D3120: Population and behavior effects of temperature within an ant-aphid mutualism on common milkweed (Asclepias syriaca) in northeast Ohio

Mutualisms are important interactions for maintaining stability in ecosystems. However, like many species interactions, mutualisms are complex and may display complicated or unexpected responses to environmental shifts. Because behavior, physiology, and population demographics may respond unequally to environmental variables like temperature, it is difficult to predict how the relationship will change in response to environmental perturbations and changing climate patterns. Aphid-ant interactions are a frequent and widespread form of mutualism, occurring in tropical, temperate, and alpine environments, making the environmental controls on these interactions of utmost scientific interest. We conducted a passive warming experiment using open-top chambers deployed in temperate prairie and woodland habitats in Northeast Ohio, focusing on interactions of ants and aphids on common milkweed (Asclepias syriaca). We hypothesized that warmer temperatures would increase ant (various spp.) aggression towards their aphid (Aphis nerii) counterparts, negatively affecting aphid abundance, particularly over 28℃, when aphid reproductive rate decreases. We conducted weekly surveys to record abundance and conduct behavioral observations associated with ant-aphid interactions under the elevated and ambient conditions. We compare our results to a sibling study conducted in an aphid-ant mutualism occuring in an alpine meadow. As climate change continues to impact the world around us, developing a better understanding of how this mutualism may shift under future scenarios will benefit our ability to make predictions in the future.