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 t he growth and survivorship of their offspring. Accordingly, they shoul d avoid habitats with high densities of competitors and predators and should choose sites with adequate food. We tested experimentally the o viposition 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 v iridis) 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 grou nd fish food and mouse chow). 3. Oviposition rates averaged approximat ely 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 conspecif ic larvae on oviposition habitat selection. 6. Our results indicate th at Culiseta females choose habitats for oviposition based on food avai lability. They also tend to avoid habitats containing Bufo tadpoles, p resumably to avoid predation and/or competition.