The demographic and life history costs of fear: trait-mediated effects of threat of predation on Aedes triseriatus

1. Predators alter prey populations via direct lethality (density-mediated effects), but in many taxa the indirect nonlethal threat of predation may be almost as strong an effect, altering phenotypically plastic traits such as prey morphology, behaviour, and life history (trait-mediated effects). There are costs to anti-predator defences and the strength of prey responses to cues of predation likely depends on both the perceived level of risk and food availability. 2. The goal of this study was to test the hypothesis that the costs of nonlethal trait-mediated interactions impacting larvae can have carryover effects that alter life history traits, adult characteristics, and ultimately population dynamics. 3. The effects of Toxorhynchites rutilus kairomones and chemical alarm cues on Aedes triseriatus were assessed in a two-level factorial design manipulating nutrient level (low or high) and chemical cues of predation (present or absent). 4. Nonlethal chemical cues of predation significan...