Eco-ethological heterogeneity of the members of the Anopheles minimus complex (Diptera: Culicidae) in Southeast Asia and its consequences for vector control.

The presence of cryptic species within Anopheles minimus s.l. Theobald, one of the most widespread malaria vectors in Southeast Asia, was suggested on the basis of behavioral heterogeneities observed within this taxon. Subsequently, two species, A and C, were recognized. However, the existence of these cryptic species did not explain all observed behavioral heterogeneities within this complex. Besides, data on the behavior of vectors are essential to understand the dynamics of disease transmission and thus evaluate the appropriateness of vector control measures. Different collection methods were used to collect Anopheles species from several localities in Southeast Asia to assess the inter- and intraspecific behavioral divergences of An. minimus A and C. Collection results were subjected to a correspondence analysis. The members of the An. minimus complex were identified by use of the octanol dehydrogenase allozyme profiles or the polymerase chain reaction-restriction fragment length polymorphism assay. Large intraspecific behavioral differences were observed among populations of An. minimus A. These populations belong to the same species on the basis of the applied genetic markers. In northern Vietnam, species A tended to be more zoophilic, whereas in the study sites of south central Vietnam, Cambodia, and Laos it showed marked antropophilic behavior when cattle were scarce. In the most northern study site, An. minimus A showed noteworthy endophilic behavior. An. minimus C was primarily zoophilic and based on this behavior, its role in malaria transmission is questionable. However, it was only found in one locality, so that intraspecific behavioral variation could not be assessed. An. minimus A is able to change its host preference in function of local situations in host availability. Hence, its role in malaria transmission can differ from region to region. Similarly, the impact of vector control on this species may differ between localities. In conclusion, intraspecific behavioral differences in Anopheles species can occur and these behavioral heterogeneities, albeit important for disease transmission and control, are not a priori indicative for the presence of cryptic species.