Field evaluation of Bacillus thuringiensis var. israelensis for control of black flies in the North Littoral Zone of Brazil's São Paulo State.

The impact of three flowable concentrate formulations of Bacillus thuringiensis var. israelensis (H-14) upon Simulium pertinax larvae was evaluated in 24 coastal streams of Brazil's São Paulo State. While no significant differences were found regarding the three formulations' effectiveness, significant correlations were found between the discharge rates of individual streams and the distances over which at least two of the formulations were carried effectively downstream to produce 80% mortality. The relatively short carry distances found for small streams could pose difficulties for control programs that need to treat large numbers of such streams, and suggests a need for research directed at increasing the distances B. thuringiensis (H-14) formulations can be carried.