PERMEABILITY OF HEDGEROWS TO PREDATORY CARABID BEETLES

Invertebrates move in the agricultural landscape at a range of spatial scales. These movements may be seasonal events or induced by farming activities such as cultivation, pesticide application etc. The animals ' activity may take them across field boundaries, which may represent impediments to such movement, especially for non-flying arthropods. In this work, marked predatory carabid beetles (Harpalus rufipes, Pteros tichus melanarius and Pterostichus madidus) were released within polyt hene-walled areas that traversed either a hedgerow or were located wit hin a barley field. The rate of recapture of the beetles at the opposi te end of the experimental areas was recorded for up to 25 days follow ing release. Recapture rates reached 100% in some cases but movement w as markedly slowed in the hedgerow treatment compared with the barley field control. There were also effects of beetle starvation and sex. S tarvation prior to release resulted in a more rapid crossing of the bo undary, especially for P. melanrius (both sexes) and H. rufipes female s. Results are compared with other studies on the role of landscape fe atures in slowing insect dispersal, involving groups such as Coleopter a, Lepidoptera and Diptera