title: Cascade effects of crop species richness on the diversity of pest insects and their natural enemies.
abstract: Understanding how plant species richness influences the diversity of herbivorous and predatory/parasitic arthropods is central to community ecology. We explore the effects of crop species richness on the diversity of pest insects and their natural enemies. Using data from a four-year experiment with five levels of crop species richness, we found that crop species richness significantly affected the pest species richness, but there were no significant effects on richness of the pests' natural enemies. In contrast, the species richness of pest insects significantly affected their natural enemies. These findings suggest a cascade effect where trophic interactions are strong between adjacent trophic levels, while the interactions between connected but nonadjacent trophic levels are weakened by the intermediate trophic level. High crop species richness resulted in a more stable arthropod community compared with communities in monoculture crops. Our results highlight the complicated cross-trophic interactions and the crucial role of crop diversity in the food webs of agro-ecosystems.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents in Agriculture, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: PeiJian
authors.initials: P
authors.lastname: Shi
authors.forename: Cang
authors.initials: C
authors.lastname: Hui
authors.forename: XingYuan
authors.initials: X
authors.lastname: Men
authors.forename: ZiHua
authors.initials: Z
authors.lastname: Zhao
authors.forename: Fang
authors.initials: F
authors.lastname: Ouyang
authors.forename: Feng
authors.initials: F
authors.lastname: Ge
authors.forename: XianShi
authors.initials: X
authors.lastname: Jin
authors.forename: HaiFeng
authors.initials: H
authors.lastname: Cao
authors.forename: B Larry
authors.initials: BL
authors.lastname: Li
mesh_terms: D000465:Algorithms; D000818:Animals; D044822:Biodiversity; D018556:Crops, Agricultural / Q000145:classification / Q000469:parasitology*; D017753:Ecosystem; D020387:Food Chain; D006790:Host-Parasite Interactions; D007313:Insecta / Q000145:classification / Q000502:physiology*; D008954:Models, Biological; D010935:Plant Diseases / Q000469:parasitology*; D011157:Population Dynamics; D011235:Predatory Behavior / Q000502:physiology