RNA interference technology as a pesticide

Western corn rootworm larvae
Wikimedia Commons

In January, Monsanto released their annual Research and Development Pipeline Review, detailing future products, their estimated rollout dates and projected impact for the agriculture industry. One such product is called SmartStax PRO, aimed at killing the Western corn rootworm.

According to the United States Department of Agriculture, “the western corn rootworm has required more acres of conventional insecticide use per year than any other pest since it invaded the Midwest in the 1960s.” In recent years, Monsanto’s patented Bt trait corn has been the gold standard in genetically engineered pesticides. Bt is a naturally occurring soil bacterium that kills the corn rootworm by producing protein crystals that bind to essential receptors in the bug’s intestine. Bt corn accounted for 75 percent of all corn planted in the United States as of 2013.

But the rootworm has developed a resistance to Bt (and to natural means of prevention, such as crop rotation). That’s why Monsanto is in such a rush to get its SmartStax PRO to market. This latest Monsanto genetically modified corn plant uses double-stranded RNA to inactivate a gene called Snf7 that is essential to protein development in the rootworm.

Monsanto calls SmartStax PRO “the first product to use novel RNAi-based mode of action for [corn] rootworm control, offering a new approach beyond traditional Bt genes.”

In January, media outlets reported that SmartStax Pro was on track for commercialization by the end of the decade, but the R&D Pipeline Review shows the product in phase IV, already submitted for regulatory review by the EPA. In this phase, the public could see the product on the U.S. market as early as next year.

Responses to RNAi technology as a pesticide are mixed — the corn industry, on one hand, is desperately searching for a new tool to combat the corn rootworm.

However, at a January meeting of EPA’s Scientific Advisory Board on the risks associated with RNAi, the National Honey Bee Advisory Board expressed concerns about the lack of research on RNAi technology:

“To attempt to use this technology at this current stage of understanding would be more naïve than our use of DDT in the 1950s.”

Respond: letters@boulderweekly.com