Spodoptera frugiperda is a highly destructive migratory pest of global concern that infests a wide range of crops, particularly maize, as well as rice and sugarcane, causing substantial economic losses in China. Since its invasion of China, S. frugiperda has experienced prolonged insecticide selection pressure, resulting in the accelerated evolution and increasing prevalence of resistance to specific insecticides. This study aimed to elucidate the role of cytochrome P450 monooxygenase (CYP) gene families in mediating resistance to chlorantraniliprole and to evaluate the efficacy of nanoparticle-mediated delivery systems combined with P450-specific synergists for controlling S. frugiperda. Toxicity bioassays conducted on field populations demonstrated that chlorantraniliprole still retained considerable insecticidal activity. Analyses of three detoxification enzyme activities revealed a significant elevation in cytochrome P450 activity, and expression profiling of candidate CYP genes was performed using quantitative real-time PCR (qPCR). Exposure to chlorantraniliprole resulted in a 2.53-fold upregulation of CYP4G75 expression. Furthermore, nano-agrochemical formulation assays showed that the combined application of LDHs-dsCYP4G75 and chlorantraniliprole exerted a significant synergistic effect, increasing mortality by 21.99% compared with either treatment applied alone. Overall, this study provides mechanistic insights into P450-mediated resistance and offers a promising strategy to reduce reliance on chemical insecticides, thereby contributing to the development of sustainable integrated pest management (IPM) programs.

Globally, the invasive fall armyworm (Spodoptera frugiperda, FAW) has been characterized by the widespread development of tolerance to multiple insecticides, a process facilitated by extensive and prolonged exposure to these compounds. This study utilized RNA interference (RNAi) to explore the potential association of cytochrome P450 genes to spinetoram resistance in S. frugiperda, with the parallel aim of investigating nanocarrier-based P450-targeting formulations as synergistic agents for improved pest management. Bioassay results from Guangdong S. frugiperda populations revealed the highest tolerance in the Meizhou population (LC₅₀ = 0.673 µg/mL). Spinetoram exposure induced a 6.5 U/mL increase in larval P450 activity and triggered marked upregulation of CYP6AN4 (4.98-fold versus control), which exhibited concentration-dependent induction (2.52-fold under tested conditions). The LDH-dsCYP6AN4 + spinetoram formulation achieved 62.87% mortality, representing an 11.31% enhancement over the LDH + spinetoram group, and maintained robust synergy across diverse field populations. These phenotypic and molecular observations indicate that CYP6AN4 upregulation is closely correlated with the spinetoram response and may potentially contribute to altered insecticide susceptibility in field populations.

The meprin and TRAF-C homology (MATH) family of proteins plays essential roles in diverse biological processes across eukaryotes. Fecundity is a key determinant underlying the rapid outbreaks of agricultural insect pests. Nevertheless, the potential involvement of MATH proteins in the regulation of fecundity in agriculturally important insects, particularly planthoppers, remains largely uncharacterized. This study identified key members of the MATH protein family that are conserved in planthoppers and involved in the regulation of insect fecundity. A total of 121 identified MATH proteins from 31 insect species were classified into five distinct clades based on protein structures, predominantly represented by the MATH-BTB, MATH-USP7, and MATH-Zf-Box subtypes, which are largely conserved across most agricultural insect species. In planthoppers, the MATH-BTB subtype gene cluster SfMATH1–NlMATH3–LsMATH3 constitutes a tripartite collinear gene set conserved across all three species. Among the four ovary-specific expressed MATH genes, NlMATH3 exhibited the highest expression level in the ovary. Moreover, silencing NlMATH3 significantly impaired ovarian development in adult females and reduced both the number of deposited and hatched eggs, which was associated with downregulation of vitellogenin (Vg) and its receptor VgR, as well as elevating activity in metabolic and immune signaling pathways. In summary, this study provides novel insights into the evolutionary dynamics of the MATH family in agricultural insects, particularly planthoppers, and elucidates the critical regulatory role of the planthopper conserved MATH-BTB protein NlMATH3 in insect fecundity. The conservation of NlMATH3 homologs across planthoppers highlights their potential as targets for RNAi-based pest control strategies.