Sources of resistance to sweetpotato weevil (Coleoptera: Apionidae) in sweetpotato vines
Keywords:Sweetpotato, Ipomoea trifida, Cylas formicarius, Host-plant resistance, Resistance mechanism
AbstractSweetpotato weevil [Cylas formicarius (F)] attacks vines and roots of the sweetpotato [lpomoea batatas (L.) Lam.] plant in the field. Because of failure to find genetic sources of resistance to the weevil in roots, 1243 sweetpotato clones were screened in three field tests for resistance to this insect in vines. Evaluation of resistance was based on the number of sweetpotato weevils found inside the stems and the number of plants damaged by the insect. Two sweetpotato clones I 123 (B 6712) and I 959 (W-115), and four progenies from crosses between sweetpotato and lpomoea trifida (HBK) G. Don showed very high levels of resistance to sweetpotato weevil. Resistant clones had practically none or fewer insects and fewer plants with weevil damage compared with the susceptible clones. There was a highly significant positive correlation between the number of weevils in vines or the number of plants damaged and the diameter of the stems used as planting materials.