D3073: Breaking up and breaking down: Looking at downstream effects of drought and warming on an insect mutualism

Anthropogenic climate change is predicted to lead to multiple abiotic stressors that are expected to influence the strength of plant-insect interactions. One way that plant-insect interactions can be resilient to climate change is through beneficial interactions, or mutualisms.  However, some mutualisms may be negatively affected by climate change due to the effects of these stressors on the services and resources exchanged in the interaction.  For instance, sap-feeding aphids forge food-for-protection mutualisms with tending ants, which hinges on the aphids ability to excrete attractive honeydew in exchange for the ants protection from predators, parasitoids, and infectious disease. Changes in precipitation and warming can potentially reduce the quality of honeydew, with unknown effects on ant attraction and interaction. 

Here, I use a factorial-design experiment to test the role of warming and drought on the tenacity of a food-for-protection mutualism. Using the host plant, bell pepper (Capsicum annuum), the insect herbivores, green peach aphids (Myzus persicae), and their generalist mutualist partners, black carpenter ants (Camponotus pennsylvanicus), I measure host plant quality and aphid abundance, fecundity and survivorship, along with ant choice to determine the downstream effects of drought and warming on mutualistic species interactions. I present my experimental design and preliminary results on climate change's potential impact on this mutualism.