Crop succession and habitat preferences drive the distribution and abundance of carabid beetles in an agricultural landscape
Résumé
This study investigated how crop type and crop succession influence the distribution and the dynamics of abundance of two dominant carabid beetle species (Poecilus cupreus and Brachinus sclopeta) at two critical stages of their life cycle: the spring reproductive and overwintering periods. The study was conducted over 9 years in an agricultural landscape of western France using both pitfall and emergence traps located within and in the margins of fields of the five dominant crops in the study area. The two carabid species used crop and non-crop habitat types differently during the reproductive period and while overwintering, suggesting two different strategies of habitat use. Both species used within-field areas during the spring reproductive period. However, B. sclopeta was only active in oilseed rape while P. cupreus was also active in the other crops. Overall, data suggested a beneficial role of oilseed rape for both species. B. sclopeta emergence from overwintering occurred predominantly in the margins of fields cropped with oilseed rape the previous year. P. cupreus used both margins and within field areas as overwintering habitats. Results suggest that inter-field movements and active selection rather than differences in survival rates may explain distribution and abundance dynamics of these two carabid species in agricultural landscapes.