Abstract
In agriculture, spontaneous field border vegetation can engender several benefits, including mitigating soil erosion, increasing carbon retention, conserving pollinators, and promoting biological control. The extension of these benefits can, however, often depend on the context of location and time. As for biological control, field borders can promote natural enemy conservation if the plants therein can provide adequate resources (e.g. shelter, alternative food, microclimate). In the context of location, field borders can be adjacent to areas with varying degrees of agricultural intensification, including fields with annual crops, perennial crops, or forest areas. While many studies have investigated how field borders can influence arthropod communities in adjacent crops, the opposite direction of effect (i.e. how crop areas can influence adjacent field borders) remains an underexplored topic. Therefore, in this three-season study we selected vegetated field borders next to annual crops, perennial crops, and forest areas, to study their communities of spontaneous plants (weeds) and arthropods as well as their potential to engender biological control. In general, our results show that the community composition of plants and arthropods was affected by land use type and season. Furthermore, field border vegetation next to areas with higher level of agricultural intensification (i.e. annual or perennial crops) harbored more herbivores, flowers and natural enemies; although some of these results were season dependent. Lastly, field borders next to annual or perennial crop areas engendered stronger biological control of aphids; possibly due to the alternative food (herbivores/aphids and flowers) provided by the plants therein. Taken altogether, our results reinforce the importance of preserving spontaneous field border vegetation, especially in areas under intensive agriculture management.