Agricultural Intensification Affects Communities of Plants and Arthropods in Field Borders and Their Potential to Engender Biological Control.

Abstract

In agriculture, spontaneous field border vegetation offers numerous benefits, such as reducing soil erosion, enhancing carbon sequestration, conserving biodiversity, and supporting biological control. However, the extent of these benefits often depends on the contexts 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 and arthropods as well as their potential to engender biological control nearby. In general, our results indicate that both plant and arthropod community composition were influenced by the type of adjacent land use and season. 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. Field borders adjacent to annual or perennial crop areas promoted stronger biological control of aphids, likely due to complementary food resources (herbivores and floral resources) provided for natural enemies by the plants within those borders. Taken altogether, our results reinforce the importance of preserving spontaneous field border vegetation, especially in areas under intensive agriculture management.