Screening of Ricebean [Vigna umbellata (Thunb.) Ohwi and Ohashi] Cultivars against Pulse Beetle [Callosobruchus chinensis (L.)]

Background: Ricebean [Vigna umbellata (Thunb.) Ohwi and Ohashi] is an important food legume grown in Nagaland, India. It is a versatile underutilized pulse crop grown as a dry pulse and also used as green manure and fodder. Insect pests are one of the major constraints encountered and the pulse beetle, [Callosobruchus chinensis (L.)] is an important pest that causes considerable damage to Vigna seeds. This experiment was carried out to determine the basis of resistance among different ricebean cultivars against pulse beetle which will help in development of resistant varieties. Methods: A laboratory experiment was conducted during January-June of 2019 and 2020 where 16 ricebean cultivars were screened against pulse beetle. The biological parameters of the pest on different cultivars were studied. Correlation between biological parameters of C. chinensis and physico-chemical parameters in different ricebean cultivars was studied. Result: Significant difference was observed in terms of the biological parameters of the pest and the physico-chemical parameters of seeds. The seed size and seed index have significant correlation with the biological parameters of pulse beetle. Cultivars with higher protein and starch content were more susceptible while cultivars with higher phenol and tannin content were less susceptible. Based on the growth index, the following three cultivars viz., Rhujo, Akixi Anila and Manyhu Rhi were found to be moderately resistant.