SEASONAL DENSITY AND MALARIA VECTOR COMPETENCE OF ANOPHELES MINIMUS AND OTHER ANOPHELINES AT A SHALLOW VALLEY IN NORTH THAILAND

Biting density of anopheline mosquitoes was monitored in both the rainy and dry seasons at 6 outdoor stations in two villages of north Thailand by 3 human and I water buffalo bait. A total of 19 Anopheles was collected. The most predominant species were An. vagus and An. annularis. They were followed by An. hyrcanus group, An. minimus. An. aconitus. An. nivipes and An. kochi. The rest species were not abundant. The fauna of Anopheles changed seasonally. An. minimus. An. aconitus and An. barbirostris were abundant in the dry season, while An. maculatus sensu lato, An. kochi. An. tesselatus. An. vagus. An. annularis and An. hyrcanus group were the rainy season Anopheles. The 'crude feeding index' was relatively high in An. maculatus and An. minimus. They were followed by An. tesselatus and An. splendidus, while that of An. vagus and An. kochi was less than 1/10 of An. minimus. An. minimus was regarded as the most important vector. The biting density of An. minimus was higher at the peripheral area of villages with scarce dwellings and rich vegetation. At stations with dense dwellings and adjoining to an open field, the density of An. minimus was low, and the malaria risk was probably higher.