Observations on the distribution of the Anopheles gambiae complex in Tanzania.

Adult male and female mosquitoes of the Anopheles gambiae group of species from fourteen localities in Tanzania were studied using either chromosomal inversions, enzyme electrophoresis or both techniques. The 6481 specimens analyzed consisted of 64.4% An. gambiae, 33.6% An. arabiensis, and 2.0% An. merus, but no An. quadriannulatus. An. gambiae and An. merus are reported from Zanzibar for the first time. An. merus was recorded at Buiko, 167 km inland. An. arabiensis is the predominant or exclusive species in dry and semi-arid areas. An. gambiae predominates or is the only species in humid coastal and humid lacustrine areas.