EFFECTS OF CEREAL HEADLAND TREATMENTS ON THE ABUNDANCE AND MOVEMENTS OF 3 SPECIES OF CARABID BEETLES

The abundance and activity of carabid beetles in the headlands of cere al fields in the Breckland ESA, England, were monitored using pitfall traps and directional barrier traps. Uncropped wildlife strips were 6 m wide headlands left unsown and unsprayed but rotovated in autumn. Ea rly the following spring they had significantly less vegetation than f ully-sprayed headlands planted with winter wheat. Pterostichus melanar ius was more common in the open field than in either headland treatmen t. Agonum dorsale was least abundant in the uncropped wildlife strip b ut this habitat was significantly preferred by Bembidion lampros throu ghout the spring and early summer. A. dorsale had clear directional mo vement out from the field boundary into the crop in early May. The pre sence of the wildlife strip did not create a significant barrier to th is movement, nor did it significantly reduce the rate at which B. lamp ros dispersed out into the crop. On the contrary it was such a favoura ble habitat for this species that it acted as an additional source of colonising individuals. The results are discussed in the context of th e effects of headland management on the colonisation of crops by polyp hagous predators and their potential for the biological control of aph id pests. (C) 1998 Elsevier Science B.V.