Sustainable Boll Weevil Management through Development of RNAi Transgenic Cotton

Though eradicated from most of the United States, the boll weevil (Anthonomus grandis) continues to be a significant threat to domestic cotton production. This threat is largely due to continuing infestations along the US-Mexico border. In fact, a recent re-infestation was observed in central Texas – an area where the pest had been eradicated for many years. Current control methods include a variety of cultural tactics along with spraying with malathion – a broad spectrum organophosphate currently under review by regulatory agencies. The potential evolution of resistance to malathion is an additional concern. Because of these factors, there is a need for novel species-specific and environmentally friendly methods of control. A relatively new technology that satisfies these criteria is RNAi. RNAi involves the delivery of gene specific sequences that trigger the suppression of gene expression. Depending on the target gene, this suppression can be lethal. These sequences are then transformed into the crop of interest where it will be delivered to the insect during feeding. The first step towards development of RNAi transgenic plants is to identify and test lethal candidate genes. We have identified several potential candidates with the use of the boll weevil published transcriptome as well as a preliminary genome assembled at our laboratory. All candidates will be cloned and sequenced in order to confirm and/or obtain full-length sequences. Target genes will be tested for efficacy in feeding assays to identify the best options for subsequent plant transformation. The use of RNAi technology to control pests is quickly gaining momentum presenting an interesting alternative to pesticides.