Responses of Cereal Aphids and Their Parasitic Wasps to Landscape Complexity

ABSTRACT The intensification of agriculture has caused a decline in the complexity of agricultural landscapes because of the expansion of arable lands and the removal of natural habitats. These landscape changes, which have substantial effects on natural enemies (e.g., parasitoids) and on biological control services, have received considerable attention recently. In the current study, we analyzed the effects of landscape complexity on cereal aphids and their parasitic wasps in 24 sites during a period of 3 yr. In total, 11 primary parasitoid species and 6 hyperparasitoid species, comprising 5,220 individuals, were collected in our experiments. With the exception of two primary parasitic wasps (Trioxys asiaticus Telenga and Toxares sp.) and one hyperparasitic wasp (Dendrocerus carpenteri [Curtis]), most species were sensitive to landscape complexity after ≥1 yr. Species diversity, primary parasitism, and hyperparasitism increased with increasing landscape complexity. However, the relationship between the p...