Floral nectar affects longevity of the aphid parasitoid Aphidius ervi and its hyperparasitoid Dendrocerus aphidum

Abstract

In this study the potential consequences of making a three or fourtrophic level system more complex by adding floral resources was studied in the laboratory for a range of plant nectar sources the aphid parasitoid Aphidius ervi and its hyperparasitoid Dendrocerus aphidum Parasitoids exposed to flowering buckwheat survived 45 times longer than those in the control (water only) and 34 times longer than those provided with phacelia alyssum or coriander Hyperarasitoids provided with buckwheat survived 56 times longer than those in the control and 35 times longer than those on the other flowering plants Buckwheat phacelia alyssum and coriander can therefore enhance the fitness of A ervi without benefiting its aphid host which does not feed on nectar However the fitness of the hyperparasitoid may increase relatively more than that of the parasitoid depending on the nectar source