As summer approaches, levels of a pollutant may rise: ozone. It's not just a greenhouse gas; it can even affect insects' ability to find suitable mates.
A recent study published in Nature Communications suggests that increasing levels of ozone pollution are degrading pheromones released by potential mates, making it difficult for insects to find mates of the same species.
Ground-level ozone, a greenhouse gas, forms when vehicle emissions react with other gases in the air. During hot summers, sunlight and high temperatures promote this reaction, leading to elevated pollution levels.
Last year, Markus Knaden and colleagues at the Max Planck Institute of Chemical Ecology in Germany found that ozone interacts with insect chemical signals—pheromones. Pheromones are crucial in insect mating. They found that as ozone levels in the air increased, male flies' attraction to female flies decreased.
The team then conducted further research to investigate whether this degradation of pheromones would affect flies' ability to distinguish between different species.
They focused on four closely related fruit fly species, including the Mediterranean fruit fly. They exposed male and female fruit flies to high levels of ozone, equivalent to urban high-temperature ozone conditions, for up to 2 hours. Then, they allowed females to choose males for mating within the same species or different species. The results showed that after ozone exposure, the likelihood of producing hybrid offspring was around 70%, compared to only 20% for the control group exposed to environmental air.
"Hybrid offspring are usually sterile," says Knaden, "so despite the effort invested by the flies in offspring, the hybrid offspring cannot pass on the genes."
"There are currently over 1500 chemically described insect pheromones, 90% of which have carbon-carbon double bonds, which can be broken by ozone," Knaden says. This means that the increase in ground-level ozone levels could exacerbate the catastrophic decline in insect populations worldwide.
Related paper: https://doi.org/10.1038/s41467-024-47117-7
