EFFICACY OF THREE INSECTICIDES AGAINST MANGO MEALYBUGS ( MEALYBUGS ( Drosicha mangiferae GREEN) DEPA R SHER-E-BANG L DH A INSECTICIDES AGAINST MANGO

Abstract

The experiment was conducted at Entomology laboratory and field of Sher-e-Bangla Agricultural University campus, Dhaka during the period from January 2021 to May, 2021 to study the efficacy of insecticides against mango mealybug. Three insecticides namely Thiodicarb (Larvin 75WP), Chlorpyriphos (Dursban 20EC), Emamectin benzoate (Emamectin benzoate 1.9EC) with different doses were tested on different stages of mango mealybug. In field the experiment was laid out in randomized complete block design (RCBD) and in laboratory it was set in completely randomized design (CRD) with four replications. The highest mortality of 1 st instar nymph of mango mealybug (88.25% in laboratory and 83.33% in field) was found in T

(Chlorpyriphos 3.0 ml/L) treated insects followed by (88.25% in laboratory and 64.67% in field) in T (Chlorpyriphos 2.5 ml/L) treated insects after 72 hrs of spray. In 2 nd 5 instar nymph of mango mealybug highest mortality (76.25% in laboratory and 42.33% in field) was also found in T (Chlorpyriphos 3.0 ml/L) after 72 hrs of spray. At 3 rd 6 instar nymph highest (16.25%) mortality was found in T (Chlorpyriphos 3.0 ml/L) at laboratory but in field, 15.33% mortality was found in T 6 which was statistically similar with T (Thiodicarb 3.0 gm/L) and the mortality was 15.67%. In case of adult female mango mealybug after 72 hrs of spray T 3 (Chlorpyriphos 3 ml/L) showed the highest (9.00%) mortality in laboratory. Lowest mortality was found in Emamectin benzoate at all doses and all life stages of mango mealybug. First instar nymph was more vulnerable to insecticides. The order of susceptibility of the different stages of mealybug was 1 st instar nymph> 2 nd 6 6 instar nymph> 3 instar nymph> adult against insecticides.