Following movements of resistant populations of Simulium soubrense/sanctipauli (Diptera: Simuliidae) by means of chromosome inversions.

Following larval insecticide treatment, resistance to the organophosphates temephos and chlorphorxim appeared in a population of the Simulium soubrense/sanctipauli group of the S. damnosum complex on the Bandama Rivers, Ivory Coast. Resistant populations were subsequently identified from other river basins in the north of Ivory Coast. A small chromosomal rearrangement, IIL-A, was found to be associated with resistant populations. Monitoring the presence of this inversion was used to detect the spread or resistance eastwards into untreated areas.