Abstract
Thrips tabaci is the main interruption of the cotton production in last ten years among the sucking insect pests of cotton in Sindh Pakistan. In the present study, five varieties of cotton (Koong, IR-3701, MNH-886, Naib-878 and non-Bt CRIS-585, CRIS-613, Saami and Nusrat) were evaluated for their resistance against thrips tabaci under field condition at Tandojam, Sindh, Pakistan during the crop season 2024. Thrips tabaci population was appeared on all Bt and non-Bt cotton varieties after the germination of cotton crop. The maximum population of T. tabaci was recorded on the Bt cotton variety Naib-878 (22.978±1.464/plant), while the minimum population of t. tabaci was found on the non-Bt cotton variety Nusrat (8.443±0.884/plant), followed by Bt varieties Koong (18.998±1.096/plant), IR-3701 (15.780 ± 1.017/plant), MNH-886 (13.233 ± 0.918/plant) and non Bt CRIS-585 (12.765 ± 0.983/plant), CRIS-613 (11.768 ± 0.958/plant), and Saami (10.202 ± 0.915 /plant), respectively. No significant differences were found between the Bt and non-Bt cotton varieties (MNH-886, CRIS-585, CRIS-613, Saami) and t. tabaci. There was some variability in the yield per acre of Bt and Non-Bt cotton types. Bt cotton varieties showed high yield potential with MNH-886 yielding highest (35.133 per acre) followed by IR-3701 (18.511 per acre) among the varieties. The varieties Koong and Naib-878 had 14.778 and 12.778 per acre, respectively, with comparatively low productivity. Among the varieties, Non-Bt cotton varieties, in which Nusrat grew with the highest yield (27.156 per acre), was found to be ranked second overall. Variety Saami yielded 12.311 per acre of crop. Lower yields were observed in CRIS-613 (10.178 per acre) and CRIS-585 (8.956 per acre). Overall, maximum temperature had the greatest effect on the all varieties of cotton (Bt and non-Bt), followed by minimum temperature and humidity. Wind speed moderately and significantly affected both types of cotton with Bt cotton slightly more sensitive than the non-Bt cotton. It finds that after the germination of the cotton crop, there were significant differences in the population of Thrips tabaci among most Bt and non-Bt cotton varieties. The Bt variety Naib-878 had the highest t. tabaci population while the non-Bt variety Nusrat had the lowest infestation level. No significant differences in t. tabaci population was observed among the varieties MNH-886, CRIS-585, CRIS-613 and Saami suggesting comparable susceptibility among these varieties