A Study of the Distribution and Abundance of the Adult Culex Mosquitoes in Ten Villages in Chitwan District Nepal

Abstract

The present study, aimed to determine the distribution of different Culex mosquito species on 10 village (5 VDCs) of Chitwan District, to determine the indoor and outdoor resting species presented in the study area and their relative density, to assess seasonal changes; to determine vector abundance and species composition in the study area and to determine the resting habit of mosquito species, was carried out from August-September, 2007 to March-April, 2008 in Chitwan District. During the study period, a total of 1197 Culex species were recorded. About 12 species were reported in post monsoon and only 5 species in pre monsoon season. A total of 718 and 479 Culex samples were collected from post monsoon and pre monsoon season. Highest samples (n=279) were collected from human dwelling and (n=226) from cattle shed in post monsoon and pre monsoon season respectively. Among 4 month September is most preferable month for the distribution of Culex species. About 12 species were recorded in September from Bramhapuri village (Patihani VDC) of Western Chitwan. Culex quinquefasciatus was most abundant species about 26.90% and 18.71% was recorded in post monsoon and pre monsoon season respectively. The indoor resting density (human) was highest (9.33) at 27.25ºc in post-monsoon, and lowest (0.72) at 21.75ºc in pre monsoon at Champanagar village. Highest indoor resting density of cattle (5.55) at 22ºc in Suryapur and lowest (0.70) was in Kholesimal at 25.37ºc in post monsoon. Highest outdoor density (0.22) at 22.5ºc was in Kholesimal and lowest (0) at 21.5ºc in Champanagar village in pre monsoon. Resting habit of Culex mimulus and Cx. tritaeniorhynchus was infinitive in post monsoon and pre monsoon respectively. Highest room density of Cx. quinuefasciatus (6.5) was recorded from Champanagar in post monsoon. The number of mosquitoes is positively correlated with temperature. The number of mosquitoes collected in post monsoon survey and pre monsoon survey is dependent. Effect of seasonal change, temperature, surrounding vegetation, monthly variation for distribution of mosquito species and their resting density is discussed.