Diversity of Hemipteran Pests of Cotton (Gossypium hirsutum) and Relative Bio-efficacy of Newer Insecticides on them

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Date
2013
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MPUAT, Udaipur
Abstract
The investigation on “Diversity of Hemipteran Pests of Cotton (Gossypium hirsutum) and Relative Bio-efficacy of Newer Insecticides on them” was conducted at Instructional Farm, Rajasthan College of Agriculture, Udaipur during kharif season (June to November 2012), with the objectives of studying their seasonal incidence, species diversity and evaluating the relative bio-efficacy of newer insecticides. The major sap-sucking insect pests recorded on cotton, included the cotton jassids (Amrasca biguttula biguttula Ishida.), aphids (Aphis gossypii Glover), whitefly (Bemisia tabaci Genn.), red cotton bug (Dysdercus koenigii Fabricius), dusky cotton bug (Oxycarenus laetus Kirby) and thrips (Thrips tabaci Linnman). The hemipteran species diversity comprised 6 different insects viz., the cotton jassid (Amrasca biguttula biguttula), aphid (Aphis gossypii Glover), whitefly (Bemisia tabaci), red cotton bug (Dysdercus koenigii koenigii), the dusky cotton bug (Oxycarenus laetus) and the predatory pyrrhocorid bug (Antilochus coqueberti Fabricius). The population peak for thrips (33.87 thrips/plant) was noted during second week of August, those for jassid (21.87 jassids/plant) and whitefly (20.33 whiteflies/plant) were recorded during fourth week of August; whereas, for aphids (36.27 aphids/plant), was recorded during last week of august, 2012. The peak population levels for red cotton bug (15.33 red cotton bug /plant) and dusky cotton bug (14.27 dusky cotton bug/plant) were observed during last week of October and first week of November 2012, respectively. The linear relationship between abiotic factors of environment and population of sap-sucking insect pests showed significant positive correlation with mean relative humidity for jassid and whitefly; but significant negative correlation for red cotton bug. The dusky cotton bug population showed a significant negative correlation with mean atmosphere temperature. The relative bio-efficacy of the tested insecticides showed that three sprays of imidacloprid 200 SL @ 125 ml ha-1 at ten days interval resulted in maximum mean reduction of aphid population with 89.44 per cent, acetamiprid 20 SP (100 g a.i. ha-1) caused maximum mean reduction of whitefly population 88.13 per cent and fipronil 200 SC (300 ml ha-1) caused maximum mean reduction of jassid and thrips (89.52 and 90.09% population reduction), respectively. Dimethioate 30 EC @ 660 ml ha-1 was least effective against jassids (69.83% population reduction), whitefly (70.80% population reduction) and thrips (77.86% population reduction) and spiromesifen 240 SC @ 500 ml ha-1 against aphids (69.68% population reduction).
Description
Diversity of Hemipteran Pests of Cotton (Gossypium hirsutum) and Relative Bio-efficacy of Newer Insecticides on them
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Citation
Kirar and Ameta, 2013
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