Carboxylesterase Precursor (EST-1) Mediated the Fungicide Jinggangmycin-Suppressed Reproduction of Sogatella furcifera (Hemiptera: Delphacidae)

Abstract

The jinggangmycin (JGM) is a widely used fungicide for controlling the rice sheath blight, Rhizoctonia solani, in China. Previous experiments under lab conditions showed that JGM foliar spray suppressed Sogatella furcifera (Horvath) reproduction. However, the molecular mechanisms of JGM-driven changes in S. furcifera reproduction are unclear. Therefore, we selected carboxylesterase precursor (EST-1) as a target gene for silencing by RNAi based on gene expression profiles. The present results demonstrated that JGM and control + dsSfEST-1 treatments significantly reduced the number of eggs laid (down by 58% and 54%, respectively), oviposition period (down by 57% and 38%, respectively), and longevity (down by 32% and 38%, respectively) in adult females compared with untreated controls, while no pronounced differences in the preoviposition period were observed. Meanwhile, the dietary control + dsSfEST-1 treatment also severely impeded protein synthesis, specifically soluble ovarian protein content (down by 20% and 24%, respectively) and soluble sugar content (down by 42% and 35%, respectively), which led to stunted growth and reduced body weight in adult females. We thereby speculate that downregulated SfEST-1 expression may be one molecular mechanism underlying JGM-driven reproduction in S. furcifera.

Keywords: RNAi; Sogatella furcifera; carboxylesterase precursor; fecundity; jinggangmycin.