Abstract:
The experiment was conducted at the central farm of Sher-e-Bangla Agricultural
University, Sher-e-Bangla Nagar, Dhaka, Bangladesh to study the efficacy of
biorational insecticides in controlling thrips country bean in summer. The
experiment
consists of the following management practices: T
1
=Spraying Neem oil @3 ml/L of
water at 7 days interval, T
2
=Spraying Neem leaf extract @200mg/L of water at 7
days interval, T
3
= Mehgoni leaf extract@200mg/L of water at 7 days interval,
T
4
=Tobacco leaf powder@30mg/L of water at 7 days interval, T
5
= Spraying Spinosad
@0.4ml/L of water at 7 days interval, T
6
=Spraying Biotrin@1.4ml/L of water at 7
days interval and T
7
= Untreated control. The experiment was laid out in
Randomized
Complete Block Design (RCBD) with three replications. Data on number of thrips as
insect pest, plant, leaf, inflorescence and pod infestation, different yield contributing
characters and yield of summer country bean were observed. Among the seven (7)
treatments the lowest number of thrips (2.50 plant
ii
-1
) was
observed in T
5
(Spraying
Spinosad @0.4ml/L of water at 7 days interval), while highest number of thrips
(16.67 plant
-1
) was observed in T
7
(Untreated control). The highest percentage of
thrips reduction over control (85.50%) was observed in T
5 (Spraying Spinosad
@0.4ml/L of water at 7 days interval) treatment. The present study revealed that the
lowest number of thrips as insect pest and increased plant, leaf, inflorescence and pod
infestation, different yield contributing characters and
yield of country bean might be
obtained by using the treatment T
5
(Spraying Spinosad @0.4ml/L of water at 7 days
interval) besides T
6
(Spraying Biotrin@1.4ml/L of water at 7 days interval) performed
as second best treatment whereas, T
7
(Control) and T
3 (Mehgoni leaf
extract@200mg/L of water at 7 days interval) may protect the country bean at lowest
rate in summer. The highest (3.08) benefit cost ratio was obtained due
to application
of T
5
(Spraying Spinosad @ 0.4ml/L of water at 7 days interval) while the lowest
(2.26) in T
7
(control).
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
