Exploring the multigenerational effects of Lippia adoensis (Lamiales: Verbenaceae) essential oil and Dichlorvos on Callosobruchus maculatus (Coleoptera: Bruchidae) life-history traits and gene expression.

The cowpea weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae), is a major stored-product pest. Resistance to synthetic insecticides such as dichlorvos (DDVP) has prompted interest in alternatives with distinct modes of action. This study compared multigenerational transcriptional responses of C. maculatus to DDVP and the botanical insecticide Lippia adoensis (Hochst. ex Walp.) (Lamiales: Verbenaceae) essential oil (EO). DDVP exposure was associated with progressive fitness recovery across generations, together with upregulated expression of detoxification-related genes (e.g. Cyp6g1-2, Cyp6g1-3, Gst, Est2, Pod) and cholesterol metabolism-related genes (e.g. Dhcr24-1, Dhcr24-3). In contrast, L. adoensis EO was associated with consistently higher mortality and did not elicit comparable transcriptional changes in these gene sets. Clustering patterns placed EO-treated populations closer to controls, with less evidence of the DDVP-associated expression pattern. An antagonistic index comparing treatment-related fold changes indicated an opposing transcriptional relationship between EO and DDVP. Overall, the findings are consistent with L. adoensis EO acting without inducing the DDVP-associated detoxification expression pattern, suggesting a distinct transcriptional profile that may inform botanical-based approaches to pest management.