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BACKGROUND: Sperm development and behavior present promising targets for environmentally safer, target‐specific biorational control strategies. Serine protease in seminal fluid proteins plays a crucial role in the post‐mating reproductive processes of lepidopteran pest insects. The serine protease 2 has been identified as the initiatorin of the seminal fluid protein in Lepidoptera, and its loss of function leads to male sterility. Nevertheless, the genetic pattern of this gene mutation and the impacts of various mutant genotypes on the hatchability of the eggs of pests remain unclear. RESULTS: This study focused on the cloning of Spodoptera exigua serine protease 2 (SeSer2), which is specifically expressed in male moths. The open reading frame of SeSer2 consists of 843 nucleotides, encoding 280 amino acids with structural characteristics typical of serine proteases in the S1 family. To validate the functional role of SeSer2 in the fertility of S. exigua, a targeted ~3574‐bp deletion of SeSer2 was introduced using the CRISPR/Cas9 genome editing system, leading to premature truncation of the SeSer2 protein. The SeSer2 mutation had no significant impact on the growth and development of individuals of either sex. However, disruption of SeSer2 resulted in heritable male sterility. Although females mated with SeSer2−/− (SeSer2 knockout homozygote) males laid eggs normally, these eggs failed to hatch. SeSer2+/− (SeSer2 knockout heterozygote) male moths crossed with female moths produced viable offspring, indicating the gene's recessive role in egg hatching. CONCLUSION: These findings strongly support the conclusion that the Ser2 gene is essential for male reproductive success in diverse lepidopterans. Targeting the Ser2 gene holds promise as a foundational element of a novel pest control strategy. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: The F116V mutation in the substrate recognition site 1 (SRS1) of Spodoptera exigua CYP9A186 has been demonstrated to confer ~200‐fold resistance to emamectin benzoate (EB). In this study, a novel mutation (F116I) in CYP9A25, orthologous to CYP9A186, was detected in a field population of Spodoptera litura (YJ22) collected from Yuanjiang, Yunnan province, China in 2022. The association of this mutation with EB resistance was investigated. RESULTS: Two homozygous strains, YJ22‐116F (wild‐type at 116 position of CYP9A25) and YJ22‐116I (mutant) were isolated from YJ22 through two rounds of crossing and DNA genotyping. Compared with YJ22‐116F, the mutant strain YJ22‐116I exhibited 31.8‐fold resistance to EB. Resistance in YJ22‐116I was shown to be incompletely dominant, and genetically linked with the F116I mutation. Further, heterologous expression and in vitro metabolism assays confirmed that the recombinant CYP9A25 protein with 116I mutation obtained metabolic capability against EB, whereas the wild‐type CYP9A25 protein (with 116F) did not metabolize EB. Molecular modeling showed that the F116I mutation within SRS1 reduces the steric hindrance to substrate entry and improves ligand‐binding interactions. CONCLUSION: The causal association between the F116I mutation in CYP9A25 and medium‐level EB resistance in S. litura has been verified. This finding is critical for the field monitoring of such mutations and thus for developing adaptive resistance management tactics for field populations of S. litura. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis (Bt) have been utilized for control of lepidopteran insect pests. The majority of known Vip3 proteins possess exceptional high toxicity against Noctuid insects such as the fall armyworm (FAW, Spodoptera frugiperda), beet armyworm (BAW, Spodoptera exigua) and cotton bollworm (CBW, Helicoverpa armigera), but generally have relatively low or even no activity against some very important pest insects, such as Asian corn borer (ACB, Ostrinia furnacalis), European corn borer (ECB, Ostrinia nubilalis), rice stem borer (RSB, Chilo suppressalis) and oriental armyworm (OAW, Mythimna separata). RESULTS: Here, we report mutant Vip3Af with a single amino acid mutation, Vip3Af‐T686R, which gains significantly higher insecticidal activity against ACB, OAW and BAW, while retaining high activity against FAW, CBW and RSB. Protein proteolytic activation in vitro showed that the proteolytic activation efficiency of the mutant protein was greater than the wild‐type protein in the midgut juice of ACB, OAW and BAW. Transgenic corn expressing this mutant Vip3Af showed high levels of resistance to ACB, OAW, FAW, BAW and CBW. CONCLUSION: Our results suggest that Vip3Af may be a superior Vip3A mutant for the development of transgenic crops with resistance to a broad range of lepidopteran pest species. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The tri-trophic interaction of plants, insect herbivores, and entomoviruses is an important topic in ecology and pest control. The susceptibility of insect herbivores to entomoviruses (e.g., nucleopolyhedroviruses) is influenced by host plants; however, the role of plant secondary metabolites in determining such susceptibility is poorly understood. Metabolomic analyses of Brassica oleracea , Glycine max , and Ipomoea aquatica plants, which differ in how they affect the susceptibility of Spodoptera exigua to nucleopolyhedroviruses among 14 plants, suggested that the plant secondary metabolites genistein, kaempferol, quercitrin, and coumarin play a role in influencing nucleopolyhedroviruses susceptibility. Subsequently, transcriptomic analysis of caterpillars, treated with nucleopolyhedroviruses alone or with one of these four phenolics, identified four genes (CYP340K4 , CXE18 , GSTe , and GSTe1) that were significantly downregulated by the phenolics. Functional characterization of these genes suggested that their downregulation significantly increased larval sensitivity to nucleopolyhedroviruses and altered aspects of the immune response. Our findings provide new insight into the role of plant defense metabolites in influencing the interactions between insect herbivores and entomopathogens and identify plant secondary metabolites as potential synergists of viral agents for the control of agricultural pests. [Display omitted] • Plant secondary metabolites (PSMs) affect caterpillars' susceptibility to NPV • Four genes of caterpillars are significantly downregulated by plant phenolics • Downregulated genes increase the susceptibility by altering the immune response • PSMs are potential synergists of viral agents to control agricultural pests Wang et al. reveal that plant defense metabolites affect the susceptibility of caterpillars to nucleopolyhedroviruses (NPVs) by altering detoxification pathways of caterpillars. Four genes (CYP340K4, CXE18, GSTe, and GSTe1) of caterpillars downregulated by plant phenolics increased larval susceptibility by altering the immune response. [ABSTRACT FROM AUTHOR]

Simple Summary: Spodoptera exigua is a migratory pest that causes regional crop loss regularly. In this study, its migratory activity was monitored using a searchlight trap in the tropical area of Hainan province, China. The results indicated that the pest migrated from Hainan Island to mainland China in the spring, primarily moved from areas of Southeast Asia to Hainan and mainland China during the summer, and returned to Southeast Asia from China in the autumn and winter. These findings provide a theoretical basis for the regional monitoring, early warning, and management of the insect in China and Southeast Asian countries. The beet armyworm Spodoptera exigua (Hübner), a global pest, feeds on and affects a wide range of crops. Its long-distance migration with the East Asian monsoon frequently causes large-scale outbreaks in East and Southeast Asia. This pest mainly breeds in tropical regions in the winter season every year; however, few studies have investigated associations with its population movements in this region. From 2017 to 2023, we monitored its population dynamics in a tropical site, located in Hainan Province of China, using a searchlight trap. Dissection of the ovaries of female S. exigua moths captured from the air revealed that most of them were reproductively mature and could be classified as a transit migratory population. Migration occurred most often in summer and least often in winter, with an increasing trend over the years. According to a trajectory model analysis based on the Weather Research and Forecasting (WRF) model, S. exigua migrated from Hainan Island to mainland China in the spring, primarily moved from the areas of Southeast Asia to Hainan and mainland China during the summer, and returned from China to Southeast Asia in the autumn and winter. Overall, our research defines the movement paths of S. exigua in the tropical area of China, establishing a theoretical foundation for its regional monitoring, early warning, and management in China and Southeast Asian countries. [ABSTRACT FROM AUTHOR]

Soil‐borne microorganisms can impact leaf‐chewing insect fitness by modifying plant nutrition and defence. Whether the altered insect performance is linked to changes in microbial partners of caterpillars remains unclear. We investigated the effects of root inoculation with soil bacteria or fungi on the gut bacterial community and biomass of the folivore Spodoptera exigua. We also explored the potential correlation between both parameters. We performed herbivory bioassay using leaves of tomato plants (Solanum lycopersicum), measured caterpillar weight gain and characterized the gut bacterial communities via 16S rRNA gene metabarcoding. All soil microbes modified the gut bacterial communities, but the extent of these changes depended on the inoculated species. Rhizophagus irregularis and Bacillus amyloliquefaciens had opposite effects on S. exigua weight. While plant inoculation with the fungus influenced gut bacterial diversity, B. amyloliquefaciens also affected the community composition. A reduced abundance of two S. exigua enterococcal symbionts correlated with decreased insect biomass. Our results show that soil microorganisms can induce plant‐mediated changes in the gut bacterial community of foliar‐feeding caterpillars. We propose that the impact of these alterations on insect performance might rely on specific adaptations within the gut bacteria, rather than solely on the occurrence of changes. [ABSTRACT FROM AUTHOR]

The silkworm (Bombyx mori) is an important model lepidopteran insect and can be used to identify pesticide resistance‐related genes of great significance for biological control of pests. Uridine diphosphate glucosyltransferases (UGTs), found in all organisms, are the main secondary enzymes involved in the metabolism of heterologous substances. However, it remains uncertain if silkworm resistance to fenpropathrin involves UGT. This study observes significant variations in BmUGT expression among B. mori strains with variable fenpropathrin resistance post‐feeding, indicating BmUGT's role in fenpropathrin detoxification. Knockdown of BmUGT with RNA interference and overexpression of BmUGT significantly decreased and increased BmN cell activity, respectively, indicating that BmUGT plays an important role in the resistance of silkworms to fenpropathrin. In addition, fenpropathrin residues were significantly reduced after incubation for 12 h with different concentrations of a recombinant BmUGT fusion protein. Finally, we verified the conservation of UGT to detoxify fenpropathrin in Spodoptera exigua: Its resistance to fenpropathrin decreased significantly after knocking down SeUGT. In a word, UGT plays an important role in silkworm resistance to fenpropathrin by directly degrading the compound, a function seen across other insects. The results of this study are of great significance for breeding silkworm varieties with high resistance and for biological control of pests. [ABSTRACT FROM AUTHOR]

Ginger (Zingiber officinale Roscoe) waste is a residue from industrial factories that has potential for utilization in the production of bio-extract for pest control. Therefore, this study aimed to investigate the toxicity of fermented ginger waste extract through contact toxicity and oral toxicity methods in controlling the common cutworm (Spodoptera litura Fabricius) and the beet armyworm (Spodoptera exigua Hübner). The experiment was a completely randomized design (CRD) with 10 replicates. Mortality rates were recorded at 48, 72, and 96 h after treatment under laboratory conditions. Fermented ginger waste extract at concentrations of 0%, 5%, 25%, 50%, and 100% (w/v) was used. The results showed that for the contact toxicity method at 100% concentration after 96 h, the common cutworm had the highest mortality rate of 76.00 ± 1.29% (LC50 = 14.450 µg larva-1), while the beet armyworm had the highest mortality rate of 66.00 ± 0.95% (LC50 = 68.426 µg larva-1). For the oral toxicity method, the common cutworm had the highest mortality rate of 52.00 ± 1.70% at 100% concentration after 96 h (LC50 = 91.275 µg larva-1), and the beet armyworm had the highest mortality rate of 58.00 ± 1.02% at 100% concentration after 96 h (LC50 = 88.400 µg larva-1). Therefore, the results of this study demonstrate the efficacy of fermented ginger waste extract in controlling common cutworm and beet armyworm under laboratory conditions, and it has the potential for further application in field conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND: The Vip3Aa insecticidal protein, produced by Bacillus thuringiensis, has been effectively used in commercial Bt‐crops to manage lepidopteran pests. Upon ingestion by larvae, the protoxin is processed by midgut proteases into the activated protein and binds specifically to its receptors in the midgut, leading to insect mortality. Cryo‐EM resolution of the trypsin‐processed Vip3Aa protein unveiled structural remodelling of the N‐terminal region during the transition from protoxin to activated protein. This conformational change has been demonstrated to be crucial for toxicity against Spodoptera exigua larvae, a major global lepidopteran pest. In this study, we investigated the relevance of the structural remodelling for the specific binding to midgut receptors. RESULTS: We conducted in vitro binding assays with radiolabelled proteins and brush border membrane vesicles (BBMV) from S. exigua, employing structural mutants that lock the protein in either its protoxin or its activated conformation. Our results indicate that both structural stages of the protein share binding sites in the midgut epithelium. Moreover, in vivo competition assays revealed that Vip3Aa is able to bind to functional receptors in S. exigua larvae both as protoxin and as activated protein. CONCLUSION: Altogether, our findings point to both structural conformations contributing to receptor binding. In vivo, either spontaneous structural shift upon proteolytic cleavage or receptor‐mediated remodelling could be occurring. However, the timing and context in which the conformational change occurs could influence membrane insertion and toxicity. Our results show the complex interplay between proteolytic processing, protein structure and receptor interactions in Vip3Aa's toxicity. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Bacillus thuringiensis serves as an effective biopesticide in controlling specific pests. Nonetheless, exposure to solar ultraviolet (UV) radiation is a significant factor that contributes to the degradation of the spores and crystals of this bacterium. Therefore, research on protective compounds against UV radiation is essential. In this study, the effects of activated charcoal, graphene oxide, and nanographene oxide in preserving the pathogenicity of B. thuringiensis var. kurstaki (Btk) against ultraviolet radiation on the beet armyworm, Spodoptera exigua (Hübner) were investigated under laboratory and field conditions. The probit analysis of concentrations of Btk on second-instar larvae of the S. exigua after 48 and 72 hours in the laboratory showed that LC50 was 1149.62 and 729.13 ppm, respectively. Additionally, the study examining the impact of UVC on the pathogenicity of Btk indicated that larvae exposed to UVC-treated Btk experienced lower mortality rates compared to those exposed to the nonirradiated bacterium. The variance analysis regarding the impact of UV radiation on spore germination, when using protective agents in comparison to the control group, demonstrated that activated charcoal showed the more effective results. Additionally, an analysis of variance regarding the UV-protective properties of the treatments in preserving the effectiveness of Btk against second-instar larvae conducted under both laboratory and field conditions revealed that activated charcoal had a higher protective effect compared to other treatments. Based on the results, activated charcoal is recommended for use with Btk against this pest. Activated charcoal can be suggested for inclusion in formulations of this biopesticide to protect it from solar UV radiation. [ABSTRACT FROM AUTHOR]

Lepidopterans commonly feed on plant material, being the most significant insect herbivores in nature. Despite plant resistance to herbivory, such as producing toxic secondary metabolites, herbivores have developed mechanisms encoded in their genomes to tolerate or detoxify plant defensive compounds. Recent studies also highlight the role of gut microbiota in mediating detoxification in herbivores; however, convincing evidence supporting the significant contribution of gut symbionts is rare in Lepidoptera. Here, we show that the growth of various lepidopteran species was inhibited by a mulberry-derived secondary metabolite, 1-deoxynojirimycin (DNJ); as expected, the specialist silkworm Bombyx mori grew well, but interestingly, gut microbiota of early-instar silkworms was affected by the DNJ level, and several bacterial species responded positively to enriched DNJ. Among these, a bacterial strain isolated from the silkworm gut (Pseudomonas fulva ZJU1) can degrade and utilize DNJ as the sole energy source, and after inoculation into nonspecialists (e.g., beet armyworm Spodoptera exigua), P. fulva ZJU1 increased host resistance to DNJ and significantly promoted growth. We used genomic and transcriptomic analyses to identify genes potentially involved in DNJ degradation, and CRISPR-Cas9- mediated mutagenesis verified the function of ilvB, a key binding protein, in metabolizing DNJ. Furthermore, the ilvB deletion mutant, exhibiting normal bacterial growth, could no longer enhance nonspecialist performance, supporting a role in DNJ degradation in vivo. Therefore, our study demonstrated causality between the gut microbiome and detoxification of plant chemical defense in Lepidoptera, facilitating a mechanistic understanding of host-microbe relationships across this complex, abundant insect group. [ABSTRACT FROM AUTHOR]

Anthropogenic-mediated climate change is expected to negatively affect pest management in agriculture. Hence, we investigated the oviposition, immature mortality, and developmental processes of Spodoptera species (Spodoptera exigua (Hübner) and Spodoptera litura (Fabricius)) under different temperatures (20, 25, and 30°C) and relative humidity (RH) (30–35, 50–55, 70–75, and 90–95%) conditions. For fecundity, mouths of each Spodoptera species were released into a rectangular box whose inner walls were covered with a sheet of white paper for each combination of temperature and RH. The mouths were kept inside the box to deposit eggs for 72 h. Temperature and RH significantly affected the fecundity, with the maximum number of eggs laid in 70–75% at 30°C. The highest egg and larval mortalities were recorded in 30–35 and 90–95% RH, respectively. Temperature and RH greatly affected the developmental period (egg–adult) and adult emergence rate. The rapid development was recorded in 70–75% RH at 30°C. Higher number of adults was found with an increase in temperature and RH. Adult longevity was significantly higher in 70–75% RH at 20°C. Based on the present study's findings, temperature and RH had an individual apparent effect on the developmental processes of Spodoptera species instead of an interactive effect. Therefore, there is need for an in-depth study of the influence of several climatic factors, including CO2, on the developmental modality and demographic changes of Spodoptera species to assess the impacts of climatic components and the sustainable development of management strategies. [ABSTRACT FROM AUTHOR]

Yunnan province is most important area of potato planting in China. Meanwhile, there are many factors constraint to its developments, especially pest damage. So, eleven potato cultivars (such as Hezuo 88, Lishu 6, Qingshu 9 and Yunshu 304) of vital commercial variety in Yunnan were selected for pests investigation. The field survey of eleven potato cultivars in two cropping seasons (spring and autumn) was conducted from 2020 to 2021 in Yunnan province, China. During autumn planting season of 2020 and 2021, populations of eight insect pests including aphid, thrips, whitefly, leafhopper, potato tuber moth, tomato leaf miner, beet armyworm and cabbage moth were surveyed. All pest's population peaked in October. Meanwhile, Qingshu 9 and Yunshu 304 has the largest population of aphid. The largest population of whitefly were reported on Hezuo 88 and Yunshu 304, respectively. The largest population of thrips were found on Hezuo 88, whereas Qingshu 9 has the lowest population of whitefly. The lowest population of aphid were observed on Lishu 6. The lowest population of thrips were found on Yunshu 304. During spring planting season of 2021, population of thrips, leafhopper and adult potato tuber moth were surveyed. The highest population was appeared in June. But there was no significant difference for the pests populations among different cultivars. These results of pests population dynamics during the cropping period would be helpful for making appropriate and sustainable pest management strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: The role of the V1848I mutation in the voltage-gated sodium channel (VGSC) concerning SCBI resistance and inheritance patterns in Spodoptera exigua was investigated by developing and characterizing a near-isogenic resistant strain called WH-1848I. This mutation confers significant resistance to indoxacarb (146-fold) and metaflumizone (431-fold) in the WH-1848I strain. The SCBI resistance in this strain is autosomal, nonrecessive, and genetically linked to the V1848I mutation. Spodoptera exigua is one of the most serious lepidopteran pests of global importance. With the intensive use of insecticides, S. exigua has evolved resistance to many insecticides, including the sodium channel blocker insecticides (SCBIs) indoxacarb and metaflumizone. In this study, we investigated the role of the V1848I mutation in the voltage-gated sodium channel (VGSC) in SCBI resistance and its inheritance patterns in S. exigua through the development and characterization of a near-isogenic resistant strain. The AQ-23 strain of S. exigua, collected in 2023 from Anqing, Anhui province of China, shows 165-fold resistance to indoxacarb compared with the susceptible WH-S strain. A frequency of 44.6% for the V1848I mutation was detected in the SeVGSC of the AQ-23 strain, while no F1845Y mutation was found. Through repeated backcrossing and marker-assisted selection, the V1848I mutation in the AQ-23 strain was introgressed into the susceptible WH-S strain, creating a near-isogenic strain named WH-1848I. This WH-1848I strain exhibits high levels of resistance to indoxacarb (146-fold) and metaflumizone (431-fold) but remains susceptible to broflanilide and spinosad compared with the WH-S strain. Inheritance analysis revealed that SCBI resistance in the WH-1848I strain is autosomal, nonrecessive, and genetically linked to the V1848I mutation. These findings establish a clear link between the V1848I mutation and SCBI resistance in S. exigua, offering valuable insights for developing molecular detection tools and resistance management strategies. [ABSTRACT FROM AUTHOR]

Volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and N-linolenoyl-L-glutamine were originally identified in the regurgitant of Spodoptera exigua larvae. These fatty acid amino acid conjugates (FACs) are known to be elicitors that induce plants to release volatile compounds which in turn attract natural enemies of the larvae such as parasitic wasps. FAC concentrations are regulated by enzymatic biosynthesis and hydrolysis in the intestine of Lepidoptera larvae. It has been proposed that FAC metabolism activates glutamine synthetase and plays an important role in nitrogen metabolism in larvae. In this study, we identified candidate genes encoding a FACs hydrolase in Spodoptera litura using genomic information of various related lepidopteran species in which FACs hydrolases have been reported. We analyzed the importance of FAC hydrolysis on caterpillar performance with CRISPR/Cas9 knock outs. Larvae of strains with an inactive FACs hydrolase excreted FACs in their feces. They absorbed 30% less nitrogen from the diet compared to WT caterpillars resulting in a reduction of their body weight of up to 40% compared to wild type caterpillars. These results suggest that the hydrolysis of FACs is an important metabolism for insects and that FACs are important for larval growth. [ABSTRACT FROM AUTHOR]

Simple Summary: Chouioia cunea Yang is a crucial natural enemy in the management of the fall webworm (Hyphantria cunea), which is a globally significant quarantine pest. The feeding behavior, dispersal, and high reproductive capacity of Hy. cunea cause substantial economic and ecological damage. Apart from Hy. cunea, C. cunea also exhibits parasitic behavior toward various Lepidoptera species, including those from the families Lasiocampidae, Lymantridae, Notodontidae, Psychidae, and Noctuidae. It also targets certain Coleoptera species, such as those from the families Chrysomelidae and Coccinellidae, most of which are leaf-eating pests. C. cunea feeds on the hemolymph of its host. Variations in the hemolymph's nutrient content, chemical properties, and immune response among different host species may influence the gut microbiome of the wasps. Moreover, microbial communities present in the host can be ingested by the parasitic wasps, leading to differences in their gut microbiome compositions depending on the host. In this study, we investigated the developmental patterns and intestinal microbiota diversity of C. cunea parasitizing various hosts. Our objective was to elucidate how different hosts impact the development and intestinal microbiota composition of C. cunea. This research provides scientific evidence for optimizing biological control strategies and applications involving insect pathogenic microorganisms. Chouioia cunea are known to exploit in varying degrees a wide range of lepidopteran species and its offspring development may vary with host species. This study examined its preimaginal development and larval gut microbiota in parasitizing five folivorous lepidopteran hosts including Hyphantria cunea (referred to thereafter as CcHc), Antherea pernyi (CcAp), Helicoverpa armigera (CcHa), Spodoptera exigua (CcSe), and Spodoptera frugiperda (CcSf). Though rates of parasitism and offspring eclosion did not change with host species, the development period and number of offspring eclosed varied with hosts, with the shortest period in CcSf and the highest number from CcAp. For offspring larval gut microbiota, though phylum Proteobacteria was dominant for attacking CcAp, Firmicutes was so for the other hosts. All microbial genera except Enterococcus were less abundant for CcSf than the other hosts. The database-based predictions indicate a significant positive correlation between Cutibacterium and Aureimonas with the relative number of wasp emergence, while Blastomonas exhibits a strong positive association with the developmental period. Our results imply the potential relevance of the gut microbial community in offspring larvae to host species attacked by C. cunea. [ABSTRACT FROM AUTHOR]

This study reviews the impact of pest and disease attacks on shallot plants (Allium ascalonium L.) and control strategies to increase plant production. Pests such as Spodoptera exigua (onion caterpillar), Thrips tabaci (thrips), Spodoptera ltura F. (armyworm), Liriomyza spp. (leaf slitting fly), and Gryllotalpa spp. (orong-orong), as well as diseases such as trotol or purple spot (Purple blotch), anthracnose (Antracnose), downy mildew, moler or fusarium wilt (Twisting disease), leaf blight (Stemphylium leaf blight), and leaf spot (Cercospora leaf spot) cause a significant decrease in production hasl. Pest and disease control still relies heavily on chemical pesticides, which pose a risk to the environment and health. Alternative sustainable control such as the use of biopesticides from mahogany seed extract (Swietenia mahagoni), Japanese papaya leaf extract (Cnidoscolus aconitifolius), and legundi weed extract (Vitex trifolia L.), as well as the application of Plant Growth Promoting Microorganisms (PGPM) from bamboo root can have a very good influence on controlling pests and diseases of shallot plants and can help in increasing plant productivity. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis, is a serious pest causing both direct feeding damage and indirect harm by transmitting the tomato spotted wilt virus. A spraying double‐stranded RNA (dsRNA) targeted at the vacuolar‐type ATPase (vATPase) gene was developed and demonstrated high insecticidal activity in the laboratory but less effective in field applications. To improve control efficacy under field conditions, three strategies were explored in this study. First, to identify a more efficient RNA interference (RNAi) target, dsRNA specific to the Snf7 gene was tested alongside dsRNA targeting vATPase, and both were found to be similarly effective in controlling the thrips. Second, to elucidate the factors contributing to dsRNA resistance, dsRNA‐degrading enzymes were annotated and their physiological roles in diminishing RNAi efficacy were investigated. Third, to suppress the dsRNA degradation from the dsRNase activities and protect it in field conditions, the dsRNA was encapsulated with chitosan. This formulation enhanced the dsRNA's resistance to environmental stressors such as ultraviolet light and the digestive enzymes in the thrips' gut. Additionally, the chitosan formulation specifically increased the RNAi efficacy, likely by facilitating more efficient entry into the target cells, thus bolstering the insecticidal activity of the dsRNA. The formulated dsRNA was applied on F. occidentalis infesting the hot peppers in a greenhouse at a concentration of 500 ppm, demonstrating an 82.4% control efficacy compared with 59.2% control efficacy observed with the application of naked dsRNA. This study further demonstrated an enhancement in the spectrum of control by combining dsRNAs specific to three distinct thrips species, while the mixture showed no adverse effects on non‐target insects, such as the lepidopteran Spodoptera exigua. Collectively, these findings reveal that the chitosan formulation of dsRNA not only improves control efficacy under field conditions but also broadens the control spectrum against three different thrips pests. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are endogenous, non-coding RNAs, which are functional in a variety of biological processes through post-transcriptional regulation of gene expression. However, the role of miRNAs in the interaction between Bacillus thuringiensis and insects remains unclear. In this study, small RNA libraries were constructed for B. thuringiensis -infected (Bt) and uninfected (CK) Spodoptera exigua larvae (treated with double-distilled water) using Illumina sequencing. Utilising the miRDeep2 and Randfold, a total of 233 known and 726 novel miRNAs were identified, among which 16 up-regulated and 34 down-regulated differentially expressed (DE) miRNAs were identified compared to the CK. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that potential target genes of DE miRNAs were associated with ABC transporters, fatty acid metabolism and MAPK signalling pathway which are related to the development, reproduction and immunity. Moreover, two miRNA core genes, SeDicer1 and SeAgo1 were identified. The phylogenetic tree showed that lepidopteran Dicer1 clustered into one branch, with SeDicer1 in the position closest to Spodoptera litura Dicer1. A similar phylogenetic relationship was observed in the Ago1 protein. Expression of SeDicer1 increased at 72 h post infection (hpi) with B. thuringiensis ; however, expression of SeDicer1 and SeAgo1 decreased at 96 hpi. The RNAi results showed that the knockdown of SeDicer1 directly caused the down-regulation of miRNAs and promoted the mortality of S. exigua infected by B. thuringiensis GS57. In conclusion, our study is crucial to understand the relationship between miRNAs and various biological processes caused by B. thuringiensis infection, and develop an integrated pest management strategy for S. exigua via miRNAs. [ABSTRACT FROM AUTHOR]

The tachinid flies (Diptera) and their host species have been studied in the corn and sugar beet fields of Kermanshah and Hamedan provinces from 2022 to 2023. The infested plants by caterpillars were collected in order to rear the larvae at the laboratory. In this study, six species of parasitoids were identified of which Drino imberbis (Wiedemann, 1830), Linnaemya neavei Curran, 1934 and Pseudogonia rufifrons (Wiedemann, 1830) parasitize the larval stages of Leucania loreyi (Duponchel, 1827) in corn fields. The species D. imberbis is newly reported here as a parasitoid of L. loreyi in Iran. The tachinid Voria ruralis (Fallén, 1810) is the first world recorded parasitoid of larval stages of Sesamia cretica Lederer, 1857. Furthermore, Periscepsia carbonaria (Panzer, 1797) and an undetermined Tachina sp. were discovered to parasitize the larvae of Agrotis segetum (Denis & Schiffermüller, 1775) and Spodoptera exigua (Hübner, [1808]), respectively, in sugar beet fields. [ABSTRACT FROM AUTHOR]

In the Brassicaceae family, a glucosinolate-myrosinase-based system exists against herbivory Glucosinolate-Myrosinase system is differentially compartmentalized but substrate glucosinolate enter in contact with the enzyme myrosinase when plant tissues are attacked by insects. The glucosinolate breakdown into a variety of biologically active toxins further deterrenting the herbivory of different chewing and sucking insect pests. The myrosinase enzyme present is in myrosin cells were genetically removed from B. napus plant during the seed development. These genetically modified myrosin cells free plants are known as MINELESS plant. Genetically modified oilseed rape (Brassica napus) was produced by removing toxic mines. Here, we evaluauted the tritrophic interaction between Brassica napus wildtype and genetically modified and polyphagous pest Spodoptera. In force feeding experiment, larval growth of S. exigua was slow and gained less weight on MINELESS seedlings as compared to wild-type seedling. Additionally, highest amount of total glucosinolate was found in MINELESS control than that of wild type control. Myrosinase activity was not affected by the S. exigua feeding on the MINELESS plants. However, reduced activity of myrosinase was observed in the wild-type seedlings. Moreover, the S. exigua induced the concentration of tryptophan derived glucosinolate (indol-3-yl-methyl, 1-methoxy-indol-3-yl-methyl) that was found slightly higher in MINELESS seedlings than on wild-type seedling. Feeding of S. exigua deregulated the level of glucosinolate hydrolysis products in both types of plants. Transcriptional data after S. exigua feeding on wildtype and MINELESS showed differential response of methyl jasmonate and glucosinolate responsive genes were observed. We also observed that after methyl jasmonate treatment, methyl jasmonate and glucosinolate responsive genes were incease in the wild-type and MINELESS seedlings showing their negative effect on the growth of S. exigua. Overall, generalist insect results are interesting by considering the function of myrosin cells and binary defense system. Further, same experiment should be performed against generalist and specialist insect herbivores of above- and below-ground. [ABSTRACT FROM AUTHOR]

BACKGROUND: Voltage‐dependent anion‐selective channels (VDACs) serve as pore proteins within the mitochondrial membrane, aiding in the regulation of cell life and cell death. Although the occurrence of cell death is crucial for defense against virus infection, the function played by VDAC in Bombyx mori, in response to the influence of Bombyx mori nucleopolyhedrovirus (BmNPV), remains unclear. RESULTS: BmVDAC was found to be relatively highly expressed both during embryonic development, and in the Malpighian tubule and midgut. Additionally, the expression levels of BmVDAC were found to be different among silkworm strains with varying levels of resistance to BmNPV, strongly suggesting a connection between BmVDAC and virus infection. To gain further insight into the function of BmVDAC in BmNPV, we employed RNA interference (RNAi) to silence and overexpress it by pIZT/V5‐His‐mCherry. The results revealed that BmVDAC is instrumental in developing the resistance of host cells to BmNPV infection in BmN cell‐line cells, which was further validated as likely to be associated with initiating programmed cell death (PCD). Furthermore, we evaluated the function of BmVDAC in another insect, Spodoptera exigua. Knockdown of the BmVDAC homolog in S. exigua, SeVDAC, made the larvae more sensitive to BmNPV. CONCLUSION: We have substantiated the pivotal role of BmVDAC in conferring resistance against BmNPV infection, primarily associated with the initiation of PCD. The findings of this study shine new light on the molecular mechanisms governing the silkworm's response to BmNPV infection, thereby supporting innovative approaches for pest biocontrol. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The globally prevalent pests, Diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) and Beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), pose significant threats to cruciferous vegetables. They have rapidly developed resistance to a wide range of insecticides, leading to significant yield losses and increased control expenses. In this study, we have established an efficient approach utilizing amplicon sequencing to detect the frequency of 15 target resistance mutant sites in 6 molecular targets, acetylcholinesterase 1 (ACE1), chitin synthase 1 (CHS1), the γ-aminobutyric acid receptor (GABAR), glutamate-gated chloride channel (GluCl), voltage-gated sodium channels (NaV), and ryanodine receptor (RyR) in P. xylostella and the frequency of 11 mutations in 5 molecular targets (except GluCl) in S. exigua in China. Our findings indicate that P. xylostella exhibits remarkably high frequency (over 88.67%) in pyrethroid resistance-related mutations T929I and L1014F of NaV. In S. exigua , the frequencies of L659F mutation were ranging from 41.92% to 74.89%. In addition, the organophosphorus resistance-related mutations A298S and G324A of ACE1 were detected at frequencies ranging from 34.29% to 75.66%, and these 2 mutations occurred simultaneously (from 29.22% to 65.79%) in P. xylostella. An interannual variation in mutation frequency from 2019 to 2021 was found for P. xylostella in HNCS. The frequency of A298S and G324A mutations steadily increased while the frequency of G4946E and I4790M mutations continuously decreased. These results unveil a worrisome scenario of multiple resistance sites in these 2 pests in China and provide valuable insights for the practical application of pesticides in the field. [ABSTRACT FROM AUTHOR]

Eicosanoids mediate insect immune responses and synthesized by the catalytic activity of phospholipase A2 (PLA2). A uniquely encoded secretory PLA2 (sPLA2) is associated with immune responses of a lepidopteran insect, Spodoptera exigua. Its deletion mutant was generated using a CRISPR/Cas9 genome editing technology. Both wild and mutant lines were then immune-challenged, and the resulting transcripts were compared with their naïve transcripts by RNASeq using the Illumina-HiSeq platform. In total, 12,878 unigenes were further analyzed by differentially expressed gene tools. Over 69% of the expressed genes in S. exigua larvae are modulated in their expression levels by eicosanoids, recorded from CRISPR/Cas9 mutagenesis against an eicosanoid-synthetic gene, Se-sPLA2. Further, about 36% of the immune-associated genes are controlled by the eicosanoids in S. exigua. Indeed, the deletion mutant suffered significant immunosuppression in both cellular and humoral responses in response to bacterial challenge as well as severely reduced developmental and reproductive potentials. [ABSTRACT FROM AUTHOR]

The beet armyworm, Spodoptera exigua (Hübner), is a major pest of maize, cotton, soybean, and many other crops globally. Despite the widespread deployment of Bt transgenic maize for pest control worldwide, the efficacy of Bt lepidopteran-resistant transgenic maize in managing S. exigua remains rarely studied. In this study, we quantified the expression level of pyramided Cry1Ab and Vip3Aa toxins in Bt maize (event DBN3601T) and evaluated their control efficiency against S. exigua under both laboratory and field conditions. The enzyme-linked immunosorbent assay (ELISA) results showed that the expression levels of Cry1Ab and Vip3Aa proteins in DBN3601T maize tissues followed a decreasing order as follows: V5-leaf > V8-leaf > VT-tassel > R2-kernel > R1-silk. Diet-overlay assay results showed that the LC50 values of Cry1Ab and Vip3Aa proteins against S. exigua larvae were 11.66 ng/cm2 and 27.74 ng/cm2, respectively, with corresponding GIC50 values at 1.59 ng/cm2 and 7.93 ng/cm2. Bioassay using various tissues of the DBN3601T maize indicated that after 7 days of infestation, mortality rates of neonates and third-instar larvae ranged from 86% to 100% and 58% to 100%, respectively. Mortality was highest on V5 and V8 leaves, followed by R2-kernel, VT-tassel, and R1-silk. Field trials demonstrated that DBN3601T maize exhibited significantly lower larval density, damage rate, and leaf damage score compared to non-Bt maize. Field cage trial showed that the control efficacy of DBN3601T maize at the vegetative stage could reach 98%. These findings provide a theoretical basis for utilizing Bt transgenic maize to enhance the sustainable management of S. exigua in Asia. [ABSTRACT FROM AUTHOR]

Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is a highly dispersive, polyphagous insect pest that severely defoliates crops. Excessive reliance on synthetic insecticides leads to ecological pollution and resistance development, urging scientists to probe eco-friendly biopesticides. Here, we explore the virulence of an entomopathogenic fungus, Beauveria bassiana, against S. exigua, resulting in 88% larval mortality. Using an age–stage, two-sex life table, we evaluated the lethal and sublethal effects of B. bassiana on the demographic parameters of S. exigua, including survival, development, and reproduction. Sublethal (LC20) and lethal concentrations (LC50) of B. bassiana impacted the parental generation (F0), with these effects further influencing the demographic parameters of the first filial generation (F1). The infected F1 offsprings showed a reduced intrinsic rate of increase (r), mean generation time (T), and net reproduction rate (R0). Larval developmental duration varied significantly between the control (10.98 d) and treated groups (LC20: 10.42; LC50: 9.37 d). Adults in the treated groups had significantly reduced lifespans (M: 8.22; F: 7.32 d) than the control (M: 10.00; F: 8.22 d). Reduced fecundity was observed in the B. bassiana-infected groups (LC20: 313.45; LC50: 223.92 eggs/female) compared to the control (359.55 eggs/female). A biochemical assay revealed elevated levels of detoxification enzymes (esterases, glutathione S-transferases, and acetylcholinesterase) in the F0 generation after B. bassiana infection. However, the enzymatic activity remained non-significant in the F1 generation likely due to the lack of direct fungal exposure. Our findings highlight the enduring effects of B. bassiana on the biological parameters and population dynamics of S. exigua, stressing its use in eco-friendly management programs. [ABSTRACT FROM AUTHOR]

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Biotic stresses caused by bacterial and fungal pathogens damage crops; identifying treatments that enhance disease resistance provides important information for understanding plant defenses and sustainable agriculture. Salt stress affects crop yields worldwide; however, studies have focused on the toxic sodium ion, leaving the effects of the chloride ion unclear. In this study, we found that irrigation with a combination of chloride salts (MgCl2, CaCl2, and KCl) suppressed the cell death phenotype of the ceramide kinase mutant acd5. Chloride salt pre-irrigation also significantly limited the cell death caused by Pseudomonas syringae pv maculicola infection and inhibited the multiplication of this bacterial pathogen in a mechanism partially dependent on the salicylic acid pathway. Moreover, chloride salt preirrigation improved plant defenses against the fungal pathogen challenge, confining the lesion area caused by Botrytis cinerea infection. Furthermore, the growth of herbivorous larvae of Spodoptera exigua was retarded by feeding on chloride salt irrigated plants. Thus, our data suggest that treatment with Clincreases broad spectrum resistance to biotic challenges. [ABSTRACT FROM AUTHOR]

The beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), has become a significant pest of chickpea in recent years. The polyphagous nature allows it to survive on various hosts during the off-season, creating a great menace to the crop in the following season. To assess the incidence and document the alternate hosts of S. exigua, a rapid roving survey was conducted in 11 chickpea-growing areas of Prakasam district, Andhra Pradesh, India. Additionally, the life history traits of S. exigua were studied on major alternate host plants under laboratory conditions (27 ± 1 °C and 70 ± 2% RH) to understand the survival, life expectancy and potential contribution to future populations. The results show that, among the different crops surveyed, the maximum larval incidence was noticed in maize (1.93 larvae/plant), cowpea (1.73 larvae/plant), and sunflower (1.68 larvae/plant) during the off-season. Life history studies of S. exigua showed that highest larval survival percentage was observed on chickpea (83.6%), while the lowest was on maize (44.5%). The mean developmental time for larvae was longest on maize (27.1 days) and shortest on chickpea (14.9 days). Larvae did not develop beyond the third instar when fed with chilli. The growth index statistics showed chickpea (9.2) was the most suitable host plant, whereas maize (0.9) was the least suitable host. The age-stage-specific survival rate (Sxj) varied across developmental stages, and the survival curves overlapped, indicating different growth rates among individuals. The life expectancy (exj) at age zero was highest on groundnut (37.06 days). The intrinsic rate of increase (r) of S. exigua was lowest on maize (0.10 ± 0.0013) and highest on chickpea (0.22 ± 0.0010). Similarly, the net reproductive rate (R0) was highest on chickpea (846.39 ± 18.22) and lowest on maize (59.50 ± 2.06). The population doubled every 3.08 ± 0.011 days on chickpea compared to 7.22 ± 0.80 days on maize. The study conclusively indicates that chickpea and sunflower, primarily cultivated during the rabi season in India, are the most preferred hosts for S. exigua. In contrast, maize and cotton, mainly grown during the kharif season, are less preferred and merely support the pest's survival. Consequently, S. exigua switches hosts between different crops growing seasons, so effective management of S. exigua during the kharif season can help prevent pest outbreaks during the rabi season. [ABSTRACT FROM AUTHOR]

Viral infection can regulate the cell cycle, thereby promoting viral replication. Hijacking and altering the cell cycle are important for the virus to establish and maintain a latent infection. Previously, Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV)-latently infected P8-Se301-C1 cells, which grew more slowly than Se301 cells and interfered with homologous SeMNNPV superinfection, were established. However, the effects of latent and superinfection with baculoviruses on cell cycle progression remain unknown. In this study, the cell cycle profiles of P8-Se301-C1 cells and SeMNPV or Autographa californica multiple nucleopolyhedrovirus (AcMNPV)-infected P8-Se301-C1 cells were characterized by flow cytometry. The results showed that replication-related genes MCM4, PCNA, and BAF were down-regulated (p < 0.05) in P8-Se301-C1 cells, and the S phase of P8-Se301-C1 cells was longer than that of Se301 cells. P8-Se301-C1 cells infected with SeMNPV did not arrest in the G2/M phase or affect the expression of Cyclin B and cyclin-dependent kinase 1 (CDK1). Furthermore, when P8-Se301-C1 cells were infected with SeMNPV after synchronized treatment with hydroxyurea and nocodazole, light microscopy and qRT-PCR analysis showed that, compared with unsynchronized cells and S and G2/M phase cells, SeMNPV-infected P8-Se301-C1 cells in G1 phase induced G2/M phase arrest, and the amount of virus adsorption and intracellular viral DNA replication were significantly increased (p < 0.05). In addition, budded virus (BV) production and occlusion body (OB)-containing cells were both increased at 120 h post-infection (p < 0.05). The expression of Cyclin B and CDK1 was significantly down-regulated at 48 h post-infection (p < 0.05). Finally, the arrest of SeMNPV-infected G1 phase cells in the G2/M phase increased BV production (p < 0.05) and the number of OB-containing cells. In conclusion, G1 phase infection and G2/M arrest are favorable to SeMNPV proliferation in P8-Se301-C1 cells, thereby alleviating the homologous superinfection exclusion. The results contribute to a better understanding of the relationship between baculoviruses and insect cell cycle progression and regulation. [ABSTRACT FROM AUTHOR]

Lepidopteran pests are destructive pests and have evolved significant resistance to many insecticides. Alternative green control strategies are urgently needed. Our previous research had revealed that overexpression or knockdown of a Plutella xylostella microRNA, pxy-miR-34-5p, could lead to high mortality and severe developmental defects in multiple lepidopteran pests, thus has great potential in lepidopteran pests control. Here, pxy-miR-34-5p was successfully expressed in cruciferous plants, Arabidopsis thaliana and Brassica campestris. Feeding on leaves of transgenic miR-34-5p rape significantly reduced the expression of ecdysone receptor gene PxEcR of P. xylostella by 56.8–70.2%. Bioassays results demonstrated that compared to that of the larvae fed on wild type Arabidopsis, the accumulated mortalities of P. xylostella fed on transgenic miR-34-5p Arabidopsis were significantly increased by 34.9%–52.0%. After feeding on transgenic miR-34-5p rape leaves for four to six days, the highest accumulated corrected mortalities of P. xylostella, Spodoptera frugiperda and Spodoptera exigua larvae reached 100.0%, 94.1%, and 100.0%, respectively. These results indicated that insect microRNAs can be used to control multiple target pests by constructing transgenic crops, which lays an important foundation for the further development of miRNA-based green pest control strategies. [ABSTRACT FROM AUTHOR]

Lepidopteran pests cause enormous economic losses to agriculture globally. The control of these pests relies heavily on chemical insecticides, resulting in severe insecticide resistance and food safety concerns. Therefore, there is an urgent need to develop alternative green strategies. Our previous research revealed that the miRNA of the diamondback moth Plutella xylostella, pxy-miR-34-5p, may be a novel molecular target for multiple lepidopteran pests. However, the application strategy for pxy-miR-34-5p is not yet clear. In this study, pxy-mir-34 was successfully expressed in Escherichia coli to produce artificial miR-34 (amiR-34) on a large scale. Treatment with amiR-34 significantly repressed the expression of the ecdysone receptor (EcR) and 12 other key genes involved in the growth and development of P. xylostella. Feeding bioassays showed that amiR-34 was highly toxic to multiple lepidopteran pests, and pot experiments demonstrated that spraying with amiR-34 led to larval mortalities of 81.7%, 89.3%, and 90.8% for P. xylostella, Spodoptera frugiperda, and Spodoptera exigua, respectively, with a persistence of up to five d. These results indicate that amiR-34 has great potential for controlling multiple lepidopterous pests and they lay an important foundation for developing miRNA-based green pest control strategies. [ABSTRACT FROM AUTHOR]

Owing to the increasingly serious greenhouse effect and rising global temperatures, pest reproduction and metabolism will accelerate, which will lead to significant reductions in crop yields. To date, many studies have applied deep learning models to pest identification tasks. However, there are many pest types with similar shapes, so in this study, we propose a parallel deep learning model with an attention mechanism module to improve the classification of tomato pest species. We used a public dataset and selected Bemisia tabaci, Helicoverpa armigera, Myzus persicae, Spodoptera exigua, Spodoptera litura, Thrips palmi, Tetranychus urticae, and Zeugodacus cucurbitae. These eight common tomato pests were selected with a total of 412 original images. The original images were enhanced to 1655 images through horizontal flipping and angle rotation. The proposed ECA-Xception-MobileNet (EXM-Net) extracted image features on the basis of Xception and MobileNetV2, added an Efficient Channel Attention (ECA) attention mechanism before the global average pooling layer, and then used the convolution operation to fuse the two model outputs to enhance model performance. The accuracy, precision, recall, F1-score, and PR-AUC score after data augmentation were 98.72, 98.44, 98.86, 99.41, and 99.76%, respectively. After experiments and testing on different datasets, it was confirmed that EXM-Net performs better than a single model and has a high degree of generalization ability. The proposed EXM-Net uses two deep learning models to extract and fuse different features to make up for important features missed by a single model, and combines the attention mechanism module to improve model efficiency and generalization capabilities. [ABSTRACT FROM AUTHOR]

Background. The beet armyworm, Spodoptera exigua (Hübner), is an important agricultural pest worldwide that has caused serious economic losses in the main cropproducing areas of China. To effectively monitor and control this pest, it is crucial to investigate its population dynamics and seasonal migration patterns in northern China. Methods. In this study, we monitored the population dynamics of S. exigua using sex pheromone traps in Shenyang, Liaoning Province from 2012 to 2022, combining these data with amigration trajectory simulation approach and synoptic weather analysis. Results. There were significant interannual and seasonal variations in the capture number of S. exigua, and the total number of S. exigua exceeded 2,000 individuals in 2018 and 2020. The highest and lowest numbers of S. exigua were trapped in September and May, accounting for 34.65% ± 6.81% and 0.11% ± 0.04% of the annual totals, respectively. The average occurrence period was 140.9 ± 9.34 days during 2012-2022. In addition, the biomass of S. exigua also increased significantly during these years. The simulated seasonal migration trajectories also revealed varying source regions in different months, primarily originated from Northeast China and East China. These unique insights into the migration patterns of S. exigua will contribute to a deeper understanding of its occurrence in northern China and provide a theoretical basis for regional monitoring, early warning, and the development of effective management strategies for long-range migratory pests. [ABSTRACT FROM AUTHOR]

Gut microbiota plays a functional role in nutrition among several insects. However, the situation is unclear in Lepidoptera. Field studies suggest the microbiome may not be stable and is determined by diet, while in the laboratory, Lepidoptera are routinely reared on diet containing antibiotics with unknown effects on microbial communities. Furthermore, molecular approaches for the characterization of lepidopteran microbiomes rarely describe the metabolically active gut bacteria. The aim of this study was to evaluate how diet and antibiotics affect Spodoptera exigua (Hübner) growth and the diversity and activity of the gut bacteria community. We assessed how alfalfa and wheat germ-based diets affected larval growth, in the presence and absence of streptomycin. Alfalfa diet improved larval growth, pupal mass, and survival, but antibiotic was only beneficial in the wheat germ diet. We observed diet-driven changes in the gut bacterial communities. In the active community, the alfalfa colony was dominated by Enterococcus and Rhodococcus whereas in the wheat germ colony, only Enterococcus was present. In contrast, spore-forming Bacilli species were very common members of the DNA community. In both cases, streptomycin had a selective effect on the relative abundance of the taxa present. Our study highlights the importance of characterizing both the diversity and activity of the gut microbiota community. DNA-derived communities may include environmental DNA, spores, or non-viable bacteria, while RNA-derived communities are more likely to give an accurate representation of the diversity of active members that are potentially directly involved in the metabolic processes of the host. [ABSTRACT FROM AUTHOR]

Various studies have addressed the impact of microbial inoculants on the composition of the resident microbiome. How microbial inoculants impact plant metabolism and interact with the resident rhizobiota under herbivory stress remains elusive. Here, we investigated the impact of two bacterial and two fungal inoculants, inoculated as single species and as a synthetic community, on the rhizosphere microbiome and volatilome of tomato plants (Solanum lycopersicum) comparing nonstress conditions to exposed to leaf herbivory by Spodoptera exigua. Based on amplicon sequencing analysis, rhizobacterial community composition was significantly affected by all four inoculants and the magnitude of this effect was dependent on herbivory stress. Fungal community composition was altered by the microbial inoculants but independent of herbivory stress. The rhizosphere volatilome was impacted by the microbial inoculation and differences between treatments were evened under herbivory stress. Each microbial inoculant caused unique changes in the volatilome of stressed plants but also shared similar responses, in particular the enhanced production of dimethyl disulfide and benzothiazole. In conclusion, the introduction of microbial inoculants in the tomato rhizosphere caused unique as well as common changes in the rhizosphere microbiome and volatilome, but these changes were minor compared to the microbiome changes induced by herbivory stress. [ABSTRACT FROM AUTHOR]

Emamectin benzoate (EB), chlorantraniliprole (CTP), chlorfenapyr (CFP), and lufenuron (LFR) are widely used to control Spodoptera exigua on cabbage. This study is aimed at establishing a universal, sensitive, accurate, and efficient method for the determination of these pesticide residues in cabbage using QuEChERS pretreatment combined with ultra-performance liquid chromatography or gas chromatography-tandem mass spectrometry (UPLC‒MS/MS or GC‒MS/MS). The recoveries of these pesticides (containing metabolites) in cabbage detected by the optimized method ranged between 80.9% and 99.9%, with relative standard deviations (RSDs) of 0.164–12.5%. The limit of quantification (LOQ) of the four pesticides was determined to be 0.01 mg/kg. The standard curve, accuracy, precision, and LOQ of the analysis method all met the requirements of pesticide residue detection. The optimized method was used to detect the dissipation dynamics and terminal residues in 12 regions. The dissipation half-lives of CTP, CFP, and LFR were 3.35–7.01 d, 2.29–4.75 d, and 3.24–6.80 d, respectively. The terminal residues of all these pesticides were below the maximum residue limits (MRLs). The dietary risk assessment indicated that the dietary risk probabilities for EB, CTP, CFP, and LFR were all less than 1 and were within the acceptable range. This study provides a comprehensive assessment of the residues and dietary risks of EB, CTP, CFP, and LFR for the scientific use of pesticides. [ABSTRACT FROM AUTHOR]

In order to evaluate the effect of different weed management treatments on weeds, pest and natural enemies populations in sesame (Sesamum indicum L.), a 2-year study was conducted in East Azarbaijan, Iran in 2020–2021. The study was conducted based on randomized complete block design with four replications. The weed management treatments consisted of trifluralin use (960 g ai ha−1), wheat straw mulch (WSM), living mulches of fenugreek (Trigonella foenum-graecum L.) (FLM), bitter vetch (Vicia ervilia L.) (VLM), calendula (Calendula officinalis L.) (CLM) and one-time hand weeding (OHW). The effect of weed management treatment was significant on densities of insect pests, natural enemies and weed and also weed biomass and sesame seed yield. The lowest densities of insect pests including Myzus persicae, Brevicoryne brassicae, Helicoverpa armigera and Spodoptera exigua were observed in CLM treatment. Also, the highest densities of natural enemies Coccinella septompunctata, Coccinella undecimpunctata and Orius niger were observed in CLM treatment. The highest reductions in grass (51.0%), broadleaf (72.0%), and total (62.6%) weed biomasses and highest seed yield (1456 kg ha−1) were obtained in OHW. The seed yields in CLM and WSM treatments were not significantly different with trifluralin treatment and could be recommended in sustainable production of sesame. [ABSTRACT FROM AUTHOR]

Cruciferous plants manufacture glucosinolates (GSLs) as special and important defense compounds against insects. However, how insect feeding induces glucosinolates in Brassica to mediate insect resistance, and how plants regulate the strength of anti-insect defense response during insect feeding, remains unclear. Here, mustard (Brassica juncea), a widely cultivated Brassica plant, and beet armyworm (Spodoptera exigua), an economically important polyphagous pest of many crops, were used to analyze the changes in GSLs and transcriptome of Brassica during insect feeding, thereby revealing the plant–insect interaction in Brassica plants. The results showed that the content of GSLs began to significantly increase after 48 h of herbivory by S. exigua, with sinigrin as the main component. Transcriptome analysis showed that a total of 8940 DEGs were identified in mustard challenged with beet armyworm larvae. The functional enrichment results revealed that the pathways related to the biosynthesis of glucosinolate and jasmonic acid were significantly enriched by upregulated DEGs, suggesting that mustard might provide a defense against herbivory by inducing JA biosynthesis and then promoting GSL accumulation. Surprisingly, genes regulating JA catabolism and inactivation were also activated, and both JA signaling repressors (JAZs and JAMs) and activators (MYCs and NACs) were upregulated during herbivory. Taken together, our results indicate that the accumulation of GSLs regulated by JA signaling, and the regulation of active and inactive JA compound conversion, as well as the activation of JA signaling repressors and activators, collectively control the anti-insect defense response and avoid over-stunted growth in mustard during insect feeding. [ABSTRACT FROM AUTHOR]

BACKGROUND: Agricultural pests have caused huge losses in agricultural production and threaten global food security. Synthetic insecticides remain the major control method. However, with the rapid development of pest resistance and the increasingly stringent regulations on pesticide usage, the development of efficient insecticides with novel structures is particularly urgent. RESULTS: Twenty‐six novel anthranilic diamide derivatives containing the thiazole moiety were designed based on the scaffold hopping strategy. Bioassay results indicated that compound 6e exhibited excellent insecticidal activity against a susceptible strain of diamondback moth (Plutella xylostella) with a median lethal concentration (LC50) of 0.65 mg L−1, which was similar to chlorantraniliprole (LC50 = 0.53 mg L−1). Compound 6e showed marginally lower (LC50 = 50.45 mg L−1) insecticidal activity than chlorantraniliprole (LC50 = 31.98 mg L−1) on chlorantraniliprole‐resistant P. xylostella larvae, suggesting a cross‐resistance of compound 6e with chlorantraniliprole (resistance ratios, 77.6‐fold and 60.3‐fold, respectively). Compound 6e also showed good insecticidal activity against fall armyworm and beet armyworm with pest mortalities of 74% and 64%, respectively, at 5 mg L−1 concentration. In addition, compounds 6e and 12a showed delayed toxicity against red imported fire ant with mortality rates of 84% and 85% (respectively) after 5 days of treatment at 1.0 mg L−1, which were superior to that of chlorantraniliprole. CONCLUSION: The introduction of thiazole into anthranilic diamide scaffolds resulted in insecticidal leads 6e and 12a with excellent insecticidal activities and potential application in controlling red imported fire ants. The work also guides the discovery of insecticidal molecules with thiazole‐containing anthranilic diamide scaffold. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plant and soil biodiversity can have significant effects on herbivore resistance mediated by plant metabolites. Here, we disentangled the independent effects of plant diversity and soil legacy on constitutive and herbivore‐induced plant metabolomes of three plant species in two complementary microcosm experiments. First, we grew plants in sterile soil with three different plant diversity levels. Second, single plant species were grown on soil with different plant diversity‐induced soil legacies. We infested a subset of all plants with Spodoptera exigua larvae, a generalist leaf‐chewing herbivore, and assessed foliar and root metabolomes. Neither plant diversity nor soil legacy had significant effects on overall foliar, root, or herbivore‐induced metabolome composition. Herbivore‐induced metabolomes, however, differed from those of control plants. We detected 139 significantly regulated metabolites by comparing plants grown in monocultures with conspecifics growing in plant or soil legacy mixtures. Moreover, plant–plant and plant–soil interactions regulated 141 metabolites in herbivore‐induced plants. Taken together, plant diversity and soil legacy independently alter the concentration and induction of plant metabolites, thus affecting the plant's defensive capability. This is a first step toward disentangling plant and soil biodiversity effects on herbivore resistance, thereby improving our understanding of the mechanisms that govern ecosystem functioning. [ABSTRACT FROM AUTHOR]

Numerous nematodes in the genus Oscheius possess entomopathogenic abilities. These nematodes also kill their insect hosts by releasing their symbiotic bacteria within 48–72 h. In this study, 12 indigenous isolates of Oscheius myriophilus based on molecular, morphological, and morphometric studies were recovered from different undisturbed soils in Thailand. Moreover, the virulence of 12 O. myriophilus at a rate of 25 IJs/cm2 against fifth‐instar larvae of Galleria mellonella ranged from 56%–86% after 72 h of exposure. Oscheius myriophilus EPNKU40 exhibited the highest efficacy in causing mortality in the insect larvae. It also killed third‐instar larvae of Spodoptera litura and Spodoptera exigua up to 60% after 72 h of exposure. The median lethal concentration (LC50) values of O. myriophilus EPNKU40 against G. mellonella larvae after 48 and 72 h of exposure were 11 and 4 IJs/cm2, respectively. The discovery of O. myriophulus is the first record in Thailand characterized using morphological, morphometric, and molecular diagnostic tools, which have shown lethal effects against insect pests and can later be utilized as biocontrol agents after several comprehensive assessments. [ABSTRACT FROM AUTHOR]

BACKGROUND: How parasitoids distinguish hosts from non‐hosts remains an unknown question. Chouioia cunea Yang (Eulophidae) is an important fall webworm parasitoid that attacks many forest and agricultural pests. To study the differences in the chemical clues used by C. cunea to distinguish host and non‐host plants, we used gas chromatography–mass spectrometry (GC–MS) to identify volatile compounds of two C. cunea hosts (Hyphantria cunea and Helicoverpa armigera) and two non‐hosts (Spodoptera exigua and Spodoptera frugiperda). Additionally, we used behavioral assays to compare the attraction of C. cunea to various compounds. RESULTS: The two natural host species were more attractive than the two non‐host species, in the following order: Hyphantria cunea > Helicoverpa armigera > S. exigua = S. frugiperda. The pupae of the natural hosts contained 1‐dodecene, which was not produced by the two natural non‐hosts. When the 'attractants' based on the difference between the species‐specific blend emitted by pupae and the optimal blend were sprayed onto the natural non‐host pupae, they significantly improved the attraction of C. cunea to the non‐host pupae. CONCLUSION: These results revealed that specific host‐produced volatile compounds guide C. cunea to distinguish between natural hosts and non‐hosts. Overall, this study provides a foundation for developing a behavior‐modifying strategy to re‐direct C. cunea attacks to control important non‐host pests. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is a highly dispersive, polyphagous insect pest that severely defoliates crops. Excessive reliance on synthetic insecticides leads to ecological pollution and resistance development, urging scientists to probe eco-friendly biopesticides. Here, we explore the virulence of an entomopathogenic fungus, Beauveria bassiana, against S. exigua, resulting in 88% larval mortality. Using an age–stage, two-sex life table, we evaluated the lethal and sublethal effects of B. bassiana on the demographic parameters of S. exigua, including survival, development, and reproduction. Sublethal (LC20) and lethal concentrations (LC50) of B. bassiana impacted the parental generation (F0), with these effects further influencing the demographic parameters of the first filial generation (F1). The infected F1 offsprings showed a reduced intrinsic rate of increase (r), mean generation time (T), and net reproduction rate (R0). Larval developmental duration varied significantly between the control (10.98 d) and treated groups (LC20: 10.42; LC50: 9.37 d). Adults in the treated groups had significantly reduced lifespans (M: 8.22; F: 7.32 d) than the control (M: 10.00; F: 8.22 d). Reduced fecundity was observed in the B. bassiana-infected groups (LC20: 313.45; LC50: 223.92 eggs/female) compared to the control (359.55 eggs/female). A biochemical assay revealed elevated levels of detoxification enzymes (esterases, glutathione S-transferases, and acetylcholinesterase) in the F0 generation after B. bassiana infection. However, the enzymatic activity remained non-significant in the F1 generation likely due to the lack of direct fungal exposure. Our findings highlight the enduring effects of B. bassiana on the biological parameters and population dynamics of S. exigua, stressing its use in eco-friendly management programs.

Cruciferous plants produce sulforaphane (SFN), an inhibitor of nuclear histone deacetylases (HDACs). In humans and other mammals, the consumption of SFN alters enzyme activities, DNA-histone binding, and gene expression within minutes. However, the ability of SFN to act as an HDAC inhibitor in nature, disrupting the epigenetic machinery of insects feeding on these plants, has not been explored. Here, we demonstrate that SFN consumed in the diet inhibits the activity of HDAC enzymes and slows the development of the generalist grazer Spodoptera exigua, in a dose-dependent fashion. After consuming SFN for seven days, the activities of HDAC enzymes in S. exigua were reduced by 50%. Similarly, larval mass was reduced by 50% and pupation was delayed by 2–5 days, with no additional mortality. Similar results were obtained when SFN was applied topically to eggs. RNA-seq analyses confirm that SFN altered the expression of thousands of genes in S. exigua. Genes associated with energy conversion pathways were significantly downregulated while those encoding for ribosomal proteins were dramatically upregulated in response to the consumption of SFN. In contrast, the co-evolved specialist feeder Trichoplusia ni was not negatively impacted by SFN, whether it was consumed in their diet at natural concentrations or applied topically to eggs. The activities of HDAC enzymes were not inhibited and development was not disrupted. In fact, SFN exposure sometimes accelerated T. ni development. RNA-seq analyses revealed that the consumption of SFN alters gene expression in T. ni in similar ways, but to a lesser degree, compared to S. exigua. This apparent resistance of T. ni can be overwhelmed by unnaturally high levels of SFN or by exposure to more powerful pharmaceutical HDAC inhibitors. These results demonstrate that dietary SFN interferes with the epigenetic machinery of insects, supporting the hypothesis that plant-derived HDAC inhibitors serve as "epigenetic weapons" against herbivores. [ABSTRACT FROM AUTHOR]

Several herbivorous insects consume certain metabolites from plants for other purposes than nutrition, such as defence. Adults of the turnip sawfly, Athalia rosae take up specific terpenoids, called clerodanoids, from Ajuga reptans. These metabolites are slightly modified by the sawflies and influence their mating behaviour and defence against predators. We characterised these metabolites and investigated their localisation in the insect and the specificity of the uptake and metabolite modification. Therefore, we performed feeding assays with adults and larvae of A. rosae as well as larvae of Spodoptera exigua, followed by chemical analyses. Two main clerodanoid-derived metabolites were detected in the abdomen and thorax but also on the surface of the adults. Small amounts were also found in larvae of the sawfly, while they were not detectable in S. exigua. Our findings provide new insights into the peculiarities of pharmacophagy and specialised metabolism in A. rosae. [ABSTRACT FROM AUTHOR]

Onion is an important crop in the province of Nueva Ecija, Philippines. Currently, its production is being constrained by onion armyworm (OAW; Spodoptera exigua). The impact of planting dates and distance on the infestation of OAW was studied across two productions. The aim is to evaluate the influence of different combinations of planting dates (November, December, and January) and row spacing [5 cm x 10 cm, 8 cm x 10 cm, 10 cm x 10 cm, and farmer's practice or waray (6-10 cm x 6-10 cm)] on the damage and population density of OAW. The count of observed OAW larvae from the earliest month (November) and during the month of the usual production period (November-December) was negligible to minimal. However, a significant increase in the OAW population during late planting (January). In terms of leaf damage caused by the OAW feeding, November, December, and January planting had an increasing percentage as the OAW population also increased. There was an increase in bulb diameter as the row spacing widens (10 cm x 10 cm), as well as an increase in the number of marketable bulb onions when it is narrow (5 cm x 10 cm). This study showed that planting dates and distances should be one of the major considerations in onion production and insect pest management. [ABSTRACT FROM AUTHOR]

Spodoptera exigua (Hübner), a highly destructive pest of agricultural crops, is often managed through the use of chemical pesticides. However, the use of chemical pesticides can have negative impacts on human health and the environment, making it important to find sustainable and alternative approaches to effectively manage this pest. One promising solution is the use of inhibitors that hinder the activity of proteases in the insect's digestive tract. Many digestive proteases, such as chymotrypsin, are produced as inactive zymogens with N-terminal pro-regions, which act as intramolecular chaperones and inhibitors of cognate catalytic regions. The present study aimed to utilize various bioinformatics tools to identify the physicochemical properties, secondary structures, and topology of chymotrypsin from S. exigua. Furthermore, we evaluated the potential of peptide inhibitors derived from the pro-region of zymogens that could be utilized as mimetic inhibitors for chymotrypsin in S. exigua. Homology molecular modeling was performed using SWISS-MODEL, with the predicted model validated by various programs. Molecular docking studies between five homologous species-derived protease inhibitors and the predicted model following by molecular dynamics (MD) simulation coupled with Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) calculations were also applied. The analysis of peptides/enzyme interactions revealed the antagonistic capacity of two screened inhibitors against S. exigua chymotrypsin. Protein-protein interaction networks demonstrated that chymotrypsin from S. exigua interacted with eleven other proteins in a high confidence score. Active site analysis revealed that S219, D230, and H232 serve as catalytic residues. These findings demonstrate a central role for computational methods in designing a potent inhibitor peptide that is highly specific and selective to its mature enzyme. Our study could be promising for future insecticide designs used in S. exigua control. [ABSTRACT FROM AUTHOR]

Plant-plant signalling via volatile organic compounds (VOCs) has been studied intensively, but its contingency on abiotic conditions (e.g., soil nutrients, drought, warming) is poorly understood. To address this gap, we carried out a greenhouse experiment testing whether soil nutrients influenced signalling between potato (Solanum tuberosum) plants in response to insect leaf herbivory by the generalist caterpillar Spodoptera exigua. We placed pairs of plants in plastic cages, where one plant acted as a VOC emitter and the other as a receiver. We factorially manipulated soil nutrients for both emitter and receiver plants, namely: unfertilized (baseline soil nutrients) vs. fertilized (augmented nutrients). Then, to test for signalling effects, half of the emitters within each fertilization level were damaged by S. exigua larvae and the other half remained undamaged. Three days after placing larvae, we collected VOCs from emitter plants to test for herbivory and fertilization effects on VOC emissions and placed S. exigua larvae on receivers to test for signalling effects on leaf consumption and larval mass gain as proxies of induced resistance. We found that herbivory increased total VOC emissions and altered VOC composition by emitter plants, but these effects were not contingent on fertilization. In addition, bioassay results showed that receivers exposed to VOCs from herbivore-damaged emitters had lower levels of herbivory compared to receivers exposed to undamaged emitters. However, and consistent with VOC results, fertilization did not influence herbivore-induced signalling effects on receiver resistance to herbivory. In sum, we found evidence of S. exigua-induced signalling effects on resistance to herbivory in potato plants but such effects were not affected by increased soil nutrients. These results call for further work testing signalling effects under broader range of nutrient concentration levels (including nutrient limitation), teasing apart the effects of specific nutrients, and incorporating other abiotic factors likely to interact or covary with soil nutrients. [ABSTRACT FROM AUTHOR]