Comparative Field Trials of Bacillus sphaericus Strain 1593 and B. thuringiensis var. israelensis Commercial Powder Formulations

Abstract

Dry powder commercial formulations of Bacillus sphaericus Neide 1593 and B. thuringiensis var. israelensis deBarjac were applied to test ponds at dosages equivalent to 0.5, 1, and 2 kg/ha. Natural populations of the Australian encephalitis vectors, Culex quinquefasciatus Say and C. annulirostris Skuse, and a potential malaria vector, Anopheles annulipes Walker, were controlled at 1 and 2 kg/ha. No evidence of residual activity beyond day 2 was seen in assessment of natural repopulation of ponds or in mortality of caged larvae confined in test ponds. B. sphaericus 1593 and B. thuringiensis var. israelensis were very similar in efficacy in these tests.