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.
Description:
A Thesis
Submitted to Department of Entomology,
Faculty of Agriculture.
Sher-e-Bangla Agricultural University,
Dhaka-
In partial fulfillment of the requirements for the degree of
MASTERS OF SCIENCE (MS)
IN
ENTOMOLOGY
