The distribution and chromosome polymorphism of Simulium dieguerense (Diptera: Simuliidae)

Simulium dieguerense has been identified from Senegal, Mali and Guinea, in the Western Zone of the World Health Organization/Onchocerciasis Control Programme thus considerably extending its known distribution and indicating the need to reassess its possible importance as a vector of human onchocerciasis. A distribution map based on these identifications has been drawn. Examination of the larval polytene chromosomes revealed the presence of a hitherto unreported sex chromosome system. About 90% of males and 17% of females were found to be heterozygous for an altered segment of the centromere region on chromosome I.