Tropical soda apple (Solanum viarum Dunal) is a major exotic weed in pastures and conservation areas in subtropical regions. Anthonomus tenebrosus Boheman (Coleoptera: Curculionidae) was found feeding on the flowers of tropical soda apple in southern Brazil and was considered a potential biological control agent. The objectives of this study were to examine the life history and host specificity of A. tenebrosus. The development from egg to adult was measured at eight constant temperatures in growth chambers. The presence of reproductive diapause was measured by using a two-way factorial design with three temperatures (20, 22.5, and 25°C) and two photoperiods (14:10 and 10:14 [L:D] h). Temperature influenced the developmental time from egg to adult of A. tenebrosus, which ranged from 49.6 d at 16°C to 13.6 d at 28°C. The longevity of males ranged from 64 to 190 d, whereas females lived from 44 to 204 d. When exposed to 10:14 (L:D) h and 20°C, 35% of females entered reproductive diapause. The fundamental host range of A. tenebrosus—based on several life-history aspects, including adult longevity, oogenesis, and oviposition—and immature development of A. tenebrosus were studied. Under no-choice conditions, ≈80% of adults survived for 30 d on several Solanum melongena L. varieties, Solanum capsicoides, S. viarum, and Solanum carolinense L. A. tenebrosus completed development from egg to adult on a number of S. melongena varieties, the native plant S. carolinense, and the exotic plants S. capsicoides All, S. viarum, and Solanum tampicense Dunal. Under paired-choice conditions, adult feeding occurred on all species, whereas oviposition occurred only on S. viarum, S. capsicoides, and S. carolinense. Because of the nontarget attack to S. melongena and a native plant, A. tenebrosus should not be considered for release as a biological control agent of tropical soda apple in the United States.