Advances in the study of Afrotropical malaria vectors.

The advances in the study of Afrotropical malaria vectors outlined in this report were obtained with the support of the EC-STD2 program by a network led by a research team of the Istituto di Parassitologia, University of Rome "La Sapienza" and including various collaborators based in different African countries. A list of authors and collaborating laboratories is given in the acknowledgements. The main results obtained are as follows. 1) Discovery of new chromosomally recognized taxa of the An. gambiae complex in Mali. One of them, the Mopti chromosomal form, is specifically adapted to breeding during the dry season and replaces other members of the complex in irrigated areas also in Burkina Faso and Northern Benin. 2) Evidence for increasing potential for P. falciparum transmission in the area of Cotonou (Benin) where highly anthropophilic An. gambiae (fresh water breeder) replaces the less effective vector An. melas (salt water breeder) when lagoon pile-dwelling traditional villages are converted into unplanned urban settlements. 3) Analysis of the vector system responsible for the P. falciparum epidemics on the Madagascar plateau showing the absence of An. gambiae, the secondary role of An. arabiensis (characterized by zoophilic and exophilic behaviour) and the primary role of An. funestus which is characterized by a peculiar focal distribution presumably depending on larval overwintering. 4) Evidence for a role for An. pharoensis (or at least of one of the taxa of this complex) in the transmission of P. falciparum malaria in the Senegal river delta. 5) Evidence for bionomical differences between An. gambiae and An. arabiensis and for intraspecific heterogeneities in both taxa associated with paracentric inversion polymorphisms.