Scientists have yet to use that discovery to develop any new weapons against bed bugs but creative solutions may become necessary as studies show that bed bugs are becoming increasingly resistant to the pesticides most commonly used to fight them.
During the winter of 2011 and 2012, a team of scientists from the University of Kentucky collected 21 populations of bed bugs from homes in four Midwestern cities. Genetic analyses revealed 14 mutations involved in resistance to pyrethroids, which are the standard insecticides used against bed bugs.
The genes worked in different ways but many reduced the ability of the toxin to penetrate the skin and reach the insects’ nerve cells, the researchers reported earlier this year in Scientific Reports. Every single population had at least two forms of resistance to the insecticide. More than 70 percent of pesticide-resistance populations used at least five mechanisms to evade the poison.
"It’s not just one little thing," Benoit said. "As people have been applying more and more pesticides, bed bugs have become more and more resistant in order to survive."
When chemicals fail, freezing the bugs out may be a viable option, suggests a new study. Based on preliminary results and anecdotal evidence that cold can kill the parasites, researchers from the University of Minnesota embarked on a systematic attempt to determine just how cold is cold enough.
Bed bugs don’t have antifreeze proteins or other strategies for tolerating frosty temperatures, the researchers reported this month in the Journal of Economic Entomology. But they can resist below-freezing conditions for weeks.
To kill bed bugs at all life stages, said University of Minnesota entomologist Joelle Olson, temperatures needed to drop below -13 degrees Celsius (8.6 F), but death did not come quickly. It took 80 continuous hours -- or more than three days -- at -16 degrees Celsius (3.2 F). Below -20 C (-4 F), death came after about 48 hours.
Kitchen freezers tend to fluctuate in temperature, Olson said, which means it might take longer than expected to freeze bed bugs to death at home. Using a thermometer can ensure you're achieving cold enough temperatures for long enough. The study also suggested bagging infested items to limit condensation and to prevent the bugs from escaping into the freezer.
As useful as freezing can be in combination with pesticides, reduction of clutter and discarding of infested items, Olson added, it will never work as the only strategy for killing bed bugs.
"Freezing is another option to kill bed bugs, but it is just one part of many steps that should occur," she said. "I want to make sure people understand they should contact pest management professionals. It is not a treatment protocol in itself."