Predation-dependent oviposition habitat selection by the mosquito Culiseta longiareolata: A test of competing hypotheses

We investigated the mechanism underlying oviposition habitat selection (OHS) in the mosquito Culiseta longiareolata. The putative outcome of a trade-off between the risk of predation and detrimental density dependence, OHS in this species presents an opportunity to test two competing alternatives: (1) a polymorphic scenario, in which a fixed proportion of females constantly avoid 'predator pools', while the remainder oviposits at random; and (2) a monomorphic scenario, in which all females oviposit in predator pools with a certain probability. We present a conceptual framework that demonstrates how a simple experimental design - whereby predator incidence in artificial pools is alternated between 0.25 and 0.75 - can distinguish between, or refute, the two scenarios. Given the proportional use, by ovipositing females, of predator-free pools observed under each treatment, and a bootstrap estimate of the ratio of daily oviposition rates, we find the monomorphic scenario twice as likely as the polymorphic.