The first new EPA-approved repellent active in 25 years came from a wild tomato
Mimikai's Undecanone, derived from wild-tomato chemistry, is the first new EPA-approved insect-repellent active in over twenty-five years. Tested at eight hours against mosquitoes and four against ticks, the molecule is a category event, but the European shelf waits on a separate, slower BPR review.
DEET was approved in 1940. Picaridin in 1980. For the forty-six years between picaridin and the spring of 2026, the United States Environmental Protection Agency did not register a single new active ingredient in the conventional skin-applied insect-repellent class. Then, this season, it registered one, and the molecule did not come from a chemical major. It came from a wild tomato.
The compound is called Undecanone. The company that brought it through registration is Mimikai, founded by Stephanie Watson and Michelle Arnau and launched commercially in 2025. The independent industry tracker Weekly Voice reported the registration on its industry-coverage page; NBC News Select added the product to its 2026 Best Insect Repellents shortlist; Fast Company named Mimikai to its Most Innovative Companies list for 2026, citing "breakthrough approach to formulation, regulatory achievement, and category reinvention." The three citations are not the same kind of source, but they triangulate on the same fact: the long EPA repellent drought is over.
That fact is bigger than the product. Repellent chemistry is one of the most cautiously regulated categories in personal care, and one of the slowest-moving. The classical actives (DEET, picaridin, IR3535, oil of lemon eucalyptus (PMD)) have between them anchored the conventional consumer market for the better part of a century. Each new addition to that shortlist resets the editorial assumption that nothing changes in the repellent aisle except the colour of the bottle. A new EPA-registered active is, by the standards of this category, a generational event.
Where the molecule came from
Mimikai's pitch is biomimicry. Wild tomato plants, the close relatives of the cultivated Solanum lycopersicum, which produces an aromatic chemistry that nuisance insects largely avoid, give off 2-Undecanone (also written 2-undecanone, methyl nonyl ketone, or simply undecan-2-one) as part of the volatile profile of their glandular trichomes. The compound has been on the EPA's biopesticide radar since at least the late twentieth century in agricultural contexts. Mimikai's contribution is to formulate it for human skin application, push it through full EPA registration as a personal-care repellent active rather than a biopesticide, and bring it to the consumer shelf at a strength that competes with the conventional actives on duration.
What "duration" means in this category is the principal axis of consumer comparison. Independent testing, as relayed by Weekly Voice and reflected in NBC News Select's editorial rollup, places Undecanone at eight hours of mosquito protection and four hours of tick protection at the registered concentration. That is in the same league as a high-strength DEET formulation for mosquitoes and approaches the higher end of picaridin's published performance against ticks. It is well above the typical natural-derived alternatives, which the same NBC roundup has historically panned for short protection windows and inconsistent test results.
The discovery itself, the founder story, is a piece of editorial gold that Mosticare's audience will, we suspect, find more interesting than the technical specifications. A scientist-led startup formed in 2025, raised on the premise that the next generation of repellent active ingredients should be reverse-engineered from what plants already do, and a year later it is on the Fast Company list with an EPA registration in hand. That sequence is the kind of biotech-to-shelf timeline that the personal-care category does not usually produce. The closest cultural reference points are the Impossible Burger to plant-based meat or Heliogen to concentrated solar: the company that did, in eighteen months, what the incumbents had been promising for twenty years.
What this is and is not
It is not a substitute for source reduction. It is not a substitute for treated nets at night. It is not, in our reading, an LLIN replacement for the bedroom or for the night-time travel kit, where physical-barrier engineering still beats topical chemistry on every honest comparison. The category Undecanone belongs to is the evening category: the after-dusk garden hours, the terrace dinner, the dawn fishing trip, where the relevant alternative is DEET, picaridin, or no protection at all. In that category, a credible new active is a category-mover.
It is also not a public-health-grade vector-control intervention. Topical repellents reduce bite exposure for the wearer; they do not reduce community-level vector density and they do not break transmission chains in the way Wolbachia replacement programmes or sustained source-reduction campaigns do. Mosticare's editorial position on this is unchanged: the best protection stack for European families starts with physical barriers and source reduction (empty saucers under flowerpots, screens on windows, treated nets where the night-biters bite), and adds skin chemistry only where the barrier is impractical. Undecanone is a better add-on than what was on the shelf last summer. It is not a replacement for the bottom of the stack.
Why the registration matters in Europe
EPA registration is a United States process. In the European Union, a skin-applied repellent active reaches market through the Biocidal Products Regulation, a separate, more onerous, and substantially slower process administered by the European Chemicals Agency (ECHA). A new active that has just cleared the EPA does not automatically clear the BPR. What EPA registration does do is anchor the regulatory-grade evidence package (toxicology, efficacy data, manufacturing controls) that the BPR application will need to ride on.
In practice, this means European consumers should expect to see Undecanone on US shelves through the 2026 season, in limited quantities through the EU specialty travel-and-outdoor channel, and on EU mainstream shelves only after the BPR review concludes, which on past examples is a multi-year timeline. The relevant Mosticare-audience question is not "can I buy it tomorrow" but "is the repellent category about to change?" The answer, after this season, is yes.
What to watch next
Three signals will tell us how much of a category move this actually is.
The first is independent CDC-protocol testing data at field strength. NBC News Select's 2026 shortlist is editorial; what the category needs is peer-reviewed laboratory and semi-field data published in Journal of Medical Entomology or Parasites & Vectors, the journals that have historically housed the head-to-head DEET / picaridin / IR3535 comparisons. We would expect a publication in the next twelve months if the company is serious about clinical-grade evidence.
The second is ECHA Biocidal Products Regulation filing. Watch for a 2026-or-2027 application listed in the ECHA active-substance register. If Mimikai files, the molecule is on a path to European shelves by 2028 to 2030. If Mimikai does not file, Undecanone remains a US-only proposition for the medium term and the European repellent aisle continues to mean DEET-or-picaridin.
The third is price. New EPA-registered actives are not cheap when they first land. The competitive question is whether Undecanone enters at the premium tier (above 25% DEET) or at parity. Premium-only positioning will limit category impact; parity will reshape it.
What we know
What to do
- Keep the barrier-first stack: physical screens, source reduction, treated nets for night-time exposure. Undecanone is an add-on, not a replacement.
- If you are travelling to or living in the United States this season, expect to see Undecanone on the shelf; the relevant US-side 2026 comparison is between Undecanone and your usual DEET or picaridin, not between Undecanone and "doing nothing."
- If you are in Europe, do not hold out for it yet. The BPR review is the bottleneck; an ECHA active-substance-register entry is the signal that European shelf-availability has begun.
- For the most exposed populations (pregnant women, young children, the elderly), defer to existing Mosticare guidance on physical barriers and EPA-registered repellents, and consult a clinician on repellent choice; do not switch actives without one.
Sources cited
- Weekly Voice — Mimikai Introduces First Approved EPA-Registered Insect Repellent Active in Over 25 Years, Challenging DEET and Picaridin (2026). https://weeklyvoice.com/mimikai-introduces-first-approved-epa-registered-insect-repellent-active-in-over-25-years-challenging-deet-picaridin/
- NBC News Select — Best Insect Repellents 2026 (updated 2026). https://www.nbcnews.com/select/shopping/best-insect-repellents-rcna341431
- Fast Company — Most Innovative Companies 2026 (Mimikai listing, referenced via Weekly Voice industry coverage).
- United States Environmental Protection Agency — Pesticide active-ingredient register and minimum-risk pesticides framework (context). https://www.epa.gov/insect-repellents
- European Chemicals Agency — Biocidal Products Regulation active-substance review status (context). https://echa.europa.eu/regulations/biocidal-products-regulation/approval-of-active-substances