The U.S. Environmental Protection Agency recently registered a new insect repellent ingredient derived from the catmint plant, or "catnip" (flower, as pictured). The ingredient, Refined Oil of Nepeta cataria, is the first new insect repellent bio-pesticide to be registered in eight years. DuPont is the registrant.
DuPont's research demonstrates that the refined oil "repels a broad range of biting insects with effectiveness similar to synthetic ingredients such as DEET."
A key benefit is that consumers could apply it to skin as often as desired. Because it smells nice, it could be mixed into an existing product or formulated as straight repellent.
Although I never noticed whether being around wild catnip resulted in fewer mosquito bites, it sounded as if "biomimcry" was one of the principles driving Dupont's discovery. So, I contacted Henry Bryndza, Director of Chemical Sciences & Engineering, DuPont Central Research & Development. Find out what I learned, below.
John Laumer for TreeHugger: I know people will be wondering 'If I use this product, will cats follow me home?' Can you address this please?
Henry Bryndza for Dupont: We don't believe it will be an issue but there are good options available if it is a concern. We've noticed no such behavior from cats in our field trials for the EPA. Catnip is actually a cat excitant, not an attractant, and interest falls off dramatically with distance.
We've also consulted with formulators who indicate that perfumers can incorporate cat repellents into formulations that use cat stimulants. One option is citronellol, another naturally derived product with mild insect repellent properties.
TH: I see that the development work was done in DuPont's Crop Protection business. Have you contemplated using the extract to "repel" insects from crops; or is the catnip extract intended only for consumer products?
HB: We have not found any extraordinary efficacy in crop protection applications that would warrant development for that purpose. Our Refined Oil seems to have the greatest efficacy against biting insects such as mosquitoes, biting flies, etc. that bother people and pets more than plants.
TH: Would this product potentially qualify for organic registration?
HB: Our Refined Oil was registered through the bio-pesticide process with EPA and is based on a natural product. The crop and oil most likely could be certified 'organic'.
TH: Will DuPont be commercially supplying catnip extracts to consumer product developers?
HB: We do have a limited supply of oil to supply to interested developers.
TH: Related question: when can we anticipate a commercial product containing catnip extract?
HB: We are actively working to find a development partner or licensee to help get this product to market. Timing to market will depend on that partner or licensee.
TH: Catnip is a semi-invasive non-native in the USA and there are numerous species. Did you have to select ones to work with; or is repellant efficacy more related to a DuPont technology?
HB: Through greenhouse studies we have selected a specific variety of the species Nepeta cataria that seems to be most efficacious for oil production. But the nepetalactone-containing oils from all of the species we have tested so far can be converted to an effective insect repellent using DuPont technology.
TH: Related question. Are the agricultural inputs for Nepeta relatively low or is intensive cultivation required?
HB: It seems to be quite a non-demanding plant that actually does best in somewhat harsh, arid environments. So agricultural inputs are relatively low, as many home gardeners can probably attest to.
TH: If the past is any guide we can expect a legion of knock off products that EPA will have to look into, as well as urban legends about smearing ones' body with catnip leaves. Can you comment about the importance of governmental pesticide registrations, then, in preserving the value of DuPont's intellectual property?
HB: First, thank you for the question — it's important to stress that the major component in unrefined oil from Nepeta cateria is nepetalactone, which is a skin sensitizer; therefore, people should be actively discouraged from "smearing ones' body" with catmint leaves. DuPont technology converts this major oil component into dihydronepetalactone, which is not a skin sensitizer and is much more stable and effective than the unprocessed oil.
We view the government regulations as prudent oversight designed to protect people rather than as a means of preserving intellectual property rights. We have many filed and issued patents, as well as the EPA registration, to protect our invention.