RNAi-Mediated Knockdown of Chitin Synthase 1 (CHS1) Gene Causes Mortality and Decreased Longevity and Fecundity in Aphis gossypii

Abstract

Chitin is a vital part of the insect exoskeleton and peritrophic membrane, synthesized by chitin synthase (CHS) enzymes. Chitin synthase 1 (CHS1) is a crucial enzyme in the final step of chitin biosynthetic pathway and consequently plays essential role towards insect growth and molting. RNA interference (RNAi) is an agent that could be used as an extremely target-specific and ecologically innocuous tactic to control different insect pests associated with economically important crops. The sole purpose of the current study is to use <i>CHS1</i> as the key target gene against the cotton-melon aphid, <i>Aphis gossypii</i>, via oral feeding on artificial diets mixed with dsRNA-<i>CHS1</i>. Results revealed that the expression level of <i>CHS1</i> gene significantly decreased after the oral delivery of dsRNA-<i>CHS1</i>. The knockdown of <i>CHS1</i> gene caused up to 43%, 47%, and 59% mortality in third-instar nymph after feeding of ds<i>CHS1</i> for 24, 48, and 72 h, respectively, as compared to the control. Consistent with this, significantly lower longevity (approximately 38%) and fecundity (approximately 48%) were also found in adult stage of cotton-melon aphids that were fed with ds<i>CHS1</i> for 72 h at nymphal stage. The qRT-PCR analysis of gene expression demonstrated that the increased mortality rates and lowered longevity and fecundity of <i>A. gossypii</i> were attributed to the downregulation of <i>CHS1</i> gene via oral-delivery-mediated RNAi. The results of current study confirm that <i>CHS1</i> could be an appropriate candidate target gene for the RNAi-based control of cotton-melon aphids.