Double strand RNA delivery system for plant-sap-feeding insects

Authors: Ghosh, Saikat Kumar; Hunter, Wayne; Park, Alexis; Gundersen-Rindal, Dawn

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2017
Publication Date: 2/9/2017
Citation: Ghosh, S.B., Hunter, W.B., Park, A.L., Gundersen, D.E. 2017. Double strand RNA delivery system for plant-sap-feeding insects. PLoS One. doi:10.1371.

Interpretive Summary: The brown marmorated stink bug (BMSB) is an invasive insect pest feeding voraciously on agricultural and specialty crops. This insect also invades houses, schools and other indoor spaces that provide a safe hiding area for mating and egg laying. Along with crop damage, BMSB may also elicit an allergic reaction in individuals sensitive to its allergens. In order to slow the spread of this pest, we have successfully tested a novel biomolecular technique known as RNA interference. This technique uses extracellular double stranded RNA (dsRNA) to target the animal’s RNA and degrades it using the cells internal machinery. Degradation of RNA in turn blocks protein translation eventually adversely affecting the pest. All earlier reports of RNAi used in BMSB have been through microinjection of dsRNA into the animal, which is impractical for use in biocontrol. For a successful biopesticide the mode of delivery into the animal must be oral ingestion. BMSB feeds by inserting its needle like stylet into the tissue of the crops and sucking the phloem thus damaging the crop. We took advantage of this feeding style and delivered dsRNA through a new oral delivery method. This information will be of benefit to scientists and biopesticide companies that are interested in delivering treatments for developing new strategies for control of BMSB.

Technical Abstract: Double-stranded RNA (dsRNA) mediated gene silencing also known as RNA interference (RNAi) is a breakthrough technology for functional genomic studies providing a potential tool for management of insect pests. Since the inception of RNAi numerous studies have documented successful introduction of synthetic dsRNA or siRNA into the organism that triggers a highly efficient gene silencing through degradation of endogenous RNA homologous to the presented siRNA. Our focus is on managing hemipteran insect pest Halyomorpha halys (Sta °l) (Heteroptera: Pentatomidae); the brown marmorated stink bug is an invasive agricultural pest in North America. The significance of its spread has affected both the rural and urban areas especially the agricultural and specialty crops. RNAi technology may serve as a viable tool for control and management of this voracious pest but has a major challenge for use in biocontrol, delivery of dsRNA. Successful RNAi reported for insects has involved dsRNAs delivered by microinjection. For use of RNAi as molecular biopesticides for biocontrol of these insects in the environment it is necessary that dsRNAs be delivered orally in vivo through ingestion. The key challenge for molecular biologists today is to find effective and reliable methods for the delivery of dsRNA. Here we have documented the effective delivery of insect-specific dsRNAs orally by feeding through this proprietary delivery system to overcome this challenge for a significant decrease in targeted gene expression. With this state of the art delivery method, RNAi could be readily applied to many insect pests for an effective molecular biopesticide.