Comparison of DNA probe and cytogenetic methods for identifying field collected Anopheles gambiae complex mosquitoes

A recently developed DNA probe method was compared with the standard cytogenetic method for identifying the species of individual mosquitoes in the Anopheles gambiae complex. The complex consists of 6 morphologically indistinguishable sibling species that include the major African malaria vectors. Half-gravid, field collected mosquitoes were split into 2 portions: the abdomen was preserved for ovarian nurse cell cytotaxonomy and the head/thorax portion was desiccated for DNA extraction. Cytogenetic examination of the Kenya specimens showed 88 An. gambiae and 108 An. arabiensis. The Zimbabwe specimens consisted of 6 An. gambiae and 55 An. Quadriannulatus. All samples of the 3 species were polymorphic for the major chromosomal inversions previously recorded in field specimens from eastern and southern Africa, indicating that the collections reflected natural levels of intraspecific variation in the field populations sampled. Approximately 97% of the cytologically identified mosquitoes were also identified to species by the DNA probe method, and in every case the DNA probe and cytogenetic methods of species identification produced concordant results.