Potential of three aquatic predators to control mosquitoes in the presence of alternative prey: a comparative experimental assessment

Abstract

Predator-induced control of pests depends on the predator’s preference for the target pest over naturally co-occurring prey species. We compared the larvivorous efficiency of three common freshwater predators: mosquitofish (Gambusia affinis; Baird and Girard, 1854), dragonfly naiads (Zyxomma petiolatum; Rambur, 1842) and copepods (Mesocyclops aspericornis; Daday, 1906) on different instars and the relative abundances of the mosquito Anopheles stephensi (Liston, 1901) in the presence of alternative cladoceran prey, either Moina macrocopa (Straus, 1820) or Daphnia similoides (Hudec, 1991). Larval removal rate decreased with increasing larval size and instar stage. The maximum consumption rate was by mosquitofish, followed by dragonfly naiads and copepods. The presence of either of the alternative prey significantly reduced larval consumption by all three predators, except in the D. similoides–mosquito larvae combination for naiads. Mosquitofish and copepods preferred early instars of the mosquito. Prey selectivity indices for early mosquito instars against D. similoides did not differ between mosquitofish and copepods, whereas naiads had significantly lower index values than the other two predators. Considering the negative impacts of mosquitofish on native assemblages, that is, its invasiveness and its lower selectivity for mosquito larvae, our results suggest that the feasibility of using copepods in large-scale control programs needs to be evaluated.