Certain tropical plants host colonies of ants in their hollow domatia and provide the ants with nutrition delivered from nectaries or food bodies. These ant colonies have become dependent on the host plants for their survival and therefore actively protect the plant; this protection can take the form of killing or warding off pests, weeds, and certain fungal pathogens. Chinese citrus farmers have capitalized on this mutualistic relationship for many years by incorporating artificial ant nests into their crops to suppress pests.