Cannibalism and intraguild predation in Rhynocoris fuscipes and Arma chinensis

Rhynocoris fuscipes and Arma chinensis are two important predatory natural enemies that can control Spodoptera litura. To investigate cannibalism and intraguild predation (IGP) between these two predatory bugs, experiments were conducted to evaluate R. fuscipes and A. chinensis under laboratory conditions. The results showed that the cannibalism effects of both species increased with insect instar, and the cannibalism effect of R. fuscipes was more severe than that of A. chinensis. Both predatory bugs had an IGP effect at all nymphal and adult stages, but few eggs were preyed upon. The survival rate of R. fuscipes was higher than that of A. chinensis at each developmental stage, especially the survival rate of 1st instar nymphs of R. fuscipes was significantly higher than that of 1st instar nymphs of A. chinensis. When S. litura was provided as prey, the IGP effects of R. fuscipes and A. chinensis at different stages were significantly reduced. These results indicated that R. fuscipes was an intraguild predator (IG-predator) and A. chinensis was an intraguild prey (IG-prey). The combined predation effect of two predators on S. litura was significantly higher than that of a single predator.