摘要 : A field experiment was conducted during 2002 and 2003 to study the response of Bt cotton genotypes, their non-Bt counter parts, <i>hirsutum</i> hybrids and few <i>hirsutum</i> local varieties to the major insect pests. The highest... 展开 A field experiment was conducted during 2002 and 2003 to study the response of Bt cotton genotypes, their non-Bt counter parts, <i>hirsutum</i> hybrids and few <i>hirsutum</i> local varieties to the major insect pests. The highest population of while fly at peak stage (75 DAS) was recorded in local <i>hirsutum</i> variety H-1098 (9.02 per leaf), whereas the population in MECH-915 (Bt) and MECH-162 (Bt) was 6.49 and 7.06 respectively. However, leaf hopper population ranged between 2.36-2.93 per leaf in all the genotypes except a bit higher (4.75) in MECH-915 (Bt). The damage due to bollworms was least in MECH-915 (Bt) with open boll damage and locule damage per five plants as 2.3 and 4.3, whereas they were 5.7 and 11.5 in its non-Bt counter part. The highest open boll damage was recorded in local variety Vikas (10.3 per five plants) and highest locule damage was recorded in hybrid variety Om Shankar (25.0 per five plants). The highest seed cotton yield (2.25 t/ha) was obtained in MECH-915 (Bt). 收起