| Investment in life history traits such as immune function and reproduction is constrained by finite available resources. A cost-of-immunity trade-off may occur in response to infection when resources are diverted away from reproductive effort and into an immune response. Alternatively, an infected individual may enhance reproductive effort to maximize terminal reproductive success in response to the survival threat inherent to infection (terminal investment). We measured male Aedes aegypti reproductive behavior following inoculations with: living bacteria; killed bacteria as an immune elicitor; and a sham control. Mating competitiveness relative to naive males was also determined through a binary mate choice experiment using wild-type and eye-color mutant populations to assess paternity. We found that male mating behaviors did not differ among immune challenge treatments, but immune challenged males had greater mating success relative to naive males, consistent with terminal investment. Though previous experiments using similar immune challenges in females show induction of immune responses, our treatments yielded no detectable effect in males based on two standard physiological immune assays. However, the eye-color mutants had high levels of immune function relative to the wild-type males. Male terminal investment has the potential to improve the success of sterile male release programs that rely on male mating performance to control mosquito populations. Increasing male sexual competitiveness after sterilization is an emerging topic within insect behavioral ecology, and illustrates the important role of evolutionary theory in contributing to the efficacy of these population control strategies for medically and economically important pests. |
