EFFECTS OF PREY DENSITY, PREY INSTAR, AND PATCH SIZE ON THE DEVELOPMENT OF THE PREDATORY MOSQUITO, TOXORHYNCHITES TOWADENSIS

Effects of prey density, prey instar, and patch size on the developmen t of the predatory mosquito larva, Toxorhynchites towadensis, were inv estigated in the laboratory. Survivors of I: towadensis showed differe nt developmental patterns in relation to prey age structure. All preda tory larvae in containers with only second instar prey developed into the third instar. However, in several containers with fourth instar pr ey, mortality of predators was observed. During the third instar, no p redatory larva died, but both prey density and prey instar significant ly affected the survival of predators during their fourth instar. Larg e prey size promoted large predator adults. and predatory larvae which grew up in small surface containers responded by developing to large sizes than those in large containers. Larval developmental time of the predators differed in each treatment. Duping first and second instars , faster predator development was observed in containers with small su rface areas and containing young prey individuals. However, when devel opment was enhanced by the presence of old prey individuals, no surfac e effect was observed. The fastest predator development was observed w ith prey of mixed instars and high density. This study suggests that a small surface container containing prey of mixed instars and high den sity is suitable for development of predators.