A research team at the Max Planck Institute for Chemical Ecology in Jena, Germany, demonstrates that increased levels of ozone resulting from anthropogenic air pollution can degrade insect sex pheromones, which are crucial mating signals, and thus prevent successful reproduction.
A research team at the Max Planck Institute for Chemical Ecology in Jena, Germany, demonstrates that increased levels of ozone resulting from anthropogenic air pollution can degrade insect sex pheromones, which are crucial mating signals, and thus prevent successful reproduction. The oxidizing effect of ozone causes the carbon-carbon double bonds found in the molecules of many insect pheromones to break down. Therefore, the specific chemical mating signal is rendered dysfunctional. The researchers show this effect in the vinegar fly Drosophila melanogaster and nine other species of the genus Drosophila. Most remarkably, the disrupted sexual communication also led to male flies exhibiting unusual mating behavior towards ozonated males of their own species (Nature Communications, DOI: 10.1038/s41467-023-36534-9, March 14, 2023).
Insect sexual communication relies to a significant extent on pheromones, chemical attractants that specifically allow males and females of a species to mate. Sex pheromones are distinctive to males and females of a species. Even the smallest differences, such as those observed in the formation of new species, ensure that mating no longer takes place, because males and females only find each other through the unmistakable odor of their conspecifics.
Most insect pheromones are odor molecules containing carbon-carbon double bonds. Such double bonds are known to be easily destroyed by ozone. "We already knew that environmental pollutants such as ozone and nitric oxide degrade floral scents, making flowers less attractive to their pollinators. Since compounds with carbon double bonds are particularly sensitive to ozone degradation, and almost all insect sex pheromones carry such double bonds, we wondered whether air pollution also affects how well insect females and males find and identify each other during mating", says Markus Knaden, who heads the Odor-guided Behavior Group in the Department of Evolutionary Neuroethology and is a lead author of the study (see also press release, September 4. September 2020, “Air pollution renders flower odors unattractive to moths").
Read more at Max Planck Institute for Chemical Ecology
Image: Courting chain of four male Drosophila flies. Male flies exhibited unusual courting behavior towards other males that had been exposed to increased ozone levels as they are nowadays often found in cities in the summer. (© Benjamin Fabian, Max Planck Institute for Chemical Ecology)