Bed bugs, hard enough to kill already, have developed a resistance to some of the most commonly used insecticides.
Virginia Tech and New Mexico State University researchers have found in a new study that a class of insecticide called neonicotinoids, or neonics, are not doing as good a job anymore at killing the nightmarish itch-inducers.
The scientists compared colonies of bed bugs from Cincinnati, Ohio and Michigan that were collected in the wild with a colony that had been kept in isolation in a special lab and had never been exposed to neonics.
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The bed bugs that had never been exposed to neonics were killed easily with small amounts of insecticide, whereas the Michigan and Cincinnati bugs showed a whopping resistance, needing multiple times the dose -- 0.3 nanograms of insecticide took care of half the lab bed bugs, while 10,000 nanograms were needed to kill just 50 percent of the resistant bugs.
"Unfortunately, the insecticides we were hoping would help solve some of our bed bug problems are no longer as effective as they used to be, so we need to reevaluate some of our strategies for fighting them," said Troy Anderson, an assistant professor of entomology at Virginia Tech and study co-author, in a release.
"While we all want a powerful tool to fight bed bug infestations, what we are using as a chemical intervention is not working as effectively as it was designed and, in turn, people are spending a lot of money on products that aren't working," Anderson added.
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Bed bug infestations have been on the rise coast to coast in the United States, infecting places such as homes, hotels, and shelters. Their bites can wreak havoc with people physically and emotionally, and eradicating them is often costly.
"Companies need to be vigilant for hints of declining performance of products that contain neonicotinoids," said study co-author Alva Romero, an assistant professor of entomology at New Mexico State University. "For example, bed bugs persisting on previously treated surfaces might be an indication of resistance."
"If resistance is detected, products with different modes of action need to be considered, along with the use of non-chemical methods," Romero said.
The study has been published in the Journal of Medical Entomology.