RNA Interference: Potato/Tomato Psyllid, Bactericera Cockerelli, Oral Delivery of Double-Stranded RNAI Construct

The potato/tomato psyllid, Bactericera cockerelli (Sulc.), is a serious and economically important pest of the potato, tomato and other solanaceous crops. This insect is the putative primary vector of the phytopathogenic bacterium Candidatus Liberibacter solanacearum which causes the Zebra Chip in potato. This disease has caused millions of dollars loss to the potato industry. While traditional management programs have minimized the negative impacts of this disease system, a sustainable alternative to chemical treatment is needed. Management of this pest by downregulation of endogenous mRNA using RNA interference (RNAi) technology is one of the best molecular method available; however, several technical challenges exist which must be overcome to demonstrate RNAi strategies in potato production. First, the oral delivery of double stranded RNA construct need to provide an effective and efficient method that can be used in the field. Second, potential genes to target and downregulate the endogenous mRNA level through RNAi technology needs to result in insect mortality or reduction in pathogen transmission. Therefore, dsRNA construct were synthesized in vitro and offered to adult potato psyllid, mortality was recorded overtime and significant downregulation of mRNA level for target gene was assessed using qPCR technology. Moreover, to study the synergism between RNAi and insecticide treatments, dsRNA against one of the xenobiotic metabolizing gene, CYP450 6BQ13 was orally delivered to the adult B. cockerelli along with the imidacloprid, a neonicotinoid insecticide, mortality caused due to the conjugal treatment was recorded overtime and qPCR was utilized to observe the possible downregulation of endogenous CYP450 6BQ13 mRNA level