Liposome encapsulation and EDTA formulation of dsRNA targeting essential genes increase oral RNAi-caused mortality in the Neotropical stink bug Euschistus heros.

BACKGROUNDThe Neotropical stink bug Euschistus heros is a major pest in soybean fields. Development of highly species-specific pesticides based on RNA interference (RNAi) could provide a new sustainable and environmentally friendly control strategy. RESULTSHere, the potential of RNAi as a pest control tool against E. heros was assessed. First, target gene selection using a microinjection approach was performed. Seven of the 15 candidate genes tested exhibited >95% mortality after hemolymph injection of 27.5ng dsRNA. Subsequently, dsRNA was administered orally using different formulations: naked dsRNA, liposome-encapsulated-dsRNA and dsRNA formulated with EDTA. Liposome-encapsulated dsRNA targeting vATPase A and muscle actin led to significant mortality after 14days (45% and 42%, respectively), whereas EDTA-formulated dsRNA did so for only one of the target genes. Ex vivo analysis of the dsRNA stability in collected saliva indicated a strong dsRNA-degrading capacity by E. heros saliva, which could explain the need for dsRNA formulations. CONCLUSIONThe results demonstrate that continuous ingestion of dsRNA with EDTA or liposome-encapsulated dsRNA can prevent dsRNA from being degraded enzymatically and suggest great potential for using these formulations in dsRNA delivery to use RNAi as a functional genomics tool or for pest management of stink bugs. (c) 2018 Society of Chemical Industry