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Pest control measures vary in their approach and overall degree of success. A. Biological methods of pest control were introduced by the ancient Sumerians, and chemical control was first used in ancient China. B. Biological control, for example, the use of natural enemies of pests, has been effective at regulating nonnative pests, though it can also threaten the existence of native species. C. Integrated pest management is a holistic approach that has been successful at controlling major pest outbreaks in locations where chemical and biological control have already failed. D. Pesticides are limited in their usefulness because pests quickly become resistant to them, and because they can harm species for which they were not intended. E. The success of biological and chemical approaches to pest control has been difficult to measure because situations vary significantly from one location to another. F. Integrated pest management, an approach that consider biological, ecological, economic, and aesthetic aspects of pest control, uses a variety of techniques adjusted to specific situations.