SPECTRUM OF INSECT PEST COMPLEX AND MANAGEMENT OF MAJOR INSECT PESTS ON SOYBEAN (Glycine max)
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Date
2016
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
Spectrum of insect pest complex and management of major insect pests on soybean (Glycine max) was studied during Kharif, 2015 at Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.). Girdle beetle, Obereopsis brevis, tobacco caterpillar, Spodoptera litura, green semilooper, Chrysodeixis acuta, white fly, Bemisia tabaci, jassid, Empoasca kerri and thrips, Thrips tabaci, were observed as major insect pests of soybean.
The peak activity of girdle beetle (1.2 damaged plants per meter row) was observed during fourth week of September. Whereas, the peak activity of defoliators pests i.e. S. litura (1.4 larvae per meter row) and C. acuta (1.2 larvae per meter row) was recorded during last week of August and that of sucking pests i.e. B. tabaci (10.0 whiteflies per three leaves) and E. kerri (0.65 jassids per plant) was recorded during second week of August and Thrips tabaci ( 6.1 thrips/plant) in third week of August, respectively.
Two species of lady bird beetle, M. sexmaculata and C. septumpunctata and orb weaver spider, Neoscona sp. were found predating mainly upon white flies, jassids and thrips. Whereas, lynx spider, Oxyopes sp. and a predatory pentatomid bug, E. furcellata was noticed sucking the body sap of lepidopterous larvae. Correlation between spiders and sucking pests was found to be positive but non significant with “r” values 0.238.
However, Correlation between coccinellid beetles and sucking pests, between pentatomid bugs and caterpillar pests and between spiders and leaf defoliator pests was found to be positive and significant with “r” values and regression equation [r = 0.532; regression equation y= 20.45x + 6.355], [r = 0.666; regression equation y =2.132X + 0.451] and [r = 0.710; regression equation y = 1.921X + 0.137], respectively.
A significantly positive correlation between all sucking pests and minimum temperature [r =0.645; regression equation y = 0.122x + 23.78] and evening relative humidity [r =0.601; regression equation y =0.1223x + 54.71] were recorded during the investigation.
In the evaluation of plant products against major insect pests of soybean garlic+green chilli @ 8.75 kg/ha was most effective against defoliators S. litura and C. acuta after first spray having 0.43, 0.52 and in second spray having 0.43, 0.37 larva/mrl, respectively and similarly in sucking pests after first spray having 4.12 whiteflies/plant and 3.80 thrips/plant and after second spray 4.24 whiteflies per plant, 4.55 thrips/plant, respectively with benefit cost ratio of 8.02.
Garlic+green chilli @ 8.75 kg/ha was comparatively most safer for both natural enemies i.e coccinellids and spider after first spray having maximum population of 0.88 coccinellid/plant, 1.05 spiders/plant and after second spray 0.82 coccinellid/plant, 1.00 spiders/plant.
In the insecticidal experiment, treatment flubendiamide @ 100ml/ha was most effective against defoliators pest viz; S. litura and C. acuta after first spray having minimum population of 0.29, 0.14 larva/mrl, respectively and in after second spray 0.20, 0.19 larva/ meter row length was recorded.
Percent reduction of pest population was maximum with 57.97%, 75.00% after first spray and 72.97, 70.31 percent after second spray of flubendiamide @ 100ml/ha treated plots against defoliators pest S. litura and C. acuta.
Triazophos @ 750 ml/ha was most effective against sucking pest viz white flies after first spray having minimum population of 5.18 white flies/plant, 3.11 thrips/plant and after second spray having 3.68 white fly/plant, 1.02 thrips/plant, respectively.
Percent reduction of insect population was maximum in the triazophos @ 750 ml/ha treated plots against sucking pest and thrips after first spray having 55.11%, 52.81% and after second spray with 59.82%, 79.14%, respectively.
Based on mean population of natural enemies emamectin benzoate @ 220g/ha was more safer for spider and coccinellids after first spray having maximum population of 0.65 coccinellid/plant, 0.76 spider/plant and after second spray having 0.61 coccinellid/plant, 0.70 spider/plant.
Percent reduction of natural enemies viz., coccinellid and spider was minimum in emamectin benzoate @ 220g/ha treated plots having 24.42% and 28.3% after first spray and after second spray having minimum reduction with 28.24%, 39.13%.
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Agricultural Entomology
Citation
198 p.