Suppression Effects of Predatory Bugs on the Stored-Product Insect Tribolium confusum (Coleoptera: Tenebrionidae)

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.