THE INFLUENCE OF INTERCROPPING AND MULCHES ON THE OCCURRENCE OF POLYPHAGOUS PREDATORS IN CARROT FIELDS IN RELATION TO CARROT FLY (PSILA-ROSAE (F)) (DIPT, PSILIDAE) DAMAGE

During 1989 and 1990 an inventory was made of beetles (Coleoptera), in the families Carabidae and Staphylinidae and spiders in carrot fields with a ley clipping mulch, a bark mulch, or lucerne (Medicago littora lis) as an intercrop. Two sites in central Sweden were included in the study. The most common carabid species at Uppsala were Bembidion quad rimaculatum, B. lampros, and Trechus quadristriatus. At Torslunda, B. lampros, Calathus melanocephalus, T. guadristriatus, Amara bifrons, an d Harpalus rufipes were the most abundant. The most abundant staphylin id genera at Uppsala were Anotylus, Arpedium, Philonthus, and Aleochar a, while at Torslunda Philonthus, Aleochara, and Anotylus were the mos t abundant. Differences in occurrence, measured as trap catch or numbe rs per soil sample, between treatments and over the season are present ed and discussed. Emphasis was placed on assessing the potential impor tance of these predators in suppressing carrot fly populations.