Elevated ozone levels have been found to disrupt mating barriers between different species of the genus Drosophila, leading to increased occurrences of mostly sterile hybrids. Researchers discovered that ozone destroys the sex pheromones of fruit fly species, thereby eradicating some natural mating boundaries maintained by species-specific pheromones. This phenomenon has implications for the global decline of insects, as it may contribute to reduced insect populations due to infertility in hybrid offspring.
The study, led by Nanji Jiang, Bill Hansson, and Markus Knaden from the Department of Evolutionary Neuroethology at the Max Planck Institute for Chemical Ecology, builds upon previous research showing that ozone severely disrupts chemical communication within fly species by breaking carbon-carbon double bonds found in insect pheromones.
In experiments involving four species of Drosophila, researchers exposed flies to ozone concentrations typical of hot summer days in urban areas. They observed that ozone exposure led to an increase in hybridization between species, as females were less able to distinguish between conspecific males and males of other species. Despite additional mating cues such as species-specific songs and visual signals, elevated ozone levels interfered with female flies’ ability to discern appropriate mating partners.
Hybridization between different fly species can lead to sterile or less fertile male offspring, contributing to population decline. However, female hybrids are typically fertile and may facilitate gene flow between species, potentially leading to the emergence of hybrid species. With over 1500 species in the Drosophila genus, the researchers suggest that pollutant-induced hybridization could lead to hybrid speciation in some species pairs.
The study highlights the underestimated threat of air pollution to insect populations, as pollutants like ozone can disrupt chemical communication crucial for mating, aggregation, and alarm signaling among insects. The researchers advocate for re-evaluating air pollutant limits to mitigate their harmful effects on insect biodiversity and counteract the ongoing decline in insect populations.
