Bed bugs: Better, stronger, faster

New study reveals that bed bugs develop resistance to widely used chemical treatments.

Humans … we think we’re pretty smart, don’t we. While many of us homo sapiens assume we have the upper hand when it comes to nature, it seems that nature has other things in mind. Just look at antibiotic-resistant bacteria – those guys are tiny yet they’ve managed to outsmart our brightest scientists.

As Friedrich Nietzsche so famously suggested, "That which does not kill us makes us stronger" – and bingo. Who knew that these meme-worthy words that have become a coping mantra for millions could be uttered by our tiniest adversaries? Bacteria that survive antibiotics become super bugs, and now it seems like our battle against bed bugs is having a similar effect.

While we haven’t yet created “super bed bugs” (shudder) we might be well on our way. A new study from Virginia Tech and New Mexico State University finds that one of the most widely used chemicals used in the war against these crazy-making insects is waning in efficacy because the persistent pests have built up a tolerance to it.

"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," said Troy Anderson, an assistant professor of entomology in the Virginia Tech College of Agriculture and Life Sciences.

The chemicals in question belong to a class of insecticides called neonicotinoids (or neonics) which are often paired with pyrethroids in commercial applications.

If you’re wondering how researchers can effectively study this, it’s thanks to one very brave scientist, Harold Harlan, at the Armed Forces Pest Management Board. Harlan has made it a point to keep an isolated colony of bed bugs for the last 30 years. (Given the slippery nature of these invincible insects, it’s a wonder he was able to keep them in check.) The research team compared domestic bedbugs from Cincinnati and Michigan that had been exposed to neonics with the isolated colony. They also included a pyrethroid-resistant population from New Jersey that had not been exposed to neonics since they were gathered in 2008.

Harlan's bed bugs, the ones that had never seen neonics, died upon exposure to a very small mount of neonics. The Jersey bugs did a bit better, showing moderate resistance to four different types of neonics. But the Michigan and Cincinnati bedbugs, tough city bugs that they are having been exposed to the chemicals, had much higher levels of resistance. It took 0.3 nanograms to kill half of Harlan’s bedbugs; it took more than 10,000 nanograms to kill 50 percent of the Michigan and Cincinnati bedbugs

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

Just 2.3 nanograms of another substance called imidacloprid was enough to kill 50 percent of Harlan's bedbugs, but it took 1,064 nanograms to kill the Michigan bedbugs and 365 nanograms to kill the Cincinnati bedbugs.

Compared with the Harlan control group, the Michigan bedbugs were 462 times more resistant to imidacloprid, 198 times more resistant to dinotefuran, 546 times more resistant to thiamethoxam, and 33,333 times more resistant to acetamiprid.

The Cincinnati bedbugs were 163 times more resistant to imidacloprid, 226 times more resistant to thiamethoxam, 358 times more resistant to dinotefuran, and 33,333 times more resistant to acetamiprid.

Houston, we have a problem.

"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," says Anderson.

"If resistance is detected, products with different modes of action need to be considered, along with the use of non-chemical methods," adds Romero.

Non-chemical methods, now there’s an idea! While of course we want the strongest ammunition to fight these insects that 30 percent of people polled said they'd prefer a root canal over, we really need to consider the monsters we create with our easy fixes.

Tags: Insects | Pesticides


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