Avoidance of conspecific odour by carabid beetles: a mechanism for the emergence of scale-free searching patterns

We monitored the movements of a starved model predator, the carabid beetle Pterostichus melanarius, in arenas containing test papers upon which beetles had previously walked and unexposed control papers. Significantly, beetles accumulated on the unexposed controls, indicating conspecific avoidance (i.e. behaviour designed to avoid locations previously traversed by individuals of the same species). This finding is novel and important because optimal Lévy-flight (scale-free) search patterns for the location of sparsely and randomly distributed prey resources can emerge from conspecific avoidance. This finding may account for the shortcomings of random-walk (scale-finite) models when used to predict large-scale movement and search patterns by extrapolating from observations made at small scales.