Lettuce germplasm resistance to western flower thrips vectors of Impatiens necrotic spot virus

Impatiens necrotic spot virus (INSV) is an orthrotopovirus transmitted by Frankliniella occidentalis (Western flower thrips, WFT). The virus has caused up to 100% yield losses in California and become a major challenge in lettuce production. Florida is the third-largest lettuce-producing state after California and Arizona. While cases of INSV have not been reported in Florida lettuce, it has been reported in ornamental crops before. The widespread of WFT poses a significant risk of INSV outbreak if it were to be introduced. An integrated pest management approach, incorporating thrips-resistant lettuce cultivars, offers a sustainable strategy to mitigate potential INSV impacts. Therefore, this study aimed to identify lettuce germplasm resistant to WFT as a proactive measure for thrips and INSV management. In no-choice experiments, 35 lettuce germplasms, including commercial cultivars, were evaluated for resistance to the thrips. Plants at the 5-6 true leaf stage were infested with 7 female thrips. Thrips were reared on the susceptible Okeechobee cultivar, which also served as the control. After 14 days, larvae and adult thrips per plant were counted. One breeding line 50100, cultivars Cherokee, Eruption, La Brillante, and Hacienda, and a plant introduction (PI)251246 showed significantly lower larvae (alpha = 0.05) than Okeechobee, indicating resistance to WFT. Conversely, Western Red cultivar had significantly higher larvae, suggesting susceptibility. These germplasms are undergoing further no-choice and choice assays to validate results. These findings highlight promising candidates for identifying genomic regions conferring resistance to WFT, supporting the development of resistant lettuce, a proactive defense against INSV in Florida.