Comparative Bollworm Infestation on BT and Non-BT Cotton

Abstract

<palign"justify"> Field studies were carried out from 2nd July to 28th October 2013 to monitor population dynamics of Earias Spp., Helicoverpa armigera (Hub.) and Pectinophora gossypiella (Saund.) On cotton varieties K.D. 57, TH-112/105, Krish-342, Sindh-1, Shahbaz-95 and NIAB-78; and these varieties were compared with Sattari-BT for bollworm infestation. The results indicated that the statistically population of boll worm complex varied significantly (P<0.05) on different varieties. Cotton variety TH-112/105 was more infested (3.44%) by Earias spp. than Sindh-1, Shahbaz-95, KD-57 and Crish-342 with insect population of 3.40, 3.35, 3.18 and 3.08%. Earias population was recorded lower on NIAB-78 (1.79%) and lowest (0.93%) on Sattari-BT. The H. armigera population was highest (0.95%) on variety TH-112/105, while the pest population was 0.94, 0.92, 0.86 and 0.81% on cotton varieties Shahbaz-95, Sindh-1, KD-57 and Crish-342, respectively. H. armigera population was relatively lower on variety NIAB-78 (0.49%); while the lowest insect population (0.26%) was observed on variety Sattari-BT. P. gossypiella Saund. population also differed significantly (P<0.05) on cotton varieties and highest population (3.21%) was observed on variety Sindh-1, while the pest population was 3.01, 2.94, 2.77 and 2.69% on cotton varieties KD-57, TH-112/105, Shahbaz-95 and Crish-342, respectively. The insect population was relatively lower on variety NIAB-78 (1.92%); while the lowest insect population (0.83%) was noted on variety Sattari-BT. Earias spp. population was at peak on 20th August, while H. armigera infestation reached its peak level on 27th August; and P. gossypiella population was at on 10th September. It was concluded that Bt variety Sattari showed considerable resistance to bollworm complex and bollworm infestation increased with increasing the number of bolls. Moreover, rising humidity instigated the development of bollworms population. The population of bollworms was negligible on variety Sattari-BT, and NIAB-78 also showed some resistance to bollworms.