A new RNA-based treatment from GreenLight Biosciences to combat varroa mites shows great promise for promoting hive health and preventing widespread mite outbreaks.
This new treatment, Norroa, uses the active ingredient vadescana, which uses RNA interference to stop the mites from reproducing. It is part of the Insecticide Resistance Action Committee’s (IRAC) Group 35.
Varroa mites, which can double its population every 30 days, have developed resistance to many chemical treatments, GreenLight Biosciences says. And data from the Honey Bee Health Coalition shows that between June 2024 and March 2025, beekeepers reported losing 1.7 million colonies, with an average loss of 62%. Varroa mites not only weaken the bee once attached they also transmit several viruses.
Mark Singleton, chief commercial officer and general manager of plant health for GreenLight Biosciences, the developer of this new treatment, says RNA is the foundation of everything and this new product is a natural and sustainable way to control mites in beehives.
“What’s very clear in the U.S. and around the world is that the existing solutions are not working as well as they used to,” Singleton says. “And that’s bad for a whole number of reasons. First of all, if you stick with the label, you get poorer control, and the bees get sicker. If you use higher use rates and you use them for longer periods, then you start to leave residues in honey. You can damage bees; you can damage the bee health by overexposure to these materials, and it’s a vicious cycle. So a new technology was needed.”
Singleton says GreenLight Biosciences acquired the solution from a company that was unable to reproduce the active ingredient economically, so GreenLight unlocked how to make the formulation and tweaked the dose to make the product successful.
“Every other treatment that is out there right now primarily controls the varroa mite after it’s latched onto the bee,” he says. “When it’s latched onto the bee, it’s already given its presence of a bunch of viruses, and it’s weakened it dramatically.”
Singleton says beekeepers place a satchel of Norroa in a hive, and the worker bees mix it in with the brood food.
“It’s deposited in the cell where the larvae are going to be, and where the foundress might go to lay her egg,” he says. “It’s actually the hatched egg of the varroa mite that actually eats the RNA, and it stops it from growing and latching onto the bee. We’re now preventing that latching on, and therefore the virus transmission.”
He says in GreenLight’s research, hives using Norroa have a 50% reduction in colony loss for up to 18 weeks. But Singleton says this needs to be used as a preventative, not a curative treatment for bees already infected with varroa mites.
“This best use is as your preventative, apply it when mite levels are low, and it’ll keep your mite levels,” he says. “And that population management is, it’s powerful because we’re stopping it before they cycle.”
GreenLight Biosciences says Norroa will be available for sale exclusively through Mann Lake Ltd. and its authorized dealer network. And Singleton says he hopes to see different iterations of Norroa in the coming years for all beekeepers.
“We need to get this product and make it available for everybody who wants to make that choice to prevent varroa mite populations in their hive, regardless of whether they are a commercial keeper with millions and millions of bees or just hobbyists,” he says.
Norroa also recently received California registration use, so growers in the Golden State can also use this product.
“The beauty of RNA is it’s fairly selective for the target,” he says. “We know that not only have we got something here that helps bees. We knew we had this technology that was good for growers, good for the environment, good for consumers to protect crops. It does that in part by not harming pollinators.”
