RECORDS OF THE BREEDING OF 'SALTWATER ANOPHELES GAMBIAE' AT INLAND LOCALITIES IN SOUTHERN AFRICA.

Abstract

RECENT1–5 work has shown that at least four genetically distinct forms comprise the A. gambiae complex. Paterson6 has outlined arguments for regarding them as separate species. On the eastern half of Africa three species occur, ‘saltwater A. gambiae’ and the two freshwater-breeding species, species A and species B (= group A and group B3). These forms are apparently morphologically inseparable, though the frequency of females bearing four white bands on their palps, as against three, is usually much higher in populations of ‘saltwater A. gambiae’ than of the two freshwater-breeding species. Identification of the species is best achieved by performing crossing experiments with ‘type’ colonies of the different species. Interspecific crosses produce sterile F1 males1–4 with testes and accessory glands reduced to varying degrees according to the cross and its direction. In crosses between ‘saltwater A. gambiae’ and either species A or species B, F1 sex ratios supply further information1,2,4, but crosses between the two freshwater species usually produce normal sex ratios4. A physiological test (salinity-tolerance test) is available7 to distinguish first stage larvae of ‘saltwater A. gambiae’ from those of either species A or species B.