Abstract:
The experiment was conducted at the Farm of Sher-e-Bangla Agricultural
University, Sher-e-Bangla Nagar, and Dhaka, Bangladesh to evaluate the effect
of sowing time and lentil (Lens culinaris) varieties on incidence of insect pests
and their predators during the period from October 2008 to April 2009. The
experiment comprised two factors, viz., Factor A: Sowing time (4 levels) - S1:
Sowing on 06 November, S2: Sowing on 16 November, S3: Sowing on 26
November and S4: Sowing on 06 December; Factor B: Variety (4 levels) - V1:
BARI Masur-3, V2: BARI Masur-4, V3: BARI Masur-5 and V4: BARI Masur6.
The experiment was laid out in Randomized Complete Block Design
(RCBD) with three replications. Incidence of insect pests was recorded for the
entire cropping season. Aphid, whitefly, jassid, pod borer were found as insect
pests and spider, lady bird beetle were predators of these pests. In consideration
of sowing time, the lowest number of aphid, whitefly, jassid, pod borer, spider
and lady bird beetle (4.07, 1.89, 2.55, 1.88, 2.00 and 2.69, respectively) was
recorded from S3 while the highest number (5.48, 2.28, 3.30, 2.42, 2.57 and
4.46) was found from S1. On the other hand, the minimum number of aphid,
whitefly, jassid, and pod borer, spider and lady bird beetle (4.56, 2.03, 2.83,
2.07, 2.36 and 3.97) was recorded from the variety V4 while the highest
number of insect pests (5.74, 2.37, 3.43, 2.54, 2.31 and 4.41) was found variety
from V1. Combined, the highest number of aphid, whitefly, jassid, pod borer,
spider and lady bird beetle (6.93, 2.70, 4.03, 2.07, 3.00, 2.87, 5.53) from S1v1
treatment combination and the lowest number (3.67,1.80,2.27,1.67,1.47, 2.10)
from S3V3. At early, mid and late fruiting stage, for different sowing time,
variety and their combined effect showed a statistically significant variation in
number of healthy pods, infested pods per plant and percentage of infestation.
