• Arbuscular mycorrhizal fungi;
  • bottom-up;
  • conservation;
  • feedbacks;
  • herbivore;
  • insect diversity;
  • plant diversity;
  • restoration;
  • soil diversity;
  • top-down

Abstract.  1. This study demonstrates that feedback loops between plants and insects contribute to both plant and insect diversity. Synthesis of several studies reveals that both bottom-up and top-down forces are important for plant and insect communities.

2. Feedback loops between plants and soil organisms contribute to plant and soil diversity. An analysis of multiple systems reveals that pathogens, mutualists, and a wide variety of soil fauna directly influence, and are influenced by, plant diversity.

3. The connection of plant–insect and soil–plant feedback loops leads to the maintenance of all three groups, and the maintenance of these feedback loops crucially affects insect diversity. Examples of the influence of soil community diversity on insect diversity, and the influence of insect diversity on soil community diversity, as well as feedbacks through all three trophic levels are provided.

4. Finally, means of conserving and restoring soil communities to influence the conservation and restoration of insect communities are discussed.