Identification of two species within the Anopheles minimus complex in northern Vietnam and their behavioural divergences

Elucidating the complex taxonomic status of the major malaria vector taxa a nd characterising the individual species within each complex is important f or understanding the complexity of the vector system in the south-east Asia n region and will allow to estimate the impact of vector control measures. This applies to countries such as Laos, Cambodia and Vietnam that spend abo ut 60% of their malaria control budget on implementing vector control activ ities. We used isozyme electrophoresis to clarify the Anopheles minimus s.l . species composition in northern Vietnam and identify behavioural divergen ces of individual species. Using different collection methods, adult mosqui toes were caught at monthly intervals from June to November 1995 in four vi llages. An. minimus s.l. could be distinguished from closely related specie s, An. aconitus and An. jeyporiensis, at the Octanol dehydrogenase (Odh) en zyme locus. Significant positive F-is values gave clear evidence of nonrand om mating within the An. minimus s.l. population. The highest heterozygote deficiency was observed at locus Odh, which was diagnostic for 2 sympatric AN. minimus species in Vietnam similar to the An. minimus A and C species k nown from Thailand. We found no evidence for restricted gene flow between m onthly samples, villages, or collection methods in either of the two An. mi nimus species. They occurred in sympatry, but in different proportions depe nding on the collection site, and had dissimilar resting and biting behavio urs. Thus a vector control strategy will have a nonuniform effect on the va rious components of this diverse vector system.