Super bed bugs may no longer be vanquished by insecticides, as the pesky parasites are growing increasingly more resistant to conventional chemicals.
The disconcerting findings have been presented in the Journal of Medical Entomology on Thursday, January 28. They stemmed from research led by two experienced entomologists: Alvaro Romero, from New Mexico State University, and Troy Anderson, from the Virginia Tech College of Agriculture and Life Sciences.
The duo’s aim was to test how effective it was to combat bedbugs by using a specific type of insecticides known as neonicotinoids.
These chemicals, also referred to as neonics, have previously been linked with a major decline in the population of honey bees and bumble bees, by reducing their capacity to reproduce, and by disrupting their ability to forage for nectar or return back to their hives.
In order to assess the potency of neonicotinoids against bed bugs, researchers conducted a comparative analysis, involving groups of parasites that had never been exposed to these chemicals and other groups that had become accustomed with the presence of such substances.
One of the colonies had been kept confined for the last 3 decades, in a research lab operated by Dr. Harold Harlan, an entomologist affiliated with the Armed Forces Pest Management Board.
Another set of bed bugs, which had been proven to show resistance to another class of insecticides called pyrethroids, had been kept in a New Jersey research facility, without being brought into contact with neonicotinoids ever since 2008.
Finally, the last two groups had been collected from Michigan and Cincinnati homes, and had become extremely familiar with neonic pesticides.
It was determined that parasites which had been introduced to such insecticides before had developed extremely high levels of tolerance to them, turning into super bugs, and requiring much higher doses of chemicals in order to be killed off.
More precisely, when treating surfaces with a neonicotinoid known as acetamiprid (commonly traded as Assail or Chipco), just 0.3 nanograms were needed to stamp out 50% of the bugs kept in Harlan’s research center.
In contrast, approximately 10,000 nanograms of this substance were required in order to combat the same number of super bed bugs taken from Cincinnati and Michigan households.
Similarly, when applying another chemical called imidacloprid (an active ingredient for insecticides such as Admire, Gaucho, Premier, Marathon, Condifor, Provado or Premise), 2.3 nanograms were all it took to do away with half the bed bugs kept in Harlan’s laboratory.
On the other hand, 1,046 nanograms of his substance had to be used against the super bed bugs from Michigan, and 365 nanograms were necessary against the parasites from Cincinnati.
Overall, when contrasted against their counterparts which had been kept in isolation, super bed bugs found in Michigan homes were 462 times more unlikely to be combated by imidacloprid, 33,333 times less vulnerable to acetamiprid, and 546 times less easily defeated by thiamethoxam.
Similarly, super bed bugs from Cincinnati were 163 times harder to kill when using imidacloprid, 33,333 times sturdier against acetamiprid, and 358 times less at risk when being exposed to dinotefuran.
When analyzing how easy it was to fight off New Jersey bed bugs by using neonics, researchers discovered that these insects had also become somewhat resistant to pesticides, but not to the extent measured among Cincinnati and Michigan parasites.
One possible explanation for this lowered vulnerability among this isolated group is the fact that bed bugs learn to release protective enzymes when exposed to insecticides. It may be that the colony had already developed this strategy before 2008, when it was taken to the New Jersey facility.
Based on these recent findings, study authors believe that modern-day insecticides containing neonics are becoming increasingly more ineffective against bed bugs, which is why alternative means of eradicating these parasites should be chosen instead.
Such pest control strategies could include mattress encasements, dry vapor steam cleaners, thermal remediation etc.
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