Electrophoretic and DNA identification of Anopheles bwambae and A. gambiae (Diptera: Culicidae) in western Uganda

Abstract

AbstractCollections of mosquitoes of the Anopheles gambiae Giles complex were made from the geothermal springs and surrounding area in the Semliki Valley, Bwamba County, Uganda, which is the only known locality of A. bwambae White. Specimens were analysed in one of three ways: rDNA-PCR for unequivocal species identification, allozyme electrophoresis to determine superoxide dismutase (Sod) and octanol dehydrogenase (Odh) genotypes, or both methods. Ribosomal DNA-PCR identification revealed the presence of A. bwambae and A. gambiae. Allozyme electrophoresis of 181 individuals showed that A. bwambae possessed the Sod105and Sod100 alleles and was not monomorphic for Sod105as reported previously. In adults reared from collections made in the vicinity of the geothermal springs, the frequency of Sod105 was found to be 0.614. Anopheles gambiae was fixed for Sod100. The majority of individuals homozygous for the Sod100 allele could be identified to species using Odh. Odh95 was found to be common in A. bwambae (frequency = 0.988) while A. gambiae appeared to be fixed for Odh100. Since Odh100occurred at a frequency of 1.2% in A. bwambae (concomitant with Sodgenotypes of 105/105, 100/105 or 100/100), individuals homozygous for Sod100 and Odh100 could be either species. Among 25 A. bwambae specimens homozygous for Sod100, one (4%) was also homozygous for Odh100. At present, this subset of the A. bwambae population can only be correctly identified to species using rDNA-PCR analysis.