Antibiosis mechanism and bases of resistance to the whitefly, Bemisia tabaci (Gennadius) in upland cotton introgression lines

Screen house leaf cage experiments were conducted under no-choice conditions to ascertain the antibiosis mechanism operating in introgression cotton lines against the whitefly, Bemisia tabaci (Gennadius) during July and September 2022. Seventeen cotton introgression lines and two parents, namely Synthetic polyploid (A2D1) and upland cotton line PIL 43, were assessed for development and survival of various biological parameters like fecundity, nymphal and pupal growth index. An antibiosis mechanism of resistance was documented in the parent, Synthetic polyploid and introgression lines, D5-BW-WF-28, C1-P-1, C1-P-31, and C1-P-36, and were categorized as resistant lines. In resistant introgression lines, survival and the nymphal/pupal growth index were lower, but the overall development period was longer. Among biophysical parameters, trichome density, leaf area and vascular bundle length showed significantly positive whereas leaf lamina thickness exhibited negative association with fecundity. Sugars were found to be higher in susceptible genotypes whereas phenols and proteins were comparatively higher in resistant lines. However, total soluble and reducing sugars showed a positive correlation, while total soluble proteins and total phenols manifested a negative correlation with fecundity. It may thus be concluded that antibiosis mechanism of resistance is operating in cotton introgression lines; and biophysical and biochemical parameters play a predominant role in imparting resistance against B. tabaci. To the best of our knowledge, this is the first report illustrating the development of whitefly resistant introgression lines using Synthetic cotton polyploid (A2D1).