The struggle between insects and plants has been going on for some 400 million years. The story is a simple one. Plants take energy from the sun and convert it into chemical energy stores. Insects exploit that resource. The plants suffer from this exploitation until the plant begins to "defend" itself by some novel method such as production of a poison, tougher leaves, bad taste or whatever. Now the insect suffers until it undergoes changes that allow it to re-exploit the plant resource. Then, the plant suffers again, until a new defense is developed, and so on…

Fast-forward to the present.

"We have altered this intricate dance between the plant and its herbivorous insect pest through the use of pesticides, selective breeding and genetic manipulation," says Douglas B. Jones, pest management educator with University of Illinois Extension. "One might think that this altering only began when genetically modified organisms (GMOs) became common. Actually, it began with the advent of human cultivation. We routinely choose plant attributes that suit us and have done so for thousands of years."

When we began extensively using pesticides in the 20th century, it was thought that insects would never again be a problem for farmers. Wrong!

"It didn't take long for those organisms that we were trying to eliminate to adapt and thrive again. Pesticide resistance is now commonplace," says Jones. "Crop rotation is not even exempt; a variant of the western corn rootworm began laying its eggs in soybeans rather than exclusively in corn. This enabled it to be present the following year in corn, thus rendering that type of crop rotation ineffective."

Pests should have no trouble overcoming genetically modified organisms as well. So what should we do? Pesticides, GMOs, cultural practices, new plant breeds, etc. are all tools in the Integrated Pest Management tool box. All are useful and can remain efficacious if used responsibly. This requires that we use each one only when needed and avoid overusing them to the point of selecting for pests that are not affected.

Jones explains that frequently farmers treat their fields for one type of pest, and in an effort to get ahead of any pest problem, tank mix another pesticide for application in a prophylactic manner, even though there are no pests present. Let's say a field needs a fungicide application. It seems to make sense to apply a pesticide such as chlorpyrifos to keep aphids under control at the same time. This saves time and money since you are already running your sprayer, right?

Simply put, this is a dangerous practice. Not only does it keep selective pressure on pest species (a long-term problem), but it could actually cause a worse problem in your field by releasing the pest species by killing its natural enemies (a short-term problem) and forcing you to make further applications for control.

The bottom line is that we all need to use our IPM tools wisely. If we don't, life will find a way around them, and our IPM tool box will be empty.