Transgenic expression of mAChR-C dsRNA in maize confers efficient locust control.

Abstract

Plant-meditated RNA interference (RNAi), by which double-stranded RNAs (dsRNAs) targeting insect genes are expressed in plants for insect ingestion, has shown great potential for herbivorous insect pest control. Locusts which are among the most destructive agriculture insect pests appear to be resistant to orally delivered naked dsRNA. Moreover, the feasibility of plant-mediated RNAi in suppressing the expression of target genes in locusts remains poorly understood. Using the migratory locust Locusta migratoria, we report here that C-type muscarinic acetylcholine receptor (mAChR-C), a G protein-coupled receptor (GPCR) belonging to bioamine receptor subfamily, played a pivotal role in chitin metabolism by regulating genes responsible for chitin synthesis and degradation. Knockdown of locust mAChR-C by injection-delivered dsRNA caused defective nymph molting and metamorphosis, accompanied by malformation, arrested development and motility. Notably, locusts feeding on transgenic maize expressing locust mAChR-C dsRNAs exhibited defective phenotypes similar to those subjected to injection of mAChR-C dsRNA. However, ingestion of transgenic maize with locust mAChR-C dsRNA had no significant effect on non-target insects including the fall armyworm Spodoptera frugiperda, the cotton bollworm Helicoverpa armigera, the Asian corn borer Ostrinia furnacalis and the oriental armyworm Mythimna separata. Our results suggest that transgene expression of locust mAChR-C dsRNA is an efficient RNAi approach for locusts, which offers a promising eco-friendly strategy for locust management.