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Assessment of avoidable losses and economic injury levels for the sorghum head bug, Calocoris angustatus Leth. (Hemiptera:Miridae) in India

OAR@ICRISAT

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Relation http://oar.icrisat.org/7521/
http://dx.doi.org/10.1016/0261-2194(89)90069-0
 
Title Assessment of avoidable losses and economic injury levels for the sorghum head bug, Calocoris angustatus Leth. (Hemiptera:Miridae) in India
 
Creator Sharma, H C
Lopez, V F
 
Subject Sorghum
Plant Pathology
 
Description Avoidable losses and economic injury levels (EILs) were computed for the sorghum head bug, Calocoris angustatus Leth., on three cultivars during three rainy seasons (1985–1987) at ICRISAT. Grain yield in plots protected with 2–5 insecticide sprays (carbaryl at 500 g a.i./ha) between the half-anthesis and the dough stage was significantly higher than in untreated plots, with cost-benefit ratios > 1. Plots that were not protected at half-anthesis and/or complete-anthesis, and at milk and dough stages, suffered a significant loss in yield. Bug damage spoiled the grain quality in terms of germination, 1000-grain mass, grain hardness and percentage floaters. Three to four sprays between complete-anthesis and the dough stage prevented a significant reduction in grain quality. Head bug density at half-anthesis, complete-anthesis, milk and dough stages was significantly and negatively associated with grain yield. Bug density at different stages explained 43–94% of the variance in yield. Direct effects of bug numbers at the milk stage and the indirect effects of head bug density at other stages through the milk stage contributed towards maximum reduction in yield. Maximum avoidable losses were recorded in cultivar ICSV 1 (88·6%), followed by CSH 1 (69·9%), and CSH 5 (53·9% in 1986 and 55·0% in 1987). Loss in grain yield/ha due to one insect/panicle at half-anthesis and that based on natural increase, were 548 and 232 kg in CSH 5 during 1986 and 1987, respectively, 251 kg in ICSV 1, and 77 kg in CSH 1. EILs based on a cost-benefit ratio of 1:1 ranged from 1·3–1·4 insects/panicle for CSH 1, 0·4 for ICSV 1, and 0·4–0·6 and 0·2–0·4 for CSH 5 during 1986 and 1987, respectively. Simple cost estimates for insecticide sprays and the resultant saving in grain yield are a useful tool for decision-making in pest management.
 
Publisher Elsevier
 
Date 1989
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://oar.icrisat.org/7521/1/CropProt_8_6_429-435_1989.pdf
Sharma, H C and Lopez, V F (1989) Assessment of avoidable losses and economic injury levels for the sorghum head bug, Calocoris angustatus Leth. (Hemiptera:Miridae) in India. Crop Protection, 8 (6). pp. 429-435. ISSN 0261-2194