Complex predator effects on larval mosquitoes

Background/Question/Methods

The study of interactions among medically important mosquitoes and their predators has the potential to offer insight into patterns of population and disease outbreaks as well as control methods. The effects of predators on mosquitoes can be particularly complex: predators impact mosquitoes both by killing them, and by inciting predator-avoidance behaviors that carry energetic costs for those mosquitoes that avoid being killed. Here, we investigate the effects of a predator, Erythemis simplicicollis (Odonata: Libellulidae) on varying densities of larval Culex quinquefasciatus (Diptera: Culicidae).  First in laboratory microcosms and later in the field, we examined both mosquito survivorship and whether any non-lethal effects of predator exposure carry over to affect the size of adult mosquito.  Survivorship from the larval to adult stage was measured along with wing length of adults.

Results/Conclusions

We found, at most densities, dragonflies were successful in reducing survivorship of mosquito larvae as well as reducing wing length compared with no-predator controls.  These data suggest larval predators can ultimately help regulate adult mosquito populations, both by reducing overall densities of mosquito adults and by reducing the robustness of those mosquitoes that evade predation. Ongoing field studies are examining how predator-community structure impacts mosquitoes through both lethal and non-lethal channels.