepper (Capsicum annuum, Solanaceae) by the green peach aphid (Myzus persicae). Aphid's orientation behavior, probing behavior and life history traits were assessed on sweet pepper using a host choice preference setup, Electrical Penetration Graph technique and clip-cage laboratory bioassays, respectively. The potential disturbance through mechanical stimulation of geranium leaves was also assessed. The composition of VOCs from G. macrorrhizum leaves was analyzed using SPME technic followed by GC–MS. This study revealed that G. macrorrhizum as a companion plant was intrinsically repellent but not enough to completely mask the attractive odor of the sweet pepper host plant. Moreover, G. macrorrhizum negatively impacted the probing behavior, fecundity and survival rate of M. persicae on sweet pepper. The effects were exacerbated when G. macrorrhizum leaves were mechanically stimulated. This could be due to the greater amount of the main VOCs germacrone and β-elemenone emitted by G. macrorrhizum following mechanical stimulation. Our results bring new insights into the use of novel companion plants to regulate aphid pest populations. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown planthopper (BPH), Nilaparvata lugens and white-backed planthopper (WBPH) Sogatella furcifera are major rice pests in many parts of Asia. This study was conducted to elucidate the action mechanisms in sublethal exposures of imidacloprid and sulfoxaflor on the feeding behavior of the planthopper. The sublethal concentrations of imidacloprid and sulfoxaflor inhibited the phloem feeding of the BPH and WBPH and decreased their reproduction longevity. Additionally, sulfoxaflor was effective in inhibiting feeding in the BPH, and imidacloprid was more effective in inhibiting feeding in the WBPH. Therefore, sublethal effects of insecticide vary according to insect pest species. The brown planthopper (BPH) Nilaparvata lugens and white-backed planthopper (WBPH) Sogatella furcifera are serious rice insect pests that cannot overwinter in Korea and migrate from southeast Asian countries and China. In this study, we investigated the sublethal effects of imidacloprid and sulfoxaflor on the biological parameters and feeding behavior of planthoppers. These sublethal concentrations significantly decreased the net reproduction rate (R0), the intrinsic rate of increase (rm), and the mean generation time (T). For BPHs, the total durations of nonpenetration (NP) waveform by imidacloprid (LC10 = 164.74 and LC30 = 176.48 min) and sulfoxaflor (LC10 = 235.57 and LC30 = 226.93 min) were significantly different from those in the control group (52.73 min). In addition, on WBPHs, the total durations of NP waveform by imidacloprid (LC10 = 203.69 and LC30 = 169.9 min) and sulfoxaflor (LC10 = 134.02 and LC30 = 252.14 min) were significantly different from those in the control group (45.18 min). Moreover, the LC10 and LC30 of these insecticides significantly decreased the phloem feeding time. In conclusion, imidacloprid had a better effect on the inhibition of feeding of the WBPH, and sulfoxaflor showed a better effect on the inhibition of feeding of the BPH. Therefore, it is suggested that treatment with sublethal concentrations of the above insecticides will reduce the feeding of BPHs and WBPHs on rice phloem. [ABSTRACT FROM AUTHOR]

Asian citrus psyllid, Diaphorina citri, transmits Candidatus Liberibacter asiaticus (CLas), the bacterial pathogen responsible for citrus greening disease. To explore the possibility that cover crops in citrus groves may serve as refuges for this pathogen vector during unfavorable host conditions, psyllid feeding was investigated on six common cover crop species and citrus using electrical penetration graph (EPG) recordings and behavioral bioassays. EPG recordings showed that the proportion of time spent by D. citri feeding on xylem was similar or higher on all tested cover crops (17%–32%) compared to the positive control (12%), the preferred host, Citrus macrophylla. Very little to no phloem feeding was observed on cover crops by the adults. In the choice assays, more D. citri adults settled on buckwheat (Fagopyrum esculentum) and cowpea (Vigna unguiculata) than on the host, C. macrophylla, 24 h after release. No-choice assays showed that the citrus cover crop species evaluated extend the survival of D. citri up to 8 d because of xylem feeding. Our results indicate that some cover crop species may be less suitable refuge sites for D. citri than others, but none served as breeding sites or supported more than 8 d of survival. [ABSTRACT FROM AUTHOR]

The adaptability of phytophagous insects to different host plants is a key determinant of their population propagation. Understanding the feeding behaviour and population dynamics of insects is crucial for elucidating host adaptability and screening for insect-resistant germplasms. Here, we investigated Toxoptera aurantii (Hemiptera: Aphididae) adaptability using electropenetrography and assessed its population growth on seven tea cultivars: Huangjinya (HJY), Qianmei601 (QM601), Fudingdabaicha (FD), Longjing43 (LJ43), Qiancha1 (QC1), Qiancha8 (QC8) and Qiancha10 (QC10). The results showed that the feeding behaviour of T. aurantii differed significantly depending on the tea cultivars. The initial probing of T. aurantii on HJY was the earliest among the seven host plants. Aphids on QC1 and QC10 displayed an increased duration of stylet probing and decreased ingestion of phloem sap, whereas a contrasting trend was observed for aphids on HJY. In addition, the mechanical resistance of T. aurantii fed on HJY and QM601 during the probing phase was significantly lower than that of aphids fed on other cultivars. Population dynamic parameters revealed that the growth rate of T. aurantii reared on HJY was the fastest, and its population quantity within 15 days was markedly higher than that of aphids fed on other cultivars. These findings demonstrate that HJY is the most suitable host plant, whereas QC1 and QC10 are less suitable hosts for T. aurantii, although the aphids successfully survived on all the selected tea cultivars. Our results provide valuable information for the biological control of T. aurantii using resistant tea varieties.

Myzus persicae (Sulzer) is an important agricultural pest worldwide causing major economic losses due to its ability to transmit over 100 viruses including Potato virus Y (PVY). Myzus persicae shows considerable variation with respect to performance on its host plants. The objective of this study was to use a survival experiment, behavioural observations, including observations of probing and feeding behaviour obtained using the electrical penetration graph (EPG) technique, and a PVY acquisition experiment to determine whether or not potato was still the more suitable host for M. persicae originating on potato and reared on a novel host, table beet, for over 15 years. In a survival experiment, the pre-reproductive period was significantly longer while adult survival and whole longevity were significantly lower for M. persicae reared on beet fed beet leaves compared to M. persicae reared on potato fed potato leaves. The number of progenies produced and fecundity were both significantly reduced (90 and 85%, respectively) for M. persicae reared on beet fed beet leaves. Ethological observations and EPG assessment of M. persicae behaviour reared on beet placed on beet leaves showed significantly impaired behavioural responses compared to M. persicae reared on potato placed on potato leaves. The rate of PVY acquisition was the same for M. persicae reared on beet and on potato. These results indicate that after 15 years on table beet, M. persicae still performs better on its original host, potato, and appears to be a specialized potato-adapted genotype. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are promising sources of effective bioactive compounds for insect pest control, especially in heavily treated agrosystems like orchards. Plants belonging to the Amaryllidaceae family – onion, garlic (Allium sativum L.), and others – present an interesting potential in apple (Malus domestica Borkh.) and pear (Pyrus communis L., both Rosaceae) tree integrated pest management due to the repellent and deterrent properties of their chemical compounds. This study explores the potential disruption by garlic EOs of the behavior of two hemipteran pests towards their host trees: rosy apple aphid, Dysaphis plantaginea (Passerini) (Aphididae), on cultivated apple, and pear psyllid, Cacopsylla pyri (L.) (Psyllidae), on pear. Effects on orientation and feeding behavior were evaluated using choice tests and the electropenetrography (EPG) technique. The results revealed that garlic EOs delivered through rubber dispensers were intrinsically repellent, but when combined with the attractive host plant, the repellents and attractants canceled each other out for the two studied hemipterans. Garlic EOs caused disruptions in the feeding behavior of the two insects, particularly the psyllids, which showed a decrease in phloem sap intake. This study highlights the mechanisms disrupting the process of host‐plant colonization, in particular the possible masking of host‐locating cues or the involvement of confusing chemical stimuli due to EO volatiles. [ABSTRACT FROM AUTHOR]

In scientific work, sonification (i.e., the use of nonspeech audio to convey information) is primarily thought of as a novel way to communicate post hoc research findings to lay audiences but only rarely, if ever, as a component of the research itself. This article argues that, rather than any inherent epistemological limitations of sound as a medium of scientific reasoning, this framing reflects a sociohistorical tendency to "silence" experimental techniques as they become widely adopted—both in terms of the literal silencing of noisy instrumentation and the elision of the role of sound (along with other nonvisual sensory media) in received discovery accounts. This tendency is well-illustrated by the history of electrophysiology research, particularly the case of the electrical penetration graph (EPG), an instrument used by entomologists to study how insects feed on plants. Combining participant observation, interviews, and analysis of EPG technical literature, this article recovers the unacknowledged role of sound in EPG's exploratory stages and gradual emergence as a standard laboratory technique as well as its gradual silencing as a consequence of this standardizing process. [ABSTRACT FROM AUTHOR]

Aboveground and belowground herbivory can alter host quality and trophic interactions. However, little research has explored the impacts of belowground herbivory on plant virus epidemiology. To understand this interaction in sweetpotato, Ipomoea batatas L. (Lam), we studied the impact of herbivory by sweetpotato weevil, Cylas formicarius elegantulus (Summers), to storage roots on vector herbivore, Myzus persicae (Sulzer), the green peach aphid, and Aphis gossypii Glover, the cotton aphid, feeding behavior (M. persicae and A. gossypii) and population dynamics (M. persicae only as A. gossypii does not colonize sweetpotato). In addition, a nonvector herbivore, Chrysodeixis includens (Walker), the soybean looper, weight gain was included for comparison. Infestations of sweetpotato weevil in storage roots reduced C. includens weight gain and M. persicae intrinsic rate of increase (rm), net reproductive rate (Ro), and finite rate of increase (λ) on aboveground portions of the plant. In probing behaviors related to nonpersistent virus spread (30 min trials), M. persicae probed less often, took longer to reach the first pd (potential drop), had shorter II-3 (intracellular subphase sap ingestion) durations, and had fewer archlets on plants infested with C. formicarius elegantulus. Total phloem duration did not differ between treatments, indicating that the lowered performance of M. persicae on infested plants was not due to discrepancies in probing duration. Results were less clear for A. gossypii. Thus, in sweetpotato, belowground herbivory can alter plant virus vector abundance and behavior. Understanding the mechanisms underlying these changes in behavior could improve plant virus vector integrated pest management. [ABSTRACT FROM AUTHOR]

Simple Summary: Crapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae), an invasive polyphagous sap feeder in the United States, has spread across 16 U.S. states in less than two decades, posing potential risks to the Green Industry. Confirming the host range is crucial for effective pest management of invasive insects. However, host range confirmation relying on greenhouse or field trials is often inefficient and time-consuming. In this study, we used the electrical penetration graph (EPG) to monitor the stylet penetration of CMBS in plant tissue in real-time. An R programming-based application was developed to better characterize the insect EPG waveforms recorded by EPG. By analyzing EPG-based EPG parameters, we demonstrated that CMBS has difficulty accessing the phloem tissue (salivation and ingestion) of a resistant plant compared to a susceptible plant. Importantly, we hereby present CMBS typical feeding behaviors on susceptible and non-susceptible plants comparatively, which provides direct evidence for revealing unknown hosts rapidly. Host range confirmation of invasive hemipterans relies on the evaluation of plant susceptibility though greenhouse or field trials, which are inefficient and time-consuming. When the green industry faces the fast-spreading threat of invasive pests such as crapemyrtle bark scale (Acanthococcus lagerstroemiae), it is imperative to timely identify potential host plants and evaluate plant resistance/susceptibility to pest infestation. In this study, we developed an alternative technology to complement the conventional host confirmation methods. We used electrical penetration graph (EPG) based technology to monitor the A. lagerstroemiae stylet-tip position when it was probing in different plant tissues in real-time. The frequency and relative amplitude of insect EPG waveforms were extracted by an R programming-based software written to generate eleven EPG parameters for comparative analysis between plant species. The results demonstrated that the occurrences of phloem phase and xylem phase offered conclusive evidence for host plant evaluation. Furthermore, parameters including the percentage of insects capable of accessing phloem tissue, time duration spent on initiating phloem phase and ingesting phloem sap, provided insight into why host plant susceptibility differs among similar plant species. In summary, this study developed a novel real-time diagnostic tool for quick A. lagerstroemiae host confirmation, which laid the essential foundation for effective pest management. [ABSTRACT FROM AUTHOR]

It is known that plant viruses can change the performance of their vectors. However, there have been no reports on whether or how a semipersistent plant virus manipulates the feeding behaviors of its whitefly vectors. Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is an emergent plant virus in many Asian countries and is transmitted specifically by B and Q biotypes of tobacco whitefly, Bemisia tabaci (Gennadius), in a semipersistent manner. In the present study, we used electrical penetration graph (EPG) technique to investigate the effect of CCYV on the feeding behaviors of B. tabaci. The results showed that CCYV altered feeding behaviors of both biotypes and sexes of B. tabaci with different degrees. CCYV had stronger effects on feeding behaviors of Q biotype than those of B biotype, by increasing duration of phloem salivation and sap ingestion, and could differentially manipulate feeding behaviors of males and females in both biotype whiteflies, with more phloem ingestion in Q biotype males and more non-phloem probing in B biotype males than their respective females. With regard to feeding behaviors related to virus transmission, these results indicated that, when carrying CCYV, B. tabaci Q biotype plays more roles than B biotype, and males make greater contribution than females.

Plants grown with vermicompost amendments are known to be harmful to sap-sucking insects, but the underlying mechanism remains to be determined. Here we investigated the feeding behavior of Diaphorina citri Kuwayama on Citrus limon (L.) Burm. F using the electrical penetration graph technique. Plants were grown in soil with different vermicompost rates (0%, 20%, 40%, and 60% w/w). Additionally, plants were tested for the activity of salicylic acid (SA) and jasmonic acid (JA) pathway-related enzymes. When compared to the control, vermicompost treatments (40% and 60%) decreased duration of phloem sap feeding and increased duration of the pathway phase of D. citri, and the 60% vermicompost made it more difficult for D. citri to reach and gain access to phloem sap. Enzymatic assays indicated that the 40% amendment rate increased phenylalanine ammonia lyase (involved in the SA pathway) and polyphenol oxidase (involved in the JA pathway), while the 60% amendment rate increased -1,3-glucanases (involved in the SA pathway) and lipoxygenase (involved in the JA pathway). The 20% amendment rate had no effect on feeding or enzyme activities. This study revealed that vermicompost amendments can reduce the efficiency of D. citri feeding, which may result from increased plant resistance via the SA and JA pathway.

Riptortus pedestris (Fabricius) and Halyomorpha halys (Stål) are the major pests that feed on soybean pods, seeds, and fruits. Higher populations and damage occur during the soybean maturity stages (podding to harvest). To compare the feeding behavior of R. pedestris and H. halys, we used the six most cultivated cultivars (Daepung-2ho, Daechan, Pungsannamul, Daewon, Seonpung, and Seoritae) in Korea using the electropenetrography (EPG) technique. Both R. pedestris and H. halys, the NP (non-penetration), a non-probing waveform, was the shortest in the Pungsannamul (298 and 268 min) and the longest in the Daepung-2ho (334 and 339 min), respectively. The feeding waveforms Pb (phloem feeding: E1-Salivation and E2-Sap feeding) and G (xylem feeding) were the longest in Pungsannamul and the shortest in Daepung-2ho. In addition, as a result of investigating the damage rate by planting six cultivars of beans in the field, as expected, the proportions of damage types B and C were highest in Pungsannamul and lowest in Daepung-2ho. These results reveal that both bug species ingest xylem sap from leaflets and stems using a salivary sheath strategy to acquire water and nutrients from soybean pods/seeds with cell-rupture tactics. This study provides perceptive information to understand the feeding behavior, field occurrence, and damage patterns of R. pedestris and H. halys, which may have key implications for the management of hemipteran pests by determining the specificity and susceptibility of host plants.