Five formulations of Bacillus thuringiensis var. israelensis (serotype H-14) were evaluated against larvae of eight mosquito species. In the laboratory, most species essentially showed similar levels of susceptibility to a given formulation. The range of activity of the various formulations against a given species was on the order of two- to sixfold. In general, the LC 90 against fourth-stage larvae ranged from 0.13 to 0.45 ppm, for high-potency formulations, to 0.45 to 0.9 ppm for low-potency formulations. Second instars were two to six times more susceptible than 4th instars to the various formulations. Under field conditions, the various formulations showed different activity levels. In clear, shallow, and nonvegetated water, the high-potency formulations yielded excellent control of larvae at rates as low as 112 to 280 g/ha. Formulations with low potency were needed at rates as high as 280 to 560 g/ha to yield effective control of larvae in these biotypes. None of the commercial formulations at mosquitocidal and fivefold these rates induced short-term effects on the dominant nontarget fauna. Mayfly and dragonfly naiads, diving beetle larvae and adults, and ostracods were not affected at the rates of 0.56 to 2.24 kg/ha of the formulations employed.
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Mulla et al. (1982) studied this question.