A Max Planck study shows that urban‑level ozone degrades fly pheromones, making females less responsive and causing males to court other males. Short ozone exposures produced long chains of male courtship, indicating a loss of sex‑specific scent cues. Researchers warn this disruption could affect many insects, undermine colony organisation and harm pollinators — about 80% of crops rely on insect pollination — and call for immediate reductions in atmospheric pollutants.
Ozone Pollution Breaks Down Fly Pheromones — Triggers Male‑Male Courtship and Threatens Pollinators
A Max Planck study shows that urban‑level ozone degrades fly pheromones, making females less responsive and causing males to court other males. Short ozone exposures produced long chains of male courtship, indicating a loss of sex‑specific scent cues. Researchers warn this disruption could affect many insects, undermine colony organisation and harm pollinators — about 80% of crops rely on insect pollination — and call for immediate reductions in atmospheric pollutants.
03:04 PM, 11/14/2025Environment
Ozone pollution is scrambling insect scent signals
Researchers at the Max Planck Institute for Chemical Ecology have found that ozone — a common component of urban air pollution — chemically degrades pheromones used by flies to find and identify mates. The study recreated ozone concentrations similar to summertime urban peak levels and observed clear changes in fly behaviour after short exposures.
Most insects rely heavily on pheromones: volatile chemical cues that are typically sex‑specific and that help males attract females while deterring rival males. In the experiment, increased ozone concentrations broke down those compounds, leaving females less responsive to male signals and making males unable to distinguish sex cues. As a result, male flies sometimes began courting one another, forming long courtship chains that surprised the researchers.
We could explain that males started courting each other after a short ozone exposure because they obviously could not distinguish ozonated males from females. However, we had not thought about this before. Therefore, we were quite puzzled by the behavior of the ozone‑exposed males, which lined up in long courtship chains. — Nanji Jiang and Markus Knaden
The implications extend beyond flies. Ozone is likely to interfere with chemical signalling in many insect species, disrupting behaviours that depend on scent cues, including species recognition, social organisation of colonies (beehives, wasp nests, ant societies) and mate finding.
That disruption could cascade through ecosystems: insects such as bees and butterflies are essential pollinators, and weakened chemical communication could reduce mating success and population sizes. This is especially concerning because roughly 80% of crop species depend on insect pollination.
The only solution to this dilemma is to immediately reduce pollutants in the atmosphere. — Bill Hansson, head of the Evolutionary Neuroethology Department and co‑founder of the Max Planck Center Next Generation Insect Chemical Ecology
Addressing atmospheric ozone will require policy changes and large emissions reductions from industry and transport. Individuals can also help by reducing car use, lowering energy consumption, choosing more sustainable products and supporting policies that cut air pollution.