Effect of crop management and landscape context on insect pest populations and crop damage

Understanding the determinants of insect–plant interactions and pest population dynamics at multiple spatial scales is a pre-requisite for developing innovative crop protection strategies and increasing the sustainability of agroecosystems. In a two-year study, we investigated the relative influence of local crop management and landscape context on pollen beetle (Meligethes spp.) abundance and damage at 8 different spatial scales around 42 oilseed rape fields using a multi-model inference approach. We found that pest abundance was mainly determined by the proportion of grassland and woodland in the landscape at scales ranging from 1500 m to 2000 m. Pollen beetle damage was affected both by local management and landscape predictors at scales ranging from 1500 m to 2000 m. Indeed, damage was negatively correlated with the nitrogen nutrition index of the plants and positively correlated with the proportion of woodland in the landscape at a large scale. Our multi-scale approach revealed that landscape complexity determines pollen beetle abundance in the spring and that nitrogen nutrition of the plants influences crop ability to compensate bud abortions resulting from pest attacks. The results are discussed in relation to crop management, pest dispersal ability and landscape structure.

► Pollen beetle density is mainly determined by landscape complexity.
► Pollen beetle density is not influenced by local crop management.
► The proportions of woodland and grassland at large scales increase pollen beetle infestations and crop damage.
► Crop damage are determined by local management and landscape complexity.
► Crop damage are negatively related to nitrogen nutrition of the plants.