Engineering strategies for insect viruses and microbes for dsRNA production and delivery to insects for targeted gene silencing

RNA interference (RNAi)-based pest control is viewed as a safe and effective method for insect pest control. However, the stability and efficient cellular delivery of the double stranded RNA (dsRNA) active molecule remains cru- cial to its success in pest control. Among the different approaches that have been proposed to improve dsRNA delivery in insects, the use of nano-carriers, engineered viruses and engineered microbes have been successfully employed in proof of-concept studies. This review focuses on engineering approaches that have been successfully employed to modify insect viruses and different microbes for dsRNA production and delivery in insects. First, the different viral vector systems based on insect RNA and DNA viruses for dsRNA delivery are discussed. Second, a comprehensive overview of different microbe-based (bacteria, fungi, microalgae) dsRNA production and delivery systems that have been developed till date are presented. Finally, future perspectives on the development of other delivery systems with potential in the context of insect pest control are provided. Overall, this review is expected to stimulate awareness, interest, insight and research into prom- ising sources of biotechnologically interesting viruses and microbes for protecting agriculture and human health against insect pests.