Extinction of one predator can trigger demise of another

The extinction of one carnivore species can trigger the demise of fellow predators, new research has found.

The findings suggest that rather than keeping focus on the conservation of a single species, a whole system approach that also includes fellow predators works better for conservation.

"If we want to protect an endangered carnivore species, for example, we might need to protect other predators around it, which is quite an important message," said one of the researchers, Dirk Sanders, from the University of Exeter in England.

Using insects, the research team set up experimental communities with complex food webs in 40 four-square metres outdoor field-cages which they observed over a spring and summer season.

These communities consisted of several species of aphids and their natural enemies, parasitoid wasps.

They found that removing one wasp species led to an increased rate of extinction in other species of wasp, an effect that was transmitted through changes in density of the aphid species.

"This is a unique experiment. Usually these research questions are tackled with theoretical approaches and researchers focus on extinctions after the loss of food species. This is the first time anyone has looked at mechanisms of horizontal extinction cascades in a natural large field experiment," Sanders noted.

The study was published in the journal Current Biology.