OVIPOSITION HABITAT SELECTION BY THE MOSQUITO, CULISETA-LONGIAREOLATA - EFFECTS OF CONSPECIFICS, FOOD AND GREEN TOAD TADPOLES

1. Ovipositing females should choose egg-laying sites which maximize the growth and survivorship of their offspring. Accordingly, they should avoid habitats with high densities of competitors and predators and should choose sites with adequate food. We tested experimentally the oviposition response of the mosquito, Culiseta longiareolata Macquart, to extra food and two species which are both potential competitors and predators of its offspring: conspecific larvae and green toad (Bufo viridis) tadpoles. 2. We conducted the experiment in outdoor artificial pools where wild C.longiareolata females were presented with choices of all combinations of the presence or absence of: (1) C.longiareolata larvae, (2) B.viridis tadpoles, and (3) extra food (a mixture of ground fish food and mouse chow). 3. Oviposition rates averaged approximately 4 times greater in response to extra food. 4. The presence of the tadpoles, particularly later in the experiment when they were larger, caused a significant reduction (approximately 50%) in oviposition rate. 5. We did not detect a statistically significant effect of conspecific larvae on oviposition habitat selection. 6. Our results indicate that Culiseta females choose habitats for oviposition based on food availability. They also tend to avoid habitats containing Bufo tadpoles, presumably to avoid predation and/or competition.