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The insecticidal and repellent activities of the four wild plant extracts: stinging nettle, Urtica dioica L., white henbane, Hyoscyamus albus L., camphorweeds, Pluchea dioscoridis L., and cocklebur, Xanthium strumarium L. were tested compared to the insecticide spirotetramat against the 3rd nymphal instar of Aphis gossypii Glover and adult females of Phenacoccus solenopsis Tinsley after 24 and 48 h of treatment. Their effects on acetylcholinesterase (AChE) and glutathione-S-transferase (GST) enzyme activities were also assessed to explore their possible mechanisms of action. The phenolic compounds of the plant extracts were investigated by high-performance liquid chromatography (HPLC) analysis. The most abundant compounds in the methanol extract from P. dioscoridis were gallic acid (14.45 µg/mL), and cinnamic acid (11.44 µg/mL); from U. dioica were caffeic acid (15.32 µg/mL) and syringic acid (13.47 µg/mL); from H. albus were syringic acid (7.12 µg/mL) and catechol (5.33 µg/mL); and from X. strumarium were p-coumaric acid (24.53 µg/mL) and pyrogallol (18.35 µg/mL). According to the LC50 values, the contact toxicity of U. dioica, H. albus, P. dioscoridis, and X. strumarium against A. gossypii was 40.3, 60.6, 56.2, and 32.3 mg/L, whereas, the contact toxicity against P. solenopsis was 56.4, 67.5, 64.3, and 36.2 mg/L, compared to the spirotetramat (17.2 and 24.5 mg/L), respectively, at 48 h of treatment. The highest repellency rates were observed with LC50 values for X. strumarium (63.2 and 60.3%), followed by U. dioica (46.2 and 43.5%), P. dioscoridis (45.3 and 42.8%), and H. albus extract (38.8 and 35.2%) compared to the spirotetramat (78.5 and 76.2%) against A. gossypii and P. solenopsis at 24 h, but decreased with time. The AChE and GST activities in pests were significantly inhibited, compared to control and spirotetramat, with dose and time-dependent effects. These findings indicate that tested wild extracts may be suggested as viable alternatives for aphids and mealybugs control. [ABSTRACT FROM AUTHOR]

Pest‐regulating natural enemies often require crop and non‐crop habitats to persist and be effective. These habitats offer hibernation sites, alternative prey or floral resources but can also be complementary in when they provide resources. The relative contribution of these different habitats to the performance of pest‐regulating insects is largely unknown, since it is difficult to study empirically. Landscape‐based population‐dynamical modelling can fill this research gap.In this study, we modelled the dynamics of predatory hoverflies (Diptera: Syrphinae) and their aphid prey in a collection of habitats. These hoverflies are dependent on different habitats for different reasons. While their larvae predate on aphids, adult hoverflies require floral resources. Resources are often segregated in different habitats. In addition, they are only temporarily available in any habitat type. In our model, hoverflies move between different habitats and select where to feed and where to produce off‐spring based on optimal foraging considerations. The model represents habitats common in arable landscapes and their temporal availability of resources is parameterized based on field observations.The model shows that effective pest suppression will only occur in the presence of at least three different habitats, including two crops that provide prey resources at different times of the year. A woody habitat with shrubs and trees provide aphid prey very early and late in the season, whereas an early crop and a late crop cover the period in between. In addition, these habitats need to provide floral resources in the same period as aphids, for example by flower strips in the margins of crop fields or blossoming trees or shrubs in the woody habitat. Under the model assumptions, the best pest suppression is obtained when the woody habitats take up 6% to 10% of the landscape. In addition to yearly population fluctuations, also bi‐ or multi‐yearly cycles may occur, depending on the composition of the landscape.Synthesis and applications. Our model shows when an agricultural landscape is 'complete' for natural enemies (and for effective pest control). For this, it needs to contain multiple habitats that supply floral and prey resources in different periods of the year. [ABSTRACT FROM AUTHOR]

Aphids are economically important sucking pests that suck the sap from different plant parts resulting in the curling of leaves, and withering of plant parts and also transmitting viral diseases. Carinostigmus costatus Krombein (Hymenoptera: Sphecidae) is a solitary predatory wasp that constructs nests in the pithy stems of Caesalpinnia pulcherrima and provisions aphids as prey to her broods. In this study, aphid prey preference, prey provisioning behaviour and nesting activity of C. costatus from January to June for two years 2022 and 2023 were studied. The predatory wasp, C. costatus foraged on six host aphids viz., Aphis odinae on Anacardium occidentale (Cashew), Aphis gossypii on Hibiscus rosasinensis (China Rose), Hyadaphis coriandri on Foeniculum vulgare (Fennel), Aphis craccivora on Cajanus cajan (Pigeon pea) and Vigna unguiculata, Rhopalosiphum maidis on Zea mays (Maize) and Aphis nerii on Asclepias curassavica (Tropical milkweed). The most abundant aphid prey species in the nests constructed by C. costatus were H. coriandri (28%), A. craccivora (24%) followed by A. gossypii (20%), R. maidis (16%) and A. odinae (8%) and A. nerii (4%). The wasp built a significantly higher number of nests during April (40.60 ± 2.30 nests) with the highest number of cells /nest (4.60 ± 0.55 cells/nest). The wasp provisioned significantly the highest number of aphids per cell during April (16.60 ± 1.14 aphids/cell) with the highest emergence rate of adult predatory wasps (92%). The observations concluded the natural predation of aphids by the solitary predatory wasp, C. costatus. Providing nesting substrates for the wasp will increase their nesting activity with aphid prey provision. This will enhance their numerical and functional response under agroecosystems, thereby helping to regulate the aphid populations. [ABSTRACT FROM AUTHOR]

The alfalfa virome has been understudied. Existing research dealing with viral incidences within the crop primarily concentrate on local factors, rather than considering a broader perspective. In this comprehensive 2‐year study, we define the alfalfa virome and the main local and landscape factors affecting the incidence and annual increase of the Alfalfa mosaic virus (AMV), the most prevalent virus in alfalfa. The study was conducted in commercial alfalfa fields located along the highly productive northeast region of the Iberian Peninsula. For the first time in Europe, next‐generation sequencing revealed the presence of 14 different viruses representing the genera Cytorhabdovirus, Alphapartitivirus, Amalgavirus, Alfamovirus, Luteovirus, Enamovirus and Flavivirus. AMV was the most prevalent species, accounting for 89% of the identified viral contigs. Enzyme‐linked immunosorbent assays showed that the incidence of AMV varied between fields, with the average incidence doubling from 34% in 2019 to 65% in 2020. To assess the effect of local and landscape characteristics on the incidence of AMV and the observed annual increase, we selected different local variables and recorded landscape structure at three different buffer radii (250, 500 and 1000 m) from the centre of each field. Both the incidence and annual increase in AMV were driven mainly by local characteristics. The incidence of AMV showed a significant relationship with crop age and field area, whereas the annual increase was mainly influenced by crop age and the cumulative number of alate morphs of the aphid Acyrthosiphon pisum. Only one landscape composition variable, the percentage of alfalfa, showed a significant relationship with AMV incidence at the 250‐m scale. These results confirm the effect of local variables on the population structure of generalist viruses. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Arbuscular mycorrhizal fungi (AMF) impact the relationships between plants, aphids (insects that feed on plant phloem), and their natural enemies (insects that prey on or parasitize aphids). The presence of AMF influences the growth and population of different aphid species and affects the development of aphid‐killing wasps and their attraction to plants. This research has been conducted also considering the insects' feeding strategy and their feeding specialization. This study provides novel perspectives on how these fungi shape interactions in the natural world, offering potential insights for the development of sustainable pest management strategies in agriculture. Summary: Arbuscular mycorrhizal fungi (AMF) are major root symbionts regulating plant physiology. Their presence affects the performance of aboveground insect herbivores in relation to their feeding strategy and their feeding specialization. For example, the effect of the arbuscular mycorrhizal (AM) symbiosis on chewing insects, positive for specialists and negative for generalists, has been previously demonstrated. Conversely, the impact of AMF on phloem‐suckers with relatively different levels of specialization remains unexplored.We tested the influence of the AM Funneliformis mosseae on the fitness of the specialist aphid Acyrthosiphon pisum and the generalist aphid Myzus persicae on Vicia faba plants. Further, we investigated the effects of AMF on the higher trophic level, the aphid parasitoids Aphidius ervi (specialist) and Aphidius colemani (generalist), by evaluating plant attractiveness and parasitoid fitness. To support the results of behavioral and biological bioassays we characterized the photosynthetic parameters, the volatilome and the transcriptome of tested plants.Mycorrhizal plants proved unsuitable for the generalist M. persicae but enhanced the fitness of the specialist A. pisum. The AM symbiosis had no effects on the behavioral response of A. colemani and enhanced the attraction and fitness of A. ervi.Volatilome and transcriptome profiling corroborated the results of bioassay highlighting a bottom‐up effect of the AMF across a plant–aphid–parasitoid system. [ABSTRACT FROM AUTHOR]

Plants encounter a myriad of biotic and abiotic stresses throughout their life cycle, among which aphids pose a significant challenge as herbivorous insect pests. Aphids cause both direct damage through feeding and indirect damage by transmitting viruses. Given the growing concerns about insecticide resistance and the non‐target effects of synthetic insecticides, there is an urgent need to develop novel pest control strategies that are dependent on plant defence strategies. In this study, we assessed the effects of exogenous prohydrojasmon (PDJ), a derivative of jasmonic acid, at 24 h (PDJ24) and 48 h (PDJ48) post‐treatment on the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae), feeding on Brassica juncea L. (Brassicaceae). The impact of PDJ treatments was assessed by conducting performance bioassays (survival and fecundity) and behavioural bioassays (settlement and attraction to volatiles in an olfactometer). Our findings reveal that the exogenous application of PDJ did not significantly affect on the performance and behaviour of B. brassicae at 24‐h post‐treatment. However, PDJ treatment significantly reduced the performance of B. brassicae at 48‐h post‐treatment, and affected the behaviour in terms of reduced settlement on and attraction to volatiles of PDJ‐treated plants. These results suggest that PDJ has the potential to effectively induce defences in Brassica against sucking pests. This study provides valuable insights into possibility of employing PDJ as an alternative approach for sustainable pest management in agriculture. [ABSTRACT FROM AUTHOR]

Aphids (Hemiptera: Aphididae) are small soft bodied plant lice, their number rapidly rise above economic threshold level in suitable climatic condition due to parthenogenetic development. They have great agricultural importance due to polyphagism, polymorphism, parthenogenetic viviparity and remarkable ability to transmit various pathogenic viruses. They damage the crops directly by sucking the nutrients that cause devitalisation of plants. Many coccinellids are predators and major biological control agents of hemipteran pests such as aphids, mealy bugs, scale insects, white flies, as well as thrips and mites and other soft bodied insects. Due to predaceous nature, seasonal synchromy with their specific preys, high foraging performance, immense predation potential and high reproductive efficacy, they possess the potential to be effectively employed in Integrated Pest Management. Globally, more than 6000 ladybird beetle species are known to us, out of which, 261 predaceous species belonging to 57 genera reported from India. In biological control programme, several coccinellids predators are reported as effective bioagent against aphids viz., Aphidecta obliterata on Adelges piceae, Cheilomenes lunata on Aphis craccivora, Coccinella sexmaculata on Aphis aurantii and Myzus persicae, Coccinella transversalis on Aphis aurantii and Myzus persicae, Coccinella undecimpunctata on several aphids. In India, 13 species of coccinellids viz., Coccinella krikkeni Iablokoff-Khnzorian, Coccinella lama Kapur, Coccinella luteopicta (Mulsant), Coccinella magnopunctata Rybakow, Coccinella marussii Kapur, Coccinella nigrovittata Kapur, Coccinella repanda Thunberg, Coccinella saucerottei Mulsant, Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricious, Coccinella transversoguttata Faldermann, Coccinella undecimpunctata Linnaeus and Coccinella undecimpunctata aegyptiaca Reiche are reported. Among these, C. septempunctata and C. transversalis are very common and widely distributed in India. [ABSTRACT FROM AUTHOR]

Piercing/sucking insects such as green peach aphid (GPA) (Myzus persicae) cause direct damage by obtaining phloem nutrients and indirect damage by spreading plant viruses. To investigate the response of peach trees (Prunus persica) to aphids, the leaf transcriptome and metabolome of two genotypes with different sensitivities to GPA were studied. The gene expression of aphid-susceptible plants infested with aphids was similar to that of control plants, whereas the gene expression of aphid-resistant plants infested with aphids showed strong induced changes in gene expression compared with control plants. Furthermore, gene transcripts in defense-related pathways, including plant–pathogen interaction, MAPK signaling, and several metabolic pathways, were strongly enriched upon aphid infestation. Untargeted secondary metabolite profiling confirmed that aphid infestation induced larger changes in aphid-resistant than in aphid-susceptible peaches. Consistent with transcriptomic alterations, nine triterpenoids showed highly significant GPA-induced accumulation in aphid-resistant peaches, whereas triterpenoid abundance remained predominantly unchanged or undetected in aphid-susceptible peaches. Furthermore, some types of transcription factors (including WRKYs, ERFs, and NACs) were strongly induced upon GPA infestation in aphid-resistant, but not in aphid-susceptible peaches. These results suggested that the accumulation of specialized triterpenoids and the corresponding pathway transcripts may play a key role in peach GPA resistance. [ABSTRACT FROM AUTHOR]

Different species of aphids, responsible for severe yield losses of cereal crops including wheat, (Triticum aestivum L.) are managed by insecticides, which are harmful to organisms and the environment under field conditions. Therefore, an environment friendly aphidicidal product of plant origin is required. Mentha spicata oil was found to be rich in carvone (81.88%), but the use of its oil and carvone in crop protection is lacking due to their volatility, poor solubility, and stability. A nanoformulaton not only solves these problems but also improve the efficacy and dose of the bioactive compounds. Thus, nano-emulsions of the oil and carvone prepared were characterized, and evaluated against Rhopalosiphum maidis (corn aphid) and Sitobion avenae (wheat aphid) The average droplet size of nano-emulsions of the oil and carvone was found to be 22.1 and 41.21 nm. Nano-emulsion of carvone exhibited higher aphid mortality (LC50 = 0.87–1.94 mg/mL) at 24 h and acetylcholinesterase inhibitory activity (IC50 = 0.07–3.83 mg/mL) compared to the nano-emulsion of the oil (LC50 = 2.87–2.81 mg/mL; IC50 = 1.66–5.34 mg/mL). The repellence index (RI) in nano-emulsion of essential oil was found to be higher (84.73 and 81.72%) at the highest concentration (0.05 µL/cm2) than that of carvone (77.59 and 80.98%) for R. maidis and S. avenae. Further, in silico studies also revealed the favourable binding energy (− 6.6 to − 8.5 kcal/mol) of the main compounds in the oil with acetylcholinesterase, facilitated by hydrophobic interactions and hydrogen bonding. This study suggests that the nano-emulsions of the essential oil and carvone can be explored under field conditions to establish efficacy for their utilization as aphidicidal and repellent products against aphids. In the present study, aphidicial and repellent activities of its essential oil and carvone were reported for the first time against R.maidis and S.avenae. [ABSTRACT FROM AUTHOR]

Melanaphis sorghi is a pest that is native to Africa but is now distributed worldwide. In 2013, its destructive capacity was demonstrated when it devastated sorghum crops in the United States and Mexico, making it a new pest of economic importance in North America. At the time, the phytosanitary authorities of both countries recommended the use of pesticides to control the outbreak, and biological control products for the management of this pest were not known. In response to the outbreak of M. sorghi in North America, several field studies have been performed in the last decade on sorghum crops in the USA and Mexico. Works have focused on assessing resistant sorghum hybrids, pesticide use, and recruitment of associated aphid predators and entomopathogens for natural control of M. sorghi populations. The objective of this review is to compile the information that has been generated in the past decade about indigenous enemies affecting M. sorghi naturally in the field, as well as the search for biological control alternatives and evaluations of interactive effects of resistant sorghum hybrids, pesticides, and natural enemies. To date, different predators, parasitoids, fungi, and bacteria have been evaluated and in many cases found to affect M. sorghi populations in sorghum agroecosystems or laboratory bioassays, and the use of resistant sorghum varieties and pesticides did not have clear toxic effects on natural enemy populations. Many of the macroorganisms and microorganisms that have been evaluated as potential biological controls have shown potential as alternatives to synthetic pesticides for keeping M. sorghi population densities below economic damage thresholds and are compatible with integrated management of sorghum aphids. While most tests of these biological alternatives have shown that they have aphidicidal potential against sorghum aphids, it is crucial to take into account that their effectiveness in the field depends on a number of abiotic and biotic factors, including soil texture, temperature, humidity, and natural enemies. [ABSTRACT FROM AUTHOR]

SUMMARY Plant trichomes are an excellent model for studying cell differentiation and development, providing crucial defenses against biotic and abiotic stresses. There is a well‐established inverse relationship between trichome density and aphid prevalence, indicating that higher trichome density leads to reduced aphid infestations. Here we present the cloning and characterization of a dominant quantitative trait locus, HIC (hirsute cotton), which significantly enhances cotton trichome density. This enhancement leads to markedly improved resistance against cotton aphids. The HIC encodes an HD‐ZIP IV transcriptional activator, crucial for trichome initiation. Overexpression of HIC leads to a substantial increase in trichome density, while knockdown of HIC results in a marked decrease in density, confirming its role in trichome regulation. We identified a variant in the HIC promoter (−810 bp A to C) that increases transcription of HIC and trichome density in hirsute cotton compared with Gossypium hirsutum cultivars with fewer or no trichomes. Interestingly, although the −810 variant in the HIC promoter is the same in G. barbadense and hirsute cotton, the presence of a copia‐like retrotransposon insertion in the coding region of HIC in G. barbadense causes premature transcription termination. Further analysis revealed that HIC positively regulates trichome density by directly targeting the EXPANSIN A2 gene, which is involved in cell wall development. Taken together, our results underscore the pivotal function of HIC as a primary regulator during the initial phases of trichome formation, and its prospective utility in enhancing aphid resistance in superior cotton cultivars via selective breeding. [ABSTRACT FROM AUTHOR]

Sudangrass (Sorghum sudanense Stapf) is widely cultivated as a summer annual forage across the southern Great Plains because of its robust forage yield potential. However, the accumulation of nitrates and the potential harm to livestock have restricted the use of Sudangrass for feeding ruminants. Since 2013, the sorghum aphid (SA), Melanaphis sorghi (Theobald) (Hemiptera: Aphididae), has been damaging sorghum and Sudangrass production. However, the interaction between SA feeding and nitrate accumulation in Sudangrass has not been determined. In this study, we evaluated the effect of SA feeding on different Sudangrass lines, comparing them to a susceptible and a resistant sorghum variety and measuring the physiological responses and nitrate concentration after aphid feeding. Additionally, we evaluated the use of these grass lines on SA demographics. Initial infestations of 100 SA per plant that were allowed to feed and proliferate for 20 days increased nitrate concentrations in Sudangrass by more than 60% compared to controls. Concurrently, the Sudangrass lines selected for high nitrate levels drastically reduced SA demographic parameters, comparable to those of the resistant sorghum control. Although the adoption of resistant cultivars is recommended for aphid management, the Sudangrass lines selected may not be the best option for SA management because their accumulation of nitrates in response to herbivory can cause ruminant poisoning. [ABSTRACT FROM AUTHOR]

Simple Summary: This work investigates the olfactory mechanism of aphids with varying preferences for TMX-coated and uncoated wheat plants. This study utilized the olfactory localization preferences of aphids to identify the volatile metabolites of both TMX-coated and uncoated wheat. The differential metabolites were then used to assess the olfactory behavior of aphids. The results indicated that four compounds had repellent activity towards aphids, while two compounds demonstrated attracting activity towards aphids. These findings highlight the potential of using TMX-induced VOCs to manage aphid behavior and develop environmentally friendly pest control strategies. Pesticides can induce target plants to release odors that are attractive or repellent to their herbivore insects. But, to date, the activity of volatile organic compounds (VOCs), singly or as mixtures, which play a crucial role in the olfactory behavior of herbivore insects, remains unclear. The objective of our research was to investigate the impact of thiamethoxam (TMX), a pesticide, on the emission of odors by wheat plants, and how these odors influence the behavior of grain aphids (Sitobion miscanthi). S. miscanthi showed a greater repellent response to the volatiles emitted by Thx-induced plants compared to those emitted by uncoated plants. Using gas chromatography–mass spectrometry (GCMS), we discovered that TMX greatly induced the release of VOCs in wheat plants. For instance, the levels of Bornyl acetate, 2-Oxepanone, Methyl acrylate, Cyclohexene, α-Pinene, and 1-Nonanol in coated wheat plants were significantly higher as compared to uncoated wheat plants. Moreover, varying concentrations also had an impact on the olfactory behavior of S. miscanthi. For instance, Cyclohexene exhibited clear attractiveness to aphids at concentrations of 100 μL/mL, whereas it displayed evident repellent properties at concentrations of 1 μL/mL and 10 μL/mL. These new findings demonstrate how TMX-induced VOCs affect the behavior of S. miscanthi and could help in developing innovative approaches to manage aphids by manipulating the emission of plant volatiles. Furthermore, these findings can also be utilized to evaluate substances that either attract or repel aphids, with the aim of implementing early monitoring and environmentally friendly methods to manage aphids, while simultaneously impeding the spread of viruses. [ABSTRACT FROM AUTHOR]

Simple Summary: Many studies have shown that pesticide use has negative environmental effects. Therefore, alternative measures to manage insect pests and protect plant health are needed. Potential tools include chemicals that cause behavioral changes in pests and are already a part of the integrated pest management toolbox. Aphids are a significant pest in sugar beet (Beta vulgaris). They cause visual damage and act as vectors for various phytopathogens that reduce the yield. When attacked by predators, aphids emit an alarm pheromone, which causes other aphids to stop feeding, move away, and sometimes even abandon the host plant. We tested whether the artificially release of this pheromone could be an environmentally friendly alternative to prevent aphid infestation in sugar beet. Application of the pheromone resulted in reduced aphid densities in experimental sugar beet patches at two out of three experimental sites. This indicates the potential of this pheromone as an aphid repellent in sugar beet production. However, more research is required to ensure the reliability of this method. The negative impact of pesticides on the environment and the potential of pest species to develop pesticide resistance make it necessary to explore new methods of pest control. Pheromones and other behavior-modifying semiochemicals are already important in integrated pest management (IPM). (E)-ß-farnesene (EBF) is a semiochemical that acts as an alarm pheromone in aphids. Upon perception of EBF, aphids stop feeding, move away, and sometimes even abandon the host plant. The aphids Myzus persicae and Aphis fabae are significant crop pests and vectors of many harmful phytopathogens affecting sugar beet (Beta vulgaris). Field trials were conducted at different locations in Germany to test whether dispensers containing a mixture of farnesene isomers (FIMs) including EBF were able to reduce the infestation of these species on sugar beet. Our results showed a reduction in aphid abundance in the FIM-treated patches in two out of three sites. Therefore, we hypothesize that FIM dispensers could prevent aphid infestation and could be used in combination with other IPM measures. However, more research is required to increase the effect and ensure the reliability of this method. [ABSTRACT FROM AUTHOR]

There is increasing interest in exploring how endosymbionts could be useful in pest control, including in aphids, which can carry a diversity of endosymbionts. Endosymbionts often have a large impact on host traits, and their presence can be self‐sustaining. Identifying useful host‐endosymbiont combinations for pest control is facilitated by the transfer of specific endosymbionts into target species, particularly if the species lacks the endosymbiont. Here, we complete a comprehensive literature review, which included 56 relevant papers on endosymbiont transfer experiments in aphids, to uncover factors that might influence transfer success. We then report on our own microinjection attempts of diverse facultative endosymbionts from a range of donor species into three agriculturally important aphid species as recipients: the green peach aphid (Myzus persicae), bird cherry‐oat aphid (Rhopalosiphum padi), and Russian wheat aphid (Diuraphis noxia). Combining this information, we consider reasons that impact the successful establishment of lines carrying transferred endosymbionts. These include a lack of stability in donors, deleterious effects on host fitness, the absence of plant‐based (versus vertical) transmission, high genetic variation in the endosymbiont, and susceptibility of an infection to environmental factors. Taking these factors into account should help in increasing success rates in future introductions. [ABSTRACT FROM AUTHOR]

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is one of the most important pests and causes major damage to cultivated plants in Turkey. It has recently become a serious problem in Antalya (southwestern Turkey) due to its high resistance to insecticides used. To address this problem, the present study aimed to evaluate the pathogenicity of five indigenous Beuveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes) isolates (BbFn-2, BbKm-2, BbSr-2, BbDs-4, and BbDm-2) with high virulence in previous studies against the pest. All the isolates were tested at five different conidial concentrations (1 × 105, 1 × 106, 1 × 107, 1 × 108 and 1 × 109 conidia mL−1) against the nymphs and adults of A. gossypii using Petri dish and pot trials in the laboratory. The results from the bioassays showed that virulence of the isolates increased significantly with elapsed time up to 10 days after inoculation. All five B. bassiana isolates at the highest concentration (1 × 109 conidia mL−1) caused mortalities ranged from 83.3% to 100% in both nymphs and adults 10 days post-treatment. While the LT50 and LT95 values of the isolates were 1.72–2.12 days and 4.81–8.49 days, respectively, for the nymphs, they were calculated for the adults as 1.65–2.54 days and 4.66–12.93 days, respectively. Results of the phylogenetic analysis showed that these five B. bassiana isolates had high similarities (ranging from 99 to 100%) with the other B. bassiana isolates in GenBank. All the results suggest that above-mentioned five indigenous B. bassiana isolates have significant biocontrol potential against A. gossypii. [ABSTRACT FROM AUTHOR]

Aphids are phloem‐feeding insects that reduce crop productivity due to feeding and transmission of plant viruses. When aphids disperse across the landscape to colonize new host plants, they will often probe on a wide variety of nonhost plants before settling on a host suitable for feeding and reproduction. There is limited understanding of the diversity of plants that aphids probe on within a landscape, and characterizing this diversity can help us better understand host use patterns of aphids. Here, we used gut content analysis (GCA) to identify plant genera that were probed by aphid vectors of potato virus Y (PVY). Aphids were trapped weekly near potato fields during the growing seasons of 2020 and 2021 in San Luis Valley in Colorado. High‐throughput sequencing of plant barcoding genes, trnF and ITS2, from 200 individual alate (i.e., winged) aphids representing nine vector species of PVY was performed using the PacBio sequencing platform, and sequences were identified to genus using NCBI BLASTn. We found that 34.7% of aphids probed upon presumed PVY host plants and that two of the most frequently detected plant genera, Solanum and Brassica, represent important crops and weeds within the study region. We found that 75% of aphids frequently probed upon PVY nonhosts including many species that are outside of their reported host ranges. Additionally, 19% of aphids probed upon more than one plant species. This study provides the first evidence from high‐throughput molecular GCA of aphids and reveals host use patterns that are relevant for PVY epidemiology. [ABSTRACT FROM AUTHOR]

Psyllids, or jumping plant lice (Hemiptera: Sternorrhyncha: Psylloidea), are a group of small phytophagous insects that include some important pests of crops worldwide. Sexual communication of psyllids occurs via vibrations transmitted through host plants, which play an important role in mate recognition and localization. The signals are species‐specific and can be used to aid in psyllid taxonomy and pest control. Several hypotheses have been proposed for the mechanism that generates these vibrations, of which stridulation, that is, friction between parts of the forewing and thorax, has received the most attention. We have investigated vibrational communication in the European pear psyllid species Cacopsylla pyrisuga (Foerster, 1848) using laser vibrometry and high‐speed video recording, to directly observe the movements associated with signal production. We describe for the first time the basic characteristics of the signals and signal emission of this species. Based on observations and analysis of the video recordings using a point‐tracking algorithm, and their comparison with laser vibrometer recordings, we argue that males of C. pyrisuga produce the vibrations primarily by wing buzzing, that is, tremulation that does not involve friction between the wings and thorax. Comparing observed signal properties with previously published data, we predict that wing buzzing is the main mechanism of signal production in all vibrating psyllids. [ABSTRACT FROM AUTHOR]

Behavior and fitness are important ecological traits frequently measured in insect bioassays. A common method to measure them in soft‐bodied herbivorous insects involves confining individuals to plant leaves using clip cages. Although studies have previously highlighted the negative effects of clip cages on leaf physiology, little is known about the impact that using this confinement method has on insect fitness. The responses of different aphid genotypes/clones to different containment methods have not previously been investigated. Here we measured key fitness traits (intrinsic rate of natural increase, mean relative growth rate, time to reach reproductive adulthood and population doubling time) in the potato aphid, Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae), when confined to plants using two methods: (1) clip cages to confine aphids to individual strawberry leaves and (2) a mesh bag to confine aphids to whole strawberry plants. Our study identified a strong negative impact on all the measured aphid fitness traits when using clip cages instead of mesh bags. We also identified genotype‐specific differences in response to confinement method, where clip cage confinement differentially affected the fitness of a given aphid genotype compared to the same genotype on whole plants. These results suggest that clip cage use should be carefully considered when experiments seek to quantify insect fitness and that whole plants should be used wherever possible. Given the prevalence of clip cage use in insect bioassays, our results highlight the need for caution when interpreting the existing literature as confinement method significantly impacts aphid fitness depending on their genotype. [ABSTRACT FROM AUTHOR]

Aphids, the important global agricultural pests, harbor abundant resources of symbionts that can improve the host adaptability to environmental conditions, also control the interactions between host aphid and natural enemy, resulting in a significant decrease in efficiency of biological control. The facultative symbiont Serratia symbiotica has a strong symbiotic association with its aphid hosts, a relationship that is known to interfere with host–parasitoid interactions. We hypothesized that Serratia may also influence other trophic interactions by interfering with the physiology and behavior of major predators to provide host aphid defense. To test this hypothesis, we investigated the effects of Serratia on the host aphid Acyrthosiphon pisum and its predator, the ladybeetle Propylaea japonica. First, the prevalence of Serratia in different A. pisum colonies was confirmed by amplicon sequencing. We then showed that harboring Serratia improved host aphid growth and fecundity but reduced longevity. Finally, our research demonstrated that Serratia defends aphids against P. japonica by impeding the predator's development and predation capacity, and modulating its foraging behavior. Our findings reveal that facultative symbiont Serratia improves aphid fitness by disrupting the predation strategy of ladybeetle larvae, offering new insight into the interactions between aphids and their predators, and providing the basis of a new biological control strategy for aphid pests involving the targeting of endosymbionts. [ABSTRACT FROM AUTHOR]

Crowding induces behavioural and lasting morphological and chromatic changes in insects. This study examined how larval rearing density of Propylea dissecta (Mulsant, 1850) affected food choice and development duration, hypothesising that larvae under stress will opt for lower quality food as larval density increases. Larvae were reared at various densities under three crowding treatments: direct physical, indirect physical, and chemical tracks. In each treatment, larvae experienced crowding at densities of 0, 2, 4, 6, 8, 10, and 12 individuals per arena. Fourth stage larvae were provided with food choice of aphids, heterospecific eggs, and conspecific eggs. Significant effect of crowding on total development duration, first consumption time, and first food consumption was observed. Decrease in development duration at densities of 4 and 6 and increase in development duration at low and high densities were observed in direct physical crowding. Indirect physical and chemical crowding yield the shortest development duration at densities of 8, 10, and 12, when compared to low and moderate crowding. First encounter time increased with increasing chemical tracks concentration, while first consumption time decreases with crowding across all groups. First consumed food was also significantly influenced by crowding, suggesting a negative impact on larval food choice. Our results indicate that crowding among larvae leads to a longer development duration and show less selectivity in their food choices. [ABSTRACT FROM AUTHOR]

Background: Aphis gossypii Glover (Hemiptera: Aphididae) is an economically important polyphagous pest species infesting many agricultural and horticultural crops causing severe yield losses. In order to develop biopesticides for the management of aphids in an environmentally safe manner, 6 indigenous entomopathogenic fungi Simplicillium subtropicum were isolated from soils of Tamil Nadu and their pathogenicity was tested against A. gossypii under laboratory conditions after characterization. Results: Phenotypic and molecular characterization was performed for all the isolates for species identification. Results of the pathogenicity test showed that the isolate S6 (PP446637) performed well among other isolates causing 58.33% mortality on 7 days after treatment (DAT) @ 1 × 108 spores/ml. The LC50 and LT50 values were found to be 2.36 × 107 spores/ml at 7 DAT and 160.20 h @ 1 × 108 spores/ml, respectively. SEM images of A. gossypii treated with the isolate S6 (PP446637) revealed that initial phase of infection, i.e., adhesion, formation of germ tube and appressoria starts within 24 h post-infection (hpi), hyphal development and penetration of cuticle occurred within 48 hpi and extrusion of mycelium and conidiogenesis occurred within 72 hpi. Conclusion: This study reveals the entomopathogenic potential of indigenous S. subtropicum isolates against A. gossypii and suggests their use for the eco-friendly management of aphids. [ABSTRACT FROM AUTHOR]

A study on influence of nutrient factors and defensive enzymes on maize hybrids was conducted where, nitrogen, phosphorous, potassium and peroxidases, polyphenol oxidases were analysed, respectively. Nitrogen and phosphorous increased susceptibility of maize hybrids to corn leaf aphid infestation whereas, potassium, peroxidase and polyphenol oxidase did not favour the infestation. Nutritional components in leaf samples of maize hybrids on the infestation of corn leaf aphid revealed that the infestation was significant and correlated positively with nitrogen (0.953**) and phosphorus (0.986**). While a significant and negative correlation was observed in case of potassium (-0.952**), peroxidase (-0.980*) and polyphenol oxidase (-0.822**). Whereas, nutritional components in tassels of maize hybrids on the infestation of corn leaf aphid was significant and correlated positively with nitrogen (0.976**) and phosphorus (0.938**). While a significant negative correlation was observed in case of potassium (-0.838**), peroxidase (-0.873*) and polyphenol oxidase (-0.968**). [ABSTRACT FROM AUTHOR]

Various aphid species, including Aphis gossypii Glover (Hemiptera: Aphididae), are considered important pests of okra and other vegetables. Previous studies under 1 environment in Cameroon, Central Africa, had found multiple okra genotypes with resistance to A. gossypii. However, the stability and yield performance of the "resistant" genotypes across different environments were unknown. Ten previously identified aphid-resistant okra genotypes along with 1 commercial variety and a local landrace (specific to a given location) were compared during 2 seasons in replicated trials in 4 agro-ecological zones of Cameroon that also represent large areas of Central Africa. Aphid populations and okra yield parameters were evaluated. Breeding values were predicted using a linear mixed model for all data, and genotypes by location interactions were identified. The area under the infestation pressure curve (AUIPC) was calculated using aphid count data and subjected to resistance analysis. The Local—the most susceptible with the highest breeding value (+2.33)—and VI060794—one of the moderately resistant—genotypes had the highest yield per hectare. The only resistant genotype VI036213 had the lowest breeding value (–2.20). Genotype × location interactions were significant for yield, pod width, and plant height, while location variance was significant for all parameters evaluated. When considering that higher aphid densities could lead to greater pesticide use and, therefore higher production and environmental costs, the high-yielding VI060794—with moderate aphid resistance across multiple environments—presents an alternative or substitute for local landraces across multiple agro-ecologies of Cameroon and (by extension) Central Africa. [ABSTRACT FROM AUTHOR]

The predatory gall midge, Aphidoletes aphidimyza (Rondani), and tobacco aphid cocoon wasp, Aphidius gifuensis Ashmead, are important natural enemies of Myzus persicae (Sulzer) (Hemiptera: Aphididae). Predation by A. aphidimyza and A. gifuensis can regulate M. persicae ; however, how interspecific interference competition affects their foraging efficiency is unknown. Here, we investigated the consumption and parasitization abilities of A. aphidimyza 3rd instar larva and A. gifuensis adults under various conditions. Consumption of parasitized aphids by A. aphidimyza 3rd instar larvae was significantly lower than that of nonparasitized controls, with a substantial increase in handling time. The presence of A. gifuensis adults did not significantly affect the predation capacity of A. aphidimyza larvae. Relative to controls, A. aphidimyza larvae predation trace (PT) and imago activity significantly decreased A. gifuensis parasitism rates at different aphid densities. Further, A. aphidimyza larvae PT increased the A. gifuensis handling time of M. persicae , whereas the presence of A. aphidimyza adults had the opposite effect. Coexistence with heterospecific natural enemies reduced the parasitic capacity of A. gifuensis , whereas A. aphidimyza larvae predation capability was influenced to a lesser extent. Our results demonstrate that intraguild interactions strongly influence the predatory and parasitic efficacy of A. aphidimyza and A. gifuensis , although the effect on A. gifuensis was more pronounced. For effective biological control of M. persicae using A. aphidimyza and A. gifuensis , we recommend releasing A. aphidimyza first to mitigate intraguild predation and enhance the overall success of the pest control program. [ABSTRACT FROM AUTHOR]

BACKGROUND: Body‐color polymorphisms in insects are often explained by environmental selective advantages. Differential fitness related to body coloration has been demonstrated in Myzus persicae (Sulzer): performance of the red morph is in general better than that of the green morph on tobacco plants. However, the molecular mechanism involved is largely unclear. RESULTS: Here we showed that the red morph of M. persicae had higher expression of a carotenoid desaturase CarD763 in the whole body, salivary gland and saliva relative to the green morph. Also, 18% individuals displayed faded red body color 5 days post dsCarD763 treatment. Furthermore, knockdown of CarD763 in the red morph significantly prolonged the time needed to locate phloem and shortened the duration of phloem feeding. Honeydew production and survival rate decreased as well. In contrast, overexpression of CarD763 in tobacco leaves facilitated aphid feeding, enhanced honeydew production and improved the survival rate of aphids. Compared with those fed by dsGFP aphids, plants infested by dsCarD763‐treated aphids had higher ROS accumulation, lower lycopene content and photosynthetic rate, and maximum photon quantum yield. The reverse was true when plants overexpressed CarD763. CONCLUSION: These findings demonstrated that CarD763, a red morph‐specific salivary protein, could enhance aphid feeding and early colonization by promoting plant photosynthesis. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Aphis gossypii Glover is a prevalent phytophagous insect that inflicts significant damage on cucumber plants. Recent studies have provided insights into plant communication and signal transduction within conspecifics. However, understanding of the effect of these communication mechanisms on adjacent cucumbers and their resident aphids, especially in the context of an aphid infestation, is still in its early stages. RESULTS: Utilizing a partitioned root configuration, a tendency for aphids to gather on nearby cucumber leaves of non‐infested plants was observed. Furthermore, neighboring plants near aphid‐infested cucumber plants showed a reduction in aphid reproduction rates. Concurrently, these plants exhibited a significant increase in reactive oxygen species (ROS) levels, along with enhanced defensive and antioxidant enzymatic responses. Analysis of the microbial community in the rhizosphere showed significant differences in species composition among the samples. Among these, the bacterial families Microbacteriaceae and Rhizobiaceae, along with the fungal species Leucocoprinus ianthinus and Mortierella globalpina, exhibited increases in their relative abundance in cucumber seedlings located near aphid‐infested plants. Significantly, this study unveiled robust correlations between dominant microbial phyla and physiological indicators, primarily associated with aphid resistance mechanisms in plants. CONCLUSION: The results show that aphid‐infested cucumber plants trigger oxidative stress responses in adjacent seedlings through complex interplant communication mechanisms. In addition, these plants cause changes in the composition of the rhizospheric microbial community and the physiological activity of neighboring plants, consequently boosting their natural resistance to aphids. This study provides essential theoretical foundations to guide the development of sustainable strategies for managing cucumber aphids. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Pterocomma (Hemiptera: Aphidinae) are large aphids found across the northern hemisphere on various willow (Salix) and poplar (Populus) trees. We provide the first records of the Poplar Bark Aphid, Pterocomma populeum in Australia from Tasmania and New South Wales, a potential pest of poplar trees. Morphological character measurements and DNA (cytochrome oxidase subunit 1) sequences are provided along with discussions around difficulties in species separation. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf virus (BYDV) is the most widespread viral disease of cereal crops vectored by aphids, causing stunting of the crop and significant yield loss. Management recommendations for autumn sown cereals has centred on the timely control of aphid vectors, particularly their management before the crop has reached Growth Stage 31 (stem elongation). In recent years two separate but related issues have emerged, (i) the detection of pyrethroid resistance in a single Sitobion avenae SA3 clone and (ii) the withdrawal of neonicotinoid insecticide seed dressing; widely used to manage aphids in the early development of cereal crops. A series of replicated field studies were conducted from 2016 to 2019 to ascertain if the pyrethroid insecticide is still effective in light of the SA3 clones' presence in aphid populations and if withdrawal of neonicotinoid seed dressings has negatively affected aphid management. Both disease levels and yields confirmed that the neonicotinoid, clothianidin, applied as a seed treatment significantly contributed to the management of BYDV in the different trials investigated. Results of this study demonstrate application of a foliar (lambda‐cyhalothrin or a sulfoxaflor) insecticide has a significant positive impact on yield. Foliar pyrethroid insecticides were as effective in protecting yield from BYDV as the neonicotinoid seed treatments. In the absence of neonicotinoid seed dressing, alternative insecticides still offer protection for winter barley crops against the aphid vectors of BYDV and associated yield loss. Furthermore, the presence of a pyrethroid resistant Sitobion avenae SA3 clone had no observable impact on field efficacy of the pyrethroid insecticide, lambda‐cyhalothrin in these trials. However, this needs continuous monitoring because of potential further increases in resistance levels or emergence of additional resistance mechanisms, which could render pyrethroid insecticides ineffective. [ABSTRACT FROM AUTHOR]

Symbiosis plays a critical role in plant biology. Temperate grasses often associate with several symbiotic fungi simultaneously, including Epichloë endophytes and arbuscular mycorrhizal (AM) fungi, in shoots and roots, respectively. These symbionts often modulate plant–herbivore interactions by influencing nutritional traits (i.e. AM fungi‐mediated nutrient uptake) and/or the secondary chemistry (i.e. endophytic alkaloids) of their host plant. Moreover, such grasses also accumulate large amounts of silicon (Si) from the soil, which can be deposited in tissues to act as a physical anti‐herbivore defence. Recent evidence suggests that both endophytes and AM fungi independently facilitate Si uptake. However, the consequences of their interactions with piercing‐sucking insects (i.e. aphids), or whether Si supply, endophytes, and AM fungi interact in this regard, are currently unknown. While Si deposition may be less effective against aphids than other herbivores (i.e. chewing caterpillars), Si supply can also alter plant secondary metabolite defences, which could affect sucking insects. In a factorial greenhouse experiment, we evaluated whether these components, acting alone or in combination, altered (1) foliar primary chemistry, (2) Si and symbiont‐chemical (endophytic alkaloids) defences, as well as (3) performance of the bird cherry‐oat aphid (Rhopalosiphum padi) feeding on tall fescue (Festuca arundinacea). Endophytes decreased all aphid performance parameters, including population growth and reproduction by 40%, but their impact was reversed by the presence of AM fungi, leading to a 52% increase in aphid performance compared with plants solely hosting endophytes. This improvement in performance was associated with reduced loline alkaloid levels and higher shoot nitrogen in AM‐endophytic plants. Endophytes and AM fungi exhibited antagonism, with endophytes reducing AM colonization by 34% and AM presence decreasing endophyte loline alkaloids by 44%. While both fungi jointly increased Si accumulation by 39% under Si‐supplied conditions, Si had no noticeable effects on aphids. Moreover, although Si supply had no identifiable effects on AM colonization, it reduced endophyte peramine alkaloids by 24%. Synthesis. Our findings indicate that symbiotic fungal partnerships and silicon provision may benefit plants but could weaken anti‐herbivore defences when combined. Revealing the complex interactions among diverse fungal symbionts and showcasing their effects on different anti‐herbivore defences (chemical and physical) and herbivore performance for the first time. [ABSTRACT FROM AUTHOR]

Phenylalanine ammonia lyase (PAL) is a pivotal enzyme in the phenylalanine metabolic pathway in plants and has a crucial role in the plant's response to environmental stress. Although the PAL family has been widely studied in many plant species, limited is known about its particular role in cucumbers under stress. We investigated the physicochemical properties, gene structure, gene duplication events, conserved motifs, cis-acting elements, protein interaction networks, stress-related transcriptome data, and quantitatively validated key stress-related genes. The main results indicated that 15 PAL genes were grouped into four clades: I, II, and III when arranged in a phylogenetic tree of PAL genes in angiosperms. The analysis of the promoter sequence revealed the presence of multiple cis-acting elements related to hormones and stress responses in the cucumber PAL genes (CsPALs). The analysis of protein interaction networks suggested that CsPAL1 interacts with eight other members of the PAL family through CsELI5 and CsHISNA, and directly interacts with multiple proteins in the 4CL family. Further investigation into the expression patterns of CsPAL genes in different tissues and under various stress treatments (NaCl, Cu2+, Zn2+, PEG6000, aphids) demonstrated significant differential expression of CsPALs across cucumber tissues. In summary, our characterization of the CsPAL family offers valuable insights and provides important clues regarding the molecular mechanisms of CsPALs in managing abiotic and biotic stress interactions in cucumbers. [ABSTRACT FROM AUTHOR]

Summary Lignin, a complex heterogenous polymer present in virtually all plant cell walls, plays a critical role in protecting plants from various stresses. However, little is known about how lignin modifications in sorghum will impact plant defense against sugarcane aphids (SCA), a key pest of sorghum. We utilized the sorghum brown midrib (bmr) mutants, which are impaired in monolignol synthesis, to understand sorghum defense mechanisms against SCA. We found that loss of Bmr12 function and overexpression (OE) of Bmr12 provided enhanced resistance and susceptibility to SCA, respectively, as compared with wild‐type (WT; RTx430) plants. Monitoring of the aphid feeding behavior indicated that SCA spent more time in reaching the first sieve element phase on bmr12 plants compared with RTx430 and Bmr12‐OE plants. A combination of transcriptomic and metabolomic analyses revealed that bmr12 plants displayed altered auxin metabolism upon SCA infestation and specifically, elevated levels of auxin conjugate indole‐3‐acetic acid–aspartic acid (IAA–Asp) were observed in bmr12 plants compared with RTx430 and Bmr12‐OE plants. Furthermore, exogenous application of IAA–Asp restored resistance in Bmr12‐OE plants, and artificial diet aphid feeding trial bioassays revealed that IAA–Asp is associated with enhanced resistance to SCA. Our findings highlight the molecular underpinnings that contribute to sorghum bmr12‐mediated resistance to SCA. [ABSTRACT FROM AUTHOR]

This study included one type of forest insect in the Nineveh of northern Iraq, which is plant sap suckers that infect a group of forest trees, including Populus Euphratica and P.deltoides. The results showed a variation in the killing rate resulting from treating poplar leaf nymph aphids with phenols of the study tree species according to the type of tree, concentration, and insect phase. The phenols of the Euphratica poplar leaves excelled on average, with the killing rate of the American type being 62.01 and 56.49% at a concentration of 10%, respectively. For Alkaloids, it was 47.21 and 43.3% for P.euphratica and P.deltoides, respectively. Meanwhile, terpenes were 43.21 and 37.69%. The average percentage of expulsion reached 36.89% in the nymph phase of P. euphratica at a concentration of 10%. The study showed significant superiority of the Alkaloids of Euphratica poplar and the average expulsion percentage over the Alkaloids of the other types. The average percentage of expulsion was 32.69% in the nymph phase at a concentration of 10%. The Euphratica poplar Terpenes outperformed the average kill rate over the Terpenes of the other type, with an average expulsion ratio of 29.92% in the nymph phase at a concentration of 10%. [ABSTRACT FROM AUTHOR]

Simple Summary: This study looked at how three different shrub species in an urban setting were affected by aphid colonisation. Analyses of fourteen factors that describe the photosynthetic pigment concentration and gas exchange to the carbon, nitrogen, and hydrogen partition were conducted. Aphid colonisation had the greatest impact on nitrogen partition and the C/N ratio, parameters that could be recommended in other studies of a similar kind. The studied shrub species had varying responses. Spiraea × vanhouttei and Cydonia japonica demonstrated the strongest responses in terms of nitrogen partition and the C/N ratio. Shrubs are a significant component of urban vegetation found in parks, but they experience various influences from biotic and abiotic agents, among which aphids play an important role. In this work, the effects of aphid colonisation on three shrub species in urban environments were examined. Fourteen parameters were analysed, describing the photosynthetic pigment content and gas exchange to carbon, nitrogen, and hydrogen partitions. While no significant effect of colonisation was found on photosynthetic pigment parameters, the effect was significant on gas exchange parameters. The strongest effect of aphid colonisation achieved was on nitrogen partition and the C/N ratio, parameters that could be suggested for further similar studies. All parameters were classified into two groups according to their principal component analysis, suggesting a correlation between nitrogen and carbon content, the C/N ratio, measured gas exchange parameters, and chlorophyll a content. The ratio between net photosynthesis and dark respiration (A/K) was classified in the second group, suggesting that this parameter provides additional information on the effect of aphid colonisation and deserves special attention in further studies. There were differences in the effect of aphid colonisation on the physiology of the examined shrub species, especially in cases where a decrease in the C/N ratio was achieved in Spirea trilobata and Cydonia japonica, while an increase in the same parameter was recorded in Hybiscus syriacus. [ABSTRACT FROM AUTHOR]

Simple Summary: Correct taxonomic identification is essential for conducting successful biological research, especially with regard to economically important insects, such as jumping plant lice or psyllids. In the present study, we identify and diagnose the morphologically characterised aphalarid species from Bulgaria using two molecular markers, cytochrome c oxidase I and cytochrome b. A total of 80 sequences of 25 Aphalaridae species were obtained and included in the BOLD and GenBank databases. This should enable even non-experts to identify these species quickly and accurately. The results of the current study show that two barcode genes are sufficient to distinguish most aphalarid species. Psyllids (Hemiptera: Psylloidea) are plant sap-sucking insects whose identification is often difficult for non-experts. Despite the rapid development of DNA barcoding techniques and their widespread use, only a limited number of sequences of psyllids are available in the public databases, and those that are available are often misidentified. Here, we provide 80 sequences of two mitochondrial genes, cytochrome c oxidase I (COI) and cytochrome b (Cytb), for 25 species of Aphalaridae, mainly from Bulgaria. The DNA barcodes for 15 of these species are published for the first time. In cases where standard primers failed to amplify the target gene fragment, we designed new primers that can be used in future studies. The distance-based thresholds for the analysed species were between 0.0015 and 0.3415 for COI and 0.0771 and 0.4721 for Cytb, indicating that the Cytb gene has a higher interspecific divergence, compared to COI, and therefore allows for more accurate species identification. The species delimitation based on DNA barcodes is largely consistent with the differences resulting from morphological and host plant data, demonstrating that the use of DNA barcodes is suitable for successful identification of most aphalarid species studied. The phylogenetic reconstruction based on maximum likelihood and Bayesian inference analyses, while showing similar results at high taxonomic levels to previously published phylogenies, provides additional information on the placement of aphalarids at the species level. The following five species represent new records for Bulgaria: Agonoscena targionii, Aphalara affinis, Colposcenia aliena, Co. bidentata, and Craspedolepta malachitica. Craspedolepta conspersa is reported for the first time from the Czech Republic, while Agonoscena cisti is reported for the first time from Albania. [ABSTRACT FROM AUTHOR]

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

Cotton aphids (Aphis gossypii Glover) are important pests of cucurbit crops. Plant defenses at different cell layers, including the leaf surface, mesophyll cells, and phloem, are employed to defend aphids. Here, we assessed differences in aphid resistance among six watermelon varieties and elucidated the defense mechanisms underlying aphid-resistant/susceptible watermelon varieties. The population abundance, offspring number per female, and meantime of phloem-feeding (E2 phase) of aphids were the highest on XiNong (XN), followed by JingXin (JX), TianWang (TW), ZaoJia (ZJ), and MeiFuLai (MFL), and these parameters were the lowest on JinMeiDu (JMD). Further analyses showed that there was no correlation between the aphid resistance of six watermelon varieties and defenses at the leaf surface. For defenses at mesophyll cells, aphid infestation increased salicylic acid (SA) content at 48 h post-infestation (hpi) and ROS accumulation at 6 and 12 hpi in six watermelon varieties. For phloem defenses, aphid infestation increased callose content in JMD plants but decreased callose content in JX, TW, ZJ, MFL, and XN plants at 6, 12, 24, and 48 hpi. Moreover, callose deposition suppressed by 2-deoxy-d-glucose (2-DDG) neutralized the resistance of JMD plants and exacerbated the susceptibility of XN plants to aphids, which exhibited a higher population abundance and E2 phase time. Collectively, phloem defenses regulated by aphid-induced callose deposition were responsible for differences in aphid resistance among the watermelon varieties. [ABSTRACT FROM AUTHOR]

The first aim of this study was to test the pulsed stress hypothesis on a system consisting of young spring wheat (Triticum aestivum L.) and the rose-grain aphid Metopolophium dirhodum (Walker) by following the age-stage, two-sex life table theory. This hypothesis predicts that fluid-feeding insects benefit from feeding on plants intermittently stressed by drought due to the increased nutrient availability and restored cell turgor. Our second aim was to illustrate the risk of drawing different conclusions if based on a single or a small subset of parameters or if the entire lifespan of a generation is not covered compared to if the study was conducted at the population level. We applied periods of drought stress (soil water capacity, SWC = 40%) on four occasions relative to the population development of the aphids and compared those treatments with well-watered (SWC = 70%) and continuous stress conditions (SWC = 40%). The timing of the stresses appeared to be important in determining the effect on aphid performance. Although we found some improvement in fecundity when the stress occurred before the aphids were placed on the plants, the overall effect of the early-timed pulsed stress treatments on the rate of increase was negative compared to the well-watered control, which was mainly due to prolonged nymph development. The drought pulse that was timed late (the second week of aphid reproduction) did not show any effect relative to the well-watered control. This study therefore provides no clear support for the validity of the pulsed stress hypothesis. [ABSTRACT FROM AUTHOR]

In aphidophagous ladybird beetles, amputation of limbs in the larval stage leads to limb regeneration in adults. Regeneration is an energetically expensive phenomenon, and altering prey species may have profound consequences on this process. Therefore, we hypothesised that the quality of prey species will impact the ability to regenerate the lost limbs in Cheilomenes sexmaculata. For this experiment, we reared the larvae of C. sexmaculata on two aphid prey species: Aphis craccivora, which is the most preferred good-quality aphid, and A. nerii, which is the least preferred, poor-quality aphid. Although regeneration occurred in both dietary regimes, the extent of regeneration was higher in the beetles fed on A. craccivora. The length of the regenerated legs was shorter than the control/unamputated beetles, and it was further reduced when the prey species was of poor-quality indicating additional utilisation of resources for tissue repair and regeneration. Regeneration delayed pupal duration, post-amputation developmental duration and relative growth rate (RGR). Poor diet negatively affected developmental durations and RGR. Our results indicate prey dependency on regeneration and highlight energetic demands of regeneration and its associated developmental allocation costs. [ABSTRACT FROM AUTHOR]

This is the first report of the occurrence of blueberry virus L (BlVL) in Japan and the complete nucleotide sequence of a Japanese isolate. BlVL was detected using reverse transcription-polymerase chain reaction in 35 of 52 highbush blueberry shrubs at Iwate University Research Farm, Japan, and in aphids (Aphis gossypii) on a BlVL-infected blueberry shrub. In the aphid transmission test of BlVL, the aphids transmitted the virus to uninfected blueberry bushes. No symptoms were observed in shrubs infected with the virus by aphid inoculation or by graft inoculation, suggesting that BlVL causes latent infection in highbush blueberry. [ABSTRACT FROM AUTHOR]

Communicating results and ideas to a wider audience has been an important, but challenging component of scientists working in an academic environment. Particularly in recent decades, various social media platforms have become increasingly important to facilitate this. In addition, many scientists have used blogging platforms to communicate and discuss their work. Although the online dynamics of science communication are continuously changing, blogging has been used in a remarkably stable form for several decades. For this work, we brought several ecology bloggers to reflect on blogging as a science communication medium. We argue that blogging can be a powerful way to present new ideas and discuss them with a wide audience. Although blogs are not the same as scientific articles, they often serve as the initial brainstorm session. Importantly, we argue that blogs are most effective when bloggers and readers actively engage in conversations. We believe that blogging will be here to stay in science communication because of its unique and independent form of outreach. [ABSTRACT FROM AUTHOR]

Elevated concentrations of atmospheric carbon dioxide (CO2), a consequence of anthropogenic global change, may profoundly interfere with natural ecological processes, perhaps even interactions across trophic levels. Even the survival prospects of organisms at higher trophic levels could be affected, as follows. We showed previously that the endoparasitoid Diaeretiella rapae, a specialized parasitoid of the cabbage aphid Brevicoryne brassicae, exposed to elevated CO2 concentrations (800 ppm) for up to 10 weeks, performed far worse (e.g., lower survival and parasitism rates) compared with ambient CO2 (400 ppm). To investigate whether these CO2‐related effects in the parasitoids were mediated by changes in the quality of the aphids as hosts, we measured the nutritional and energy content of cabbage aphids under the above conditions. Specifically, we measured lipid, protein and water‐soluble carbohydrate concentrations. We tested the hypothesis that when insects feed from plants with altered nutritional content, they incur a cost in dealing with such biotic stresses. That cost reduces their metabolic well‐being and, thus, reduces their nutritional status with respect to parasitoids developing at their expense. We found that CO2 had significant effects on aphid body mass (i.e., wet weight) and chemical composition, with elevated CO2 concentrations reducing aphid mass by more than 50%. Aphids grown under elevated CO2 also had significantly reduced soluble carbohydrates but significantly more lipids, on a weight‐per‐weight basis, than aphids grown under ambient CO2. A significant decrease in total energy reserves (i.e., the sum of total proteins, lipids, and water‐soluble carbohydrates) thus typified aphids grown under elevated CO2. Our results contribute to explaining the impaired performance of the aphid B. brassicae and its parasitoid D. rapae previously reported under elevated CO2, and provide evidence that under future climate change, host plants might affect the development and performance of parasitoids through their impacts on the nutritional quality of their herbivorous hosts. [ABSTRACT FROM AUTHOR]

Temperature can interact with chemical pesticides and modulate their toxicity. Sublethal exposure to pesticides is known to trigger hormetic responses in pests. However, the simultaneous effects of temperature and sublethal exposure to single or mixture-based insecticides on the insects' stimulatory responses are not frequently considered in toxicological studies. Here we investigated the combined effects of temperature on the lethal and sublethal responses of the green peach aphid Myzus persicae after exposure to commercial formulations of a neonicotinoid (thiamethoxam) and a pyrethroid (lambda-cyhalothrin) and their mixture. Firstly, the concentration-response curves of the insecticides were determined under four temperatures (15 °C, 20 °C, 25 °C, and 28 °C) by the leaf dipping method. Subsequently, the sublethal concentrations C0, CL1, CL5, CL10, CL15, CL20, and CL30 were selected to assess sublethal effects on aphids' longevity and reproduction under the same temperatures. The results showed that the mixture of thiamethoxam + lambda-cyhalothrin caused greater toxicity to aphids compared to the formulations with each active ingredient alone and that the toxicity was higher at elevated temperatures. Furthermore, the exposure to low concentrations of the mixture (thiamethoxam + lambda-cyhalothrin) and the separated insecticides induced stimulatory responses in the longevity and fecundity of exposed aphid females, but the occurrence of such hormetic responses depended on the insecticide type, its sublethal concentration, and the temperature as well as their interactions. [ABSTRACT FROM AUTHOR]

Plum pox virus (PPV, genus Potyvirus) is one of the most economically important plant viruses. The PPV M strain (PPV-M) was first isolated in Japan in 2016. While a broad host range of the PPV M strain from trees to weeds has been widely reported, host range and the contribution of weeds to the PPV infection cycle in Japan remained unknown. In this study, we examined the host range of PPV-M in Japan within the Asteraceae weeds and explored its potential role as an intermediate host. By mechanically inoculating twelve herbaceous species belonging to Asteraceae (alternatively Compositae) in orchards with PPV-M, we found that all were susceptible to the virus. Of those, Hemisteptia lyrata showed high infection rates on the upper leaves, typically favored by aphids. A subsequent survey of multiple aphid species feeding on H. lyrata showed a seasonal infection cycle in which the aphid Aphis fabae solanella likely transmitted PPV-M from Japanese apricot leaves to H. lyrata in the spring. Then, A. spiraecola, an efficient PPV vector known to shift between hosts in summer and autumn, transmitted the disease to healthy Japanese apricot seedlings from PPV-M infected H. lyrata in autumn. It is conceivable that PPV-M in Japanese apricot orchards follows a seasonal infection cycle, potentially involving an intermediate host (Asteraceae) and two aphid species. [ABSTRACT FROM AUTHOR]

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Alfalfa (Medicago sativa L.) is an economically important forage legume. As a result of the extensive and intensive cultivation of alfalfa planting and the gradual expansion of planting areas, pest occurrence has increased in frequency. Aphids are one of the main pests that threaten the growth and productivity of alfalfa. After an aphid outbreak, alfalfa yield and quality are commonly greatly reduced. At present, there are few studies on alfalfa plants infested with aphids, so it is imperative to study the regulatory mechanisms of aphid infestation tolerance in alfalfa. In this study, alfalfa plants from the variety "Wudi" were investigated, and pea aphids were selected for inoculation. The transcriptome and metabolome data were analyzed at three time points (0 d, 1 d, and 4 d), revealing 3458 differentially expressed genes and 358 differential metabolites. Trend analysis of DEGs and DAMs revealed that the former were significantly enriched in three distinct trends, whereas the latter were significantly enriched in only one. Moreover, 117 important hub genes associated with alfalfa response to aphid infestation were screened by WGCNA. By mapping DEGs and DAMs to KEGG pathways, it was found that the "phenylpropanoid biosynthesis", "flavonoid biosynthesis", and "isoflavonoid biosynthesis" pathways play an important role in alfalfa responses to aphid infestation. These results further elucidate the regulatory mechanism of alfalfa in response to aphid infestation and provide valuable information for breeding new aphid-resistant plant varieties. [ABSTRACT FROM AUTHOR]

Abstract Different species of aphids, responsible for severe yield losses of cereal crops including wheat, (Triticum aestivum L.) are managed by insecticides, which are harmful to organisms and the environment under field conditions. Therefore, an environment friendly aphidicidal product of plant origin is required. Mentha spicata oil was found to be rich in carvone (81.88%), but the use of its oil and carvone in crop protection is lacking due to their volatility, poor solubility, and stability. A nanoformulaton not only solves these problems but also improve the efficacy and dose of the bioactive compounds. Thus, nano-emulsions of the oil and carvone prepared were characterized, and evaluated against Rhopalosiphum maidis (corn aphid) and Sitobion avenae (wheat aphid) The average droplet size of nano-emulsions of the oil and carvone was found to be 22.1 and 41.21 nm. Nano-emulsion of carvone exhibited higher aphid mortality (LC50 = 0.87–1.94 mg/mL) at 24 h and acetylcholinesterase inhibitory activity (IC50 = 0.07–3.83 mg/mL) compared to the nano-emulsion of the oil (LC50 = 2.87–2.81 mg/mL; IC50 = 1.66–5.34 mg/mL). The repellence index (RI) in nano-emulsion of essential oil was found to be higher (84.73 and 81.72%) at the highest concentration (0.05 µL/cm2) than that of carvone (77.59 and 80.98%) for R. maidis and S. avenae. Further, in silico studies also revealed the favourable binding energy (− 6.6 to − 8.5 kcal/mol) of the main compounds in the oil with acetylcholinesterase, facilitated by hydrophobic interactions and hydrogen bonding. This study suggests that the nano-emulsions of the essential oil and carvone can be explored under field conditions to establish efficacy for their utilization as aphidicidal and repellent products against aphids. In the present study, aphidicial and repellent activities of its essential oil and carvone were reported for the first time against R.maidis and S.avenae.

Abstract Transmission of plant viruses by insect vectors is facilitated by unequivocal tri-partite interactions among host plants, viruses, and associated vectors. The advent of next-generation sequencing including whole genome sequencing, RNA/small RNA sequencing, proteomics, and metabolomics aided in elucidating the molecular mechanisms involved in virus transmission by insect vectors and infection in host plants.