اندازه‌گیری تخم‌گذاری Callosobruchus maculatus بر روی دانه‌های لوبیا چشم‌بلبلی تیمار شده با کودهای مختلف

Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae), a major pest of stored cowpea Vigna unguiculata L. Walp., causes critical losses by decreasing the grain weight, germination ability and nutritional quality. Plant fertilization may enhance the resistance of seeds against post-harvest insects. Improving host-plant resistance by using a suitable fertilizer would be beneficial in reducing C. maculatus infestation in storage. Two cowpea cultivars (Mashhad and 1057) were planted in the field and fertilized with chemical fertilizer triple superphosphate (TSP) (200 kg/ha) and urea (70 kg/ha) and bio-fertilizers, Bradyrhizobium japonicum (1 L/kg seed), Pseudomonas putida (1 L/kg seed), mycorrhizal fungi (1 kg/kg seed), and a mixture of them (1 L/kg seed), and cultivated at a farm with three plots and 7 treatments. Ripe seeds were harvested and used in the experiments. The weevil rearing and tests were carried out in a growth chamber set at 28±1°C, relative humidity of 65±5%, and 24 h darkness. Evaluation for resistance of fertilized cowpea to C. maculatus performed by a no-choice test. For each treatment, 3 pairs of 1-d-old male and female adults were placed in separate plastic containers (diameter 10 cm), each containing 10 cowpea grains as oviposition substrates from the treatment or control. Every 24 h, the number of eggs deposited by females were counted, and the grain having the egg was replaced with a new uninfested grain. This experiment was performed in 5 replicates. The General Linear Model was utilized to analyze the data using Minitab version 18.0. The number of eggs laid on tested cultivars showed significant difference. However, among 14 treatments, the number of eggs laid was the highest on Mashhad cultivar treated with no fertilizer control treatment (121.2 eggs), and lowest on 1057 cultivar treated with B. japonicum (48.8 eggs). On 1057 cultivar, the number of eggs laid on seeds fertilized with B. japonicum was lower than the other treatments. Cowpea seed color, size, smoothness, and hardness play an important role in the oviposition choice of C. maculatus. According to the results of this study, using B. japonicum on 1057 cultivar is recommended to decrease the damage of C. maculatus in storage.