Testing the susceptibility of Simulium damnosum (Diptera: Simuliidae) to insecticides in the laboratory and in the field.

There are several methods for measuring the susceptibility of blackfly larvae to insecticides. In 1970 the provisional method suggested by the World Health Organization was used with a view to establishing baseline data on the susceptibility of S. damnosum larvae to insecticides; this method was found to be unsuitable. Thereafter, attempts were made to develop a reliable susceptibility testing method for S. damnosum. This report describes the method that yielded the best results in the laboratory; a second method suitable for use in the field is also described. The results from several replicates of such tests gave reasonably straight log-dosage-probit-mortality curves from which values of LC(50) could be calculated. The overall control mortality in the laboratory series of tests was about 9% and that in the field series was about 4%.