Comparative studies on sibling species of the Anopheles gambiae Giles complex (Dipt., Culicidae). III. The distribution, ecology, behaviour and vectorial importance of species D in Bwamba County, Uganda, with an analysis of biological, ecological, morphological and cytogenetical relationships of Ugandan species D

Abstract

AbstractStudies on mosquitoes of the Anopheles gambiae Giles complex at Bwamba, Uganda, showed that the newly recognized sibling species D may be restricted to breeding areas where waters contain unusual solutes, the effluent from hot springs at Buranga being particularly favourable. Two other members of the complex, species A and B, were also detected in the neighbourhood apparently breeding only in more normal situations. Species D specimens were usually identified cytotaxonomically, from the presence of XR potytene chromosomes of the type also occurring in species C and A. melas (Theo.) (neither of which is known from the area). Most species D females have distinctively pale palps, a valuable although limited distinguishing feature. Features of setation on larvae and pupae were discerned which might serve usefully as meristic chaetotaxonomic factors, at least locally, if tested further. Although it is unquestionable that a large proportion of species D females forage in the Semliki forest, feeding on primates, bovids, suids or unsuspected hosts, it was demonstrated that many species D females are markedly anthropophilic and display strong endophilic and endophagic tendencies, to the extent that they may be primary vectors of human malaria and filariasis over a limited range. Species D males were rare indoors and remained mainly within the forest, where great numbers rest low on vegetation in company with unfed females, near to breeding areas of brackish marsh. Two polymorphic chromosomal inversions in species D apparently embody the genetical causes of its differentiation. Cytogenetical evidence indicates that species D is phylogenetically nearly intermediate between A. melas and species C of the A. gambiae complex.