Plant-derived differences in the composition of aphid honeydew and their effects on colonies of aphid-tending ants Elizabeth G. Pringle1,2,3, Alexandria Novo2, Ian Ableson2, Raymond V. Barbehenn2,4 & Rachel L. Vannette5 1Michigan Society of Fellows, University of Michigan, Ann Arbor, Michigan 48109 2Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109 3School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan 48109 4Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 5Department of Biology, Stanford University, Stanford, California 94305 Keywords Abstract Aphis nerii, Asclepias spp., carbohydrate, – – cardenolides, Linepithema humile, milkweed, In plant ant hemipteran interactions, ants visit plants to consume the honey- phloem chemistry, tritrophic interactions. dew produced by phloem-feeding hemipterans. If genetically based differences in plant phloem chemistry change the chemical composition of hemipteran Correspondence honeydew, then the plant’s genetic constitution could have indirect effects on Elizabeth G. Pringle, Michigan Society of ants via the hemipterans. If such effects change ant behavior, they could feed Fellows, University of Michigan, Ann Arbor, back to affect the plant itself. We compared the chemical composition of hon- Michigan 48109. Tel: 734-615-4917; eydews produced by Aphis nerii aphid clones on two milkweed congeners, Fax: 734-763-0544; E-mail:
[email protected] Asclepias curassavica and Asclepias incarnata, and we measured the responses of experimental Linepithema humile ant colonies to these honeydews. The compo- Funding Information sitions of secondary metabolites, sugars, and amino acids differed significantly This work was supported by a Michigan in the honeydews from the two plant species.