DENSITY PATTERNS OF GALL MITES (ACARINA, ERIOPHYIDAE) IN A POLLUTED AREA

Trends in the densities of six species of gall mites on European aspen (Populus tremula) and on two birch species (Betula pubescens and B. p endula) were compared in an air pollution gradient from the Harjavalta copper-nickel smelter, SW Finland. The densities of gall mites on bot h birch species decreased towards the smelter and were negatively corr elated with the levels of copper and nickel in the birch leaves. In co ntrast, the densities of aspen mites correlated neither with distance from the pollution source nor with the content of heavy metals in aspe n leaves. Both birch and aspen trees tended to produce smaller leaves near the smelter, but a significant correlation between gall mire dens ities and site-specific leaf areas was only found for one species of m ite. Copyright (C) 1996 Elsevier Science Ltd