| dc.description.abstract | The biological control service supplied to croplands is a result of the predator community present within
a focal crop, which is likely influenced by surrounding landscape composition and configuration. In this
study, using cage experiments in two regions near Santiago, we determined if predator communities supplied
a significant biological control service in alfalfa fields, examined how the abundance of exotic and
native coccinellids, as well as other key predator groups, influenced biological control of aphids and measured
how landscape composition and heterogeneity at three spatial scales influenced this service. We
found that predators significantly suppressed aphid populations in both regions, but the relative importance
of predators versus landscape variables on biological control differed between regions. In the region
where predators were abundant, biological control was higher and related to the abundance of native
coccinellids and syrphids, highlighting the importance of native species as providers of crucial ecological
services. In the region where predators were not abundant, biological control was lower, and it was
related to landscape composition, being positively associated with the abundance of woodlots and urban
habitats, and negatively associated with fruit crops in the landscape. Therefore, landscape effects on biological
control service may be weaker than local factors, and only become important when local predator
abundance is low. | |
