Larval habitats and species composition of mosquitoes in Darjeeling Himalayas, India

BACKGROUND & OBJECTIVES: A preliminary survey of larval mosquito habitats and temporal variation in mosquito diversity in the hill town of Darjeeling, India was made during 2003, for a qualitative and quantitative assessment of mosquito distribution. METHODS: The possible larval habitats of mosquitoes were surveyed and the species diversity in the sites positive for mosquito larvae was noted. Bi-weekly sampling from a particular habitat was carried out to reveal the temporal variation in mosquito species. RESULTS: A good number of lentic aquatic habitats were found to be hosting mosquito immatures, though difference in the physical and biological features of these habitats was prominent. Altogether, immatures of six mosquito species, belonging to four genera--Aedes, Armigeres, Culex and Toxorhynchites were noted with significant difference in temporal variation in their relative and absolute numbers. A positive correlation (r = + 0.707) was found between population of the prey mosquito immatures and the population of immatures of Tx. splendens. The species diversity index (H') for the mosquitoes remained between 0.87 and 1.53. The evenness components ranged between 54.03 and 95.03% and differed significantly. INTERPRETATION & CONCLUSION: In the present study, the aquatic bodies could be categorised into six types depending on the size and structural complexity that may account for the observed variation in the species composition of the larval habitats. In addition to this, other factors like temperature, rainfall and other related climatic attributes may be responsible for the observed species variation, which needs to be confirmed through further studies.