The research reported in Nature today (18 March) demonstrates how species that never meet may nevertheless influence each other's ecology through shared parasites, and confirms the action of an important ecological theory in the highly biodiverse rain forest environment.

Ecologists have long believed that species which have nothing in common but a 'natural enemy' - something that eats or parasitises both of them - may interact indirectly. The patterns that result parallel those caused by traditional competition for food, hence the name given to the effect: 'apparent competition'.

To test the theory scientists conducted a painstaking field experiment in Belize, Central America, measuring the effects of removing a beetle and a fly on other species with which they share natural enemies.

The beetle and fly belong to a very diverse group of insects whose larvae, named leaf miners, feed inside the leaves of plants. To take away just these particular insect leaf miners, researchers removed all traces of the plant that sustains only them.

A year after their removal, researchers surveyed the health of the insect species that shared natural enemies with the beetle and fly and found significantly lower parasitism and significantly higher abundance.

"This is basic ecological research intended chiefly to increase our understanding of these insect communities, but it also speaks to a number of biodiversity and management issues," said Professor Charles Godfray from the Natural Environment Research Council (NERC) Centre for Population Biology at Imperial, and author of the research.

If the results are typical of herbivore communities, say the authors, the development of this theory, and its associated experimental tests,
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Contact: Tom Miller
t.miller@imperial.ac.uk
44-207-594-6704
Imperial College London
18-Mar-2004