Gluten hydrolase gene silencing using RNAi and its effect on the Sunn pest growth and development

RNAi technology has been described as a tool to study gene function and is of great potential as a next-generation biopesticide. Thus, in the present study, we identified and sequenced the Sunn pest Gluten hydrolase (GH) gene partially. Then, evaluated GH-dsRNA effects on the GH expression of the fifth instar nymphs and adults, as well as, on the insect growth and development using topical and injection assays. Results indicated that the topical application of GH-dsRNA on the fifth instar nymph caused a severe reduction (99.9%) of gut GH expression in comparison with control and, at the same time, high induction of the salivary gland’s expression profile. Gene upregulation indicates that the insect compensates for the reduction of the one gene expression with the induction of a gene in the other tissue to meet its demand. Also, the GH expression profile in the gut and salivary glands were evaluated 6, 12, and 21-hour post injections. Results revealed that the GH expression profile of both gut and salivary glands was reduced early hours after injection, but their expression profile was recovered 21-hour post-treatment. Thus, the results showed that dsRNA does not have a systemic effect since gene knockdown was not persistent. GH-dsRNA also affected nymphal development time, adult weight, survivability, and adult emergence. These effects indicated that the GH gene plays an essential physiological role(s) in addition to having a role in food digestion. Therefore, RNAi technology has the potential to be used to develop novel strategies for Sunn pest IPM programs.