Physical basis of resistance in cowpea, Vigna unguiculata against Callosobruchus maculatus (Fab.) (Chrysomelidae: Coleoptera)

The present study was aimed to find out resistant sources against bruchid, Callosobruchus maculatus in 60 cowpea coreset accessions. The resistance to Callosobruchus maculatus Fab. in an entire set of 60 distinct accessions of cowpea was evaluated using no-choice artificial infestation conditions. There was significant difference in the specific growth parameters of C. maculatus such as oviposition rate, per cent adult emergence and no. of exit holes. There was significant variation in the percentage of weight loss per cent in seed (PSWL) due to bruchid infestation. Further, quantitative seed parameters viz., seed length and seed width of diverse cowpea accessions varied significantly. However, there was a positive correlation observed between seed physical parameters and specific growth parameters of C. maculatus. Further, per cent seed weight loss showed significant and positive association with oviposition period and emergence holes. The 60 coreset accessions were characterized into five categories viz., highly resistant, resistant, moderately susceptible, susceptible and highly susceptible based on per cent seed weight loss (PSWL). The two (IC426810 and IC420591) out of 60 accessions were grouped as highly resistant, and these were also found with lower oviposition rate and adult emergence. The present investigation was conducted during the years 2021 and 2022 at Division of Plant Quarantine, ICAR-National Bureau of Plant Genetic Resources (NBPGR), New Delhi and it suggests that IC426810 and IC420591 accessions could be utilized in various breeding programs for bruchid resistant cultivars development in cowpea and its other related Vigna species.