This is Chapter 8 of the book Sweetpotato postharvest assessment: Experiences from East Africa. The chapter focuses on a collaborative study between Tanzanian institutes and the Natural Resources Institute (NRI) in the UK. The objectives of the study were (1) to determine the extent of susceptibility of sweetpotato cultivar to Cylas spp., (2) to examine the factors that determine sweetpotato cultivar susceptibility to this pest and (3) to produce strategies for selecting cultivars with reduced susceptibility.