Elucidating resistance in cotton genotypes to whitefly, Bemisia tabaci, by population buildup studies

Abstract

Plant resistance has become an important component of integrated pest management (IPM) for management of whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), an important pest of cotton in India. The present studies were undertaken to standardize the plant stage and identify resistant cotton genotypes against whitefly. Nine plant stages of F846, a susceptible cotton genotype, were exposed to whitefly for 25 days under no-choice conditions. The population buildup (eggs, nymphs, pupae and adults) was recorded. The 12-, 14-and 16-leaf stages were suitable for plant resistance studies against whitefly, and the 14-leaf stage was taken for further studies. Ten cotton genotypes of Gossypium hirsutum and two of G. arboreum were covered with split cages in which five pairs of B. tabaci (F 1 ) were released. The population buildup was recorded to categorize genotypes as resistant, moderately resistant, moderately susceptible or susceptible. The experiment was repeated with F 2 and F 3 generation whiteflies. Based on overall average score of three experiments, LD694 was rated as resistant; LK861, Supriya, RS2013, CNH911 and PA183 as moderately resistant; IS-376/4/1/20/72, NHH44, TxMaroon2-78, Bt 6304 and RS2098 as moderately susceptible; and F846 as susceptible. LD694 was found to be resistant in three consecutive generations of whitefly.

Mechanisms of resistance in cotton to whitefly (Bemisia tabaci): Tolerance

“…The Gossypium arboreum genotypes LD 694 and PA 183 were rated as moderately tolerant and the remaining ones as moderately susceptible. Tolerant genotype NHH 44, however, was rated as moderately susceptible when population buildup/antibiosis studies were conducted (Jindal and Dhaliwal 2009;Jindal et al 2007). …”

“…The plants of selected genotypes were raised up to standardized 14-leaf stage (Jindal and Dhaliwal 2009) in pots of the same size filled with an equal quantity of mixture of soil and farmyard manure (1:1). Two pots with a single plant of each genotype, with the same height and number of nodes were arranged in the screen house, represented one replication and there were three replications.…”

“…The genotypes were categorized in statistically different classes and rated on a scale of 1-4 (with 1 = tolerant, 2 = moderately tolerant, 3 = moderately susceptible, and 4 = susceptible) for each parameter (Jindal and Dhaliwal 2009). The overall scores based on all the parameters were calculated by considering the mean of scores of the two experiments, based on which the genotypes that scored 0.5-1.5 were rated as tolerant, 1.5-2.5 moderately tolerant, 2.5-3.5 moderately susceptible and 3.5-4.5 as susceptible.…”

“…Researchers have investigated the role of antibiosis and non-preference in imparting resistance; however, only a few studies were conducted to identify tolerant lines in cotton (Jindal et al 2007;Singh et al 2001), citrus (Shapiro and Gottwald 1995), rice (Guessan et al 1994), wheat (Unger and Quisenberry 1997), zucchini (Cardoza et al 1999) and potato (Lefko et al 2000). It has also been reported that the same genotypes behave differently when studied for the presence of different mechanisms of resistance (Jindal and Dhaliwal 2009;Jindal et al 2007). Therefore, the present studies were conducted with the objective to detect tolerance against B. tabaci in cotton genotypes and to determine the level of tolerance mechanism operational in resistant plants.…”

Development of Transgenic Cotton Lines Expressing Allium sativum Agglutinin (ASAL) for Enhanced Resistance against Major Sap-Sucking Pests

“…Forty five-day old plants were challenged with jassid/whitefly and after three weeks, when the untransformed controls exhibited complete damage, the experiments were terminated. The resistance exhibited by the transgenic plants against jassids and whitefly was evaluated based on a scale of 1 to 4 [42], [43].…”