On the Bionomics of Bromeliad-Inhabiting Mosquitoes X. Toxorhynchites r. rutilus as a predator of Wyeomyia vanduzeei (Diptera: Culicidae)

In southern Florida, USA, predatory larvae of Toxorhynchites r. rutilus sometimes cohabit leaf axils of the bromeliad Tillandsia utriculata with larvae of Wyeomyia vanduzeei and Wy. mitchellii . Weekly sampling during 1973–1975 showed that late-instar Wyeomyia larvae were more numerous in bromeliads containing Toxorhynchites . Laboratory trials evaluated effects on Toxorhynchites of a range of prey availability (daily prey density in artificial containers) using Wy. vanduzeei larvae as prey. Larval development time varied inversely with prey availability. Pupal weight varied inversely with larval development time. Fecundity of Toxorhynchites varied with pupal weight. Survival of late-instar predator larvae was poor when prey were few, and survival of 1st-instar larvae was reduced when prey were large. All instars killed some prey without consuming them. Development time of pupae was a constant 4 to 5 days and was 21% of the total larval and pupal development time at highest prey availability. The small percentage (5%) of Toxorhynchites pupae collected in the field was attributed primarily to slow larval development resulting from few prey. Though hundreds of prey larvae were present in each Tillandsia, Toxorhynchites larvae were confined to individual leaf axils and did not have access to enough prey to permit rapid development.