A half-inch long moth that devours kale, broccoli, and Brussels sprouts may not inspire the same fear as a Zika-carrying mosquito, but the two insects have something in common. Both are being genetically tweaked by UK-based biotech firm Oxitec. Last year, the company made news when it proposed a Florida-based trial of a self-destructive mosquito—designed to stop the spread of Zika virus in native Aedes aegypti mosquitoes.
Now, Oxitec wants to test a genetically modified version of the male diamondback moth to mate with—and eventually destroy—a pest that damages $5 billion worth of cruciferous crops every year worldwide. Like the mosquito, the moth passed laboratory and greenhouse trials and now must pass approval in a open field test. But while the mosquito had to wind its way through the FDA, Oxitec’s moth faces a different set of regulatory hurdles at the USDA. Officials at that agency are currently reviewing whether to allow Cornell University and Oxitec to release tens of thousands of GM moths into a 10-acre site in New York.
For decades, agricultural researchers have battled insect pests that are growing resistant to chemical pesticides. The diamondback moth has a short reproductive cycle and lays a lot of eggs, which speeds up the development of resistance. “It is able to select for resistance for a wide variety of toxins,” says University of Georgia entomologist David Riley. “If I had to pick a poster child for resistance world wide, this would be in my top 10.”
Already, the diamondback moth has become resistant to 95 different chemical compounds. That’s a huge problem for growers in southern states like Georgia and Florida, where up to 15 generations of veggie-munching larvae are born every year on constantly rotating crop fields.
In the past, scientists have released sterile male insects—zapped with gamete-bursting radiation—to help crash the population of pests like the New World screwworm (which infected livestock and people) or the onion maggot. But this would be the first GM sterile pest control effort.
Oxitec scientists made two tweaks to their moth. The first is the killer. “Our diamondback moth carries a self-limiting gene, that prevents female offspring from surviving to adulthood,” says Oxitec research lead Neil Morrison. “This allows us to release adult males only, which are harmless to the crop. When they mate with a pest female in the field, none of her female progeny would survive.” The next generation of larvae won’t have any female moths to mate with—and the population dies off. They also added a gene for a protein that glows red under UV light. Why? That’s so researchers can distinguish the trial moths from wild diamondback moths and see if the GM moths (imported from the UK) are spreading beyond the test site.
USDA officials have already received more than 600 public comments on the GM diamondback moth proposal since the docket opened last month. Backers include ag scientists and biotechnology advocates like Nobel chemistry laureate Richard Roberts, who argues that reducing pesticides will boost food production. “The food security challenge ahead is formidable—especially given the fragile environment—and the innovation pipeline must be enabled to drive sustainable growth in agriculture,” Roberts wrote.
But other commenters, like Dana Marsh of Bloomington, Ind., worry about the unintended consequences of releasing a GM moth. If a gene drive escapes beyond the targeted area and proliferates widely, it could engineer the destruction of an entire species. “As of today, we do not have complete understanding of how every insect and plant works,” Marsh wrote. “We still do not grasp the diversity that currently exists. The consequences of genetic engineering are untold and could prove fatal to our precious ecosystem. PLEASE leave nature alone.”
The company says any GM moths that survive the experiment will be killed by pesticides or the region’s cold winters. Still, some local organic farmers say the dead larvae produced when genetically-engineered males mate with female moths could stay on the vegetables and pose potential risks to the environment and health. “The release of any novel organism into the open is a significant issue,” Liana Hoodes, policy adviser for the Northeast Organic Farming Association of New York told Bloomberg BNA. “Clearly, insects don’t stay in the borders of the land that’s owned by Cornell.”
USDA officials are accepting comments until May 19. Oxitec said if its trial is approved, the trial would take less than a month to complete—though that timeline might be ambitious. Oxitec’s genetically engineered mosquito has been released in parts of Grand Cayman, Panama, and Brazil—places where Zika is a big threat. But even though the Florida trial was approved by residents of Monroe County, those plans have stalled: No single neighborhood wants to be the site of the mosquito release. The same may be true for a 10-acre plot in upstate New York.