Predation of codling moth eggs is affected by pest management practices at orchard and landscape levels

The low sustainability of pesticides calls for alternative pest control practices. Among these, the conservation of pest natural enemies is governed both by the local farming practices and by the presence of resources in the surrounding landscape. We investigated the effect of landscape composition on predation of sentinel eggs of the codling moth (Cydia pomonella), a key pest in apple orchards. Thirty egg cards of approximately 15 eggs were exposed twice in each of 12 orchards. Orchards were characterized by their area, their crop protection practices, the abundance of their codling moth population and the abundance of predatory earwigs. The landscape was characterized by the area and management of orchards host to the pest and by the characteristics of the hedgerow network in 50 m and 100 m wide buffers. On average, 12.4% and 48.3% of the egg cards were attacked by predators in June and August, respectively. Predation depended mostly on the toxicity of the crop protection programs. Predation rates were also lower in orchards surrounded by large areas of conventional orchards. No other landscape variable was significant. This indicates that the spatial distribution of pesticides around orchards impacted the within orchards natural enemies.