RNA-based pesticides aim to get around resistance problems
L. H. Shaffer
Abstract
The half-inch-long corn rootworm larva packs a surprising punch. It feasts on the root system of corn before pupating into a black and yellow beetle that does further damage to the plant’s leaves. Before the advent of genetically modified (GM) crops that produce insecticidal proteins to fight rootworm, these insects cost US farmers an estimated $1 billion annually in damage and control measures. As destructive agricultural pests such as the corn rootworm evolve resistance to conventional pesticides, researchers and farmers are looking to RNAi-based treatments as a promising possible alternative. Image credit: Science Source/USDA/Nature Source. But as insects such as the corn rootworm evolve resistance to the suite of traits baked into commodity crops, scientists are queuing up a new application for a biotech tool that targets the protein-making machinery of insects. First identified in 1990, RNA interference (RNAi) entails using double-stranded RNA (dsRNA) to block messenger RNA from its usual function (i.e., sending out instructions to make proteins). With impressive specificity, RNAi can potentially block nucleotide sequences that are only found in a target pest and not in friendly insects or humans. As a result, some scientists are keen on making RNAi the next big tool in agricultural science. The EPA first approved an RNAi pesticide in 2017. That product, called SmartStax Pro, is a GM corn seed that will deploy both transgenic insecticidal proteins and RNAi to fight western and northern corn rootworm. It’s expected to be released in the United States in the next few years (1), according to its maker, Bayer AG, which is headquartered in Leverkusen, Germany. But GM crops are just one of many agriculture-related applications for RNAi. As the cost of producing dsRNA has dropped precipitously, biotech companies are developing dsRNA formulations that could also serve as spray pesticides, making the technology more …