Laboratory efficacy tests for fungal metabolites of Chrysosporium tropicum against Culex quinquefasciatus.

Efficacy of fungal metabolites of Chrysosporium tropicum was evaluated against Culex quinquefasciatus larvae in the laboratory to determine their larvicidal activity at 6 concentrations, with a mortality range of 10-95%. Efficacy of C. tropicum was analyzed by probit analysis procedures. The LC50 (concentration lethal to 50% of the population) values were 38.9, 63.7, 79.0, and 122.6 microl/ml for the 1st, 2nd, 3rd, and 4th instars, respectively. The LC50 values were 79.5, 95.6, 136.9, and 174.5 microl/ml against the 1st-, 2nd-, 3rd-, and 4th-stage larvae, respectively. Lethal concentrations of fungal metabolites were significantly different among the 4 instars. The 1st-stage larvae were most susceptible, whereas 4th instars were least susceptible to C. tropicum metabolites. The larvicidal potential of C. tropicum metabolites warrants field trials against various species of mosquitoes.