Sublethal effects of chlorantraniliprole on juvenile hormone levels and mRNA expression of JHAMT and FPPS genes in the rice stem borer, Chilo suppressalis.

BACKGROUND: Juvenile hormone (JH) regulates the development and reproduction of insects. The sublethal effects of chlorantraniliprole on JH levels and mRNA expression of JH acid methyltransferase gene (CsJHAMT) and farnesyl diphosphate synthase genes (CsFPPS1 and CsFPPS2) in Chilo suppressalis (Walker) were investigated.

RESULTS: Exposure of sublethal concentrations of chlorantraniliprole (LC10 and LC30 ) to the third instar larvae of C. suppressalis significantly increased the JH levels in all developmental stages investigated including larvae 72 h after treatment, the first, third and fifth day of female pupae, as well as newly emerged, 12-h-old and 24-h-old female adults. A general trend of increased mRNA expression levels of CsJHAMT, CsFPPS1and CsFPPS2 was also observed in LC10 and LC30 treatment groups. Notably, the mRNA expression level of CsJHAMT significantly increased by 7.46-fold in the larvae 72 h after LC30 treatment. A significant increase of the mRNA expression levels of CsFPPS2 was also observed in the fifth day female pupae of LC10 and LC30 treatment groups (2.60-fold and 2.62-fold, respectively) as well as in 12-h-old female adults of the LC30 treatment group (3.45-fold).

CONCLUSION: Sublethal concentrations of chlorantraniliprole might upregulate the expression of JH biosynthesis genes and in turn result in an increase of JH level in C. suppressalis. © 2017 Society of Chemical Industry.