Reversal of low-level resistance to Bacillus sphaericus in a field population of the southern house mosquito (Diptera:Culicidae) from an urban area of Recife, Brazil.
A larval population of Culex quinquefasciatus Say from an urban area (Coque) of Recife, Brazil, submitted to selection with Bacillus sphaericus Neide for a 26-mo trial, was 10 times less susceptible to B. sphaericus and slightly more susceptible to Bacillus thuringiensis israelensis, compared with untreated populations. The low-level resistance to B. sphaericus was unstable in the absence of selection pressure. The LC50 of B. sphaericus to the Coque population declined gradually and attained a susceptibility level similar to that observed in a laboratory control colony 16 mo after the treatment period was interrupted. In parallel to the recovery of B. sphaericus susceptibility. Coque larvae also were as susceptible as laboratory larvae to B. thuringiensis israelensis.
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Departamento de Entomologia, Fundação Oswaldo Cruz (FIOCRUZ), Recife-Pernambuco, Brazil.
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D000818:Animals; D001407:Bacillus; D001938:Brazil; D003465:Culex; D007305:Insecticide Resistance; D009032:Mosquito Control; D010572:Pest Control, Biological