RNAi-mediated silencing of key genes in pepper weevil via oral dsRNA delivery

Pepper weevil (Anthonomus eugenii Cano) is an important pest of pepper crops. The pest originated in Mexico and at present is a major pest of peeper in Mexico, the southern United States, Central America, and the Caribbean. Pepper weevil damages crop plants by direct feeding on the fruits and flowers by its immature stages. The oviposition and feeding in fruits results in abscission of fruits leading to around 30 to 100% yield losses. The annual economic losses are estimated to be around $23 million. Different measures have been used to control this pest but at present, the application of pesticides is the primary control measure. The application of insecticide kills the adults, but the eggs immature stages are inside the fruit and remain unaffected resulting new adults keep on emerging. This restricts the effective management through conventional insecticides. The advancements in the genetic information of his important pest prompted the development of sustainable control measure using RNA interference by oral dsRNA delivery. In the present study, we evaluated the effect of oral dsRNA administration targeting elongation factor 1-alpha, laccase 2, and DNA-directed RNA polymerase II subunit RPB2. The three targeted genes were amplified, and dsRNA was synthesized using T7 RiboMAX™ Express RNAi System. The dsRNA was mixed with the artificial diet and larvae and adults were allowed to feed on it. The dsRNA delivery resulted in significant mortality and down regulation of the target genes. The results indicate the potential of RNAi to manage pepper weevil in pepper crops.