Observations on nocturnal activity and man biting habits of malaria vectors, Anopheles fluviatilis, An. annularis and An. culicifacies in the hill tracts of Koraput District, Orissa, India.

Biting and feeding behavior of malaria vectors were studied in nine villages (5 from Jeypore zone and 4 from Malkangiri zone) of Koraput District. Man biting catches comprised of 16 anopheline species including the incriminated vectors of this area: An. fluviatilis, An. annularis and An. culicifacies. An. fluviatilis was predominant and biting of this species recorded indoors throughout the year in both the zones. The period, during which the biting activity peaked, was different between the two zones and consequently the time of peak transmission was also different between the zones. The biting activity was at its peak between 21.00 and 03.00 hours in both the zones. However, in cold season the biting activity peaked in the first quarter of the night in Jeypore zone. The anthropophilic index (AI) of An. fluviatilis was 26.2% in Jeypore and 83.7% in Malkangiri and of An. culicifacies the AI was 0.4% in Jeypore and 7% in Malkangiri. Analysis of gonotrophic stages of night resting females indicated that in Jeypore zone, the majority of An. fluviatilis female left indoors for outdoor resting before the completion of gonotrophic cycle, but in Malkangiri, the females remained indoors till the end of the gonotrophic cycle. The presence of full-fed females in night resting catches in Jeypore village further suggested that the females do not leave the house immediately after taking blood meal but rest for some time.