In this globalised world of interconnected economies, we need to ensure that our food crops are protected from pests and diseases and our preparedness to address biosecurity risks. The ongoing usefulness of chemical pesticides suffers from issues such as residual toxicity, run-off, pest specificity and resistance. RNA interference as a natural regulatory mechanism has proved to be a powerful strategy to engineer disease resistance against viruses, viroids, nematodes, insect pests and fungi in plants. RNA based biopesticides or ‘RNA sprays’ for plants as a next generation crop protection platform without the need for genetic modification is gaining momentum globally, with pests and pathogens targeted with accuracy and specificity. Series of papers have shown that exogenous application of double stranded RNA (dsRNA) can induce RNAi-mediated protection.

We are investigating different carriers for delivery of RNAi effectors specifically double stranded RNA (dsRNA) as the key trigger molecule towards providing a non-GM, specific, stable, and environmentally sustainable alternative to chemical pesticides. BioClay technology using degradable layered double hydroxide clay particles has been shown to provide protection against viruses, insect pests and fungi for extended periods. It includes protection against multiple life cycle stages of whitefly, vector of large number of viruses and a pest with a very wide host range and Botrytis cinerea, a fungus that infects both horticultural and broad acre crops. The platform is being extended to investigate risks such as Cotton leaf curl disease, citrus Huanglongbing and myrtle rust. We are also working on another delivery platform, BenPol designed to target chewing insect pests such as fall army worm and sugar cane grubs.

Real world application of RNA based biopesticides will be governed by factors such as cost-effective production of dsRNA, stable delivery, risk identification and mitigation strategies, regulatory landscape and community acceptance.