Azadirachtin exposure inhibit ovary development of Spodoptera litura (Lepidoptera: Noctuidae) by altering lipids metabolism event and inhibiting insulin signaling pathways

Lipids are main energy source for insects reproduction, which are becoming emerging target for pest management. Azadirachtin (AZA) is a multi-targeted and promising botanical insecticide, but its reproduction toxicity mechanism related to lipids metabolism is poorly understood. Here, we applied lipidomic and transcriptomic to provide a comprehensive resource for describing the effect of AZA on lipids remodeling in ovary of Spodoptera litura. The results showed that AZA exposure obviously altered the contents of 130 lipids subclasses (76 upregulated and 54 downregulated). In detail, AZA exposure changed the length and saturation degrees of fatty acyl chain of most glycerolipid, phospholipid and sphingolipid as well as the expression of genes related to biosynthesis of unsaturated fatty acids and fatty acids elongation. Besides, following the abnormal lipids metabolism, western blot analysis suggested that AZA induce insulin resistance-like phenotypes by inhibiting insulin receptor substrates (IRS) /PI3K/AKT pathway, which might be responsible for the ovary abnormalities of S. litura. Collectively, our study provided insights into the lipids metabolism event in S. litura underlying AZA exposure, these key metabolites and genes identified in this study would also provide important reference for pest control in future.

Automated summary

Lipids are an important energy source for insect reproduction, making them a target for pest management. The insecticide Azadirachtin (AZA) shows promise but its reproductive toxicity mechanism related to lipid metabolism is not well understood. This study used lipidomic and transcriptomic approaches to investigate the effects of AZA on lipid remodeling in the ovary of Spodoptera litura. The results revealed significant alterations in the content of 130 lipid subclasses, including changes in fatty acyl chain length and saturation degrees, as well as gene expression related to fatty acid biosynthesis and elongation. Western blot analysis also indicated that AZA induced insulin resistance-like phenotypes by inhibiting the insulin receptor substrate (IRS)/PI3K/AKT pathway. These findings provide insights into the lipid metabolism events and potential mechanisms involved in AZA exposure, and could serve as important references for future pest control.