RELATIONSHIPS BETWEEN SOIL FAUNA AND APETHYMUS FILIFORMIS OUTBREAKS IN ROMANIA

Apethymus filiformis is a new defoliator in Moldavia oak forests which eonymph stages remain under diapause in the soil. To understand its develop-ment, soil fauna analyses were realised in nine locations presenting an infesta-tion. It appeared that carabid fauna was very low in relationships with the proximity of a pesticide factory. Carabid densities were inversely correlated to DDT concentrations in soil samples. In the same time, densities of eonymphs were related to carabid assemblages indicating the potential role of ground beetles in the control of that new pest. Our hypothesis is thus that A. filifomis became resistant to the pesticide produced by the factory and transported by wind to the forest, whereas the predatory fauna was strongly reduced. This inverse relation had created the condition of that new pest outbreak. Key words: Apethymus filiformis, oak forests defoliation, predatory soil fauna, carabid species, invertebrate soil fauna composition and abundance