LIMITED PREDATION CAPACITY BY GENERALIST ARTHROPOD PREDATORS ON THE CEREAL APHID, RHOPALOSIPHUM-PADI

Predatory species that are considered beneficial in the limitation of cereal aphids might be expected to display a high preference for aphid s. Experiments with several potential generalist aphid predators have revealed a low preference for the aphid Rhopalosiphum padi and a low t olerance limit to the consumption of aphids. In these experiments, the limited tolerance of some carabid beetles and linyphiid spiders to Rh opalosiphum padi is demonstrated. Twenty four h food consumption (mg d w mg(-1)) of two prey types, R padi and Drosophila melanogaster, was d etermined in both satiated and starved predator individuals. In most c ases the feeding capacity for aphids was found to be consistently lowe r than for fruit flies. Aspects of the natural control of a pest that is of low preference and is not well tolerated by its predators are di scussed.