The sexual life of insects confused by ozone pollution
Two male Drosophila flies attempt to copulate.
Flies, in full sexual confusion, unable to distinguish males from females: air pollution, which already threatens the pollination of plants, is also wreaking havoc in the reproduction of certain insects, shows a study published in Nature Communications< /em> (in English).
At the origin of the phenomenon, ozone, one of the most common pollutants which, even at a moderate dose, has the effect of degrading the olfactory perceptions of insects. And it also affects pheromones, those smelly chemicals that cause unconscious sexual or social reactions on an individual of the same species.
The result: in experiments with typical big-city ozone levels on fruit flies, those little gnats that very often hover around fruit, the males suddenly find themselves robbed of all charm in the eyes of the females, who are no longer encouraged to mate.
And some males, sexually in the fog, even find themselves pursuing their congeners of the same sex with their assiduities, reducing to nothing any possibility of reproduction.
Male fruit flies exhibit unusual behavior associated with reproduction after being exposed to high levels of ozone.
This disturbed sexual communication is mainly triggered by the oxidative effect of air pollution on the carbon chains of pheromones and lasts for several days.
This problem is found in nine out of ten species fruit flies studied, but could also affect other insects whose behavior is also based on pheromones, the scientists point out.
This factor, hitherto unknown, could accentuate the decline that has affected nearly half of insect species in recent decades.
We are talking about millions of species, Markus Knaden, one of the study's contributors and member of the Max Planck Institute, told AFP, citing butterflies in particular. night, butterflies, ants, bees, wasps.
Prior to industrialization, natural ozone levels in the air averaged around 40 parts per billion (ppb) globally. But today, in cities and industrial areas, ozone levels can easily reach 210 ppb, or around five times that.
“Everything was fine, until we arrived… It was all our fault. ”
— Markus Knaden, researcher at the Max Planck Institute
The study showed that even short-term exposure to high levels of 100 ppb ozone caused significant pheromone degradation. And the higher the concentration of ozone, the greater the impact.
Not to mention the influence of other pollutants, such as nitrogen monoxide which oxidizes at even faster rates and could come reinforce the phenomenon.
Experiments by scientists at the University of Reading in England are underway to determine the extent to which other flying and crawling insects might be affected.