Effect of habitat complexity on the predation of Buenoa fuscipennis (Heteroptera: Notonectidae) on mosquito immature stages and alternative prey

Abstract

Notonectids are well-known predators in aquatic habitats, where mosquito larvae, chironomids and cladocerans constitute their main diet. Here we aimed to assess the effect of structural complexity on the predatory ability of Buenoa fuscipennis, a common predator in aquatic habitats of Buenos Aires city (Argentina). Buenoa fuscipennis showed type 2 functional responses in both the presence and the absence of prey refuge, and no differences in attack rate or handling time between refuge treatments. Regarding mosquito size classes, B. fuscipennis exhibited a significantly higher preference for second instar larvae, and no predation on pupae. In the presence of mosquito larvae and alternative prey, B. fuscipennis preferred mosquito over chironomid larvae, and adult cladocerans over mosquito larvae. No switching behavior was detected in our experiments. Habitat structure affected slightly the predator´s consumption rates on mosquito larvae. Overall, the preference did not vary in the presence of refuge for prey, except the preference for mosquito over chironomid larvae, which was significantly decreased in the presence of refuge as a consequence of reduced predation on mosquito larvae. The results suggest that B. fuscipennis could efficiently control mosquitoes in structurally simple habitats, where chironomids are the most abundant alternative prey, but not in temporary pools where cladocerans attain high abundances.