5.6 Pest Control Methods

Chemical Pest Control

Synthetic pesticides (insecticides, herbicides, fungicides) kill target pests quickly and cheaply but cause biomagnification, bioaccumulation, water pollution, and harm to non-target species like pollinators. Overuse leads to genetic resistance, where surviving pests reproduce and pass on resistance genes, requiring stronger chemicals over time — a costly cycle called the pesticide treadmill.

Biological & Cultural Controls

Biological control uses natural predators, parasites, or pathogens to reduce pest populations without chemicals, though introduced species risk becoming invasive. Cultural controls include crop rotation, polyculture, and altering planting times to disrupt pest life cycles. These methods are more sustainable but often slower and less predictable than chemical pesticides.

Integrated Pest Management (IPM)

IPM combines multiple strategies — biological, cultural, mechanical, and limited chemical use — to control pests while minimizing environmental harm and resistance development. It emphasizes monitoring pest levels and using the least harmful effective method, reducing pesticide use, cost, and ecological damage over the long term.

Key terms

Genetic resistance

Evolved trait allowing pests to survive pesticide exposure, passed on to offspring, reducing pesticide effectiveness over time.

Pesticide treadmill

The cycle of needing increasingly stronger or more frequent pesticide applications as pests develop resistance.

Biological control

Using natural predators, parasites, or pathogens to control pest populations instead of chemicals.

Cultural control

Farming practice adjustments (crop rotation, polyculture, timing) used to reduce pest establishment and spread.

Integrated Pest Management (IPM)

A strategy combining biological, cultural, mechanical, and minimal chemical methods to control pests sustainably.

Try an AP-style question

Why do pesticides become less effective over time?

1. The pesticide evaporates
2. Pests stop eating crops
3. Pesticides become more toxic
4. Resistant pests survive and reproduce