Predation byNotonecta undulata(Heteroptera: Notonectidae) on Larvae of the Yellow-Fever Mosquito

Abstract

In various laboratory tests, individual 2nd, 3rd, 4th, and 5th instars of Notonecta undulata Say consumed more Aedes aegypti (L.) larvae than either 1st instars or adults. Fourth and 5th instars consumed the greatest number of larvae. Although all mosquito larval instars were attacked, 2nd instars were killed most often. The mean number of larvae killed per hour increased with increasing prey density. Water temperature had no significant effect on predation rate. Starved adult N. undulata required about 3 hr of active feeding (equivalent to about 30 fourth instars of the mosquito larvae) before they became satiated. Adult backswimmers consistently selected mosquito larvae and pupae over 6 other aquatic prey types. The backswimmer's predatory behavior, elucidated by video recordings and microscope observations, suggests it is well suited to capturing mosquito larvae and pupae. Its ability to kill all aquatic stages of mosquitoes at some time in its life history suggests that N. undulata is well adapted as a predator of A. aegypti and that it warrants further consideration as a mosquito-control agent.