Distribution, dispersal and population size of the ground beetles, Pterostichus melanarius (Illiger) and Harpalus rufipes (Degeer) (Coleoptera, carabidae), in field margin habitats

Abstract

Dispersal can be an important factor in the ecology of beneficial carabids in agroecosystems. Predicting the large-scale effects of changing landscape structure and management of agricultural systems on fragmented invertebrate populations requires a modelling approach in which dispersal is a critical metapopulation parameter. This paper reports the use of mark-recapture techniques in a pilot experiment to estimate dispersal, population size and distribution of two large carabids, Pterostichus melanarius and Harpalus rufipes, in a cereal field, its established hedgerow and an experimentally sown field margin. Distributions of both species changed with time, P. melanarius moving from the field margins into the cropped area, H. rufipes remaining within the hedgerow and field margins. Population size of P. melanarius was estimated at approximately 0.6 m(-2). 60% of P. melanarius dispersed 0 to 2.5 m day(-1) and approximately 5% moved 7.5 to 10 m day(-1).