Agricultural pests are any unwanted species of plant, animal, insect or microorganism that damages or reduces the productivity of crops and livestock. They may seem like an ever-present challenge in agriculture, but pest outbreaks are uncommon in natural landscapes, where they have to compete for limited resources and avoid their predators. For example, more than 100,000 species of plants, insects, nematodes and other organisms (most are microscopic) may live on a typical farm. But in any given year, only about a dozen species might reach pest status. If you manage your farm correctly, there could be far more beneficial species than pests, and these beneficial species provide important ecosystem services, or benefits gained from biodiversity. The ecosystem services that beneficial species contribute to include nutrient cycling (by breaking down plant residues), crop pollination and pest regulation (by eating pests).

Diverse Farm System
Natural features in the landscape support biodiversity and protect soil. Tree lines protect fields from heavy winds and native plants attract beneficial organisms. Photo by Stacie Clary, Western SARE 

Think of pests as a symptom of ecological imbalances on your farm and in the surrounding landscape. In natural environments, pests do not typically reach threatening levels because they experience more competition and predation. In contrast, the management practices we use alter this balance and directly influence the likelihood of developing pest problems. Many agricultural systems are designed to maximize production of a few crop species. Excess tillage, over-fertilization, monoculture cropping and routine pesticide sprays are common examples of practices that disturb ecological processes and create environments favorable to pests. At the same time, these practices reduce biodiversity, meaning fewer beneficial organisms such as natural predators and parasitoids are around to keep pests in check compared to natural systems.