Evaluation of Exotic and Ornamental Sweetpotato Germplasm for New Sources of Sweetpotato Weevil (Cylas formicarius) Resistance.

The most harmful pest of the sweetpotato Ipomoea batatas L.(Lam.) is the sweetpotato weevil Cylas formicarius (Fabricus). Crop losses due to weevil damage can reach as high as 100%. Even though chemical control measures and traps are available, the discovery and development of cultivars with genetic resistance to weevil damage are a vital part of an effective IPM (Integrated Pest Management) program. From September 2015 to January 2016, storage roots of eighteen different varieties of exotic and or ornamental origin were evaluated for their weevil resistance as compared to a know control, the cultivar ‘Beauregard.’ Each root was measured, and exposed to exactly six adult female weevils in an enclosed cardboard tube for one week. After one week of laying eggs, females were removed. Subsequent adult weevil emergence began exactly thirty days later. Emerging adults were counted for exactly thirty more days and scores were averaged for each cultivar. A vast majority of the exotic and ornamental cultivars were found to have higher weevil resistance than ‘Beauregard’. One exotic cultivar ‘Unduandopa’ was discovered to have over twelve times the resistance of ‘Beauregard’.