Refuges of Genetic Variation: Controlling Crop Pest Evolution (1 of 2)

Pests evolve resistance to our pesticides at an alarming rate. However, evolutionary theory tells us how we can slow the rate at which genes for pesticide resistance spread: by providing refuges where non-resistant insects thrive.

Insects persistently nibble away at crops in the fields and at the narrow profit margin they offer. What’s a farmer to do? Spray, of course. Or, plant crops that have been genetically engineered to produce their own pesticides.

But evolutionary theory tells us that these solutions will not work indefinitely. Pest insects have short generation times and large population sizes—which means that they evolve quickly. If pesticides are widely applied, or if fields are widely planted with pesticide-producing plants, insects resistant to the pesticide will evolve. Some degree of resistance has been documented for every major class of insecticide used in agriculture.1

Pesticide application
Pesticide application on leaf lettuce

Potato beetle
Potato Beetle



Read more about pesticide resistance from the North Carolina State entomology tutorial.


• Pesticide photo courtesy of USDA, photo by Jeff Vanuga
• Potato beetle photo courtesy of USDA, photo by Scott Bauer
1 Committee on Strategies for the Management of Pesticide Resistant Pest Populations (1986). Pesticide Resistance Strategies and Tactics for Management. National Academy Press, Washington DC.

next page