Spodoptera frugiperda (J. E. Smith), commonly known as the fall armyworm (FAW), causes significant damage to many different crop species. In this study, age-stage, two-sex life table analysis was used to investigate the effects of sublethal concentrations of emamectin benzoate and chlorantraniliprole on FAW development and reproduction. In the F₀ generation, exposure to emamectin benzoate and chlorantraniliprole significantly impacted the duration of FAW, thus prolonging the development duration of each instar, but not the prepupal stage. Furthermore, the weight of FAW pupae was significantly reduced by emamectin benzoate at LC₂₅ and chlorantraniliprole at LC₂₅ in the F₀ generation. With respect to fecundity, emamectin benzoate and chlorantraniliprole significantly reduced fecundity in the F₀ generation. In the F₁ generation, emamectin benzoate at LC₁₀ had no significant effect on the preadult or adult stages, whereas LC₂₅ significantly shortened the preadult period. The preadult and adult stages of FAW exposed to chlorantraniliprole at LC₁₀ and LC₂₅ were significantly prolonged. Furthermore, emamectin benzoate had no significant effect on the pupal weight of the F₁ generation. Chlorantraniliprole had no significant effect at LC₁₀, but significant reduced pupal weight occurred at LC₂₅ in the F₁ generation. With respect to fecundity, emamectin benzoate significantly reduced fecundity in the F₁ generation. Interestingly, chlorantraniliprole significantly increased fecundity in the F₁ generation, which could promote population growth and pest resurgence. These findings have important implications for the integrated pest management of FAW and provide a reference for the more effective control of FAW.

The fall armyworm (FAW) Spodoptera frugiperda, a highly invasive, polyphagous pest, poses a global agricultural threat. It has two strains, the C-corn and R-rice strains, each with distinct host preferences. This study compares detoxification enzyme gene families across these strains and related Spodoptera species to explore their adaptation to diverse host plant metabolites. A total of 1,995 detoxification-related genes, including cytochrome P450 monooxygenases (CYPs), carboxylesterases (COEs), glutathione S-transferases (GSTs), UDP-glucuronosyltransferases (UGTs), and ATP-binding cassette transporters (ABCs), were identified across the genus Spodoptera, including S. littoralis, S. litura, S. picta, S. exigua, and both FAW strains. A higher abundance of phase I detoxification enzymes (CYPs and COEs) and GSTs was observed in Spodoptera species, while FAW strains exhibited fewer detoxification genes, with notable differences in copy numbers between the C and R strains. Analyses at the subfamily level revealed significant variation in gene distribution and expression, particularly within phase I and II detoxification enzymes. Expansions in CYP6AE were detected in the C strain, while contractions in GST-ε, CYP9A, CYP4M, UGT33B, and UGT33F occurred in both strains. In contrast, no substantial variation was observed in phase III ABC enzymes. Functional predictions and protein interaction networks suggest a broader expansion of metabolism-related genes in the R strain compared to the C strain. These findings emphasize the pivotal role of phase I and II detoxification enzymes in host adaptation, providing molecular insights into FAW’s capacity for host range expansion, which are crucial for devising targeted and sustainable pest management strategies. The differential expression of detoxification enzyme gene families in different strains of Spodoptera frugiperda.

The fall armyworm (FAW, Spodoptera frugiperda) is a polyphagous pest known for causing significant crop damage. The gut microbiota plays a pivotal role in influencing the biology, physiology and adaptation of the host. However, understanding of the taxonomic composition and functional characteristics of the gut microbiota in FAW larvae fed on different host plants remains limited. This study utilized metagenomic sequencing to explore the structure, function and antibiotic resistance genes (ARGs) of the gut microbiota in FAW larvae transferred from an artificial diet to four distinct host plants: maize, sorghum, tomato and pepper. The results demonstrated significant variations in gut microbiota structure among FAW larvae fed on different host plants. Firmicutes emerged as the dominant phylum, with Enterococcaceae as the dominant family and Enterococcus as the prominent genus. Notably, Enterococcus casseliflavus was frequently observed in the gut microbiota of FAW larvae across host plants. Metabolism pathways, particularly those related to carbohydrate and amino acid metabolism, played a crucial role in the adaptation of the FAW gut microbiota to different host plants. KEGG orthologs associated with the regulation of the peptide/nickel transport system permease protein in sorghum-fed larvae and the 6-phospho-β-glucosidase gene linked to glycolysis/gluconeogenesis as well as starch and sucrose metabolism in pepper-fed larvae were identified. Moreover, the study identified the top 20 ARGs in the gut microbiota of FAW larvae fed on different host plants, with the maize-fed group exhibiting the highest abundance of vanRC. Our metagenomic sequencing study reveals significant variations in the gut microbiota composition and function of FAW larvae across diverse host plants. These findings underscore the intricate co-evolutionary relationship between hosts and their gut microbiota, suggesting that host transfer profoundly influences the gut microbiota and, consequently, the adaptability and pest management strategies for FAW.

Bactrocera dorsalis is a major pest causing economic losses in fruit and vegetable production. Current control methods, such as synthetic pesticides and male annihilation techniques, have drawbacks, including health risks, resistance development, and ineffectiveness against females. This study investigates the attractions and oviposition stimulant activities of five common volatiles—[isobutyl acetate (A), isoamyl acetate (B), isobutyl butyrate (C), isoamyl isovalerate (D), and isoamyl butyrate (E)]—from the most preferred hosts: mango, guava, orange, and banana. These volatiles were tested at three different concentrations, both individually and in complex blends. Choice tests were performed using a Y-tube olfactometer and Petri plate with agarose assays, and antennal responses were determined using electroantennogram (EAG) recordings. Among them, a blend comprising 1.25% isoamyl acerate (10.95 µg/µl), 1.25% isoamyl isovalerate (10.75 µg/µl), and 20% isoamyl butyrate (172.40 µg/µl) (B1D1E3) emerged as the most potent attractant for both sexes and oviposition stimulant for females. Moreover, combining B1D1E3 with mango, banana, or orange juice significantly enhanced egg-laying behavior. Electrophysiological recordings supported these findings, with B1D1E3 eliciting the strongest antennal responses. Results suggest B1D1E3 could be used to elicit strong oviposition responses in mass rearing of B. dorsalis for the Sterile Insect Technique.

The development and reproduction of the fall armyworm (FAW), Spodoptera frugiperda, which were reared on artificial diets containing nano-graphene oxide (GO), were determined based on age-stage, two-sex life table analysis. The results showed that GO had adverse effects on FAWs. Compared with the control, the duration of the egg stage and first, second, and sixth instar larval stages increased with increasing GO concentrations; however, the lifespan of male and female adults decreased with increasing GO concentrations. Weights of FAW pupae that were supplied with GO-amended diets increased by 0.17–15.20% compared to the control. Intrinsic growth, limited growth, and net reproductive rates of FAWs feeding on GO supplemented diets were significantly lower than the control, while mean generational periods (0.5 mg/g: 38.47; 1 mg/g: 40.38; 2 mg/g: 38.42) were significantly longer than the control. The expression of genes encoding vitellogenin (Vg) and vitellogenin receptor (VgR) expression was abnormal in female FAW adults feeding on GO-amended diets; the number of eggs laid decreased relative to the control, but Vg expression increased. In conclusion, GO prolonged the developmental period of FAWs, decreased fecundity, and led to a decline in the population size. The study provides a basis for the rational use of GO as a pesticide synergist for FAW control.

Spodoptera frugiperda is one of the world’s major agricultural pests and it occurs in many countries around the world. In Lepidoptera, the peritrophic membrane in the midgut protects the midgut epithelial cells and facilitates the digestion and absorption of food. Its main components are chitin and protein. Chitin synthase (CHS), as the last enzyme in the chitin biosynthesis pathway, is very important. Here, the expression of chitin synthase B (CHSB) gene identified from midgut was inhibited by RNA interference to explore its function in the metabolism of trehalose and chitin of S. frugiperda larvae. The results were as follows: SfCHSB was highly expressed in actively feeding larvae. Second, knockdown of SfCHSB resulted in decreased expression of most genes involved in chitin metabolism, including chitinase, and abnormal phenotypes of S. frugiperda were observed. In addition, membrane-bound trehalase activity and glucose content increased, and trehalose content decreased at 24 h after dsSfCHSB injection. Trehalase activities increased significantly and the glycogen content decreased at 48 h after dsSfCHSB injection. Finally, the activity of chitinase decreased and the content of chitin increased significantly. Our results indicate that SfCHSB expression is specific, SfCHSB has a large role in regulating chitin metabolism, and it has broad application prospects in the biocontrol of S. frugiperda.