BIORATIONAL MANAGEMENT OF MOSQUITO LARVAE IN BANGLADESH

Abstract

The present study evaluated the efficacy of nine larvicides for bio-rational management of mosquito larvae in Bangladesh from 30 September 2018 to 11 February 2019. Experiment was conducted in the laboratory of SAU and insecticides used in this experiment are spinosad, emamectin-benzoate, pyrazine, buprofezin, cyfluthrin, lambda-cyhalothrin, temephos, neem seed kernel extract, neem leaf extract at different concentration. Dosages used in this experiment were; spinosad (dose:1 ppm, 2 ppm, 5 ppm and 10 pmm), cyfluthrin (dose: 1 ppm, 2 ppm, 5 ppm and 10 pmm), lambda-cyhalothrin (dose:1 ppm, 2 ppm, 5 ppm and 10 pmm), pyrazine (dose: 25 ppm, 40 ppm, 80 ppm, 160 ppm), emamectin-benzoate (dose: 25 ppm, 40 ppm, 80 ppm, 160 ppm), buprofezin (5 ppm, 10 ppm, 20 ppm, 40 ppm) temephos (10 ppm, 5 ppm, 2 ppm, 1 ppm) and two botanical as neem leaf extract(dosages: 30000 ppm, 50000 ppm, 100000 ppm, 200000 ppm) and neem seed kernel extract(dose:1.0 ppm, 2.0 ppm, 5 ppm,10 ppm). Of the nine larvicides tested lambda-cyhalothrin gave the lowest median lethal concentration of LC 0.000848 thereafter temephos gave second lowest median lethal concentration of LC 50 0.00114 after 48 hours and spinosad gave third lowest median lethal concentration of LC 50 0.00433. It was followed by cyfluthrin with LC 50 1.1067, buprofezin with LC 50 50 1.7650, neem seed kernel with LC 50 2.3360, pyrazine with LC 50 6.0700, emamectin-benzoate with LC

7.5823 and neem leaf extract gave median lethal concentration of LC 10534. From the study it was revealed that order of toxicity of nine larvicides is lambda-cyhalothrin > temephos > spinosad > cyfluthrin > buprofezin > neem seed kernel extract > pyrazine > emamectin -benzoate > neem leaf extract. Mortality percentage also calculated to find out the efficacy of nine larvicides. Lambda-cyhalothrin and temephos gave highest mortality percentage of 100% after 48 hour. From the study we found the order of mortality percentage of nine larvicides is lambda-cyhalothrin > temephos > spinosad > pyrazine > emamectin-benzoate > buprofezin > neem seed kernel extract > neem leaf extract > cyfluthrin. Considering environmental safety temephos and spinosad could be effectively used for mosquito larvae control in stagnant water bodies and lambda-cyhalothrin in small containers retaining water temporarily with appropriate dosages.