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Keywords:

  • Adult body size;
  • diving beetle;
  • larval period;
  • phenotypic plasticity;
  • predator kairomone

1. Natural selection favours females who can correctly assess the predation risk and hence avoid high-risk oviposition sites and reduce the mortality rate of their offspring. In spite of the potential significance of such behaviour, relatively few studies have assessed the relationship between oviposition behaviour and predation risk.

2. The present study aimed to determine the sublethal effects of predators on oviposition site selection by gravid females, the foraging activity of larvae, and the life history traits of two mosquito species that breed in different habitats, Aedes albopictus Skuse (container breeder) and Culex tritaeniorhynchus Giles (wetland breeder).

3. Female C. tritaeniorhynchus avoided laying eggs at oviposition sites in the presence of a predator cue. In contrast, female A. albopictus laid eggs in both the absence and presence of the predator cue.

4. To examine the effects of predator cues on larval behaviour, experiments were conducted in the absence and presence of a predator cue. Although larval activity was lower in the presence of the predator cue than that in its absence in both species, C. tritaeniorhynchus responded to the predator cue more strongly than A. albopictus. Female A. albopictus that had been reared with caged predators exhibited an extended larval development period, whereas the adult C. tritaeniorhynchus reared in the presence of predators were smaller than those reared in their absence.

5. This finding might explain why C. tritaeniorhynchus avoid laying eggs in predator-conditioned water, for example to increase the fitness of their offspring, but A. albopictus either cannot detect predator cues or are not sensitive to them.