UNIVERSITY PARK, Pa. — A fungal biopesticide that shows promise for the control of bed bugs is highly effective even against bedbug populations that are insecticide resistant, according to research conducted by scientists at Penn State and North Carolina State universities.
The study suggests that Aprehend, a mycoinsecticide developed at Penn State, likely will provide an important new tool for managing bedbug infestations, which have surged in recent years.
"Bedbugs were all but eradicated from the United States and other industrialized nations after World War II, likely due to the use of DDT and other broad-spectrum insecticides," said study co-author Nina Jenkins, senior research associate in entomology, College of Agricultural Sciences, Penn State. "But in the last few decades, they have re-emerged globally as an important public-health pest."
The researchers noted that pyrethroid insecticides are a mainstay of bedbug control, but there is compelling evidence that many bedbug populations have developed resistance. In addition, this resistance may lead to cross-resistance to other classes of insecticides.
"In fact, high levels of resistance to four neonicotinoids recently were detected in field populations of bedbugs," Jenkins said.
Alternative control measures vary in complexity, cost and efficacy, explained the researchers, who reported their results online in Pesticide Management Science. For instance, the use of high temperatures to kill bedbugs can be effective and has increased in popularity in the last decade. But the cost can be prohibitive, ranging from $500 to $1,000 per room. Other available methods often do not provide satisfactory control.
The need for a solution to the resurgence of this pest led Jenkins and colleagues at Penn State to look at entomopathogenic fungi, which have demonstrated effectiveness against other public-health pests, such as malaria vectors, cockroaches and house flies. Researchers also have shown fungal pathogens to be effective against insecticide-resistant mosquitoes.
The result was the development of Aprehend, a patent-pending compound based on Beauveria bassiana, a natural fungus that causes disease in insects. Previous studies have shown that the formulation can be applied as a long-lasting barrier treatment. Bedbugs that cross the barrier acquire fungal spores and go on to spread these among insects that remain in their harborages, resulting in greater than 95 percent mortality within a week.
"The goal of this study was to evaluate the efficacy of this product on an insecticide-susceptible lab strain of bedbug, and compare that to its effect on three field-collected strains known to be resistant to insecticides," Jenkins said. "We also compared mortality of these four bedbug strains after exposure to either a commercial pyrethroid insecticide or Aprehend."