Chickpea fertilization with chemical- and bio-fertilizers affected oviposition preference, population growth and digestive enzymatic activity of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae)

Abstract

The cowpea weevil, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) is one of the most pernicious pests of stored pulses. The use of fertilizers can induce resistance in plant organs against insect pests. In this study, chickpea grains were treated with chemical- (urea and phosphorus) and bio-fertilizers (mycorrhizal fungi, Azotobacter chroococcum, and Mesorhizobium ciceri Strain C-15), and cultivated at farm conditions. After harvesting the ripe grains, C. maculatus oviposition preference, population parameters and digestive enzymatic activity on treated grains and control were evaluated at controlled conditions. The cowpea weevil reared on the grains treated with A. chroococcum and mycorrhizal fungi showed the lowest pre-adult survival and amylolytic activity. Fecundity of females on control grains was higher than on A. chroococcum-treated grains. The oviposition preference on control grains was higher than on mycorrhizal fungi-treated grains. The intrinsic rate of increase (r) and net reproductive rate (R0) of C. maculatus on grains fertilized with A. chroococcum and mycorrhizal fungi were significantly lower than the control. The high amount of tannins and phenolics in the grains treated with A. chroococcum and mycorrhizal fungi can be the reason for their resistance to C. maculatus attack. Therefore, these two treatments have good potential to be included in chickpea fertilization programs and integrated management of C. maculatus.