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Wheat plants infested by Russian wheat aphids (RWA) induce a cascade of defence responses, which include increased activity of β-1,3-glucanase and peroxidase (POD). There is a lack of information regarding β-1,3-glucanase and POD synergistic effects on the plant cell wall modification and characterisation during wheat-RWA infestation. This study aimed to characterise the physicochemical properties of the cell wall-bound POD and β-1,3-glucanase during RWA-wheat interaction. The susceptible Tugela, moderately resistant Tugela-Dn1, and resistant Tugela-Dn5 cultivars were planted in a glasshouse to a seedling stage before being infested with RWASA2 for 14 days. The findings showed a significant increase in β-1,3-glucanase and POD activities in the infested Tugela-Dn5 and Tugela-Dn1 cultivars over the 14 days. However, in the Tugela enzymes were repressed. In addition, it was shown for the first time that β-1,3 − 1,4-glucanase activity specific toward mixed-linked glucan was significant in the resistant cultivar over 14 days. β-1,3-glucanase, β-1,3 − 1,4-glucanase and POD displayed optimum at pH 5. β-1,3-glucanase and POD displayed temperature optimum at 40 and 50 °C, respectively. However, β-1,3 − 1,4-glucanase had temperature optimum at 25 °C. β-1,3-glucanase and POD had a thermo-stability at 37 °C followed by about 80% relative activity at 70 °C, but β-1,3 − 1,4-glucanase displayed thermostability at 25 °C and retained more than 75% at 70 °C, confirming that β-1,3 − 1,4-glucanase and β-1,3-glucanase induced in the resistant cultivars cell wall were two different enzymes. Mechanism of actions and oligosaccharide displayed that β-1,3-glucanase was highly active against β-1,3-glucan and required a triose and higher oligosaccharide to be active. Our findings demonstrated cell-wall bound POD and β-1,3-glucanase activities significantly increased in wheat after RWASA2 infestation, revealing they acted synergistically to reinforce the cell wall to deter RWASA2 feeding in resistant cultivars. [ABSTRACT FROM AUTHOR]

Aphidius platensis Brèthes (Hymenoptera: Braconidae) is a parasitoid of cereal aphids. Its foraging, recognition, and host acceptance processes may be related to chemical cues inherited from the host during development. This study aimed to evaluate the influence of the maternal host, that is, Rhopalosiphum padi (L.) (Rp), Schizaphis graminum (Rondani) (Sg) (from the Aphidini tribe), Metopolophium dirhodum Walker (Md), and Sitobion avenae (Fabricius) (Hemiptera: Aphididae) (from the Macrosiphini tribe) (all Hemiptera: Aphididae) on parasitism and chemotactic responses of A. platensis. Parasitism by A. platensis was investigated in non‐choice bioassays along four generations, as well as in choice bioassays. Females originating from a S. graminum laboratory colony (SgLab) were reared for four generations on all four aphid species. Chemotaxis experiments were conducted in a four‐armed olfactometer with two A. platensis strains: one originated from SgLab and another after three generations on Rp (RpF4), both exposed to the four aphid species simultaneously. The highest SgLab A. platensis parasitism rates, in both choice and non‐choice tests, were observed on S. graminum, followed by R. padi and S. avenae. No parasitized hosts were found in M. dirhodum. Furthermore, SgLab A. platensis exhibited a stronger attraction to the odors emitted by S. graminum. However, after the third generation on R. padi (RpF4), A. platensis behavior altered, displaying a preference for R. padi over S. graminum, both in terms of parasitism and chemotactic responses. In conclusion, A. platensis showed a preference for hosts within the Aphidini tribe, indicating innate affinities. Nevertheless, its preference can be modified within this tribe based on the chemical cues inherited from the host during development. [ABSTRACT FROM AUTHOR]

Aphids are sap‐feeding plant pests that depend on their symbiotic relationships with the primary endosymbiont Buchnera aphidicola to adapt to impoverished diets. However, how the host plant affects the aphid primary symbiont and aphid adaptation to host plant transfer are poorly known. In this study, aphid symbiont screening and genotype identification were used to establish 2 aphid strains (Rhopalosiphum maidis [Rm] and Rhopalosiphum padi [Rp] strains) containing only Buchnera without any secondary symbionts for both wheat aphid species (R. maidis and R. padi). Aphid fitness and Buchnera titers were unstable on some of these host plants after transferring to novel host plants (G1–G5), which were influenced by host plant species and generations; however, they stabilized after prolonged feeding on the same plants for 10 generations. The electropenetrography (EPG) records showed that the allocation of aphid feeding time was significantly distinct in the 6 host plants; aphids had more intracellular punctures and spent more nonprobing time on green bristlegrass which was not conducive to its growth compared with other plants. The content of soluble sugar, soluble protein, and amino acid in the leaves of the 6 host plants were also clearly separated. The correlation coefficient analysis showed that the nutrient contents of host plants had significant correlations with aphid feeding behaviors, fitness, and Buchnera titers. In the meantime, aphid fitness, and Buchnera titers were also affected by aphid feeding behaviors. Also, Buchnera titers of aphid natural populations on 6 host plants showed a visible difference. Our study deepened our understanding of the interaction among aphids, endosymbionts, and host plants, indicating that the host plant nutrient content is a predominant factor affecting aphid adaptation to their diet, initially affecting aphid feeding behaviors, and further affecting aphid fitness and Buchnera titers, which would further contribute to exploiting new available strategies for aphid control. [ABSTRACT FROM AUTHOR]

The ecological niche of aphids is largely defined by the phloem sap of plants, which they consume. Previous studies revealed that aphids may change the phloem sap metabolome and that a previous aphid infestation may benefit them. As aphids reproduce parthenogenetically, the performance and preference of aphids of the same monoclonal aphid lineage can be compared between previously uninfested and previously aphid‐infested plants.Wheat (Triticum aestivum) leaves were infested by clonal lineages of Sitobion avenae aphids for 9–10 days. Leaf phloem exudates were analysed using amino acid profiling and metabolic fingerprinting, capturing mainly specialised metabolites. It was investigated whether aphid colony sizes differ between leaves that were previously uninfested or infested by aphids of a different clonal lineage or by aphids of the same clonal lineage and whether aphids show a preference for any of these leaves.The relative concentrations of metabolites in the phloem exudates were not affected by aphid infestation. Aphid colonies were partly larger on previously aphid‐infested leaves than on control leaves. However, this effect was transient and finally colonies had similar sizes. Given a choice between previously aphid‐infested and uninfested leaves, S. avenae nymphs showed no preferences.The findings that positive effects of previous aphid infestation on aphid performance are transient and that the performance but not the preference of the aphids was affected by previous aphid infestation highlight the temporal dynamics and complexity of aphid–plant interactions. Niche alteration processes may be partly involved in these interactions. [ABSTRACT FROM AUTHOR]

Plants can respond to insect egg deposition by emitting oviposition‐induced plant volatiles (OIPVs) recruiting parasitoids. The recruitment of carnivore insects in response to egg deposition is considered an indirect defence strategy that is widespread in the plant kingdom. In recent years, there has been increasing evidence showing that microbial colonization can influence the strength of plant responses to insect herbivory, yet no information is available on how beneficial microbes modulate indirect defences induced by insect egg deposition.In this work, we evaluated the effects of inoculation with the beneficial soil fungus Trichoderma harzianum strain T22 on a tritrophic system consisting of tomato, the southern green stink bug Nezara viridula and its associated egg parasitoid Trissolcus basalis. We used Y‐tube olfactometer assays to evaluate the behavioural responses of the parasitoids to OIPVs emitted by plants colonized with beneficial soil microbes. We also used gas chromatography coupled with mass spectrometry (GC–MS) to investigate whether and how root inoculation with T. harzianum T22 affects the chemical composition of induced plant volatiles.In olfactometer assays, we found that root inoculation with T. harzianum T22 enhanced the attraction of the egg parasitoid towards tomato plants induced by N. viridula feeding and oviposition activities. In particular, the egg parasitoid preferred OIPVs emitted by tomato plants previously inoculated with T. harzianum T22 over OIPVs emitted by non‐inoculated plants. Furthermore, chemical analysis showed that root inoculation with T. harzianum T22 resulted in changes in the composition of OIPVs, which was consistent with the behavioural observations. Among the compounds that strongly contribute to the chemical differences between OIPVs from non‐inoculated and inoculated plants, chemical analysis identified green leaf volatiles ((Z)‐3‐hepten‐1‐ol, (E,E)‐2,4‐hexadienal), along with terpenoids (terpinen 4‐ol, α‐tujene and δ‐elemene).Taken together our results indicate that beneficial soil microbes enhance indirect plant defences induced by feeding and oviposition, broadening our understanding of plant responses to insect eggs. Our results underscore the importance of taking into account the role of microorganisms to fully comprehend the intricate interactions among plants, herbivore eggs and their associated egg parasitoids. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

BACKGROUND: Soybean is the third‐greatest global commodity crop with respect to grain production, Brazil is the largest soybean producer in the world. We performed the first extensive survey including all the five main soybean cultivation regions in Brazil over three seasons (2018/2019, 2019/2020, and 2020/2021). A total of 2386 localities were sampled, corresponding to 145 municipalities in 11 states. Sampling was carried out between the R1 and R8 soybean growth stages, using a beating sheet. RESULTS: Fifteen species were recorded, with five species accounting for more than 99% of the sampled insects. The Neotropical brown stink bug, Euschistus heros (F.), was the most abundant species (82.4% of the adults and 84.1% of the nymphs overall), with differences in the mean abundance between soybean macroregions. The melacanthus green belly stink bug, Diceraeus melacanthus Dallas was the second most abundant species overall, followed by the brown winged stink bug, Edessa meditabunda (F.), the furcatus green belly stink bug, Diceraeus furcatus (F.) and the red‐banded green stink bug, Piezodorus guildinii (Westwood). The relative abundance of each species differed between soybean macroregions. The mean abundance of nymphs and adults of Euschistus heros at different soybean reproductive stages showed an increase from early reproductive stages to the beginning of the late reproductive stages (R5 or R6). CONCLUSION: This large‐scale assessment of stink bugs provides a basis for outlining integrated pest management programs and drives the development of monitoring and control strategies, as well as future studies investigating population dynamics over time and space in soybean fields. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Sitobion miscanthi and Schizaphis graminum (Rondani) are the 2 main aphid species that occur simultaneously, causing significant loss to wheat production. Acetamiprid has been used to control a variety of pests, including aphids. In this study, the sublethal effect of acetamiprid on S. miscanthi and S. graminum was evaluated using life-table analyses. The results showed that acetamiprid has a high toxicity to S. miscanthi and S. graminum with a LC50 of 1.90 and 3.58 mg/L at 24 h, respectively. The adult longevity and fecundity of S. miscanthi and S. graminum F0 generation were significantly reduced after being exposed to a sublethal concentration of acetamiprid. Additionally, the sublethal concentration of acetamiprid had negative transgenerational effects on S. miscanthi and S. graminum , which showed a significant decrease in fecundity and population life-table parameters involving age-stage-specific survival rate (s xj ), age-specific survival rate (l x ), and intrinsic rate of increase (r). Furthermore, the population projections showed that the total population size of S. miscanthi and S. graminum was significantly lower in the aphid group exposed to sublethal concentration of acetamiprid compared to the control group. These results suggest that sublethal concentration of acetamiprid suppresses the population growth of S. miscanthi and S. graminum. This finding is beneficial to the control of wheat aphids, and is important to fully understand the role of acetamiprid in integrated pest management. [ABSTRACT FROM AUTHOR]

Background: Yield gap is distance between potential yield and attainable yield (yield gap= potential yield-attainable yield) in order to increase the crop yield and the goal of sustainable agriculture. Methods: This study was conducted in Bam, Narmashir and Fahraj counties in 219 separate farms (79 farms in Bam, 72 farms in Narmashir and 68 farms in Fahraj) during the years 2019 and 2020 to investigate the yield gap of wheat and determine the limiting factors and their contributions to yield reduction, using the Comparative Performance Analysis (CPA) method. All information related to soil factors, management factors, climatic factors and agronomic traits (53 variables) were measured and recorded. The relationship between wheat yield and all variables was examined using a stepwise multiple regression method. A production model was determined for soil and management factors. Result: The results showed a yield gap between actual yield and potential yield in the regions of Bam, Narmashir and Fahraj, which were 1770.8, 1817.61 and 1605 kg per hectare, respectively. Since the actual yield in these regions was 4248, 4228 and 3161 kg per hectare, the yield gap was observed to be 33.6%, 30% and 29.4%, respectively. The effective factors in reducing the yield in the Bam region included water shortage (19.48%), nitrogen deficiency (16.09%), delayed planting (15.40%), soil available phosphorus deficiency (10.14%), weed density (10.8%), soil organic carbon (13.59%) and inappropriate plant density (14.47%). In the Narmashir region, water shortage (26.68%), nitrogen deficiency (18.86%), soil organic carbon (11.78%), inappropriate plant density (12.43%), wheat aphid (19.58%) and weed density (10.64%) caused yield reduction. In the Fahraj region, water shortage (20.65%), nitrogen deficiency (19.62%), delayed planting (9.44%), soil available phosphorus deficiency (8.45%), weed density (12%), soil salinity (12.80%) and black stem disease (17%) caused a decrease in wheat yield. [ABSTRACT FROM AUTHOR]

Silicon (Si) is a versatile nutrient that plays an instrumental role in mitigating biotic and abiotic stresses besides improving growth and yield of graminaceous crops. We hypothesized that application Si would significantly improve productivity and resilience of wheat. Hence, the objectives were a) to assess the impact of Si application on wheat growth, productivity, nutrient uptake, water use efficiency, and b) to determine the potentiality of Si in mitigating lodging and aphid density. Therefore, we conducted a field experiment with five levels of Si (0, 2, 4, 6, and 8 g Si liter−1) at three growth stages (crown root initiation, tillering, and jointing stage) using a factorial randomized block design replicated three times. The results showed that increasing Si doses positively influenced plant height, dry matter accumulation (DMA), leaf area index (LAI), yield, and nutrient uptake. The highest grain and straw yield were observed with 8 g Si liter−1, followed by 6 g Si liter−1, while the control had the lowest yields. With 8 g Si liter−1, grain yield, straw yield, and Si uptake increased by 10.5%, 13.5%, and 26.3%, respectively, compared to the control. Additionally, Si application at 8 g Si liter−1 significantly reduced the density of S. avenae (aphids) by 81.4% and lodging by 75.1% compared to the control. Overall, the study demonstrated that increasing Si doses enhanced various growth and yield parameters, with 8 g Si liter−1 and 6 g Si liter−1 showing superior results. Among the growth stages, foliar application of Si during the tillering stage exhibited better performance in terms of growth, yield, and nutrient uptake in wheat. Therefore, the study concludes that Si fertilization at a rate of 8 g Si liter−1 during the tillering stage can effectively improve growth, productivity, and nutrient uptake in wheat in the southern region of Rajasthan. [ABSTRACT FROM AUTHOR]

Cytochrome P450 monooxygenases (CYP450s) play a variety of physiological roles, including pesticide resistance, plant allelochemical detoxification, and hormone metabolism catalysis. However, limited information is available on the classification and expression profiles of the CYP450 gene family in aphid species. This is the first study to identify the cytochrome P450 gene family in 19 aphid species at the whole genome level. A total of 1100 CYP450 genes were identified in 19 aphid species. Three hundred CYP450 genes belonged to six cereal crop aphid species, which were further classified into four subfamilies according to the phylogenetic relationship. The conserved motifs, exon-intron structures, and genomic organization of the same subfamilies were similar. Predictions of subcellular localization revealed that the endoplasmic reticulum harbored the majority of CYP450 proteins. In Sitobion avenae and Rhopalosiphum maidis, the increase in the CYP450 gene was primarily caused by segmental duplication events. However, only tandem duplication occurred in the CYP450 gene family of Diuraphis noxia, Rhopalosiphum padi, Schizaphis graminum, and Sitobion miscanthi. Synteny analysis found three continuous colinear CYP450 gene pairs among six cereal crop aphid species. Furthermore, we obtained the expression profiles of four cereal crop aphids, including R. padi, D. noxia, S. graminum, and S. avenae. Differential expression analysis provided growth stage specificity genes, tissue specificity genes, organ specificity genes and some detoxification metabolic genes among these four cereal crop aphids. Meanwhile, their expression patterns were showed. The related functions and pathways of CYP450s were revealed by GO and KEGG enrichment analysis. Above all, we picked the differentially expressed CYP450 genes from all of the differentially expressed genes (DEGs). These differentially expressed CYP450 genes provided some new potential candidates for aphid control and management. This work establishes the foundation for further investigations into the regulatory functions of the CYP450 gene family in aphid species and beyond. [ABSTRACT FROM AUTHOR]

Global warming is affecting the severity of yield losses due to increased pest abundances. However, few studies have investigated how warming may affect interspecific competitions in multi-pest systems. Here, we investigated the effects of a 2 °C temperature increase on the population growth and distribution on plants of the aphids Rhopalosiphum padi and Sitobion avenae in single versus mixed species releases. We also investigated how the distribution of aphids across plant parts (lower leaves, upper leaves and stems) could be explained by plant tissue content in soluble sugars, free amino acids and flavonoids and by plant tissue microenvironment (leaf temperature and water potential). Populations of R. padi were higher under increased temperature, which caused increased competition on S. avenae. This in turn decreased S. avenae's niche breadth under increased temperature. Contents in soluble sugar, free amino acids and flavonoids were higher in lower and upper leaves compared to stems, but were not affected by temperature. The number of aphids in different plant parts was strongly and negatively correlated with plant tissue water potential, an indicator of reduced content in flavonoids and soluble sugars. Our study shows that even relatively small increases in temperature reflecting climate change may disturb species interactions notably through plant-mediated effects, but consequences for crop productivity are difficult to predict. [ABSTRACT FROM AUTHOR]

One of the successful strategies developed for studying the gene function of aphids is to silence aphid gene expression by plant-mediated RNA interference (RNAi). In this study, we analyzed the expression patterns and the biological functions of genes related to chitin metabolism ApCht7 and ApCht10 by using gene-specific plant-mediated RNAi in the green pea aphid, Acyrthosiphon pisum (Ap). The RT-qPCR results demonstrated that the RNAi-mediated silencing of these ApChts suppressed the expression of most genes involved in the chitin degradation pathway, but enhanced the expressions of ApHK, ApGFAT, ApPGM and ApCHS, indicating that the RNAi of ApChts could affect the expression of genes related to chitin metabolism and regulate the chitin metabolism. Furthermore, it resulted in a decrease in aphid body weight of aphids, with mortality rates ranging from 3.3 to 26.1%. Abnormal phenotypes (e.g., molting defect and wrinkled integument) were observed in the treated nymphs, leading to early lethality. The aphid reproduction rate reduced by 27.9–40.5% at 120 h after RNAi of ApChts. The target genes ApCht7 and ApCht10 expression were also downregulated in the progeny nymphs born from the mothers exposed to dsRNA-plants with significantly lower body weights. The previously mentioned results suggest that the effects of RNAi ApCht7 and ApCht10 are heritable and passed down to offspring. Our study provides a foundation for the practical application of the plant-mediated RNAi of ApCht7 and ApCht10 as a powerful tools and methods for controlling field aphid outbreaks. [ABSTRACT FROM AUTHOR]

Simple Summary: The tomato leaf miner Phthorimaea absoluta is a harmful invasive pest first reported in China in 2017. As an alternative to chemical methods for pest control, recent research has focused on green prevention, specifically light-induced control. However, current light-trapping technology is non-specific, attracting both pests and non-target organisms. Our study aimed to understand the phototactic behavior of P. absoluta and to develop a targeted light-trapping technology. Using in situ hybridization, we found widespread opsin expression throughout the insect body. We also investigated tropism using a wavelength-lamp experiment, revealing that 365 ± 5 nm light accurately traps P. absoluta without affecting natural enemies. Additionally, we found that long-wavelength opsin gene mutants (LW2−/−) and short-wavelength opsin gene mutants (BL−/−) showed significant differences in phototactic behavior. The LW2(−/−) strain was attracted to light at 390 ± 5 nm, whereas the BL(−/−) strain was unresponsive. Our findings contribute to the development of precise light-trapping technology for controlling the tomato leaf miner, contributing to our understanding of pest population dynamics and the protection of crops from natural enemies. Phthorimaea absoluta (Meyrick) is an invasive pest that has caused damage to tomatoes and other crops in China since 2017. Pest control is mainly based on chemical methods that pose significant threats to food safety and environmental and ecological security. Light-induced control, a green prevention and control technology, has gained attention recently. However, current light-trapping technology is non-specific, attracting targeted pests alongside natural enemies and non-target organisms. In this study, we characterized the phototactic behavior of tomato leaf miners for the development a specific light-trapping technology for pest control. In situ hybridization revealed opsin expression throughout the body. Furthermore, we investigated the tropism of pests (wild T. absoluta, Toxoptera graminum, and Bemisia tabaci) and natural enemies (Nesidiocoris tenuis and Trichogramma pintoi) using a wavelength-lamp tropism experiment. We found that 365 ± 5 nm light could accurately trap wild P. absoluta without trapping natural enemies and other insects. Finally, we analyzed the phototactic behavior of the mutant strains LW2(−/−) and BL(−/−). LW2 and BL mutants showed significant differences in phototactic behavior. The LW2(−/−) strain was attracted to light at 390 ± 5 nm and the BL(−/−) strain was unresponsive to any light. Our findings will help to develop specific light-trapping technology for controlling tomato leaf miners, providing a basis for understanding pest population dynamics and protecting crops against natural enemies. [ABSTRACT FROM AUTHOR]

Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae), commonly known as the southern green stink bug, poses a significant threat to agricultural productivity due to its destructive feeding nature which leads to substantial reductions in crop quality and yield. The entomopathogenic fungal genus Metarhizium (Hypocreales: Clavicipitaceae) has been known as a promising biological control agent with a wide range of arthropod hosts. Among them, Metarhizium anisopliae has shown potential as an alternative management strategy for controlling pests within crop ecosystems. This study aimed to assess the efficacy of different doses of M. anisopliae AUMC 3262 air-dried conidia (0.5, 2.5, and 5 g) against N. viridula adults and evaluate physiological and structural alternations under laboratory conditions. Results indicated that M. anisopliae AUMC 3262 dry conidia induced significant mortality in N. viridula in a time- and dose-dependent manner. Mortality rates reached 86.65%., 99.98% and 100 % of N. viridula after 5 and 6 days of exposure to 0.5, 2.5 and 5 g of dry conidia, respectively. Also, a significant reduction in the total soluble proteins was observed. Scanning Electron Microscope analysis confirmed deformation in the body structure of N. viridula, highlighting fungal penetration and proliferation within the insect's body. Overall, M. anisopliae AUMC 3262 is a virulent strain for N. viridula, which might qualify this strain to be used as a strong candidate for further investigation as a control agent for N. viridula. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fusarium species are responsible for Fusarium head blight (FHB) in wheat, resulting in yield losses and mycotoxin contamination. Deoxynivalenol (DON) and enniatins (ENNs) are common mycotoxins produced by Fusarium, affecting plant, animal and human health. Although DON's effects have been widely studied, limited research has explored the impact of ENNs on insects. This study examines the influence of DON and enniatin B (ENB), both singularly and in combination, on the wheat aphid Sitobion avenae and one of its predators, the lacewing Chrysoperla carnea. RESULTS: When exposed to DON (100 mg L−1) or DON + ENB (100 mg L−1), S. avenae exhibited significantly increased mortality compared to the negative control. ENB (100 mg L−1) had no significant effect on aphid mortality. DON‐treated aphids showed increasing mortality from 48 to 96 h. A dose–response relationship with DON revealed significant cumulative mortality starting at 25 mg L−1. By contrast, C. carnea larvae exposed to mycotoxins via cuticular application did not show significant differences in mortality when mycotoxins were dissolved in water but exhibited increased mortality with acetone‐solubilized DON + ENB (100 mg L−1). Feeding C. carnea with aphids exposed to mycotoxins (indirect exposure) did not impact their survival or predatory activity. Additionally, the impact of mycotoxins on C. carnea was observed only with acetone‐solubilized DON + ENB. CONCLUSIONS: These findings shed light on the complex interactions involving mycotoxins, aphids and their predators, offering valuable insights for integrated pest management strategies. Further research should explore broader ecological consequences of mycotoxin contamination in agroecosystems. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The interaction between thermal stress and chemical insecticides in agricultural pests has become more common owing to the global warming and human activities. Although research has shown the interaction of constant temperature or single thermal stress with insecticides, the ecological effects of sublethal thermal stress and low-dose insecticide interaction, which are more applicate to field conditions, are limited. Therefore, this study investigates the interaction of sublethal thermal stress (TS) (34 °C/180 min, 36 °C/30 min, and 38 °C/10 min) and low-dose imidacloprid (IM) applications in the maternal and offspring phenotype of the important grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae). In the F0 generation, single TS significantly reduced the longevity, fecundity, survivorship, and population parameters of S. avenae, and the interaction between TS and IM (TS-IM) had a significant negative effect on the intrinsic rate of increase in the order 34 °C/180 min + IM > 36 °C/30 min + IM > 38 °C/10 min + IM. In the F1 generation, the development duration of nymph was increased and the intrinsic rate of increase was reduced after F0 underwent TS. However, the intrinsic rate of increase of F1 generation showed the greatest decrease under 38 °C/10 min + IM, and the lowest decrease under 34 °C/180 min + IM. The results of this study reveal the significance of evaluating together different abiotic factors, such as the interaction between thermal stress and insecticides, in the risk assessment of climate change, emphasizing the importance of the combination of different stresses in pest control. [ABSTRACT FROM AUTHOR]

Climate change may have diverse and complex impacts on species interactions, destabilizing food webs and ecosystem services. The effects of warming on the top‐down biological control of crop pests have been considerably less studied than bottom‐up effects through crop physiological changes.We studied the effect of a 2°C warming in the laboratory and in wheat fields on the predation and metabolism of Harmonia axyridis on wheat aphids using molecular gut content analysis. We also measured the effects of warming on the predation rate and functional response of H. axyridis on each aphid species in the laboratory, as well as on DNA degradation rate.Field densities of Sitobion avenae and Rhopalosiphum padi, the two most abundant wheat aphid species, were increased by 2 and 2.5 times, respectively, under experimental warming, but densities of H. axyridis were not. Field predation rate of H. axyridis on these two aphid was found to be about 25% lower under elevated temperature. This could have been due to faster prey digestion, since degradation of the preferred aphid species, Sitobion avenae, was 1.5 times faster under elevated temperature. However, the functional response of H. axyridis larvae on these two species was 1.5 times higher under warming over the range of prey densities tested (50–250 over 24 h). The total predation rate of H. axyridis larvae on a mixture of S. avenae, R. padi and Schizaphis graminum aphid prey was also increased by 1.4 times, but consumption of R. padi aphids was increased while that of S. graminum was decreased under warming.Overall, our results show that global warming could strongly increase pest outbreaks and destabilize biological pest control, which would likely result in accrued yield losses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) is cultivated as a monocotyledonous plant in a large part of the world. The Wheat aphid, Schizaphis graminum Rondani (Hemiptera: Aphididae), is among the most important pests of wheat. One of the most important predators of this pest is Hippodamia variegata Goeze. Considering the use of insecticide spirotetramat in cereal fields, in this study, the lethal and sub-lethal effects of this insecticide were investigated on the biological characteristics and parameters of the life table of S. graminum and predator H. variegata. The experiments were performed at a temperature of 27 ± 1℃, relative humidity of 65 ± 10%, and a photoperiod of 16:8 (light:dark). For this purpose, biometric and life table experiments were performed by immersing wheat leaves in insecticide and placing adult aphids on them, and feeding adonis ladybird larvae from the treated aphids. Insecticide side effects were estimated using the International Organization for Biological Control (IOBC) method and a two-sex life table. The LC50 level of spirotetramat insecticide for aphids and predators was 210.93 and 725.86 mg/l, respectively. The results of this study indicate that there is a significant difference between treatments in terms of the intrinsic rate of increase (r), finite rate of increase (λ), mean generation times (T), net reproduction rate (R0), and gross reproduction rate (GRR) parameters in aphids and adonis ladybird. The highest and lowest rates of the reproduction and population growth of the studied insects were related to the control and LC30 spirotetramat treatments, respectively. According to the IOBC classification, the concentration of LC10 in spirotetramat was harmless to the adonis ladybird H. variegata, while the LC30 concentration of this insecticide was slightly harmful to this species. Experiments showed that the sub-lethal concentrations of the insecticide spirotetramat had a significant negative effect on the life table parameters of the Wheat aphid. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum) is a major cereal crop of the world and provides 20% of the world's food calories. Pakistan's average wheat production is 24.946 million tons, contributing 1.7% of the country's gross domestic product (GDP). Aphids are a significant insect pest of wheat, causing crop injury by sucking cell sap, releasing honeydew, interfering with the photosynthetic activities of the crop, and transmitting pathogenic viruses. In the present study identification of wheat, aphid species and assessment of IPM modules for aphid management have been worked out. Aphids can be identified based on body color, cornicle tube (length, shape, orientation etc.) and length of antennae. Coccinella septempunctata, Hover flies, Chrysoperla carnea and spiders play a significant role in the management of wheat aphid as a biocontrol agent. So, it is concluded that natural enemies, seed dressing, botanical extracts and sticky traps were found effective and eco-friendly as compared to synthetic insecticides. [ABSTRACT FROM AUTHOR]

Simple Summary: The pea aphid, Acyrthosiphon pisum, is a serious pest of legume crops that can produce winged and wingless offspring in response to the environmental conditions. We found that, under crowded conditions, the red morph A. pisum produced more winged offspring than the green morph. The signaling pathways involved in aphid wing determination also play important roles in regulating growth, development, and metabolism. Thus, we examined the association between the wing-producing ability and the growth rate, development time, reproductive capacity, and energy metabolism in these two color morphs. The growth rate, levels of glycogen and triglycerides in red morphs were significantly higher than those of green morphs, whereas green morphs produced more offspring. Red morphs also consumed more triglycerides during starvation and had stronger starvation tolerance. Furthermore, the expression levels of genes involved in the insulin pathway, glycolysis, and lipolysis in red aphids were also higher. These results suggest that the wing-producing ability of the pea aphid may be associated with its growth and metabolism. The pea aphid, Acyrthosiphon pisum, is a major pest of legume crops, exhibiting distinct polymorphism in terms of wings and body color. We found that, under crowded conditions, the red morph A. pisum produced more winged offspring than the green morph. The signaling pathways involved in aphid wing determination, like insulin and ecdysone, also play important roles in regulating growth, development, and metabolism. Thus, here, we examined the association between the wing-producing ability and the growth rate, development time, reproductive capacity, and energy metabolism in these two color morphs. The growth rate of red morphs was significantly higher than that of green morphs, whereas green morphs produced more offspring during the first 6 days of the adult stage. Red morphs accumulated higher levels of glycogen and triglycerides and consumed more triglycerides during starvation; however, green aphids consumed more trehalose during food deprivation. Red aphids exhibited stronger starvation tolerance, possibly due to their higher triglyceride catabolic activity. Furthermore, the expression levels of genes involved in the insulin pathway, glycolysis, and lipolysis in red aphids were higher than those in green aphids. These results suggest that the wing-producing ability of the pea aphid may be associated with its growth and metabolism, which may be due to the shared regulatory signaling pathways. [ABSTRACT FROM AUTHOR]

Simple Summary: In Mississippi, the stink bug complex infesting soybean is mainly composed of the brown stink bug, southern green stink bug, green stink bug, and redbanded stink bug. This study conducted spray bioassays to assess the susceptibilities of these stink bugs to seven commonly used formulated insecticides. Stinks bugs were collected from soybeans in Leland, MS, USA, at the Southern Insect Management Research Unit (SIMRU) Farm during 2022 and 2023, as well as from wild host plants in Clarksdale, MS. While the green stink bug exhibited consistent susceptibility across two years, the redbanded stink bug showed slightly increased susceptibility to neonicotinoids in 2023 compared to 2022. In 2022, the susceptibility ranking among species was redbanded stink bug ≤ green stink bug ≈ southern green stink bug, whereas in 2023, it was redbanded stink bug ≤ green stink bug ≤ brown stink bug. Enzyme activity analysis revealed no significant differences between the southern green and the green stink bug. However, compared to SIMRU-2023, populations of brown stink bug and redbanded stink bug from SIMRU-2022 and Clasksdale-2023 exhibited elevated enzyme activities, indicating potential variations in resistance mechanisms. These findings provide valuable insights for monitoring and managing insecticide resistance in Mississippi soybean. In Mississippi, the Pentatomidae complex infesting soybean is primarily composed of Euschistus servus, Nezara viridula, Chinavia hilaris, and Piezodorus guildinii. This study employed spray bioassays to evaluate the susceptibilities of these stink bugs to seven commonly used formulated insecticides: oxamyl, acephate, bifenthrin, λ-cyhalothrin, imidacloprid, thiamethoxam, and sulfoxaflor. Stinks bugs were collected from soybeans in Leland, MS, USA during 2022 and 2023, as well as from wild host plants in Clarksdale, MS. There was no significant difference in the susceptibility of C. hilaris to seven insecticides between two years, whereas P. guildinii showed slightly increased susceptibility to neonicotinoids in 2023. Among all four stink bug species, susceptibility in 2022 was ranked as P. guildinii ≤ C. hilaris ≈ N. viridula, while in 2023, it was ranked as P. guildinii ≤ C. hilaris ≤ E. Servus. Additionally, populations of E. servus and P. guildinii collected from Clarksdale exhibited high tolerance to pyrethroids and neonicotinoids. Moreover, populations of E. servus and P. guildinii from SIMRU-2022 and Clarksdale-2023 showed elevated esterase and cytochrome P450 activity, respectively. These findings from spray bioassays and enzyme activity analyses provide a baseline for monitoring insecticide resistance in Pentatomidae and can guide insecticide resistance management strategies for Mississippi soybean. [ABSTRACT FROM AUTHOR]

In agroecosystems, insects contend with chemical insecticides often encountered at sublethal concentrations. Insects' exposure to these mild stresses may induce hormetic effects, which has consequences for managing insect pests. In this study, we used an electrical penetration graph (EPG) technique to investigate the feeding behavior and an age-stage, two-sex life table approach to estimate the sublethal effects of thiamethoxam on greenbug, Schizaphis graminum. The LC5 and LC10 of thiamethoxam significantly decreased longevity and fecundity of directly exposed adult aphids (F0). However, the adult longevity, fecundity, and reproductive days (RPd)—indicating the number of days in which the females produce offspring – in the progeny generation (F1) exhibited significant increase when parental aphids (F0) were treated with LC5 of the active ingredient. Subsequently, key demographic parameters such as intrinsic rate of increase (r) and net reproductive rate (R0) significantly increased at LC5 treatment. EPG recordings showed that total durations of non-probing (Np), intercellular stylet pathway (C), and salivary secretion into the sieve element (E1) were significantly increased, while mean duration of probing (Pr) and total duration of phloem sap ingestion and concurrent salivation (E2) were decreased in F0 adults exposed to LC5 and LC10. Interestingly, in the F1 generation, total duration of Np was significantly decreased while total duration of E2 was increased in LC5 treatment. Taken together, our results showed that an LC5 of thiamethoxam induces intergenerational hormetic effects on the demographic parameters and feeding behavior of F1 individuals of S. graminum. These findings have important implications on chemical control against S. graminum and highlight the need for a deeper understanding of the ecological consequences of such exposures within pest management strategies across the agricultural landscapes. [ABSTRACT FROM AUTHOR]

Wheat aphids are major pests of wheat and a significant threat to global food security. Eupeodes corollae Fabricius is one of the dominant species of wheat field hoverflies, but its ability and role in wheat aphid control lack systematic research. This study on the predatory function responses of E. corollae to Rhopalosiphum padi Linnaeus, Schizaphis graminum Rondani, and Sitobion miscanthi, Takahashi showed that the maximum daily predation (1/Th) of 2nd instar E. corollae larvae was 166.67, 125.00, and 142.86, and that of 3rd instar larvae was 333.33, 250.00, and 250.00, respectively. The cage simulation test indicated that the wheat aphid population decline rate was 100% at the 60th hour of inoculation of 3rd instar E. corollae larvae at a 1:100 ratio. Eupeodes corollae exhibited a predatory relationship with all three wheat aphid species in the wheat fields of Hebei Province, China, and the corrected predation detection rates of E. corollae larvae against R. padi, S. graminum, and S. miscanthi were 12.36%, 1.08%, and 28.77% in 2022, and 6.74%, 0.82%, and 37.56% in 2023, respectively. The results of this study clarify the predatory ability of E. corollae on wheat aphids and the predatory relationship between them and provide technical support for the management of wheat aphids using the bio-control ecological service function of E. corollae. [ABSTRACT FROM AUTHOR]

Simple Summary: The study investigated how different types of fertilizers affected wheat aphids, a harmful pest for wheat plants. The nano-Cu fertilizer had negative effects on the aphids, leading to shorter lifespans and fewer babies. In contrast, the nitrogen fertilizer was not effective in controlling the aphids. The nano-Fe and nano-Zn fertilizers had fewer negative impacts compared to nano-Cu. While nitrogen treatment had positive effects on wheat aphid lifespan. Overall, the study suggests that incorporating nano-Cu into pest control strategies for wheat aphids could be a promising approach. In conclusion, choosing the right fertilizer can make a big difference in managing pests like aphids on wheat plants, and using nano-Cu could be a valuable tool in protecting crops. The use of nanofertilizers has both advantages and concerns. One benefit is that nano-fertilizers can enhance plant resistance against insect pests, making them a valuable strategy in integrated pest management (IPM). This study focused on the effect of wheat leaves treated with nano-chelated fertilizers and nitrogen (N) fertilizer on the wheat aphid (Schizaphis graminum Rondani), a harmful pest of wheat plants that transmits dangerous viruses. The nano-Cu treatment showed the longest pre-adult longevity. Additionally, the nano-Cu treatment resulted in the lowest adult longevity, fecundity, nymphoposition day number, intrinsic rate of population growth (r), finite rate of population increase (λ), and net reproductive rate (R0) and gross reproductive rate (GRR). Also, nano-Cu treatment led to the highest amount of (T). The N treatment led to the highest levels of fecundity, nymphoposition days, r, λ, and R0. Nano-Fe and nano-Zn demonstrated fewer negative effects on S. graminum life table parameters than nano-Cu. Our results indicate that N treatment yielded numerous advantageous effects on the wheat aphid while simultaneously impeding the efficacy of the aphid control program. Conversely, nano-Cu treatment exhibited a detrimental influence on various parameters of the aphid's life table, resulting in a reduction in the pest's fitness. Consequently, the integration of nano-Cu should be seriously considered as a viable option in the IPM of the wheat aphid. [ABSTRACT FROM AUTHOR]

The succession and seasonal incidence of insect pests and predatory fauna in black gram were studied in a field experiment at the Agronomy farm, Anand Agricultural University, Anand during kharif 2019 and 2020. The results revealed nine species of insects (7 pests and 2 predators) from seedling to pod maturity stage. Besides, the peak incidence of whitefly, jassid, flower thrips, tobacco caterpillar, Bihar hairy caterpillar, and spiders were observed during 37th standard meteorological week (SMW); with spotted pod borer and coccinellids, maximum incidence was observed during 38th SMW, and the green stink bug during 35th SMW. Correlation coefficients revealed that tobacco caterpillar had a significant positive correlation with minimum temperature, morning RH and evening vapour pressure; and the incidence of spotted pod borer showed a significant negative correlation with bright sunshine hours and rainfall. [ABSTRACT FROM AUTHOR]

The study was conducted to identify novel simple sequence repeat (SSR) markers associated with resistance to corn aphid (CLA), Rhopalosiphum maidis L. in 48 selected bread wheat (Triticum aestivum L.) and wild wheat (Aegilops spp. & T. dicoccoides) genotypes during two consecutive cropping seasons (2018–19 and 2019–20). A total of 51 polymorphic markers containing 143 alleles were used for the analysis. The frequency of the major allele ranged from 0.552 (Xgwm113) to 0.938 (Xcfd45, Xgwm194 and Xgwm526), with a mean of 0.731. Gene diversity ranged from 0.116 (Xgwm526) to 0.489 (Xgwm113), with a mean of 0.354. The polymorphic information content (PIC) value for the SSR markers ranged from 0.107 (Xgwm526) to 0.370 (Xgwm113) with a mean of 0.282. The results of the STRUCTURE analysis revealed the presence of four main subgroups in the populations. Analysis of molecular variance (AMOVA) showed that the between-group difference was around 37 per cent of the total variation contributed to the diversity by the whole germplasm, while 63 per cent of the variation was attributed between individuals within the group. A general linear model (GLM) was used to identify marker-trait associations, which detected a total of 23 and 27 significant new marker-trait associations (MTAs) at the p < 0.01 significance level during the 2018–19 and 2019–20 crop seasons, respectively. The findings of this study have important implications for the identification of molecular markers associated with CLA resistance. These markers can increase the accuracy and efficiency of aphid-resistant germplasm selection, ultimately facilitating the transfer of resistance traits to desirable wheat genotypes. [ABSTRACT FROM AUTHOR]

Rice grain dark spots are harmful, damaging the grains and, eventually, affecting the grain quality. Dark spots appear due to insect pests of the family Pentatomide, which feed on caryopsis tissues with a bite-puncture from the upper lip of their oral apparatus transformed into a needle. Mechanical damage to the grain leads to the penetration of microbes into the grain tissues, resulting in its darkening. The practical study aimed to determine the effects of the ripening stage on the ratio of dark spots on rice grains and their damage. Experiments assessed the influence of panicle age on rice grain damage caused by the southern green stink bug (Nezara viridula L.). Data recording on various parameters progressed by placing one and three bugs on the rice panicle. After crop maturity, evaluating the cut panicles continued based on empty grain content, grain size, and damaged grains. Other treatments had bugs placed during the flowering and five, 10, 15, 25, and 30 days after. Higher rice grain damage occurs when infested with three stick bugs in the first 10-15 days after flowering, revealing this period was the most vulnerable. Infection at later stages of ripening caused no significant damage to rice grains. The scientific literature does not provide information on dividing rice varieties into groups according to the degree of grain damage in the field in the form of dark spots. Based on the results, groups of pecky rice appeared for the first time according to the degree of damage, depending on the infection period, i.e., surface type, medium degree, and extensive damage type to the rice grains. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max) is the world's most widely grown seed legume. One of the most important pests that decrease seed quality and reduce yield of soybean crops is the southern green stink bug (Nezara viridula). Insect damage triggers accumulation of defensive compounds such as protease inhibitors (PIs), isoflavonoids and reactive oxygen species, which are regulated by the lipoxygenase (LOX)-regulated jasmonic acid (JA) to stop insect feeding. This study identified and characterised the role of LOX isoforms in the modulation of chemical defences in seeds of field-grown soybean that decreased digestive enzyme activities of N. viridula after insect attack. Stink bugs attack increased LOX 1 and LOX 2 expression, and activities of LOX 1 and LOX 3 isoenzymes in developing soybean seeds. In addition, stink bug damage and methyl jasmonate application induced expression and activity of both cysteine PIs and trypsin PIs in developing soybean seeds, suggesting that herbivory induced JA in soybean seeds. High PI activity levels in attacked seeds decreased cysteine proteases and a-amylases activities in the gut of stink bugs that fed on field-grown soybean. We demonstrated that LOX isoforms of seeds are concomitantly induced with JA-regulated PIs by stink bugs attack, and these PIs inhibit the activity of insect digestive enzymes. To our knowledge, this is the first study to investigate the participation of LOX in modulating JA-regulated defences against stink bugs in seeds of field-grown soybean, and our results suggest that soybean PIs may inhibit a-amylase activity in the gut of N. viridula. [ABSTRACT FROM AUTHOR]

Palomena prasina, the green shield bug (GSB), is widely distributed in the Eurosiberian region. In the Southwest of France, it is considered as a serious pest of hazelnuts, its feeding punctures lead to blank hazelnuts and kernel necrosis, causing heavy losses in commercial orchards. To date, no Integrated Pest Management strategy is available to control P. prasina. Control strategies often focus on the pests' spring–summer ecology, when they are in the field or in the vicinity of crops. However, the abundance of pest populations in crops is also related to their autumn‐winter ecology. The present work focussed on the autumn‐winter ecology of P. prasina to identify new opportunities for this pest suppression. We investigate (i) where P. prasina overwinters, (ii) if it aggregates in its overwintering sites and (iii) if it mates while overwintering. Samples were collected over a 2‐year period in different ecosystems (forests, hedges, orchards), in human‐made structures and habitats (litter, bushes/trees, dead trees). The reproductive status of GBS individuals was monitored in winter, and in spring when they emerged from overwintering sites. Our results show that 97% P. prasina adults overwinter in the leaf litter of orchards and natural ecosystems and that 70% overwinter individually. The abundance of GSB in those sites is negatively correlated with litter temperature and positively correlated with humidity levels. Furthermore, adults only mate after leaving their overwintering site. Finally, unexpectedly, there was an important number of overwintering adults hosting endoparasitoids (32%). The fact that GSB overwinters alone in the leaf litter means controlling its populations by destroying the overwintering sites is not a solution. All the same, our results point out some promising lines of research for developing methods to control P. prasina. First, the emergence traps, in particular the cone traps, proved efficient for collecting emerging adults and could be considered for monitoring. Moreover, our observations suggest the existence of long‐range mating signals that could be exploited for trapping. Last but not least, the important number of overwintering parasitised adults is a potential biocontrol avenue. [ABSTRACT FROM AUTHOR]

Sitobion avenae F. is a highly prevalent and devastating pest in wheat crops, leading to significant yield losses. Silicon (Si) has been widely recognized as an effective inducer of plant resistance against aphids. Nevertheless, the underlying mechanisms governing the physiological and biochemical responses of plants induced by Si defense against S. avenae F. remain incompletely understood. In this study, we conducted experiments by treating wheat leaves with varying concentrations of Tetraethyl orthosilicate (TEOS) spray under aphid infestation. We meticulously observed and recorded the life cycle of S. avenae F. and measured the content of plant hormones, secondary metabolites, and the activity of defense enzymes in wheat leaves. Furthermore, we utilized structural equation modeling to discern the causal correlation between aphid performance and the physiological-biochemical responses of wheat under TEOS sprays. Our findings revealed that a concentration of 3 mmol/L TEOS significantly shortened the net reproductive rate, intrinsic rate and finite rate of increase, and mean generation time of S. avenae F., while simultaneously prolonging the population doubling time. Additionally, the content of lignin, total phenolics, flavonoids, alkaloids, tannin, jasmonic acid (JA), and salicylic acid in wheat leaves exhibited a substantial increase. Furthermore, the activity of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), catalase, and lipoxygenase in wheat leaves was significantly enhanced. Our results suggest that TEOS spray reduced the survival and population growth of S. avenae F. while enhancing the defense response of wheat against aphids by activating the activity of PAL and PPO in wheat, and increasing the content of total phenolic and JA. This work provides valuable insights for the development of appropriate Si fertilizers for effective pest management and offers robust theoretical support for wheat aphid control through agricultural fertilization strategies. [ABSTRACT FROM AUTHOR]

Eight lines of grain sorghum [Sorghum bicolor (L.) Moench], which can be used as a promising source material in heterotic hybrid breeding as pollen fertility restorers and donors of resistance to the greenbug (Schizaphis graminum Rondani), are characterized. The new restorer lines (R-lines) were developed by crossing the maternal sterile line Nizkorosloe 81s (CMS A1) with two lines selected from the grain sorghum collection accessions VIR-928 and VIR-929 as the paternal forms. The R-lines were genotyped using PCR markers, and also characterized by height, duration of the seedling–flowering period, and some of the technological properties of flour. With the use of microsatellite markers linked to the Rf genes and by hybridological analysis, it was shown that the new lines carry the dominant allele of the gene Rf2. The PCoA analysis demonstrated clear differences of each R-line from the parents. The genotypes of the new lines and their parental forms for the Rf2 locus were confirmed by applying three allele-specific codominant CAPS markers which detected SNPs in the candidate Rf2 gene. All new lines were highly fertile, as demonstrated by cytological analysis of acetocarmine-stained pollen preparations. A high resistance to the greenbug was demonstrated for each new R-line both in the laboratory and field conditions against a severe aphid infestation. Grain quality parameters such as protein content and dough rheological properties varied widely and were quite satisfactory in some R-lines. Characteristics common to all eight sorghum lines studied, such as the ability to restore pollen fertility in the F1 generation, good pollen quality, greenbug resistance, early ripening, spreading panicle, and low stature, allow us to recommend them for producing commercial F1 hybrids with satisfactory grain quality for both fodder and food purposes. [ABSTRACT FROM AUTHOR]

Various Neonicotinoid guanidine/amidine analogues 1–3 were synthesized by the reaction of cyanoguanidine with acetylpyrimidines or diacetylpyridine. Their spectral analyses identified the synthesized compounds 1–3. The preliminary bioassays showed that all synthesized compounds showed moderate insecticidal activities against cotton leafworm Spodoptera littoralis (Boisd.) and Wheat Aphid (Schizaphis graminum). [ABSTRACT FROM AUTHOR]

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The Russian wheat aphid, Diuraphis noxia, is a significant pest for grain crops worldwide. Bioagents such as the parasitoid, Aphidius colemani and the predator, Coccinella undecimpunctata have been shown to be effective against many aphid species. This study aimed to investigate the combined effect of releasing these two bioagents on controlling D. noxia without using pesticides. To achieve this, three systems of release were evaluated in the field: (1) the parasitoid A. colemani at rate of 4 mummies/m2, (2) the predator C. undecimpunctata at rate of 10 individuals (3rd larval instar)/m2, and (3) A. colemani (4 mummies/m2) + C. undecimpunctata (10 individuals/m2) and control. After four releases, the combination of A. colemani and C. undecimpunctata resulted in the highest percentage of reduction in aphid population, with a reduction of 95.58, 95.53% in 2020 and 2021, followed by 86.94, 83.92% in A. colemani plots and the lowest reduction percentage in C. undecimpunctata plots, with 65.1, 68.92%, in 2020 and 2021, respectively. Based on these results, it is recommended to use the combination of the two bioagents, A. colemani and C. undecimpunctata for controlling D. noxia in a wheat field. Therefore, the use of a combination of natural enemies, carefully timed and repeated releases, and consideration of intraguild predation dynamics can help to achieve effective biological control of aphids in wheat crops. The use of natural enemies such as A. colemani and C. undecimpunctata can reduce the application of pesticides and promote sustainable pest management practices. [ABSTRACT FROM AUTHOR]

The southern green stink bug, Nezara viridula (L.), occurs worldwide and can transmit disease-causing organisms in cotton, Gossypium hirsutum L., and other high-value commodities. Variable coloration in adults has long been known, with the common “entirely green” color morph occurring throughout its known range, including Central Texas in the United States. A female adult N. viridula with dorsal yellow coloration along the anterior margins of the lobes, anterior margin of pronotum, and connexivum was collected in Central Texas. This color pattern aligns with a different color morph - N. viridula type F – and this report constitutes the first record of this color morph in the United States. To date, adults of the species have been detected in 16 different forms/coloration. Also, this report reconciles some inconsistencies in earlier reports to clarify distribution of N. viridula type F. This information should prove useful to growers who might encounter this color morph and to researchers and taxonomists specializing in the biology and ecology of N. viridula. [ABSTRACT FROM AUTHOR]

Neem formulations viz. aqueous extract of neem and NSKE along with standard check thiamethoxam were evaluated for their efficacy against wheat aphids Rhopalosiphum padi (L.) and Rhopalosiphum maidis (Fitch). It was observed that aphids' incidence on shoots started in the first week of January with a peak (40.90 aphids/shoot) during third week of March. Thiamethoxam 25 WG @ 50 g/ha was found significantly superior giving 93.53% reduction after 7 DAS (days of spray). Different formulations of neem also yielded comparable results in controlling wheat aphids. Aqueous extract of neem @ 5 l/ha resulted maximum (74.21%) reduction followed by NSKE @ 10% (69.04%) after 7 DAS. Occurrence of coccinellids was more in treatments with neem formulations than in thiamethoxam. The treatments resulted in 2.48-9.25% increase in yield and it can be concluded that aqueous extract of neem and NSKE can be recommended over the most commonly used thiamethoxam for controlling wheat aphids. [ABSTRACT FROM AUTHOR]

Imidacloprid is a neonicotinoid insecticide that efficiently controls piercing-sucking mouthparts pests. However, the impact of low lethal concentration of imidacloprid on key demographic parameters of wheat aphids, Schizaphis graminum (R.) and Rhopalosiphum padi (L.) has been scarcely studied. In this study, we used the age stage, two-sex life table approach to investigate the sublethal effects of imidacloprid on the biological traits of S. graminum and R. padi. Bioassays showed that imidacloprid possesses high toxicity to adult S. graminum and R. padi, with LC50 of 3.59 and 13.78 mg L−1 following 24 h exposure. A low lethal concentration of imidacloprid (LC25) significantly decreased adult longevity and total longevity of progeny generation aphids (F1) of S. graminum. Nevertheless, imidacloprid (LC25) had no significant effects on the fecundity and longevity of directly exposed parental parental S. graminum and R. padi (F0). Our results showed that the low lethal concentration of imidacloprid affected the demographic parameters that ultimately impact on the population of S. graminum. This study provides detailed information about the overall effects of imidacloprid on S. graminum and R. padi that might help to manage these two key pests. [ABSTRACT FROM AUTHOR]

The Hessian fly (Hf) and greenbugs (Gb) are major pests of wheat, causing severe economic losses globally. Deploying resistant wheat is the most effective strategy for managing these destructive insects. However, the resistance is not effective against all Hf or Gb biotypes and can impose selection pressure on insects, resulting in the development of virulent biotypes. These challenges must be met through the discovery of new and novel sources of resistance to these pests. Synthetic Hexaploid Wheat (SHW)-developed cultivars are a rich source of resistance against a diverse array of pathogens and pests. In this study, 80 SHW lines were evaluated for their resistance to Hf and Gb under controlled environmental conditions. Of these, a total of 36 SHW lines showed resistance independently to Hf biotype L and Gb biotype E, while 27 lines showed combined resistance to both Hf and Gb. Further, a subset of 10 SHW lines showed resistance to additional Hf biotypes, Great Plains and vH13. The identification of SHW lines resistant to multiple insects and biotypes offers an invaluable resource to breeders who are looking to stack resistance traits to develop elite cultivars as a strategy to alleviate economic impacts upon global wheat production. [ABSTRACT FROM AUTHOR]

The greenbug, Schizaphis graminum, is a dangerous pest of barley and other grain crops in the south of Russia. An effective and environmentally friendly way to control this insect is to cultivate resistant varieties. The differential interaction between the phytophage and host plants necessitates the search for new donors of resistance. Seven hundred and seventy-eight accessions of barley from East Asian countries (313 from China, 450 from Japan, and 15 from Nepal) were evaluated for greenbug resistance. The Krasnodar population of the insect and clones isolated from it were used in the experiments. Forty heterogeneous accessions were identified, in which plants with a high level of resistance to the aphid were found. As a result of damage assessment by the 108 S. graminum clones of 11 lines selected from heterogeneous accessions, 52 insect virulence phenotypes were identified. Experiments with aphid test clones showed that all 11 lines possess diverse greenbug resistance alleles, which differ from the previously identified Rsg1, but their efficiency is low. The frequency of clones virulent to ten lines and the cultivar Post (a carrier of the Rsg1 gene) varies from 60.4% to 98.0%. The exception is line 15903, which is resistant to the aphid population and protected by one dominant gene. The high resistance of other lines against a part of the natural population of S. graminum is also under oligogenic control. Lines 15600 and 16190 each have one dominant resistance gene, and line 28129 is protected by two genes, the dominant and recessive ones. A recessive resistance gene is presumably present in line 15600. Lines 16237/1 and 16237/2, isolated from the same collection accession, each have one dominant gene effective against individual aphid clones. The loss of effectiveness of distinctly manifested resistance genes causes the expression of previously masked genes with a weak phenotypic manifestation, which differentially interact with insect genotypes. [ABSTRACT FROM AUTHOR]

An experiment was performed to measure the effect of Cereal Yellow-Dwarf Virus (CYDV), strain CYDV-RPV, on gene expression in its insect vector, greenbug aphid (Schizaphis graminum (Rondani)). RNA was sampled in three replicates from four treatments (biotypes B and H with or without carried CYDV), at 0, 1, 2, 3, 5, 10, 15 and 20 days from the introduction of carrier and virus-free greenbugs to uninfected wheat cv. 'Newton'. Illumina paired-end sequencing produced 1,840,820,000,000 raw reads that yielded 1,089,950,000 clean reads, which were aligned to two greenbug, Trinity transcriptome assemblies with bowtie2. Read counts to contigs were analyzed with principal components and with DESeq2 after removing contaminating contigs of wheat or microbial origin. Likelihood ratio tests with one transcriptome showed that CYDV influenced gene expression about seven-fold less than time or biotype, which were approximately equal. With the other transcriptome, virus, time, and biotype were about equally important. Pairwise comparisons of virus to no virus for each timepoint yielded estimates of fold-change that comprised expression profiles for each contig when ordered by timepoint. Hierarchical clustering separated expression profiles into 20 groups of contigs that were significantly differentially expressed for at least one timepoint. Contigs were also sorted by timepoint of maximally differential expression between virus and no virus. All contigs that were significantly differentially expressed at FDR = 0.05 were annotated by blast searches against NCBI nr and nt databases. Interesting examples of up-regulation with virus included a lysosomal-trafficking regulator, peptidylprolylisomerase, RNA helicase, and two secreted effector proteins. However, carried virus did not consistently change aphid gene expression overall. Instead there was complex interaction of time, biotype, host response, and virus. [ABSTRACT FROM AUTHOR]

A walnut–wheat intercropping pattern is practiced widely in southern Xinjiang to alleviate the contradiction between the lack of cultivated land resources and to increase economic value. Previous studies have confirmed that an alley cropping pattern could change the microclimate by supplying additional ecological functions such as windbreak, light interception, water conservation, etc. Cereal aphids (including Sitobion avenae, Rhopalosiphum padi, Metopolophium dirhodum, etc.) are commonly spread pests that harm wheat plants. But, the difference in population numbers between local patterns is still unknown. Pesticide reduction is the national strategy in China to alleviate the contraction between the demand of grain yield and environment protection. Plant protection-unmanned aerial vehicles (UAV) spraying pesticides are the most efficient method to control pests. However, compared to traditional artificial spraying method, how the UAV spraying method affect the control effect of reduced concentration pesticide is unclear. In order to address this problem, we conducted field investigations at Zepu county in southern Xinjiang to test the difference between walnut–wheat intercropping and wheat monocropping patterns for three consecutive years. And, we employed the field experiments to ensure the effectiveness of the reduced concentration common pesticides through the UAV spraying method. In conclusion, we conducted a comparison of the control effects of two spraying methods under conditions of reduced pesticide usage. Our findings revealed that the population of cereal aphids was larger in the intercropping pattern compared to the monocropping pattern. Although the control effect of the reduced treatment was lower than the regular dosage, some treatments still demonstrated sufficient capability to eliminate aphids, particularly when considering the effect within major varieties. Additionally, the use of the UAV spraying method exhibited a satisfactory effect when compared to the traditional artificial spraying method. [ABSTRACT FROM AUTHOR]

Background: Leaf-associated microbes play an important role in plant development and response to exogenous stress. Insect herbivores are known to alter the phyllosphere microbiome. However, whether the host plant's defense against insects is related to the phyllosphere microbiome remains mostly elusive. Here, we investigated bacterial communities in the phyllosphere and endosphere of eight wheat cultivars with differing aphid resistance, grown in the same farmland. Results: The bacterial community in both the phyllosphere and endosphere showed significant differences among most wheat cultivars. The phyllosphere was connected to more complex and stable microbial networks than the endosphere in most wheat cultivars. Moreover, the genera Pantoea, Massilia, and Pseudomonas were found to play a major role in shaping the microbial community in the wheat phyllosphere. Additionally, wheat plants showed phenotype-specific associations with the genera Massilia and Pseudomonas. The abundance of the genus Exiguobacterium in the phyllosphere exhibited a significant negative correlation with the aphid hazard grade in the wheat plants. Conclusion: Communities of leaf-associated microbes in wheat plants were mainly driven by the host genotype. Members of the genus Exiguobacterium may have adverse effects on wheat aphids. Our findings provide new clues supporting the development of aphid control strategies based on phyllosphere microbiome engineering. [ABSTRACT FROM AUTHOR]

Ants (Hymenoptera: Formicidae) play a relevant ecological role across terrestrial ecosystems. Recent studies suggest that the presence of ants in crops could lead to a decrease in the populations of insect pests, but how these actions can vary along the different trophic levels is not well known. The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), is a cosmopolitan agricultural pest which is regularly found on horticultural agroecosystems closely associated with its main egg parasitoid, Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae). We conducted laboratory experiments to test whether two Mediterranean ant species, the generalist predators Crematogaster scutellaris (Olivier) and Tapinoma magnum Mayr, attack N. viridula eggs or nymphs, and whether they interfere with the parasitization activity of T. basalis. The experiment showed that both ant species significantly increased the mortality of N. viridula nymphs, whereas they do not attack their eggs and do not interfere with the egg parasitoids. Our results suggest that ants and egg parasitoids may have an integrable role in biocontrol strategies against this pest. [ABSTRACT FROM AUTHOR]

The numbers per tiller (abundance) and per unit area of ground (population density) of the dominant cereal aphids in winter wheat crops, Sitobion avenae (Fabricius) and Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) were recorded from 2000–2015. The results were used to test the hypothesis that at the population peak and 4 weeks previously, the population density of aphids in winter wheat crops (Triticum aestivum L., Poaceae) is uniformly distributed with respect to surface area and, as a result, their abundance is high in sparse stands (SPA) where the colonizing aphids are scattered among a small number of tillers (ca. 80 m−2), and low in dense stands (DEN) where they are scattered among a larger number of tillers (ca. 440 m−2). This prediction was verified for S. avenae, the population density of which did not significantly differ between SPA and DEN stands throughout this period. This species feeds mainly on the ears, whose nutritional quality for aphids varies little with crop density and during the course of ripening. In contrast and contrary to our prediction, the population density of M. dirhodum increased throughout this period more rapidly in SPA than in DEN stands. This species lives on leaves whose quality is better and remain present for longer during the course of ripening of the crop in SPA than DEN stands. The abundance of both species was higher in SPA than in DEN stands. Greater direct damage to cereal crops can be expected when using technologies and cultivars of winter wheat that need to be planted sparsely. [ABSTRACT FROM AUTHOR]

Background and Objectives Wheat (Triticum aestivum L.) holds crucial significance as a primary global food source, providing approximately 18% of required calories and 19% of essential protein for human consumption. The greenbug, Schizaphis graminum, poses a substantial threat to wheat crops worldwide, including in Iran, causing significant annual damage. Traditional methods for identifying induced resistance in host plants involve pest pre-infestation and the assessment of demographic parameters. Considering the adverse environmental and health implications of excessive pesticide use in wheat fields, the exploration of "induced resistance" as a biorational method has gained notable attention in recent years within the wheat-integrated pest management domain. This study's main objectives included examining induced responses in three distinct wheat varieties to S. graminum and determining the optimal pre-infestation period to activate this defensive reaction in the host varieties. Materials and Methods Seeds from three wheat varieties (Kohdasht, Morvarid, and Aseman) were planted in growth chamber conditions (temperature: 25±2°C, relative humidity: 60±5%, and a photoperiod of 14:10 L: D). Upon reaching the two-leaf stage, five one-day-old female apterus aphids were introduced to each plant, allowing them to feed for 0, 2, 4, 6, and 8 days (considered as the experimental pre-infestation treatment duration). After the designated pre-infestation period, aphids were removed from the wheat plants, and the plants remained aphid-free for 48 hours. Following this interval, an age-specific two-sex life table of aphids was separately constructed for each wheat variety and pre-infestation duration. Using a cohort of 30 one-day-old first-instar nymphs, the biological and demographic parameters of aphids were measured and compared using the paired bootstrap test. Results The Aseman variety exhibited heightened resistance to S. graminum in comparison to Morvarid and Kohdasht varieties, as evidenced by the demographic parameter values. Notably, Aseman's extended nymphal developmental time and mean generation time (T), coupled with decreased longevity and fecundity, resulted in a significantly lower intrinsic rate of increase (rm) at 0.245 1/day, in contrast to Morvarid and Kohdasht varieties (0.348 and 0.358 1/day, respectively). Across all varieties, pre-infestation by aphids led to reductions in biological and demographic parameters, with the effective pre-infestation duration varying based on the variety and specific parameters studied. The nymphal developmental time increased, while fecundity and intrinsic rm significantly decreased as the pre-infestation duration progressed from 0 to 8 days. In Aseman, Morvarid, and Kohdasht varieties, rm decreased from 0.245 to 0.187, 0.348 to 0.275, and 0.385 to 0.335 1/day, respectively, with an increase in pre-infestation duration from 0 to 8 days. In the relatively more resistant Aseman variety, significant changes in nymphal developmental time and intrinsic rm occurred after a 2-day pre-infestation period, while aphid fecundity changed significantly after a 6-day pre-infestation duration. Morvarid exhibited significant changes in nymphal developmental time, female fecundity, and intrinsic rate of increase after 6, 4, and 2-day pre-infestation durations, respectively. Across all three varieties, the intrinsic rm, identified as a crucial demographic parameter, experienced significant changes after a 2-day pre-infestation period. Discussion Diverse demographic responses were observed for S. graminum across the studied wheat varieties, with the Aseman variety exhibiting heightened relative resistance to wheat green aphid. Pre-infestation of wheat plants with aphids induced resistance in all three varieties, resulting in a reduction in the biological and demographic potential of green aphid. Due to their favorable induction reactions to S. graminum, it is recommended to cultivate Kohdasht (resistant to pathogenic fungi, suitable for dry and semi-arid drylands) and Morvarid (resistant to pathogenic fungi, suitable for humid and plain areas) varieties. This approach can contribute to diminishing the aphid population and enhancing wheat production in these specified regions. The research outcomes offer valuable insights into identifying sources of resistance, understanding mechanisms, and facilitating the implementation of integrated aphid management strategies in wheat fields across Iran. [ABSTRACT FROM AUTHOR]

Greenbug (Schizaphis graminum, Rondani) is a serious insect pest in many wheat growing regions and has been infesting cereal crops in the USA for over a century. Continuous occurrence of new greenbug biotypes makes it essential to explore all greenbug resistant sources available to manage this pest. Gb1, a recessive greenbug resistance gene in DS28A, confers resistance to several economically important greenbug biotypes and is the only gene found to be resistant to greenbug biotype F. A set of 174 F2:3 lines from the cross DS28A × Custer was evaluated for resistance to greenbug biotype F in 2020 and 2022. Selective genotyping of the corresponding F2 population using single nucleotide polymorphism (SNP) markers generated by genotyping-by-sequencing (GBS) led to the identification of a candidate genomic region for Gb1. Thus, SSR markers previously mapped in this region were used to genotype the entire F2 population, and kompetitive allele specific PCR (KASP) markers were also developed from SNPs in the target region. Gb1 was placed in the terminal region of the short arm of chromosome 1A, and its location was confirmed in a second population derived from the cross DS28A × PI 697274. The combined data analysis from the two mapping populations delimited Gb1 to a < 1 Mb interval between 13,328,200 and 14,241,426 bp on 1AS. [ABSTRACT FROM AUTHOR]

Background: The green aphid (Myzus persicae) found in Taif Governorate is a sap-sucking insect that occurs globally. These insects target all the plant parts in both their nymphal and adult stages, causing them to discolor and dry out. Methods: In this study, 250-300 aphids were widely collected from rose plants in different locations in the Taif Governorate. These insects were identified using morphological traits and mitochondrial gene sequencing. Result: According to morphological traits, these samples belonged to the species Myzus persicae. Considering that aphid species are very similar morphologically, the identification of samples that were similar to more than one species was performed using their genetic characteristics. Aphid strain characterization through Sanger sequencing with multilocus sequence typing (MLST) and phylogenetic analysis revealed significant diversity and comparing mitochondrial gene sequences of aphids with extant sequences in GenBank showed high similarity and a new strain was recorded in the NCBI database for the first time in Taif Governorate. For microbiome isolation, five bacterial species were isolated from M. persicae (Bacillus spp., Serratia spp., Staphylococcus, Micrococcus spp. and Escherichia coli). Our results showed a significant correlation between M. persicae and microbial communities. Future research should focus on discovering new strains of M. persicae and understanding the eco-evolutionary patterns of aphid-symbiont interactions in the Taif Governorate, particularly in biological control. [ABSTRACT FROM AUTHOR]