Predation and the evolution of prey behavior: an experiment with tree hole mosquitoes

We tested for facultative changes in behavior of an aquaticinsect in response to cues from predation and for evolutionof prey behavior in response to experimental predation regimes.Larvae of the tree hole mosquito Aedes triseriatus reducedfiltering, browsing, and time below the surface in responseto water that had held a feeding larva of the predator Toxorhynchitesrutilus. We subjected experimental A. triseriatus populationsto culling of 50% of the larval population, either by T. rutiluspredation or by random removal. After two generations of laboratoryculling, behavior of the two treatment groups diverged. Aedestriseriatus in control-culled lines retained their facultativeshift from filtering to resting, but tended to lose the responseof reduced browsing below the surface in water that had helda feeding predator. Predator-culled lines lost their facultativeresponse of reduced filtering in water that had held a feedingpredator and evolved toward more time resting and less timefiltering in both water that had held a feeding predator andwater that had held only A. triseriatus. Predator-culled linesretained their facultative response of reduced browsing belowthe surface in water that had held a feeding predator. Twofield populations and their reciprocal hybrids responded similarlyto cues from predation and did not differ in their evolutionaryresponse to experimental culling. We conclude that consistentpresence or absence of predation can select rapidly for divergencein prey behavior, including facultative behavioral responsesto predators.