Long‐term developments in the carabid and staphylinid (Col., CArabidae and Staphylinidae) fauna during conversion from conventional to bilogivcal farming

Abstract

In two field experiments over periods of 6 and 8 years the activity density and diversity of carabids and staphylids were measured in pitfalls traps during the conversiion fron conventional to biological farming. Positive effects of the conversion were observed for many carabid species; among them Harpalus rufipes and several Amara , Bembidion and Pterostichus species, and the staphylinid fly parasitoid Aleochara bipistulata . The increased number of weed species present could at least partly explain the rise. Negative effects of the conversion were observed for several staphylinid species, among them Philonthus cognatus and Tachyporus species, and the carabid Trechus quadristriatus . It is hypothesized that the reduction in stapjylinids could partly be due to competition from the rising numbers of carabids.