Mechanism of trace acetamiprid-caused reproductive disorders in silkworm, Bombyx mori

Neonicotinoid insecticides are widely used in the prevention and control of pests in agriculture and forestry, but they can also affect the development of nontarget economic insects. In order to determine the effects of trace acetamiprid on the development of reproductive system of silkworm, we studied the gonad development and endogenous hormone metabolism in silkworms exposed to trace acetamiprid.

The silkworm showed mild poisoning symptoms after being exposed to trace acetamiprid (0.01 mg L^-1 ). After 96 h of acetamiprid exposure, the body weight of silkworm was decreased by 7.67% and the ovary and fallopian tube were abnormally developed. The egg production in adults was decreased by 197 ± 29, and the egg weight was decreased by 0.52 ± 0.01 mg. Quantitative RT-PCR analysis showed that the relative expression levels of ovarian development-related genes Vg, Ovo, Otu, Sxl-S and Sxl-L were downregulated by 0.71, 0.77, 0.47, 0.67 and 0.88-fold, respectively. The transcriptional expression of ecdysone metabolism-related gene (EcR) in the ovary was downregulated by 0.46-fold while the expression of juvenile hormone-related gene (JHBP2) was upregulated by 1.36-fold. In hemolymph of acetamiprid exposed larvae, the content of ecdysone was reduced whereas the content of juvenile hormone was increased.

Trace acetamiprid may cause reproductive dysfunction in silkworms through regulating the metabolism of endogenous hormones. Our study provides a reference for elucidating the mechanism of acetamiprid-induced reproductive disorders in insects. © 2019 Society of Chemical Industry.