Abstract. Mau YS, Wadu MN, Ndiwa ASS, Markus JER, Arsa IGBA. 2021. A screening of resistance to sweet potato weevil (Cylas formicarius Fab.) in a collection of sweet potato clones under laboratory conditions. Intl J Trop Drylands 5: 41-47. Sweet potato is a potential carbohydrate source as a rice substitute in Indonesia, especially in East Nusa Tenggara (ENT). However, the productivity of this crop is still low at the farmer level due to, among others, the use of low-yielding varieties and yield loss caused by sweet potato weevil (SPW), Cylas formicarius. The use of SPW resistant varieties is considered the most effective and eco-friendly way of controlling the pest. However, the availability of resistant varieties is currently limited. This study aimed to evaluate the SPW-induced damage intensity and SPW-resistance level in a collection of sweet potato clones. The study was conducted in the laboratory of Universitas Nusa Cendana, Kupang, Indonesia. Observed variables included the percentage of damaged roots, the intensity of root damage, the number of C. formicarius per root, the number of feeding tunnels per root, root epidermal thickness, and root latex level. Observed data were subjected to analysis of variance followed by Duncan's post hoc test of 5%, except root latex level that was subjected to descriptive analysis. A correlation analysis was also performed. The damaged root percentage ranged from 77.8% to 100%, and the intensity of root damage was from 14.0% to 76.6%. The laboratory assay categorized the tested genotypes into Moderately Resistant, Moderately Susceptible, and Susceptible levels, with the Resistant category being absent. The SPWs ranged from 1.4 to 31.9 per root, while the number of feeding tunnels ranged from 1,4 to 31.1 per root. The observed sweet potato genotypes possessed root epidermal thickness between 1 mm to 4 mm, and the root latex was low to a high level. The study revealed a strong correlation between the damaged root intensity and the number of feeding tunnels per root or SPWs per root. A highly positive correlation was also observed between the number of SPWs and the number of feeding tunnels per root. A weak and positive correlation was found between root epidermal thickness and the number of SPWs or feeding tunnels per root.