Ozone Induces Distress Behaviors in Fig Wasps with a Reduced Chance of Recovery

SIMPLE SUMMARY: Ecological interactions among organisms underpin the stability of ecological networks, which are responsible for species biodiversity in ecosystems. These interactions are currently threatened by environmental risks, mainly due to human activities, such as air pollution. Among air pollutants, tropospheric ozone (O(3)) is known to disrupt chemical communication between plants and their pollinators. Alarmingly, its concentration is likely to increase by two–four-fold in the next two decades. However, the direct effects of O(3) on the behavior of pollinators themselves have not been investigated so far, even though insect behavior is key to their ecological interactions. In this study, we evaluated the potential effects of O(3) at different field-realistic concentrations on the behavior of the fig wasp Blastophaga psenes, the exclusive pollinator of the Mediterranean fig species Ficus carica. We found that O(3), even at low concentrations, induced abnormal motility in fig wasps, and that exposed individuals might only have a reduced chance of recovery. Overall, our findings indicate that O(3) can affect pollinator behavior, which may have detrimental implications for pollination systems. ABSTRACT: Among anthropogenic environmental risks, air pollution has the potential to impact animal and plant physiology, as well as their interactions and the long-term survival of populations, which could threaten the functioning of ecosystems. What is especially alarming is that the concentration of tropospheric ozone (O(3)) has dramatically increased since pre-industrial times. However, the direct effects of O(3) on the behavior of pollinators themselves have not been investigated so far even though insect behavior is key to their ecological interactions, which underpin the stability of ecological networks responsible for species biodiversity in ecosystems. In this study, we aim to determine the potential effects of O(3) episodes at different field-realistic concentrations (0, 40, 80, 120, and 200 ppb for 60 min) on the behavior of the fig wasp Blastophaga psenes by monitoring exposed individuals hourly for 5 h after exposure. We found that ozone episodes induced major changes in insect behavior, which were already significant at 80 ppb with individuals displaying abnormal motility. The tracking over time clearly showed that exposed individuals might only have a reduced chance of recovery, with a decreasing proportion of active fig wasps despite the cessation of an O(3) episode. These findings illustrate that O(3) episodes can affect pollinator behavior, which may have detrimental implications for pollination systems. It is, therefore, of importance to assess the effects of O(3) on insect behavior in order to predict how it could modify ecological interactions and species biodiversity in ecosystems.