Suppression effects of predatory bugs on the stored-product insect Tribolium confusum (Coleoptera: Tenebrionidae)

Abstract

The impact of two predatory bugs, Xylocoris flavipes and Joppeicus paradoxus, on the stored-product insect, Tribolium confusum, was examined. Five pairs of adult T. confusum were placed in a plastic container (dia. 15 cm, height 8 cm) containing 10 g of whole-wheat flour. After 3 d, the following four experimental groups were set up: Control (no predator release), X. flavipes (four pairs of adult X. flavipes released), J. paradoxus (four pairs of adult J. paradoxus released), and X. flavipes+ J. paradoxus (two pairs each of X. flavipes and J. paradoxus released). Twenty-five days after the release of the predatory insects, we counted the number of living T. confusum, X. flavipes, and J. paradoxus. The number of T. confusum in the X. flavipes-treated and J. paradoxus-treated groups was 3 and 33% of the control, respectively. On the other hand, the suppressive effect of X. flavipes+ J. paradoxus treatment was lower than that of the above two treatments, probably due to intraguild predation between X. flavipes and J. paradoxus.