Oviposition habitat selection by the mosquito Culiseta longiareolata in response to risk of predation and conspecific larval density

Abstract. 1. Most female Culiseta longiareolata (Diptera: Culicidae) avoid ovipositing in pools that contain the predatory backswimmer Notonecta maculata . Such oviposition habitat selection has been suggested to reflect a trade‐off between the risk of predation on larvae and potential density‐dependent fitness costs. This putative trade‐off was examined. In particular, evidence was sought in support of direct female response to local heterogeneity in habitat quality. 2. Three habitat types were established using artificial outdoor pools: predator pools, and non‐predator pools with either low or high densities of Culiseta larvae. During each experimental night, females were offered one of the three possible pair‐wise treatment combinations. 3. The majority (≈88%) of females oviposited in low‐density pools rather than in the predator‐ or high‐density pools. Furthermore, a substantially higher proportion of females oviposited in predator pools when faced with the high‐density alternative, however this was due largely to fewer females ovipositing in high‐ vs low‐density pools. 4. Females of a second mosquito species ( Culex laticinctus ), the larvae of which are at a lower risk of predation, were predicted to exhibit weaker aversion to N. maculata ; this prediction was supported only weakly. 5. Oviposition habitat selection by female C. longiareolata does not appear to involve a behavioural response that is based on individual assessment of local heterogeneity in relative pool quality, at least not at the spatial scale examined here; alternative explanations are discussed.