Advances in RNA Interference and Pest Management- Moving Towards Large-Scale Field Trials

RNA interference (RNAi) is a technological breakthrough that has changed current thinking on the possibilities to reduce insect pests using highly specific, natural, gene targeted approaches.  We demonstrated the efficacy of orally ingested dsRNAs as a means to reduce psyllids and leafhoppers in citrus trees and grapevines.  This study demonstrates the persistence of a dsRNA in citrus trees for up to 2.5 months under field conditions, supporting RNAi strategies for area wide pest population suppression.  Psyllids- Diaphorina citri and Bactericera cockerelli, spread bacterial pathogens of trees and potato, (ie. Candidatus Liberibacter spp, associated with huanglongbing (aka. Citrus Greening disease) and Zebra chip) both of which are of great economic concern.  Leafhoppers (like Homalodisca vitripennis) spread the bacterial pathogen, Xylella fastidiosa, causing Pierce's disease of grapevines and citrus variegated chlorosis.  The robust nature of dsRNAs and their semi-persistence in whole-plant systems and systemic activity in these two insects were detectable between 5-8 days post-ingestion, while the detection of dsRNAs in citrus trees occurred out to 57 days post-treatment with the resulting siRNAs being detectable on day 86 post treatment.  We propose current abilities to produce massive amounts of dsRNA now make RNAi field tests feasible to evaluate the efficacy and costs in area-wide population suppression management programs.