TY - JOUR

T1 - Multitrophic effects of experimental changes in plant diversity on cavity-nesting bees, wasps, and their parasitoids

AU - Ebeling, Anne

AU - Klein, Alexandra-Maria

AU - Weisser, Wolfgang W

AU - Tscharntke, Teja

PY - 2012/6

Y1 - 2012/6

N2 - Plant diversity changes can impact the abundance, diversity, and functioning of species at higher trophic levels. We used an experimental gradient in grassland plant diversity ranging from 1 to 16 plant species to study multitrophic interactions among plants, cavity-nesting bees and wasps, and their natural enemies, and analysed brood cell density, insect diversity (species richness), and bee and wasp community similarity over two consecutive years. The bee and wasp communities were more similar among the high (16 species) diversity plots than among plots of the lower diversity levels (up to 8 species), and a more similar community of bees and wasps resulted in a more similar community of their parasitoids. Plant diversity, which was closely related to flower diversity, positively and indirectly affected bee diversity and the diversity of their parasitoids via increasing brood cell density of bees. Increasing plant diversity directly led to higher wasp diversity. Parasitism rates of bees and wasps (hosts) were not affected by plant diversity, but increased with the diversity of their respective parasitoids. Decreases in parasitism rates of bees arose from increasing brood cell density of bees (hosts), whereas decreasing parasitism rates of wasps arose from increasing wasp diversity (hosts). In conclusion, decreases in plant diversity propagated through different trophic levels: from plants to insect hosts to their parasitoids, decreasing density and diversity. The positive relationship between plant diversity and the community similarity of higher trophic levels indicates a community-stabilising effect of high plant diversity.

AB - Plant diversity changes can impact the abundance, diversity, and functioning of species at higher trophic levels. We used an experimental gradient in grassland plant diversity ranging from 1 to 16 plant species to study multitrophic interactions among plants, cavity-nesting bees and wasps, and their natural enemies, and analysed brood cell density, insect diversity (species richness), and bee and wasp community similarity over two consecutive years. The bee and wasp communities were more similar among the high (16 species) diversity plots than among plots of the lower diversity levels (up to 8 species), and a more similar community of bees and wasps resulted in a more similar community of their parasitoids. Plant diversity, which was closely related to flower diversity, positively and indirectly affected bee diversity and the diversity of their parasitoids via increasing brood cell density of bees. Increasing plant diversity directly led to higher wasp diversity. Parasitism rates of bees and wasps (hosts) were not affected by plant diversity, but increased with the diversity of their respective parasitoids. Decreases in parasitism rates of bees arose from increasing brood cell density of bees (hosts), whereas decreasing parasitism rates of wasps arose from increasing wasp diversity (hosts). In conclusion, decreases in plant diversity propagated through different trophic levels: from plants to insect hosts to their parasitoids, decreasing density and diversity. The positive relationship between plant diversity and the community similarity of higher trophic levels indicates a community-stabilising effect of high plant diversity.

KW - Ecosystems Research

KW - Community similarity

KW - Hymenotera

KW - Jena Experiment

KW - Structural equation model

KW - Wild bees

KW - Community similarity

KW - Hymenotera

KW - Jena Experiment

KW - Structural equation model

KW - Wild bees

KW - Biology

UR - http://www.scopus.com/inward/record.url?scp=84861197182&partnerID=8YFLogxK

U2 - 10.1007/s00442-011-2205-8

DO - 10.1007/s00442-011-2205-8

M3 - Journal articles

C2 - 22120706

VL - 169

SP - 453

EP - 465

JO - Oecologia

JF - Oecologia

SN - 0029-8549

IS - 2

ER -