Formica-Euphorbia: ambiguous interactions

ant-euphorbiaI photographed this ant hanging on a Euphorbia flower in Bellwald, Switzerland. The ant probably belongs to the genus Formica, and the plant seems E. cyparissias.
Since my time in Madagascar I pay much more attention to flowers and pollinators than I used to do. I guessed that the ant was probably foraging on the flowers, but the pollen grains on its head and abdomen suggested that it could also act as a pollinator: what was it then, herbivore or pollinator? “Good” interactor or “bad” interactor?I did a bit of research: S. Schurch, M. Pfunder and B. A. Roy experimentally demonstrated the role of ants as pollinators of E. cyparissias in 2000 (OIKOS 88: 6 – 12).
The ecological implications of ants and other animals that can act both as “predators” and pollinators, thus creating interactions that are contextually positive and negative, surely deserves more attention.

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