Population studies of three stored grain pests on two common legumes, the common pea and the Indian pea

Abstract:

Callosobruchus maculatus, Sitophilus oryzae and Tribolium castaneum are capable of infesting various food grains, including legumes. Population studies of these stored grain pests were conducted on the common pea and the Indian pea. The primary and secondary phytochemicals present in the selected host grains were profiled, and correlations between host metabolites and the growth of the pest populations were drawn. On both hosts, the immature period was longest in T. castaneum, followed by C. maculatus and S. granarius. In contrast, S. granarius greatly outlived the other two in terms of adult longevity. Based on the population parameters such as gross reproductive rate (GRR), net reproductive rate (NRR), and population size of the 2^nd generation (PF₂), the intrinsic rate of increase (r_m), the finite rate of increase (λ) and population growth rate (PGR), the susceptibility of both hosts to the pests has been classified in the order of: S. oryzae > C. maculatus > T. castaneum. S. granarius and C. maculatus thrive better on common pea than Indian pea, and T. castaneum thrives better on Indian pea. Nevertheless, both common pea and Indian pea require more control measures against S. granarius than C. maculatus or T. castaneum. An understanding of the degree of susceptibility of the grains to the pests may help in modifying grain phytochemical profiles for a more sustainable management of the pests.