Unveiling the Role of Two Rhodopsin-like GPCR Genes in Insecticide-Resistant House Flies, .

Insecticide resistance in insects, driven by the overexpression of P450 enzymes, presents a significant challenge due to the enhanced metabolic detoxification of insecticides. Although the transcriptional regulation of P450 genes is not yet fully understood, G-protein-coupled receptor (GPCR) genes have emerged as key regulators in this process. This study is the first to associate GPCR genes with insecticide resistance in . We identified two key rhodopsin-like GPCR genes, and , which were significantly overexpressed in the resistant ALHF strain compared to sensitive strains. Notably, both and were mapped to autosome 2, where critical but unidentified regulatory factors controlling resistance and P450 gene regulation are located. This supports our hypothesis that GPCRs function as trans-regulatory factors for P450-mediated resistance. Functional analysis using transgenic demonstrated that overexpression of these rhodopsin-like GPCR genes increased permethrin resistance by approximately two-fold. Specifically, overexpression significantly upregulated the resistance-related P450 genes , , and , while increased and expression, thereby enhancing insecticide detoxification in rhodopsin-like GPCR transgenic lines. These findings suggest that these rhodopsin-like GPCR genes on autosome 2 may act as trans-regulatory factors for P450-mediated resistance, underscoring their critical role in insecticide detoxification and resistance development in .