The U.S. Environmental Protection Agency (EPA) announced on September 29, 2023, that it is proposing to register pesticide products containing the new active ingredient ledprona for three years, a timeframe consistent with EPA’s approach to other novel pesticide products. EPA states that ledprona “is a new type of pesticide that relies on a natural mechanism — called RNA interference (RNAi) — used by plants and insects to protect against disease.” The proposed biopesticide involves a sprayable double-stranded ribonucleic acid (dsRNA) product targeting the Colorado potato beetle (CPB), a major pest of potato crops grown in the United States, including in the potato-growing states of Colorado, Idaho, Maine, Michigan, Minnesota, North Dakota, Oregon, Washington, and Wisconsin. According to EPA, the sprayable dsRNA product “kills the pest by ‘silencing’ the CPB gene needed to produce the PSMB5 protein, whose role is essential to keeping the CPB alive, without resulting in a genetically modified organism.” If EPA approves the registration, it “would be the first sprayable dsRNA pesticide in the world allowed to be used commercially and sprayed on plants.” More information is available in docket EPA-HQ-OPP-2021-0271. Comments are due October 13, 2023.

EPA notes that consistent with its obligation under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) to ensure that the product does not pose unreasonable adverse effects on the environment, including that residues of that product are safe for consumption, it conducted a robust evaluation of the product, including an Endangered Species Act (ESA) evaluation. EPA states that in considering the risk for this technology, it has engaged with international partners and experts in the field via its leadership of the Organization for Economic Cooperation and Development (OECD) Working Party on Pesticides Ad Hoc Expert Group on RNAi-based Pesticides.

EPA approved an experimental use permit (EUP) under FIFRA in May 2023 for testing in ten states (Idaho, Maine, Michigan, Minnesota, New York, North Dakota, Oregon, Virginia, Washington, and Wisconsin). The EUP required the permittee to notify EPA immediately of any findings from the experimental uses that have a bearing on safety. According to EPA, no such findings have been reported to date. EPA notes that it may use data generated from the EUP testing on product efficacy and application methods in a future application for this product to amend its directions for use.

In addition to proposing to limit the duration of the registration to three years to receive and assess any data from the EUP testing, EPA proposes to require the same personal protective equipment (PPE) as required under the EUP, “including long-sleeved shirt, long pants, socks, shoes, protective eyewear, and a particulate filtering respirator.”

EPA has reviewed and approved multiple genetically modified crops containing RNAi technology. Ledprona is the first biopesticide active ingredient containing sprayable RNAi technology that reached this milestone, however. This is a significant development, especially given the product specificity and the fact that it does not produce a genetically modified organism.