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New Zealand Plant Protection 59 (2006): 178-183

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

S.A. Araj, S.D. Wratten, A.J. Lister A and H.L. Buckley

ABSTRACT

In this study, the potential consequences of making a three- or four-trophic 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 4-5 times longer than those in the control (water only) and 3-4 times longer than those provided with phacelia, alyssum or coriander. Hyperarasitoids provided with buckwheat survived 56 times longer than those in the control and 3-5 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.

Keywords: biological control, longevity, Acyrthosiphon pisum, Aphidius ervi, Dendrocerus aphidum, Phacelia tanacetifolia, Lobularia maritima, Coriandrum sativum, floral nectars, resource subsidies, trophic cascades, trophic levels.

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