Fish predation limiting abundance and distribution of Glaenocorisa p.propinqua

The effect of fish predation on abundance and distribution of the water-bug Glaenocorisa propinqua propinqua (Fieb.) (Corixidae, Hemiptera-Heteroptera) was studied. The results showed that fish predation can reduce a population of G.p.propinqua to a level not detectable with the sampling techniques used. Moreover, the species turned up in a lake where it was never before recorded when the fish population was eliminated. This indicates that fish predation may limit not only the local but also the regional distribution of G.p. propinqua. This suggestion is supported by the recent colonization by the species of many of the lakes in southwestern Sweden which have lost their fish population due to acidification.