Prey choice by a freshwater copepod on larval Aedes mosquitoes in the presence of alternative prey.

ABSTRACT

Predator-prey interactions can have a significant impact on the abundance and distribution of species, but the outcome of these interactions is often context-dependent. In small freshwater habitats, predacious copepods are potential biological control agents for mosquito larvae. Through laboratory experiments, we tested if the presence of a non-mosquito prey (neonate Daphnia pulex) influenced prey selection of the predaceous copepod (Acanthocyclops vernalis) on 1st instar Aedes mosquitoes (Aedes aegypti and Aedes albopictus). Copepods were starved for 12 h prior to being exposed to the two prey types (larval mosquitoes and Daphnia) at three densities 25 mosquitoes75 Daphnia, 50 mosquitoes50 Daphnia, 75 mosquitoes25 Daphnia. Single prey choice trials for each species as well as no-predator trials were also established for controls. Copepods were effective predators, with a single copepod consuming up to 37 1st instar mosquito larvae during the 24-h trials. The number of mosquitoes consumed increased with their relative density, but the proportion of mosquitoes consumed was highest when Aedes made up only 25% of the population. Results from our study show that in a simple predator/two-prey system, two species of larval mosquitoes (Ae. aegypti and Ae. albopictus) are preferentially consumed over an alternative zooplankton by the copepod predator Acanthocyclops vernalis.