Posted: June 16, 2017

A new fungal biopesticide is achieving mortality rates from 95.5 to 99 percent within 14 days.

A fungal biopesticide that shows promise for the control of bed bugs is highly effective even against bed bug populations that are insecticide resistant. According to research conducted by scientists in the college, Aprehend, a mycoinsecticide developed at Penn State, likely will provide an important new tool for managing bed bug infestations, which have surged in recent years.

"Bed bugs 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," says Nina Jenkins, senior research associate in entomology. "But in the last few decades, they have re-emerged globally as a public-health pest."

The researchers note that pyrethroid insecticides are a mainstay of bed bug control, but there is compelling evidence that many bed bug populations have developed resistance.

Aprehend, a patent-pending compound based on Beauveria bassiana, a natural fungus that causes disease in insects, can be applied as a long-lasting barrier treatment. Bed bugs 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 bed bug, and compare that to its effect on three field-collected strains known to be resistant to insecticides," Jenkins says. "We also compared mortality of these four bed bug strains after exposure to either a commercial pyrethroid insecticide or Aprehend."

To perform the experiments, researchers applied the fungal-based Aprehend to a quilt fabric commonly used by manufacturers of bed box springs. They similarly applied a deltamethrin-based, commercial insecticide at both high and low concentrations to the same type of fabric. Treated fabric was allowed to dry before bed bugs briefly were exposed to it. The researchers exposed a control group of bed bugs to fabric sprayed with water.

The results demonstrated that Aprehend was equally effective against all four strains of bed bug--including those with insecticide resistance. It achieved mortality rates from 95.5 to 99 percent within 14 days.

"B. bassiana has a unique mode of action with no known resistance or cross-resistance in bed bugs, and it is highly effective on pyrethroid-resistant bed bugs, making it an excellent candidate for use in bed bug management," says Jenkins, who has formed a company, ConidioTec, to commercialize Aprehend. The findings appear online in the journal Pesticide Management Science.

-- Chuck Gill