Estimation of Losses in Blackgram Due to Insect Pests
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Date
2013
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Publisher
MPUAT, Udaipur
Abstract
A field trial on, “Estimation of losses in blackgram due to insect pests” was
carried out at the Instructional Farm, Rajasthan College of Agriculture, MPUAT,
Udaipur during kharif 2012 with the objectives of recording the qualitative and
quantitative abundance of insect pests infesting blackgram; quantifying the associated
natural enemies; and estimating the losses caused by major insect pests at different
stages of crop growth. Jassids, aphids, whiteflies and thrips were the major sap
sucking insect pests; while, blister beetle and the spotted pod borer were recorded
during the post flowering stage. The sucking pest infestation began in August and
their numerical abundance peaked during September with 16.50 jassids per plant in
sole blackgram and 17.25 jassids per plant when blackgram was farmscaped with
niger; in a respective manner the numbers of whiteflies per plant were 26.50 and
24.75 on blackgram sole and blackgram with niger; 19.65 and 19.05 thrips per plant
in blackgram sole and blackgram with niger and likewise, 43.50 and 37.0 aphids per
plant, respectively during the last week of September. The maximum mean population
of blister beetle was 2.75 per plant in the sole crop of blackgram and 2.50 per plant in
blackgram with niger. The pod borer infestation was in traces. The mean density
values were the maximum for aphids on blackgram during the crop season
irrespective of whether blackgram was cultivated sole or with niger as barrier crop for
blister beetles. Natural enemies included coccinellids, the big-eyed predatory bug,
syrphid flies and spiders that were relatively more when blackgram was cultivated
with niger. The estimated avoidable loss due to insect pest infestation in blackgram
was 55.20 per cent when sole crop of blackgram was exposed to insect infestation;
21.13 per cent when blackgram was farmscaped with niger (in a 3: 1 ratio) and
exposed to insect infestation; 17.90 per cent when the vegetative stage of the crop
(pre-flowering) was protected, but post flowering stage had access to insect
infestation; 2.25 per cent when only reproductive stage of the crop (post flowering)
was protected, but the vegetative stage was unprotected and had access to insect
infestation.
Description
Estimation of Losses in Blackgram Due to
Insect Pests
Keywords
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Citation
Vikrant and Swaminathan, 2013