Resistance to the Bacillus sphaericus toxin in cultured mosquito cells.

Increasing doses of Bacillus sphaericus toxin were used to select a toxin-resistant cell line from the Culex quinquefasciatus line. This resistant cell line was proven to be C. quinquefasciatus in origin by isozyme analysis and karyotype. The resistant line bound fluorescent-labeled toxin as did the unselected susceptible line. A high level of resistance was quickly achieved, and this level was maintained after 4 mo. culture in the absence of toxin.