FITNESS OF A TREEHOLE MOSQUITO - INFLUENCES OF FOOD TYPE AND PREDATION

Leaves and flowers, the two main components of oak litter, were compared in the laboratory as growth substrates for larval Aedes triseriatus. Time to pupation was significantly faster and adult size significantly greater when flowers were the resource. Fitness, as measured by a composite index of performance (r'), was significantly higher among cohorts reared on flowers. A subsequent field experiment compared r' of cohorts developing in water-holding automobile tires, a common alternative habitat for treehole mosquitoes. In tires protected from oviposition by predatory Toxorhynchites rutilus, A. triseriatus larvae were offered equal amounts of dried oak leaves or flowers, or no particulate food. A fourth treatment exposed larvae to predation. The presence or absence of particulate litter and predator access, but not litter type, significantly affected the fitness of A. triseriatus. Female mosquitoes produced from tires with flowers were significantly larger than those from tires with leaves, but this effect did not significantly influence r'. We conclude that the presence or absence of particulate detritus and of a larval predator are more important determinants of adult fitness than food type, although the vernal input of flowers may enhance the seasonal growth of A. triseriatus larvae.