Anopheline population genetics.

Population genetic studies of vectors are essential for (i) the determinati on of their taxonomic status and consequently the definition of their vecto rial role in the transmission of pathogenic agents; (ii) the evaluation of the species genetic variability and the estimation of their capacities of a daptation to selection pressure; (iii) an estimation of gene flow among pop ulations in order to evaluate their degree of isolation and gene circulatio n, especially resistance genes, Among the malaria vectors taken as examples on three continents Africa, South-East Asia and Latin America, the large m ajority of the species showed an important polymorphism. The Gambiae Complex, which is by far the most studied one, includes at pres ent 7 species with the recent description of An. quadriannulatus A and B fr om Ethiopia. An. gambiae s.s. includes itself 5 chromosomal forms One of th em, the Mopti form, should be considered as a species unto itself For An. a rabiensis, a strong differentiation has been observed among the populations from Senegal and the Indian Ocean islands. The kdr mutation, which confers resistance to pyrethroid knockdown effect has never been found either in t he Mopti form, or An. arabiensis, indicating a restricted gene flow between these latter two and An. gambiae s.s. The speciation process of the Gambia e Complex seems to be a recent phenomenon due to environmental selection pr essure. Species of the Funestus Group are distinguishable by morphological characters. The genetic study of An. funestus s.s. did not show the presenc e of a complex, in spite of high polymorphism and population structure. Anophelines from eastern areas present an important biodiversity. The Minim us Complex includes two species, A and C, which are widely distributed in S outh-East Asia. Species A is strongly endophilic, on the contrary species C is at once more exophilic and zoophilic. The latter species might have bee n selected by DDT indoor house spraying. After numerous taxonomic investiga tions, the Dirus Complex includes now 7 species. In Latin America, An. pseudopunctipennis clustered into three geographic po pulations which are under a speciation process. One covers North America an d Guatemala, the other South America and Belize, whilst the last one is res tricted to Grenada island On the contrary, An. darlingi showed little morph ologic and genetic variability throughout the species geographic range sugg esting the existence of a single species. The main objective of these studies is to implement a more selective approa ch of vector control programs in relation to the incriminated species, thei r bioecology and their role in malaria transmission. The improvement of eff iciency and selectivity of vector control is becoming a major goal in order to make the best out of the available tools and control the impact of inte rventions on the environment Resume.