Impact of ozone on the perception of olfactory signal by generalist pollinators

Although generalist bee species such as bumblebees are able to forage on a wide range of plant species, they do not show equivalent development on all pollen. Host-plant recognition is then of primary importance. While bumblebees use visual cues to find their preferred hosts, plant volatiles also play an important role in attraction and discrimination. Actually olfactory signal is a primary cue that influences the bumblebee's flower decision and reduces uncertainty regarding visual cues. In the current context of global changes, increased levels of atmospheric pollutants, such as ozone, could affect volatile perception by bumblebees impacting the plant-pollinator chemical communication and threatening the plant-pollinator network. To investigate the effects of ozone on the perception of floral volatiles by Bombus terrestris foragers, electrophysiological experiments were carried out using electroantennogram recordings. In order to simulate a peak of ozone, naïve foragers were exposed to ozone at a given concentration (i.e. 0, 80, 120 or 200 ppb) for 60 min or 180 min. Following the exposition, the responses of bumblebee antennae were measured for different concentrations (i.e. 0.1, 1, 10 and 100 µg/µL) of three synthetic volatile organic compounds mimicking compounds generally found in floral scents (i.e. (-)-linalool, benzaldehyde and nonanal). Our results show that ozone exposition affects volatiles perception by bumblebees but that this effect depends on the ozone exposure (i.e., concentration and duration) as well as on the volatile compound and its concentration. These results indicate that such impact can affect plant-bumblebee interactions, interfering with both host detection and attraction.