Entomologists at Ohio State University say bedbugs may have boosted their natural defenses by generating higher levels of enzymes that can cleanse them of poisons, The Wall Street Journal reported Wednesday.
Researchers at the University of Massachusetts in Amherst have found that bedbugs in New York are 250 times more resistant to the standard pesticide than bedbugs in Florida, because of changes in a gene controlling the resilience of the nerve cells targeted by the insecticide.
Laboratory tests in the United States, Europe and Africa show bedbugs can survive pesticide doses 1,000 times greater than the lethal level of 10 years ago.
"There is a phenomenal level of resistance," said bedbug entomologist Michael Siva-Jothy at Britain's University of Sheffield. "It has evolved very recently."
Repeated applications of insecticides act as a form of natural selection for bedbugs, as any surviving insects pass on resistant traits to their offspring and to succeeding generations.
"Insect resistance is nothing more than sped-up evolution," said insect toxicologist John Clark, who led the research team at the University of Massachusetts.
"We have changed the genetic make-up of the bedbugs we have in the United States," said urban pest-management specialist Dini Miller at Virginia Tech. "That's what I call unnatural selection."