Insect Infestation on Bt. and Non-Bt. Cotton Cultivars

Abstract

A field study was carried out to examine the resistance potential of promising cotton cultivars to insect pest infestation, during the year 2012. Five cotton varieties were examined for their resistance against insect pests including Hari Dost, Shahbaz-95, NIAB-78, Sindh-1 and Bt Cotton. The insect pests monitored in this study included thrips, jassid, whitefly and bollworms. The experimental process for monitoring the insect pests was initiated on 15^th June 2012 and lasted on 12^th October, 2012. The results showed that thrips population was significantly (P<0.01) lowest (6.28/plant) on Haridost, against 9.22/plant on NIAB-78, 13.79/plant on Bt cotton 14.89/plant on Sindh-1. while the highest thrips population (15.21/plant) was recorded on  Shahbaz-95. The peak thrips population was noted on 12^th July observation on all three verities while on Bt cotton, the peak thrips population was recorded on 19^th July. Bt Cotton. The peak activities of jassid was recorded in the month of August. Overall mean showed that the signifactly highest (P<0.01) population of jassid was recorded as (3.59/leaf) on Sindh1 followed by Bt cotton (2.81/leaf), Shahbaz (2.80/leaf), Niab -78 (2.19/leaf) and Hari dost (1.63/leaf). Similarly, whitefly was found active in month of July and Augest. Significantly, more population (P<0.01) was recorded on Sindh-1 (3.20/leaf) and minimum on Haridost (1.40/leaf). Bollworms infestation was significantly lowest (P<0.01), (2.04/plant) on Bt cotton against 2.56/plant on NIAB-78, 3.04/plant on Haridost, 3.22/plant on Sindh-1; while the highest bollworms population (3.36/plant) was observed on cotton variety Shahbaz-95. Bt cotton variety showed considerable resistance against bollworm complex, while NIAB-78 also showed some resistance against sucking. The infestation of sucking insect pests on haridost. Shahbaz and Sindh-1 as compared to Bt cotton. The infestation of thrips, and whitefly was  peaked in the month of July. While Jassid was found most active in August. Bollworms appeared in first week of July and remained active in the field in relatively higher population upto the mid of September and later decreased to negligible level.

Keywords: Cultivar Resistance, Insect Infestation