Identification of constitutively overexpressed and induced genes in spinosad-resistant Phthorimaea absoluta (Lepidoptera: Gelechiidae)

Abstract

Spinosad plays a crucial role in the control of Phthorimaea absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), a major pest of tomato, as it is approved for use in both conventional and organic tomato production. However, loss of efficacy due to resistance development has been reported. In this study, we assessed the susceptibility of five field-collected P. absoluta strains to spinosad. Additionally, comparative transcriptome analyses were performed to investigate expression changes of constitutively overexpressed and induced genes associated with spinosad resistance in P. absoluta. Reduced susceptibility (up to 79-fold resistance) to spinosad was identified in the field strains. Transcriptome analysis revealed 3438 genes with constitutive overexpression and 799 genes exhibiting differential expression following spinosad treatment. Further analysis showed that 117 constitutive and 245 spinosad-induced gene expressions related to defense, insecticide detoxification, transport, and stress response, which may play a role in spinosad resistance in P. absoluta. Gene Ontology (GO) enrichment analysis revealed that the up-regulated differentially expressed genes (DEGs) were significantly enriched in neural regulatory processes, potentially indicating neuronal adjustments following spinosad exposure. Our research lays an important basis for a better understanding of spinosad resistance and its management.