On our patio we have strawberry plants in pots. For the past two years we have noticed that large numbers of ants systematically bring small bits of dirt, gravel and woodchips, and pile them around the bases of the plants and their runners (see Photo). It seems they are cultivating the plants. When the strawberries are grown, however, the ants do not always eat them, but sometimes bury them. The plants seem to thrive 鈥� what is going on?
鈥淭he ants are not cultivating the plants, they are using the roots as a structure for their nests鈥�
The ants are not cultivating the plants; they are using the roots as a structure for their nest. It is easier to run up and down a root than to clamber over soil particles. As the ants excavate their nest, they carry the soil to the surface and extend their nest upwards, covering the plant. This is the beginning of an anthill.
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The plants thrive because their roots have a good air and water supply, are kept clean and are supplied with abundant waste products from the nest. It is a form of symbiosis. It can also help gardeners 鈥� on my lawn, where the ants colonise dandelion plants, they loosen the soil around the roots making it quite easy for me to pull up the weeds.
Richard Lucas, Hawley, Hampshire, UK
No ants, as far as I am aware, are known to cultivate green plants in the way described. I suspect that what is happening is that the ants are incorporating the stems and runners of the strawberry plants into their nest excavations, perhaps using them as supports for galleries. You do see this on anthills where plants that have colonised the mounds become partially buried by the ants鈥� activities.
Jeff Ollerton, Landscape and Biodiversity Research Group, University of Northampton, UK