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Interactions of the ant Crematogaster scutellaris with the fig/fig wasp mutualism

Authors


Bertrand Schatz, Centre d'Ecologie Fonctionnelle et Evolutive (CEFE) CNRS, 1919 route de Mende, 34293 Montpellier Cedex 5, France. E-mail: schatz@cefe.cnrs-mop.fr

Abstract

Abstract. 1. A classical example of specialised pollination mutualisms is the relationship between fig trees and their pollinating wasps, in which each partner depends completely on the other for its reproduction; however the fig/fig wasp association is also the target of a great diversity of other species, ranging from specialised parasites to opportunistic foragers, among them ants.

2. The ant community and the sources of ant attraction observed on the Mediterranean fig tree Ficus carica were characterised.

3. A guild of ants attracted by homopterans tended on the plant was distinguished from a second guild composed of two co-dominant ant species (Crematogaster scutellaris and Pheidole pallidula) that prey mostly on pollinating wasps, abundant during certain parts of the fig cycle.

4. Foraging workers of C. scutellaris search for prey on the fig inflorescence (syconium), capturing pollinating wasps mostly at the peak of wasp emergence and at a rate estimated to reach 600 prey per day for an entire tree.

5. Detailed study of the predatory sequences displayed under experimental conditions showed that ant workers captured 100% of the pollinating wasps offered, while they captured only 5.5% of the parasitoid wasp specific to the pollinator. The respective impacts of the interaction on ants and on the figs are discussed, as well as several behavioural traits of predation by the dominant ant on pollinators.

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