Predicting Species Interactions Based on Behaviour: Predation and Competition in Container-Dwelling Mosquitoes

Abstract

1. We tested the hypothesis that competitive ability and vulnerability to predation are primarily products of behaviour using larvae of three container-dwelling mosquitoes. 2. Aedes aegypti was more active, spent more time browsing, more time at the bottom and less time resting than did Aedes triseriatus. These differences lead to the prediction that A. aegypti is a more effective forager and competitively superior to A. triseriatus. 3. In the presence of the predator Toxorhynchites rutilus, A. aegypti spent more time thrashing, less time resting, more time at the bottom and less time at the surface than did A. triseriatus. These differences lead to the prediction that A. aegypti is more vulnerable to predation than A. triseriatus. 4. Survival time with T. rutilus was significantly lower for A. aegypti than for A. triseriatus, confirming the prediction of greater short-term (minutes) vulnerability of A. aegypti. 5. When exposed to T. rutilus (hatch to adult), cohorts of A. aegypti usually failed to produce adults, but cohorts of A. triseriatus always produced adults. At high Aedes density, predation by T. rutilus indirectly lowered development time and increased adult mass and estimated finite rate of increase for A. triseriatus, probably due to release from density dependence. These patterns confirm the prediction of greater vulnerability of A. aegypti. 6. For both Aedes species, survivorship and estimated finite rate of increase were not differentially affected by interspecific vs. intraspecific competition. Estimated finite rates of increase achieved when in competition gave no indication of a strong competitive advantage for either species. For female A. aegypti, mass at adulthood and development time were more detrimentally affected by intraspecific vs. interspecific competition. For A. triseriatus, development time was more detrimentally affected by interspecific vs. intraspecific competition. These results provide, at best, only weak support for the predicted competitive advantage for A. aegypti. 7. We suggest that in some systems, prey behaviour patterns are more related to vulnerability to predation than to competitive ability.