Toxicity of (S)-(-)-palasonin on various life stages of Plutella xylostella (Lepidoptera: Plutellidae)

Abstract

Plutella xylostella has developed resistance to most commercially available insecticides, resulting in an urgent need for novel insecticides. It was found in our previous study that (S)-(-)-palasonin (PLN) has great value in the management of P. xylostella. Extracted from Butea monosperma seeds, (S)-(-)-palasonin has been discovered to have stomach and contact toxicity against P. xylostella larvae. However, it is not clear whether PLN has other modes of action. In this study, (S)-(-)-palasonin had strong stomach and fumigation activity against P. xylostella adults with an LC50 (48 h) values of 50.50 and 16.49 mg/L, respectively. The selective antifeedant rate and non-selective antifeedant rate of (S)-(-)-palasonin at 25 mg/L were 92.86 % and 97.27 % respectively. Normal growth and development of P. xylostella larvae was inhibited by (S)-(-)-palasonin. The larval weight and weight gain were significantly inhibited, the relative growth inhibition rate was increased, and the instar stage was significantly prolonged. The larval survival rate, pupal weight, pupation rate and adult emergence rates were significantly reduced. Wing deformity in P. xylostella adults was observed. And the life span of adults was shortened. These results show that (S)-(-)-palasonin has various modes of action in P. xylostella and can be used as a potential new botanical insecticide for the control of P. xylostella.