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Indiscriminate use of pesticides is producing strains of “monsterbugs” that scientists say are resistant to nearly every chemical weapon available to be used against them.
The problem isn’t new, but it’s time something is done about it in an organized manner, said Brian Croft, a professor of entomology at Oregan State University. Pesticide resistance poses an increasing threat to agriculture, world food supplies, and human health. The problems range from pear production in Oregon to cotton growing in Mexico and malaria in Central America.
Resistance to chemical pesticides has its roots in basic evolution - every species from the smallest aphid to the human immune system, has biological mechanisms to resist attacks on it, Mr. Croft said. Mutation can produce a gene that protects an organism against toxic chemicals, and when,insects are constantly exposed to these poisons, those with such genes are much more likely to survive and reproduce.
The life history of the insect population is another factor - organisms with many generations per season, or rapid reproductive rates develop resistance more rapidly and more frequently than do other pests. Overuse of pesticides not only accelerates the evolution of resistant strains, but also leads to a short shelf life for these chemicals.
“The earliest insecticides like DDT were highly effective for many years,” added another entomologist, Robert Metcalf of the University of Illinois. “The usefulness of the latest insecticides is often measured in months.” An example is isofenphos, a promising corn rootworm insecticide that had to be withdrawn from
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