Landscape structure and habitat management differentially influence insect natural enemies in an agricultural landscape

Increasing evidence suggests that landscape composition is an important driver of beneficial insect populations and resulting ecosystem services. Additionally, local-scale manipulations such as planting floral strips are used at the field-level to provide resources for beneficial insects to increase their services. It has been proposed that the benefits of local manipulations will depend on the landscape context, with greater benefits in simplified landscapes and smaller benefits in landscapes with an abundance of non-crop resources. To test this, we used soybean aphid, Aphis glycines, and its coccinellid predators as a model system to elucidate the effects of habitat management and landscape on biocontrol services in soybean. We selected pairs of soybean fields in landscapes of varying composition and planted buckwheat, Fagopyrum esculentum, strips adjacent to one field in each pair. We measured coccinellid abundance and biocontrol in each field. Coccinellid abundance was higher in buckwheat than in control field margins in all landscapes, and coccinellid abundance in soybean was positively related to amount of semi-natural vegetation in the landscape. We found no evidence of an interaction between landscape and local variables, and biocontrol services were high in all contexts. For soybean aphid suppression, landscape factors are the key drivers of predator abundance.

► Landscape may influence the effect of local manipulations on predators and biocontrol.
► We test flowering buckwheat effects on coccinellids in landscapes of varying composition.
► Coccinellids were more abundant in buckwheat than in typical field margins.
► Coccinellids in soybean fields increased with semi-natural habitat in the surrounding landscape.
► We found no evidence of an interaction between landscape and local effects in this system.