 |  Environmental Science: A Global Concern, 7/e William P. Cunningham,
University of Minnesota
Mary Ann Cunningham,
Vassar College
Barbara Woodworth Saigo,
St. Cloud State University
Pest Control
BE ALERT FOR: Pest Resurgence
One of the most puzzling outcomes of continued pesticide application is the phenomenon of pest resurgence described in your text. Briefly stated, pest resurgence refers to the rise in pest numbers after repeated exposure to pesticides to levels that exceed the population size before pesticide application began.
How can this happen? Your authors explain it well. Pesticides typically don't kill all the pests present. A few of the creatures by chance have genes that make them immune to the toxin at the exposure levels experienced. These survivors then have a higher probability of passing on the genes for resistance to the next generation. With the passing of each generation, a greater and greater proportion of the individuals are immune to the effects of the pesticide. In the meantime, the pesticide has likely killed off natural predators of the pests, leaving them unhindered in reproductive efforts.
|
|
2003 McGraw-Hill Higher Education