STUDIES ON SUCKING INSECT PESTS OF GROUNDNUT (Arachis hypogaea L.) AND THEIR MANAGEMENT
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Date
40865
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Investigations on incidence and management of sucking insect pests were carried
out during kharif 2010. Twelve sucking insect pest species were recorded on all the
growth stages of the groundnut crop at Chintamani (Chikkaballapur). Among them,
thrips, leaf hoppers, planthoppers, and aphids were the major pests. Eurybrachid bug,
pentatomid bug were the minor sucking insect pests. The peak activity of sucking insect
pests commenced 30 days after sowing and peak incidence was recorded during
September, 2010.
Total developmental period of Scirtothrips dorsalis ranged from 13.30 ± 1.69
days from egg to adult emergence. Adult female was characterized by yellow body with
rectangular head, pink prominent eyes, 8 segmented antenna and arc like brownish
patches on the dorsal side of 2nd to 7th abdominal segments. Female thrips oviposited
singly on tender pods and leaves towards veins and margins.
Studies on screening of 56 genotypes of groundnut revealed that no genotype
reacted as immune, however 13 genotypes reacted as resistant, 25 genotypes as
moderately resistant, 11 genotypes as moderately susceptible and 7 genotypes proved to
be susceptible and none of genotypes were highly susceptible with respect to per cent
foliage damage in case of thrips. Similarly 23 genotypes showed resistance, 11 genotypes
were moderately resistant, 18 genotypes were moderately susceptible and 4 genotypes
proved susceptible and none of genotypes showed highly susceptible with respect to per
cent foliage damage in case of leafhoppers. Among the various biochemical constituents
analysed in groundnut, phenols and tannins had significant and negative relationship with
number of thrips, leafhoppers and their damage per cent. Total sugars, amino acids and
reducing sugars shown positive relationship with number of thrips, leafhoppers and their
damage per cent. Linear regression analysis revealed that higher tannins and phenols
were the major contributing factors for resistance against thrips and leafhoppers.
Among indigenous materials, NSKE recorded comparatively higher per cent
reduction of thrips and leafhoppers number; among new insecticide molecules acetamprid
20 SP and imidachloprid 200 SL proved highly effective in the control of thrips and
leafhoppers. The acetamprid 20 SP application resulted in highest B:C ratio (24.24)
followed by imidachloprid 200 SL (7.54).