Opportunistic foraging by heteropteran mosquito predators

Abstract

Tropical aquatic environments host a large number of predatory insects including heteropteran water bugs Anisops bouvieri Kirkaldy, 1704 (Heteroptera: Notonectidae), Diplonychus (=Sph-aerodema) rusticus Fabricius, 1781 (Heteroptera: Belostomatidae), and Diplonychus (=Sphaerodema) annulatus Fabricius, 1781 (Heteroptera: Belostomatidae) feeding on a range of organisms. In tropical and subtropical wetlands, ponds, and temporary pools these predators play a role in regulation of dipteran populations, particularly mosquitoes and chironomids. Their relative abilities to control mosquitoes depend in part on predator preference for mosquitoes in relation to other natural prey, and the predators' propensities to switch to mosquitoes as mosquito density increases. The prey electivity and switching dynamics of these predatory water bugs were evaluated in the laboratory under various prey densities, using two instars (II and IV) of chironomid and mosquito larvae as prey. Studies of electivity at relatively high densities (20 prey L -1 ) in small (5 L) vessels demonstrated that all predators showed opportunistic foraging as the mosquito:chironomid ratio changed, with some evidence that mosquito larvae were positively selected over chironomids. In particular, Anisops showed strong electivity for mosquitoes when presented with any ratio of large mosquito and chironomid prey in the high density experiment, although the preference was not expressed in lower density (2.5 prey L -1 ) treatments executed in 40 L vessels. In these lower density treatments, D. rusticus demonstrated higher electivity for mosquitoes when the mosquito:chironomid ratio was high, consistent with non-significant trends observed in the higher density experiment. The positive electivity of D. rusticus for mosquitoes was reinforced in an experiment executed over 16 days at varying prey ratios, in which D. rusticus mosquito electivity was high and consistent while D. annulatus showed slight avoidance of mosquito larvae, and Anisops remained largely opportunistic in foraging on prey in proportion with availability. Anisops and D. rusticus are potentially good biocontrol agents for mosquito larvae, in that they preferentially consume mosquitoes under many circumstances but can readily forage on other prey when mosquito density is low.

Sex chromosome differentiation in Belostoma (Insecta: Heteroptera: Belostomatidae)

“…These are animals with predatory habits, and their ecological importance lies in the role they play as biocontrol agents, where aquatic arthropods, fish, and amphibians are its main prey (Cullen et al, 1969;Saha et al, 2010).…”

Predators ofAnopheles gambiaesensu lato (Diptera: Culicidae) Larvae in Wetlands, Western Kenya: Confirmation by Polymerase Chain Reaction Method

“…arabiensis DNA (Table 1). Although it has been suggested that Belostomatidae are important mosquito predators (Saha et al 2007(Saha et al , 2010, this family was found to have the lowest positive rates of the Hemiptera included in our study. A previous serological study (Service 1977) also showed that the positive rate in Belostomatidae (genus Sphaerodema) was lower than for other Hemipteran species.…”

Effects of water bugs on crustacean zooplankton in a shallow littoral zone

“…Previous observations have devoted much attention to the Notonectidae, which have a significant influence on the regulation of water invertebrates and even young fish and amphibians (Louarn and Cloarec, 1997;Kopp et al, 2006;Vandekerkhove et al, 2012). It has been demonstrated that they can be effective regulators of mosquitoes and help to control them, and that, if necessary, they can also feed on Chironomidae (Saha et al, 2008(Saha et al, , 2010. As shown in small water bodies, they can regulate the abundance and diversity of the entire invertebrate population (including plankton), as confirmed by experiments similar to those presented in our study (Eitam and Blaustein, 2010).…”