Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments

Abstract

Al-Issa, Z., M.N. Salti, M. Nabahan and A. Khalifa. 2023. Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments. Arab Journal of Plant Protection, 41(2): 173-182. https://doi.org/10.22268/AJPP-41.2.173182 Plants have developed defense systems to cope with pests’ challenge, especially insects to reduce their damage. In this study, some resistance traits in 30 cotton (Gossypium hirsutum) genotypes against cotton’s whitefly, Bemisia tabaci (Genn.) were evaluated through semifield experiments, where antixenosis of certified varieties and promising strains to the insect where studied by designing adhesive cage placed on leaves of the plant third upper, insect development from egg to adult were regularly observed and rates of development and survival, lifespan, sex ratio, and total emergence of adults were monitored. Preference test was conducted through recording numbers of different insect stages in 1cm2 area. Field experiments were carried out by planting cotton genotype for two successive seasons (2018, 2019). Insect density was evaluated by measuring whiteflies density every 15 days until the end of the growing season. During the 2020 season, trichome density in 1cm2 area was determined and their length and diameter were also determined at the 8 th node of cotton genotypes. The results showed that no significant differences among cotton genotype in relation to insect survival rate, lifespan, sex ratio, and emergence rate of adult. This study revealed that there were significant differences in trichome density in 1 cm2 of leaf area ranged between 86.33 to 160.7/cm2 . The correlation was significantly negative between egg and trichome density (R= -0.984). However, no significant correlation between length and diameter of trichome with nymph and egg density. The egg density varied from 32 to 54 egg/cm2 , whereas nymph’s density varied between 3.8 to 6.1 181 Arab J. Pl. Prot. Vol. 41, No. 2 (2023) nymphs/cm2 , and the variety Raqqa 5 had the highest density of whitefly nymphs and eggs during the two seasons. Whiteflies density peak was around mid-September and started to decline until mid-October. The results obtained suggested that there is a role for trichome density in resistance to whiteflies and there aren’t antixenosis between studied cotton’s genotypes. There is a need to investigate cotton genotypes from different cotton species such as G. arboreum, G. barbadens, G. thuberi for the presence of insect resistance traits. Incorporation of such resistance in cotton cultivars is a key for sustainable pest management. Keywords: cotton’s whiteflies, egg number, nymph number, resistance traits, preference, trichome