2017 ASHS Annual Conference

The sweet potato whitefly (Bemisia tabaci) is one of the most horticulturally detrimental pests to cultivated tomatoes (Solanum lycopersicum). Besides direct feeding injury, which can result in irregular ripening of fruit, whiteflies vector many viruses, including the highly damaging Tomato yellow leaf curl virus (TYLCV). Whitefly resistance has been identified in the wild tomato species S. habrochaites and S. pennellii, which may serve as useful sources of insect resistance genes for backcrossing into cultivated tomatoes. The development of whitefly-resistant cultivars could reduce the damages caused by the insect as well as the amount of insecticides needed for its control. Although several wild accessions have demonstrated whitefly resistance under laboratory and greenhouse conditions, little work has verified the durability of this trait under field conditions over time. Whitefly resistance in S. habrochaites accession LA1777 was evaluated over two field seasons in Balm, Florida. Replicated experiments included two susceptible controls, ‘Florida 47’ and the inbred line, Fla. 8059; and two advanced lines with whitefly-resistance derived from S. pennellii. Tomatoes were transplanted to the field three times at two-week intervals to compare resistance among different plant ages. Data was collected at three, five, and seven weeks after transplanting, and included counts of whitefly eggs, nymphs, and adults. Incidence of TYLCV infection was assessed to determine if whitefly resistance reduces virus transmission. Egg and nymph counts among LA1777 tended to decrease throughout the season, suggesting that whitefly resistance is stable over time. Lines with fewer eggs and nymphs also tended to have lower incidence of TYLCV infection, implying that whitefly resistance can be used for management of the vectored viruses. Results suggest that whitefly resistance in LA1777 is suitable for developing resistant cultivars.