April 30, 2009

Study IDs a strange plant-ant relationship

A Harvard University biologist says there are many beneficial relationships between organisms but she has discovered a rather strange ant-plant arrangement.

Harvard researcher Megan Frederickson said Myrmecophyte plants often provide home for several species of ants by sheltering them in hollow spaces in its limbs or leaves. The ants, in turn, protect the plant from other insects or encroaching vegetation.

But Frederickson says sometimes that balance tips toward one partner or the other.

Frederickson confirmed a rather tumultuous relationship between the ant-plant C. Nodosa and the ant species A. octoarticulatus. The relationship is much like that of other ants and ant-plants until it comes time for the plant to reproduce. When Nodosa begins to flower, the ants attack the buds, in effect, sterilizing the plant.

When researchers first described this intriguing behavior over a decade ago, they suggested that perhaps the ants destroy flowers to promote the growth of their host plants, much as gardeners prune roses to encourage the growth of their rose bushes, Frederickson said, noting the larger the plant, the more living space the ants have.

To test the theory, Frederickson measured growth rates of sterilized and non-sterilized Nodosa plants. She found that, indeed, the sterilized plants grew faster, providing more space for ants to inhabit.

Frederickson reports her research in the May issue of The American Naturalist.