Earliness index deters Pectinophora gossypiella incidence on advanced cultivars of Bt cotton

Pink bollworm (Pectinophora gossypiella) is recognized as an important pest of cotton and can damage flowers and bolls of both Bt and non-Bt cultivars. Cry-1Ac in Bt cultivars is considered very effective in controlling lepidopterous larvae; therefore, the present study was carried out to investigate the impact of Cry1-Ac and the earliness index on the natural incidence of P. gossypiella at the Cotton Research Institute, Faisalabad. During 2015–2016, ten cultivars were used to determine the incidence of pink bollworm infestation. The experiment was repeated for 2 years. During the next year, Cry1-Ac and earliness traits of selected cultivars were also observed to determine their impact on pink bollworm. Correlation coefficient results regarding days to first flower (r value = 0.66) as well as the earliness index (r value = − 0.62) exhibited a strong association with pink bollworm, but Cry1-Ac had a weak association (r value = − 0.058) with pink bollworm. The coefficient of determination (R 2) explained that variability of pink bollworm due to Cry1-Ac, the earliness index, and days to first flower was 18.0, 38.5, and 43.5%, respectively. Principal component analysis results showed that the first two PCs expressed 87% of the total variability. Clusters made on the basis of the studied parameters revealed that clusters 2 and 3 comprised the cotton cultivars possessing earliness traits compared with cluster 1. Therefore, it can be concluded that the earliness index in cotton is an important component for the sustainable management of pink bollworm infestation, the need for which is endless to evade the pink bollworm problem in the era of climate change.