Impact of urbanization on bionomics of An. culicifacies and An. stephensi in Delhi.

Study on bionomics of malaria vectors was carried out in riverine and non-riverine areas, on account of tremendous ecological changes in the topography of Delhi. The densities of adult anophelines were estimated by two techniques, hand catch and total catch index. Percentage of An. stephensi (15.68) collected by both the techniques was more than An. culicifacies (3.16) in both the areas. Day-time resting preferences of vector species in human dwellings and cattlesheds did not differ significantly. Preferred larval habitats of An. culicifacies in riverine area shifted to large lakes, channels and ponds. In malaria transmission, An. culicifacies played a role only in the northern part of the riverine area where water pollution was at minimal level, while An. stephensi played an equal role in the malaria transmission in both the areas. High sporozoite rates were found in type form of An. stephensi in localities where its proportion was high, thus confirming its active role in malaria transmission. The overall sporozoite rate of vectors was 0.7 per cent and P. falciparum sporozoite infections of the vectors were detected in An. stephensi only. P. vivax and P. falciparum infections were found in the ratio of 68:32. The non-riverine area was more malarious than the riverine area.