"It suggests that removal or addition of species, for example through selective logging or the release of a biological control agent, may have knock-on effects mediated by the network of natural enemies," said Professor Godfray.

The authors of the research from the NERC Centre for Population Biology at Imperial College London and the University of Oxford carried out the large-scale field experiment at the Natural History Museum's Las Cuevas Research Station in Belize, Central America.

Their experiment wasn't simple or easy: while scientists have carried out tests of apparent competition along coastal shorelines and in laboratory systems, manipulative experiments on insect communities in an environment as complex as a tropical forest are difficult and challenging and have rarely been attempted. Parasitism and predation can be especially intense, and levels of insect biodiversity are exceptionally high.

Previous work at the site by the same group led by one of the authors, Dr Owen Lewis, revealed the complexity of the food web they were studying: 93 species of leaf miner were attacked by 84 species of parasitoid wasp. Of the plants that were host to leaf miners, most were attacked by a single species but the researchers found that the vine plant Lepidaploa tortuosa was home to two leaf miners - a fly and a beetle (Latin names Pentispa fairmairei and Calycomyza sp. 8 respectively).

To test the apparent competition theory the researchers removed all of the L.tortuosa in their experimental fieldwork plots, alongside a 6-km stretch of track, in December 2001. In control plots the same biomass of plant material was removed from randomly chosen plant species that were not attacked by leaf miners.

Ten to 12 months, or five to six leaf miner generations, later, the scientists returned to measure the diffe
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Contact: Tom Miller
t.miller@imperial.ac.uk
44-207-594-6704
Imperial College London
18-Mar-2004