Response of field populations of helicoverpa armigera (hubner) to bt cotton (cry1ac) and its management
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Date
2008
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UAS, Dharwad
Abstract
Studies on response of Helicoverpa armigera collected from different cotton growing
areas of Karnataka to Cry1Ac, synchrony in H. armigera adult emergence from Bt cotton and
other alternate hosts, estimation of crop yield gain in Bt cotton against bollworms, validation
of integrated resistance management (IRM) strategy to Bt cotton and exploitation of Bt cotton
as a trap crop in conventional cotton pest management were carried out at RARS, Raichur.
The maximum LC50 of 0.028 μg/ml of diet was recorded in Raichur population. In
late season, higher LC50 values of 0.037 and 0.026 μg/ml of diet were recorded in Dharwad
and Raichur populations, respectively. But there was no significant difference among six
different populations of H. armigera response to Cry1Ac toxin.
The total number of H. armigera moths emerged from Bt and non Bt cotton were 6.60
per cent and 42.80 per cent, respectively and total per cent emergence of H. armigera moths
from red gram was maximum (95.60%). In late season, moths emerged from Bt cotton were
very less (10.80%). On cultivated Bt cotton, larval survivability was from zero to 0.16 larvae
per plant as compared to 0.00 to 1.56 larvae/plant in non Bt cotton.
Reaction of different Bt cotton hybrids against bollworms indicated that RCH-144Bt
recorded maximum GOB per plant (59.17/plant) which was on par with RCH-371Bt
(55.71/plant) and RCH-2Bt (54.67/plant). Significantly highest seed cotton yield of 19.60q/ha
was recorded in RCH-144Bt.
Bt IRM recorded significantly superior seed cotton (38.73 q/ha) yield compared to Bt
farmers practice (35.92 q/ha). The net profit per ha was maximum in Bt IRM module (Rs.
68392/ha) as compared to Bt farmers practice (Rs. 59875/ha).
Cotton IPM plot and Bt border trap crop treatment recorded maximum good opened
bolls (41.93 and 42.11/plant) with least bad opened bolls (9.17 and 10.22/plant). These two
treatments also excelled and registered higher seed cotton yield of 20.60 and 20.60 q/ha
respectively.
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Agricultural Entomology