EPA Registers Norroa, a Tool Against Growing Varroa Mite Threat

The U.S. Environmental Protection Agency has approved the registration of Norroa, the first-ever RNA-based treatment for varroa mites, the leading threat to honeybee colonies. The new product from GreenLight Biosciences comes as existing chemical acaricides and miticides become less effective and reliable against varroa mites, creating a threat to the broader agriculture system.

Norroa’s RNA interference technology precisely targets varroa mites, breaking down safely in the hive and environment within days. Field trials demonstrated over 90 percent success in mite prevention, supporting hive health and more resilient pollination across more than 100 U.S. crops.

A product like this couldn’t come at a better time. 

Since the 1970s, amitraz has been the most effective approach to varroa mites, which can double their population every 30 days. However, varroa mites have recently been showing an increasing resistance to that acaricide and other oft-used chemical treatments. And this past year has been among the worst for bee colonies.

Recently analyzed data from the Honey Bee Health Coalition reveals staggering honey bee colony losses, with 1.7 million colonies lost and commercial beekeepers sustaining an average loss of 62 percent between June 2024 and March 2025. As mites are less controlled, they bring high virus loads into colonies, leading to loss. Experts warn of ripple effects that could disrupt food production, drive up farmer costs, and threaten the survival of commercial beekeeping operations.

Entomologists at Washington State University also project colony losses could rise to 70 percent in 2025 without substantive action.

Norroa’s active ingredient, vadescana, leverages RNA interference (RNAi), a natural biological process that precisely targets varroa mites and ultimately stops their reproduction. It is part of the Insecticide Resistance Action Committee’s Group 35, offering beekeepers a brand-new mode of action in the fight against these mites. The nucleic acids in the product are found in nature, and vadescana breaks down quickly in the environment.

“The EPA registration of Norroa marks a pivotal moment in protecting honey bee colonies that are essential to our food system,” said Andrey Zarur, Chief Executive Officer, GreenLight Bio. “By harnessing the precision of our proprietary technologies, we’re providing beekeepers with an environmentally conscious solution that specifically and effectively targets one of the most devastating threats to honey bee health. Norroa is safe for the bees and preserves the beneficial biodiversity and ecosystem balance of the surrounding area, aligning with sustainable agricultural practices.”

Rigorous, replicated field trials conducted across multiple U.S. regions demonstrated extended mite control of up to 18 weeks, resulting in improved overall colony health. Researchers confirmed Norroa’s performance against varroa mites and its safety for honey bees, humans, other insects, and the environment.

“As a fifth-generation beekeeper, I’ve seen firsthand how varroa mites can devastate colonies and jeopardize livelihoods. It is the number one enemy for all beekeepers,” said Jason Miller, President, Miller Honey Farms. “Norroa offers a genuinely effective and environmentally responsible option to protect our bees, which is critical for the health of our operations and the future of our nation’s food supply.”

Norroa will be available for sale exclusively through Mann Lake Ltd. and its authorized dealer network.