SURVEY OF MOSQUITO PREDATORS IN DHAKA DISTRICT AND AN ASSESSMENT OF THEIR PREDATORIAL CAPACITY AGAINST MOSQUITO (Culex sp.)

Abstract

Two experiments were conducted on the survey of mosquito predators in Dhaka districts and an assessment of their predatorial capacity against immatures of mosquito/Culex annulirostris during the period of October, 2018 to February, 2019. For survey water logged area in Dhaka city and selected water logging areas of Dhaka district (different upazila nearby Dhaka city and selected different location or point in Dhaka city) in Bangladesh were selected to find out the inspection of mosquito‘s predators. As a result, the order of survey of mosquito predators found in terms of plenty of the different locations were different upazila nearby Dhaka city > selected different point in Dhaka city. Lab experiments were laid out in a Completely Randomized Design (CRD) with five replications. Firstly three aquatics predators such as Giant water bug, Belostomata indica; Diplonychus bug, Diplonychus sp and Water striders, Aquarius adelaides were used to determine the mosquito consumption capacity for assessment of their predatorial capacity against mosquito (C. annulirostris). Secondly, the experiment consists of six treatments to determine the immature mortality of mosquito for assessment of predatorial capacity of mosquito predators . Six treatments, viz. T =Water Boatman Nymph + Low density (20 Larvae); T 2 1 = Water Boatman Nymph + High Density (40 Larvae); T = Water Boatman Adult + Low Density (20 Larvae ); T 4 3 = Water Boatman Adult + High Density (40 Larvae ); T =Water Strider + Low Density (20 Larvae); T =Water Strider + High Density (40 Larvae) were used. In considering percentage of mosquito consumption by aquatic predators in different hours on the multifarious developing stages of mosquito, larval consumption rate and predatorial capacity was the highest in Giant water bug, Belostomata indica , whereas the lowest in Water striders, A. adelaides. But the highest percentage of mosquito pupae consumption capacity was in Diplonychus bug, Diplonychus sp, the lowest percentage of mosquito consumption capacity in Giant water bug, B. indica and no mosquito consumption capacity (0.0%) recorded in aquatic predator Water striders, A. adelaides. In considering the predatory potentiality, the highest percentage of mortality after different days, in case of 1 6 st , 2 nd , 3 rd , 4 th instar larvae and pupae of mosquito were observed from T treatment, whereas the lowest percentage of mortality were recorded in T 5 3 treatment, but in case of 4 th instar larvae and pupae of mosquito the lowest percentage of mortality were recorded in T treatment. The percentage mortality rate decreased with the increase of prey size. But, the predatory capacity of adult was observed higher than the nymph.