20195--R Tamilselvan 27 June-2020 Indian Journal of Entomology Online published (Preview) DoI No.: RESISTANCE TO THE WHITEFLY BEMISIA TABACI (GENNADIUS) IN COTTON GENOTYPES R TAMILSELVAN*, C A MAHALINGAM, S MOHANKUMAR** AND K SENGUTTUVAN*** Department of Agricultural Entomology; **Department of Biotechnology; ***Department of Cotton, Tamil Nadu Agricultural University, Coimbatore, 641003 *Email:
[email protected] (corresponding author) ABSTRACT This study on the whiteflyBemisia tabaci (Gennadius) on cotton (Gossypium spp.) evaluates the resistant mechanisms viz., antixenosis, antibiosis and tolerance under free-choice and no-choice conditions. Results reveal that the whiteflies select the host only after initial probing. The genotypes, LRA-5166 and DSC-1501 were the least preferred for oviposition under free-choice condition and reduced the nymphal survival (47.50 and 52.50 days), net reproductive rate (R0) (5.45 and 6.31/ female/ lifetime) and intrinsic rate of increase (rm) (0.061 and 0.063) under no-choice condition, respectively. These exhibited antixenosis and antibiosis. The genotype CCH-4474 demonstrated tolerance with less reduction in the plant height (20.77%), number of internodes (15.27%) and chlorophyll content (13.44%). The high level of resistance in the genotypes LRA-5166 and DSC-1501 could be exploited for genetic improvement of resistant cotton cultivar. Key words: Gossypium hirsutum, Bemisia tabaci, antixenosis, antibiosis, tolerance, free choice, no choice, LRA 5166, DSC 1501, CCH 4474, oviposition, nymphal surivival, reproductive rate, Whitefly Bemisia tabaci (Gennadius) (Hemiptera: overlap each other. However, systematic studies on Aleyrodidae) is a highly polyphagous pest causing these aspects are lacking, and hence this study evaluated substantial losses and occur in more than 600 the antixenosis (ovipositional preference), antibiosis agricultural crops and ornamental plant species (fitness parameters) and overall tolerance capacity of (Vázquez et al., 1996).