Feeding preference and efficiency of mosquito fish, Gambusia affinis and its density in the natural water resources of higher altitude areas of The Nilgiris, Western Ghats, India

The mosquito fish, Gambusia affinis is the best alternative to insecticides and a good biological control agent. The mosquito fish collected from natural water resources, is about 2000 meter above mean sea level areas viz. Avalanche, T.R.Bazaar, Gori, Murlimund, Katteri and Ralia Dam are located in the Ooty and Coonoor Taluks of Nilagiri district of Tamil Nadu state. In order to assess the food preference of G.affinis in the natural water resource i.e. affinity towards mosquitoes immature, individual mosquito fish 50 numbers from every area were dissected the gut content and examined for the remnants of mosquito larvae, zooplanktons and other food and further estimated in terms of percentage. The result indicates that except at T.R.Bazaar and Murlimund the presence of mosquito larvae in the gut content is almost zero. The mosquito larvae forms food share 12.0% and 9.0 % in T.R.Bazaar and Murlimund, respectively. Gut content analysis shows that the other prey forms the major share in all the natural water than mosquito immature. Due to cold climate prevailing in the higher altitude areas, density of mosquitoes immature was recorded very low and it may be the limiting factor.