CONSUMPTION BY CARABID BEETLES OF 3 CEREAL APHID SPECIES RELATIVE TO OTHER PREY TYPES

The cereal aphid Rhopalosiphum padi has previously been found to be a low quality prey for a range of generalist arthropod predators. The ai m of this study was to reveal, using food consumption experiments whet her this applies to other cereal aphids. The question of whether preda tor feeding capacity increased when several aphid species were offered relative to a single aphid species was also addressed by measuring fo od consumption on a mixed aphid diet relative to single aphid diets. F ood consumption by five carabid beetles of the three cereal aphid spec ies Rhopalosiphum padi, Sitobion avenae and Metopolophium dirhodum was determined relative to fruit flies Drosophila melanogaster and the co llembolan Isotoma anglicana. Feeding rate was measured as food consump tion over 24 hour both for previously satiated and beetles starved for 7 days. Generally the largest aphid consumption was of M. dirhodum an d the lowest of R. padi, with S. avenae in between. The mixed aphid co nsumption experiments did not reveal a higher feeding rate on mixed ap hid diets relative to single aphid diets. The results indicate low pre ference for R. padi and S. avenae.