Importance of aquatic plants Pistia stratiotis and Eichhornia crassipes in refreshment of environment and in biological control of mosquito larvae on field level

The aquatic plants Pistia stratiotis commonly called as water lettuce and Eichhornia crassipes commonly called as water hyacinth were used for biological control of mosquito larvae with locally available, larvivorous fish, Tilapia mossambicus commonly called as Mozambique or mouth breeder. The two types of plants and the fish gave interesting and satisfactory results. The plants were released @ 10 plant/m2, while the fish @ one fish/m2. The plants and the fish was used in sewage, stagnant and polluted water, in which mostly the Culex spp. of the mosquito develops. The fishes were released after one week of the release of plants. Both plants were released 50% each (5+5=10 plant/m2) in the beginning stage to see the successful propagation of the plant type. The successful plant was used in that area and the observations were made weekly in the start for one month and then after the successful propagation of the plants, on monthly basis. The observations were made up to six months, on monthly basis. The results were recorded, tabulated and analyzed. The satisfactory results were achieved in six months giving maximum, and better results. Both plants, covered the surface of water, reduce the area of water, cleaned the water, and suppressed the bad smell of sewage water. Whereas the fish predated on the mosquito larvae, and the larvae population was reduced remarkably in six month. The population of mosquito larvae remained controlled up to 99%. The environment of that experimental place becomes odourless, giving beautiful scene (Nazara). As the P. stratiotis and E. crisspies are the main breeding host of Anopheles and Mansonia mosquitoes, therefore in the present work the Tilapia fish was used which not only controlled the Culex mosquitoes in sewage water but also controlled the population of Anopheles, Aedes and Mansonia mosquitoes in this experiment.