Lethal RNA interference response in the pepper weevil

The pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) is an important pest of peppers (Capsicum spp.) in the southern United States, Mexico, and Central America. Current management practices rely on chemical control of adults although grower options are limited. A more integrated strategy to manage the pepper weevil infestations may benefit from measures that can control this pest specifically such as RNA interference (RNAi). We cloned and sequenced transcript fragments of two possible essential genes of the pepper weevil, Snf7 and V-ATPase-A. We treated pepper weevil females with the double-stranded RNAs (dsRNAs) of these genes and found that orally delivered dsRNA of either gene was not effective in eliciting strong RNAi response or causing mortality. In contrast, Snf7 and V-ATPase-A dsRNAs delivered through injections produced robust gene silencing and led to more than 90% mortality within 12 days. Our results suggest that the pepper weevil possesses the molecular machinery needed for a robust RNAi response and that Snf7 and V-ATPase-A genes likely encode essential functions in this insect. Moreover, RNAi-mediated silencing of essential genes can potentially be used to control this pest if strong RNAi response can be induced by orally delivered dsRNA.