Gaylene Ewing, CC BY 2.0)

Type of Relationship / Interaction: Commensalism
Example from Agricultural Ecosystem: Pest control solution: Planting polycultures—two or more crops simultaneously growing in close proximity—in order to attract natural enemies and improve biological pest control.

(Photo by United Soybean Board, CC BY 2.0)

Type of Relationship / Interaction: Competition
Example from Agricultural Ecosystem: Pest problem: Competition from weeds will reduce output (yield and quality) by removing nutrients, water and, at certain stages, sunlight from the crop. In sustainable systems, the goal is to maximize yields by suppressing weed competition during critical periods of crop development.

(David Cappaert, Michigan State University, Bugwood.org)

Type of Relationship / Interaction: Parasitism
Example from Agricultural Ecosystem: Pest control solution: Use of parasitic wasps to control various pests. The wasps lay their eggs directly in the organism.

(Debbie Roos, N. Carolina Coop. Ext.)

Type of Relationship / Interaction: Predation
Example from Agricultural Ecosystem: Pest control solution: Attracting and encouraging predators such as lady beetles or lacewing larva to control aphid pests.

(Dan Forgey)

Type of Relationship / Interaction: Mutualism (symbiosis)
Example from Agricultural Ecosystem: Rhizobium bacteria in association with the roots of leguminous crops fixes atmospheric nitrogen.