A Cascade of Consequences

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Science  17 Aug 2012:
Vol. 337, Issue 6096, pp. 778
DOI: 10.1126/science.337.6096.778-c
CREDIT: SATO ET AL., ECOL. LETT. 15, 786 (2012).

Specialized interactions between pairs of species can have wide and surprising consequences for the wider ecosystem they inhabit. Sato et al. investigated the case of the nematomorph parasitic worm, which has a life cycle involving a free-living adult stage and several parasitic larval stages, the last of which parasitizes cricket hosts. The relationship is manipulative, in that the worm induces the cricket to head for stream waters, where the adult worm will emerge to complete its free-living reproductive phase. The authors show experimentally that the addition of crickets to a Japanese stream ecosystem diverts predatory trout toward this attractive source of food and away from their normal diet of benthic invertebrates, in turn leading to a decrease in benthic algae and an increase in the rate of leaf-litter breakdown. Because of the ubiquity of nematomorphs at streams and streambanks globally, the cascading effects of their manipulative parasitism may be a common feature of these ecosystems.

Ecol. Lett. 15, 786 (2012).

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