Effect of sublethal doses of chlorantraniliprole on the activity of detoxification and protective enzymes in <i>Galleria Mellonella</i> (Lepidoptera: Pyralidae)

Galleria mellonella Linnaeus (Lepidoptera: Pyralidae) is a pest that feeds on the spleen of honey bee nests worldwide. In this study, the toxicity of chlorantraniliprole (CAP) to G. mellonella was determined by ingestion toxicity and contact toxicity methods. We compared the effects of sublethal doses of CAP on the activity of major detoxification and protective enzymes as well as gene expression of related enzymes under the 2 treatment methods. The median lethal concentrations of CAP administered using ingestion toxicity and contact toxicity methods were 217.666 and 50.453 mg L-1, respectively. Compared with the control group, both methods increased the activities of carboxylesterase (CarE) and cytochrome P450 (CYP450), decreased the activities of glutathione S-transferase (GST) and peroxidase (POD), and had no effect on catalase activity. Superoxide dismutase activity decreased under ingestion toxicity but remained unchanged under contact toxicity. Significant changes were observed in the gene expression levels of detoxification and protective enzymes under both treatment methods; the expression levels of GmCarE4a, GmCarE2a, GmCarE1f, and GmPOD1a were significantly upregulated, whereas those of GmGST2a and GmGST2b were significantly downregulated. CAP exhibited both ingestion toxicity and contact toxicity against G. mellonella, with better contact toxicity effects. Galleria mellonella responded to CAP stress by adjusting enzyme activities (increasing CarE and CYP450 activities and decreasing GST and POD activities) and related gene expression levels (upregulating the relative expression levels of GmCarE4a, GmCarE2a, GmCarE1f, and GmPOD1a and downregulating those of GmGST2a and GmGST2b). The findings from the 2 distinct poisoning methods offer a scientific foundation for optimizing the application of CAP in the effective control of G. mellonella, while also providing valuable insights into the development of CAP resistance.