Ozone Pollution Alters Olfaction and Behavior of Pollinators.

Concentration of air pollutants, particularly ozone (O), has dramatically increased since pre-industrial times in the troposphere. Due to the strong oxidative potential of O, negative effects on both emission and lifetime in the atmosphere of plant volatile organic compounds (VOCs) have already been highlighted. VOCs alteration by O may potentially affect the attraction of pollinators that rely on these chemical signals. Surprisingly, direct effects of O on the olfaction and the behavioral response of pollinators have not been investigated so far. We developed a comprehensive experiment under controlled conditions to assess O physiological and behavioral effects on two pollinator species, differing in their ecological traits. Using several realistic concentrations of O and various exposure times, we investigated the odor antennal detection and the attraction to VOCs present in the floral scents of their associated plants. Our results showed, in both species, a clear effect of exposure to high O concentrations on the ability to detect and react to the floral VOCs. These effects depend on the VOC tested and its concentration, and the O exposure (concentration and duration) on the pollinator species. Pollination systems may, therefore, be impaired in different ways by increased levels of O, the effects of which will likely depend on whether the exposure is chronic or, as in this study, punctual, likely causing some pollination systems to be more vulnerable than others. While several studies have already shown the negative impact of O on VOCs emission and lifetime in the atmosphere, this study reveals, for the first time, that this impact alters the pollinator detection and behavior. These findings highlight the urgent need to consider air pollution when evaluating threats to pollinators.