Effects of cereal headland treatments on the abundance and movements of three species of carabid beetles.

Abstract

The abundance and activity of carabid beetles in the headlands of cereal 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. Early the following spring they had significantly less vegetation than fully-sprayed headlands planted with winter wheat. Pterostichus melanarius was more common in the open field than in either headland treatment. Agonum dorsale was least abundant in the uncropped wildlife strip but this habitat was significantly preferred by Bembidion lampros throughout the spring and early summer. A. dorsale had clear directional movement out from the field boundary into the crop in early May. The presence of the wildlife strip did not create a significant barrier to this movement, nor did it significantly reduce the rate at which B. lampros dispersed out into the crop. On the contrary it was such a favourable habitat for this species that it acted as an additional source of colonising individuals. The results are discussed in the context of the effects of headland management on the colonisation of crops by polyphagous predators and their potential for the biological control of aphid pests.