Quantifying movement of the predator carabid beetle Pterostichus melanarius in arable land
Abstract: Current knowledge on entomophagous arthropod distribution and movement patterns, in particular for soil-dwelling predators, is insufficient to provide advice on how a production landscape should be re-arranged to maximally benefit from biological pest control. Movement has mainly been measured in single habitats rather than in habitat mosaics, and little information is available on behaviour at the border between two habitats, i.e. a habitat interface. In this paper we summarize results of a meta-analysis on motility μ (L2 T−1), a measure for diffusion of a population in space and time, of carabids in arable land and on the quantification of dispersal behaviour of the predator carabid beetle Pterostichus melanarius in arable land. Movement of this species was measured using video equipment in experimental arenas and at much larger scale in the field using mark-recapture. Interpretation of the results was supported by diffusion models that accounted for habitat specific motility, preference behaviour at habitat interfaces and beetle losses. We found distinct differences in motility of this species between habitat types and preferential movement behaviour at habitat interfaces. Especially the crop-margin interface resulted in a strong bias in movement directed towards the crop, indicating that semi-natural elements act as barriers for movement of P. melanarius during the growing season. Based on the parameter values obtained in this study we expect little redistribution of beetles between fields during summer, especially when fields are separated by semi-natural elements.