Bedbugs Have Developed Strong Resistance To Insecticides

(Photo : Getty Images/Brian Kersey) Common insecticides used to kill bedbugs may not be as effective as you think, according to a new study.

Common insecticides used to kill bedbugs may not be as effective as you think, according to a new study.

The study from Virginia Tech and New Mexico State University found that bedbugs have built up a resistance to the common chemicals used to kill the insects due to overuse, writes Nature World News.

"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 it was designed and, in turn, people are spending a lot of money on products that aren't working," Troy Anderson, an assistant professor of entomology in the Virginia Tech College of Agriculture and Life Sciences, said in a news release.

Researchers studied the effects of neonicotinoids or neonics, a class of neonicotinoids that are generally used in conjunction with pyrethroids treat bedbugs at a commercial level.

"Companies need to be vigilant for hints of declining performance of products that contain neonicotinoids," Alvaro Romero, co-author and an assistant professor of entomology at New Mexico State University, added. "For example, bedbugs persisting on previously treated surfaces might be an indication of resistance."

The researchers studied two groups of bedbugs. The first group came from homes in Cincinnati and Michigan and had been exposed to neonic treatments. The other colony had been kept in isolation in a laboratory. The researchers also looked at a pyrethroid-resistant population that were collected from New Jersey and had not been exposed to neonics since 2008.

The bedbugs that had been kept in isolation died after exposure to a small amount of the insecticide. The New Jersey bedbugs displayed moderate resistance to the New Jersey bedbugs, with resistance to four different types of the neonics.

The researchers found that the bedbugs collected from Michigan and Cincinnati, which were collected after the introduction of combined insecticides in the US, had a much higher resistance to neonics. Researchers had to administer more than 10,000 nanograms of a chemical known as acetamiprid, to kill 50 percent of the bedbugs from Michigan and Cincinnati, while it only took 0.3 nanograms to skill 50 percent of the bedbugs that had been kept in isolation.

The researchers also tested the effectiveness of a substance called imidacloprid. They found that 2.3 nanograms was enough to kill 50 percent of the bedbugs kept in isolation, but they had to raise the dose to 1,064 nanograms to kill the bedbugs from Michigan and 365 nanograms to kill those collected in Cincinnati.

Researchers believe the New Jersey bedbugs may have developed neonicotinoid because of pre-existing resistance mechanisms.

"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," added Anderson.

After exposure to insecticides, bedbugs react by producing "detoxifying enzymes". As the New Jersey bedbugs have had more exposure to insecticides in the past, they produce more enzymes to ensure their survival.

Their findings were recently published in the Journal of Medical Entomology.