title: Fate of Bacillus sphaericus 1593 and 2362 spores used as larvicides in the aquatic environment.
abstract: Dry powders produced from insecticidal Bacillus sphaericus strains 1593 and 2362 were applied against Culex tarsalis and Anopheles franciscanus mosquito larvae in small-plot field trials. Good control of C. tarsalis, but not of A. franciscanus, was produced at 0.1 and 0.2 lb/acre [ca. 0.122 and 0.244 kg/ha]. B. sphaericus spores settled rapidly from upper water layers and accumulated in bottom muds. Control of third/fourth-instar C. tarsalis larvae was maintained through day 4 after testing and was related to the presence of at least 100 spores per ml in the upper water layer 2 days earlier. B. sphaericus was shown to recycle in dead larvae both in the laboratory and in the field, producing an increase of 100- to 1,000-fold in spore numbers. There was no evidence of recycling in treated water nor of significant spore persistence upon reflooding of ponds after a very hot, dry period.
mesh_terms: D000818:Animals; D000852:Anopheles; D001407:Bacillus / Q000502:physiology*; D003465:Culex; D007814:Larva; D009032:Mosquito Control / Q000379:methods*; D010572:Pest Control, Biological / Q000379:methods*; D013171:Spores, Bacterial; D014871:Water Microbiology