Assessing the Functionality of RNA Interference (RNAi) in the Phloem-feeding Maize pest Dalbulus maidis

Dalbulus maidis [(DeLong & Wolcott), corn leafhopper], a phloem-feeding insect, is the most efficient vector of maize stunting pathogens (Spiroplasma kunkelii, Maize bushy stunt phytoplasma, and Maize rayado fino virus) in the Americas. Studies involving gene editing in insects are rapidly providing information that can potentially be used for insect vector and plant disease control. RNA interference (RNAi), a sequence-specific gene silencing method, is one of the most widely used molecular tools in functional genomics studies. RNAi uses exogenous double-stranded RNA (dsRNA) or small interfering RNA (siRNA) to prevent the production of proteins by inhibiting the expression of their corresponding messenger RNA (mRNA). In this study, we measured the efficacy of gene silencing, and its effects on D. maidis mortality as proof of concept that RNAi is a viable tool for use in genetic pest control of phloem-feeding insects. Oral delivery of dsRNA using an artificial diet was used to silence two key insect genes, vacuolar ATP synthase subunit B, and subunit D (V-ATPase B and V-ATPase D). Our results showed reduced gene expression of V-ATPase B and V-ATPase D after ingestion of dsRNA, and significantly higher mortality, and wing deformation, associated with reduced gene expression, compared to control insects that were not orally fed dsRNA. These results reveal RNAi as a viable tool for use in genetic pest control of phloem-feeding insects, and a way for further functional genomic studies, such as identification of potential target genes for either population suppression or population replacement of this vector of maize diseases.