Drivers of insecticide resistance in major Spodoptera species: A global synthesis

Insecticide resistance represents one of the greatest threats to sustainable crop protection, reducing the effectiveness of chemical control and increasing economic losses worldwide. Although resistance has been extensively documented in agricultural pests, knowledge remains fragmented across species, regions, and cropping systems, limiting our understanding of the ecological and management factors driving its evolution. This study provides a global synthesis of insecticide resistance in three economically important Spodoptera species (Spodoptera litura, Spodoptera frugiperda, and Spodoptera exigua) to identify large-scale resistance patterns and their underlying drivers. A systematic literature review was conducted using Web of Science, Scopus, the Arthropod Pesticide Resistance Database, and backward citation searching. Studies published from 1990 onwards reporting standardized insecticide susceptibility bioassays on field-collected populations were screened according to predefined inclusion criteria. Data on toxicological responses (LC₅₀/LD₅₀ and corresponding confidence limits), active ingredients, bioassay methodology, population characteristics (e.g., tested generation and population type), sampling location, and collection year were extracted using a standardized protocol. Resistance ratios were calculated for each resistance record and analysed as effect size using random-effects meta-analysis and meta-regression. Meantime, environmental, climatic, landscape, and cropping system datasets were integrated to investigate ecological drivers of resistance. Species distribution models were further developed to explore potential future resistance risk under changing climatic conditions. The study synthesizes over three decades of global evidence, providing one of the most comprehensive datasets on insecticide resistance in Spodoptera species. By integrating toxicological, spatial, and environmental information, this work identifies key factors associated with resistance heterogeneity across geographic regions. The results contribute to a broader understanding of resistance evolution and provide an evidence base for improving insecticide resistance management, supporting integrated pest management strategies, and informing phytosanitary risk assessment and policy development under ongoing global environmental change.