Prey-size selection by Triops longicaudatus (Notostraca: Triopsidae) feeding on immature stages of Culex quinquefasciatus.

The tadpole shrimp, Triops longicaudatus, was found to be a size-dependent predator of Culex quinquefasciatus larvae in the laboratory. However, changes in tadpole shrimp size were accompanied by changes in prey-size preference: larger-sized predators consumed an increasing proportion of larger prey items. Very large tadpole shrimp may be nonselective predators of this mosquito species. Quantified behavioral observations indicated that while second instar mosquito larvae were encountered significantly less frequently than were fourth instar larvae or pupae, they were captured at significantly greater rates and with shorter handling times. It is hypothesized that prey vulnerability has an important influence on tadpole shrimp prey size "preferences."