Biochemical and Morphological Basis of Resistance in Groundnut to Groundnut Bruchid, Caryedon gonagra

Seven groundnut (Arachis hypogaea L.) genotypes were evaluated for resistance against the groundnut bruchid, Caryedon gonagra, under storage conditions at the Department of Entomology, S.V. Agricultural College, Acharya N.G. Ranga Agricultural University, Tirupati. Key parameters recorded were fecundity, adult emergence, developmental period, pod damage, weight loss and susceptibility index. Based on the susceptibility index, groundnut genotypes were classified as moderately resistant (Kadiri Chitravathi, K-1687), moderately susceptible (K-1677, Dharani, Kadiri Lepakshi), susceptible (K-6), and highly susceptible (K-7 Bold). The moderately resistant genotypes recorded the lowest number of eggs (24.33–34.00 eggs/100 pods), reduced adult emergence (45.67–48.00%), extended developmental period (76.02–76.27 days), and minimal pod damage (20.67–25.33%) with low weight loss (4.14–4.34%). Bruchid resistance was associated with lower protein (18.46–18.81%) and lower total soluble sugars (5.03–5.27%), and higher phenol content (243.07–265.01 mg/100 g). In contrast, the highly susceptible genotype K-7 Bold recorded the highest oviposition (227.67 eggs/100 pods), adult emergence (195.67), pod damage (100%), and weight loss (30.27%). Susceptibility was correlated with higher pod and seed weights, greater intergranular space, and higher protein (23.68%) and sugars (6.76%), coupled with lower phenol content (172.67 mg/100 g).The findings suggest that both morphological and biochemical traits significantly influence resistance in groundnut genotypes to groundnut bruchid, offering valuable insights for breeding programs targeting bruchid resistance.