Date of Award
Throughout the southeastern USA, tobacco thrips (Frankliniella fusca Hinds) are the primary thrips (Thysanoptera: Thripidae) pest species of cotton (Gossypium spp.) seedlings and are often detrimental to the establishing crop. In 2020, cotton yield losses from thrips and their management cost USA growers $70.7 million. Heavy reliance on prophylactic insecticides, primarily used as seed treatments, has led to insecticide-resistant populations of tobacco thrips. Currently, no known commercial cotton cultivar provides protection to prevent injury from thrips feeding. A sustainable, alternative management tactic is needed to address insecticide-resistant populations of and reduce damage from thrips in cotton. Our research evaluated day-neutral, exotic Upland cotton genotypes (Gossypium hirsutum L.) for resistance to thrips. In 2018 and 2020 field trials, 164 exotic Upland cotton genotypes were screened for resistance to thrips in North Carolina and South Carolina. Using a novel selection index, thrips resistance was determined from counts of thrips and ratings of injury from thrips at the first and third true-leaf stages in untreated plots and differences in dry biomass between treated and untreated plots at 42 days after planting. Genotypes were also assessed for thrips species composition. The most abundant thrips species were F. fusca in North Carolina in 2018 and in South Carolina in 2020 and Frankliniella tritici (Fitch) (i.e., flower thrips) in South Carolina in 2018. Eight putatively thrips-resistant and four putatively thrips-susceptible genotypes were determined from the field trials.
Christian, Sophia, "Quantifying and Identifying Mechanisms of Resistance To Thrips (Thysanoptera: Thripidae) In Landraces Of Upland Cotton (Gossypium hirsutum)" (2022). All Dissertations. 3215.