Meeting Abstract

10.3  Saturday, Jan. 4 08:30  The balance between immune resistance and immune tolerance is dynamic and influenced by the environment STAHLSCHMIDT, Z.R.*; ACKER, M.; KOVALKO, I.; ADAMO, S.A.; Georgia Southern University; Dalhousie University; Dalhousie University; Dalhousie University zstahlschmidt@georgiasouthern.edu

Animal immune systems must adaptively balance immune resistance (ability to destroy pathogens) with immune tolerance (ability to withstand self-damage caused by immune resistance mechanisms). Insects offer unique insight into this balancing act because phenoloxidase (PO)-mediated melanization is a key feature of immune resistance, but PO activation obligates the production of non-specific reactive species that can cause self-damage. We hypothesized that the resistance-tolerance balance is dynamic and, thus, influenced by the environment. Specifically, we tested two predictions using factorial manipulations of food availability and immune status throughout adulthood in female Texas field crickets (Gryllus texensis). We predicted that chronic immune activation would elicit increased levels of antioxidant capacity (a proxy for immune tolerance). Because resource (food) availability affects other important dynamics (e.g., the tradeoff between the number and quality of offspring), we also predicted the resistance-tolerance balance would be influenced by resource availability. Chronic immune activation (but not food limitation) led to greater immune tolerance (ability to survive exposure to paraquat, an oxidative stressor) in support of our first prediction. Chronic food limitation led to a reduction in the protein content of crickets’ hemolymph. This, in turn, led to reduced total PO activity of hemolymph in food-limited crickets in support of our second prediction. We demonstrate that the balance between immune resistance and tolerance in insects is dynamic and affected by ubiquitous environmental factors (pathogen exposure and food availability).