Aphid–ant mutualism: how honeydew sugars influence the behaviour of ant scouts |
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Authors: | CLAIRE DETRAIN FRANÇOIS J VERHEGGEN LISE DIEZ BERNARD WATHELET ERIC HAUBRUGE |
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Institution: | 1. Unit of Social Ecology, Université libre de Bruxelles, Brussels, Belgium;2. These authors contributed equally to this study.;3. Department of Functional and Evolutionary Entomology, Gembloux Agro‐Bio‐Tech, Université de Liège, Liège, Belgium;4. Department of Biological Chemistry, Gembloux Agro‐Bio‐Tech, Université de Liège, Liège, Belgium |
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Abstract: | Honeydew is the keystone on which ant–aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a recruitment trail by scouts of the aphid‐tending ant Lasius niger Linnaeus, and thus may enhance collective exploitation by the ant mutualists. The feeding preferences shown by L. niger for honeydew sugars are: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose. Although feeding is a prerequisite to the launching of trail recruitment, the reverse is not necessarily true: not all ingested sugar solutions elicit a trail‐laying behaviour among fed scouts. Trail mark laying is only triggered by raffinose, sucrose or melezitose, with the latter sugar being specific to honeydew. By comparing gustatory and recruitment responses of ant foragers to sugar food sources, the present study clarifies the role of honeydew composition both as a source of energy and as a mediator in ant–aphid interactions. Lasius niger feeding preferences can be related to the physiological suitability of each sugar (i.e. their detection by gustatory receptors as well as their ability to be digested and converted into energy). Regarding recruitment, the aphid‐synthesized oligosaccharide (melezitose) could be used by ant scouts as a cue indicative of a long‐lasting productive resource that is worthy of collective exploitation and defence against competitors or aphid predators. |
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Keywords: | Ant aphids Aphis fabae decision‐making feeding preference honeydew sugars Lasius niger trail recruitment |
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