Quality of two aphid species (Rhopalosiphum padi and Sitobion avenae) as food for the generalist predator Tachyporus hypnorum (Col., Staphylinidae)

Abstract

Abstract: The quality of two aphid species (Rhopalosiphum padi and Sitobion avenae) as food for the staphylinid generalist predator Tachyporus hypnorum was investigated. Fruit flies (Drosophila melanogaster) were used as prey for comparison. T. hypnorum has been reported to prey on aphids, to consume large quantities and to show a high preference for aphids. This study showed that compared with fruit flies aphids are not high‐quality prey for neither adult females nor larvae of T. hypnorum. Larvae were less able to utilize aphids than adult females. Reproduction was affected by both aphid species; a diet of S. avenae reduced fecundity, and a diet of R. padi reduced egg hatching success and prolonged the time spent in the egg stage compared with a fruit fly diet. For the T. hypnorum larvae pure diets of both S. avenae and R. padi resulted in high larval mortality. Overall ranking of the three prey types based on several fitness parameters differed between larvae and adults. The adult fitness parameters gave rather conflicting rankings of all three prey types though the two aphid species were of approximately the same overall value, whereas the larval fitness parameters gave identical rankings: D. melanogaster > S. avenae > R. padi. In the larval stage survival was greatly reduced by both aphid diets, while this was not the case for the adult females.