DESIGN AND USE OF A TIME-SORTING PITFALL TRAP FOR PREDATORY ARTHROPODS

An electronically-controlled time-sorting pitfall trap was designed wh ich improves upon earlier models in having a 24-h rotation time, and i n being capable of running continuously for at least one week without attention. Four prototypes were built, using readily available, inexpe nsive components, and used from June to October, 1995, to collect cara bid beetles and linyphiid spiders in clover-undersown and weeded cabba ges. The traps operated without malfunction during the hottest weather ever recorded in Aberdeen, when soil surface temperatures exceeded 40 degrees C, and also during periods of torrential rain. Three spider a nd two carabid species dominated the catch, their nocturnal and diurna l patterns of activity being in general agreement with other published data. Some predators were apparently able to adapt to the contrasting vegetation in the two treatments, two species of Erigone spiders bein g nocturnal in weeded cabbages but tending to be diurnal in undersown crops. (C) 1997 Elsevier Science B.V.