Influence of crop edges on movement of generalist predators: a diffusion approach
1 Diffusion models were applied to recapture data for the generalist predator Pterostichus cupreus (Coleoptera: Carabidae) moving between two adjacent crop habitats (perennial ley and annual barley) first excluding, and then including, terms in the model quantifying the influences of edges on beetle movements.
2 Adult beetles were released at the centre of experimental 3 × 3 m plots that overlapped the edge separating perennial ley (mixed perennial crop of grass and clover) and annual barley crops, both early and later in the growing season.
3 Mathematical description of the data improved when the attractive or repulsive effects of habitat edges on dispersal were considered in the model.
4 Early in the season, when a sharp habitat edge was present, P. cupreus beetles appeared ‘attracted’ to ley.
5 Diffusion rates were consistently higher in barley than in ley early in the season, and vice versa late in the season. These patterns were probably linked to variation in prey availability.
6 Despite the risk of experiencing food limitation in the annual crop, our analyses suggest that these beetles regularly move from ley into the early barley habitat and then continue to disperse within the barley, providing opportunities for enhanced biological control of pest species.
Document Type: Original Article
Affiliations: Department of Biology, Arizona State University, Tempe, AZ 85287-1501, USA
Publication date: February 1, 2002