The effectiveness of a combined bacterial larvicide for mosquito control in an endemic urban area in Brazil

Lysinibacillus sphaericus (Lsp) and Bacillus thuringiensis svar. israelensis (Bti) based biolarvicides have been applied in Culex or Aedes breeding sites in Agua Fria, a neighborhood in Recife City (Brazil), to control these vectors. The effectiveness of a single Bti/Lsp conjugated biolarvicide was evaluated in one subarea (SA2) of Agua Fria, compared to a contiguous subarea (SA1) where two individual formulations of biolarvicides were used, during a two-year trial. Potential breeding sites were recorded and treated bimonthly. In SA2 a significantly greater reduction of 65.7% in adult density of Culex quinquefasciatus was achieved in year-1 (P < 0.05), than the 43.8% observed for SA1, when compared to the pre-intervention period. In year-2 the lower density compared to preintervention was maintained in both areas. The average number of C. quinquefasciatus adults collected in SA2 decreased from 44.2 +/- 59.3 to 15.2 +/- 32.4 mosquitoes/house after year-1. A reduction in the Aedes aegypti adult population was not proven in SA2 but a significant decrease in egg density was detected in year-2, compared to year-1. The replacement of two bacterial larvicides with a single conjugated product has proved to be effective and can offer operational advantages for the control of coexisting species in breeding sites from endemic urban areas.