Identification of host plant resistance to tobacco thrips in exotic Upland cotton landraces

Throughout the southeastern U.S., tobacco thrips are the primary thrips pest of cotton seedlings and are often detrimental to the establishing crop. In 2020, cotton yield damage from thrips and their management cost U.S. growers $70.7 million. Heavy reliance on prophylactic insecticides, used as seed treatments, has led to insecticide-resistant tobacco thrips populations. Currently, no commercial cotton cultivar protects against thrips. A sustainable, alternative management tactic is needed to address insecticide-resistant thrips populations in cotton. Our research aims to evaluate day-neutral, exotic Upland cotton for thrips-resistance traits, allowing easy crossing with U.S. breeding lines. In 2018 and 2020 field trials, 164 exotic Upland cotton genotypes were screened for their resistance to North Carolina and South Carolina thrips populations. Eleven putatively thrips-resistant and four putatively thrips-susceptible genotypes were determined from the field trials. These 15 genotypes were then used in choice tests to determine ovipositional and host non-preference (i.e., antixenosis). No-choice tests determined host antagonism for adults and hatching larvae (i.e., antibiosis). Thrips-resistance was found in a few cotton genotypes and will be further evaluated in metabolomic and volatile analyses to serve as biomarkers for cotton breeding efforts.