The relationship between ants and aphids is an example of:
The ant–aphid association is classed as defensive mutualism because ants protect aphids from predators and parasitoids, while aphids provide carbohydrate-rich honeydew. Aphids excrete honeydew after feeding on sugar-rich phloem sap; attending ants collect it and may stimulate release by antennation. In return, ants attack ladybird beetles, lacewing larvae, or parasitoid wasps, remove dead aphids, and sometimes shelter aphid colonies. Both partners can therefore gain increased fitness: ants acquire an accessible energy source, and aphids experience lower enemy mortality. The interaction is not
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13
