1 © The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. Plant Resistance Categories of resistance in cotton genotypes, Gossypium spp. against cotton-melon aphid, Aphis gossypii (Hemiptera: Aphididae) Pirithiraj Uthirapathy 1, , Murugan Marimuthu 1,*, , Balasubramani Venkatasamy 2, , Senguttuvan Kannan 1, , N. Manikanda Boopathi 3, , Hari Ramakrishnan Selladurai 4, , Premalatha Nallathambi 5, 1 Department of Agricultural Entomology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Lawley Road, Coimbatore 641 003, Tamil Nadu, India, 2 Department of Agricultural Entomology, Controllerate of Examinations, Tamil Nadu Agricultural University, Lawley Road, Coimbatore 641 003, Tamil Nadu, India , 3 Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Lawley Road, Coimbatore 641 003, Tamil Nadu, India, 4 Department of Genetics and Plant Breeding, Tamil Nadu Agricultural University, Agricultural Research Station, Kovilpatti, Thoothukudi 628 501, Tamil Nadu, India, 5 Department of Cotton, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Lawley Road, Coimbatore 641 003, Tamil Nadu, India * Corresponding author, mail: entomurugan@rediffmail.com, muruganmarimuthu@tnau.ac.in Subject Editor: Michael Stout Received on 7 January 2023; revised on 14 June 2023; accepted on 29 June 2023 Cotton-melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is emerging as a potential threat to cotton cultivation worldwide. The resistance categories in Gossypium arboreum to A. gossypii still need to be explored. We screened 87 G. arboreum and 20 Gossypium hirsutum genotypes against aphids under natural field conditions. Twenty-six selected genotypes from these 2 species were tested under glasshouse conditions for resistance categories (antixenosis, antibiosis, and tolerance). Resistance categories were assessed by no-choice antibiosis assay, free-choice aphid settling assay, cumulative aphid days using popula- tion buildup tests, chlorophyl loss index, and damage ratings. No-choice antibiosis experiment revealed that the G. arboreum genotypes GAM156, PA785, CNA1008, DSV1202, FDX235, AKA2009-6, DAS1032, DHH05-1, GAM532, and GAM216 had a significant adverse effect on aphid development time, longevity, and fecundity. Gossypium arboreum genotypes CISA111 and AKA2008-7 expressed a low level of antixenosis but possessed antibiosis and tolerance. Aphid resistance persisted uniformly at different plant developmental stages studied. The chlorophyl loss percentage and damage rating scores were lower in G. arboreum than in G. hirsutum genotypes, indicating the existence of tolerance in G. arboreum to aphids. Logical relations analysis of resist- ance contributing factors depicted the presence of antixenosis, antibiosis, and tolerance in the G. arboreum genotypes PA785, CNA1008, DSV1202, and FDX235, indicating their utility for evaluating the mechanisms of resistance and aphid resistance introgression breeding into G. hirsutum to develop commercially cultivated cotton lines. Key words: aphid resistance, desi diploid cotton, antixenosis, antibiosis, tolerance Journal of Economic Entomology, XX(XX), 2023, 1–12 https://doi.org/10.1093/jee/toad136 Research Downloaded from https://academic.oup.com/jee/advance-article/doi/10.1093/jee/toad136/7220905 by ESA Member Access user on 11 July 2023