‘Amazing’ bedbug remedy stops insects in their tracks — without chemicals -
Generations of Eastern European housewives doing battle against bedbugs spread bean leaves around the floor of an infested room at night. In the morning, the leaves would be covered with bedbugs that had somehow been trapped there. The leaves, and the pests, were collected and burned – by the pound, in extreme infestations.
Now a group of U.S. scientists is studying this bedbug-leaf interaction, with an eye to replicating nature’s Roach Motel.
A study to be published Wednesday in The Journal of the Royal Society Interface details the scientists’ quest, including their discovery of how the bugs get hooked on the leaves, how the scientists have tried to recreate these hooks synthetically and how their artificial hooks have proved to be less successful than the biological ones.
At first glance, the whole notion seems far-fetched, said Catherine Loudon, a biologist at the University of California, Irvine, who specializes in bedbug locomotion.
“If someone had suggested to me that impaling insects with little tiny hooks would be a valid form of pest control, I wouldn’t have given it credence,” she said in an interview. “You can think of lots of reasons why it wouldn’t work. That’s why it’s so amazing.”
But even though there is no indication that the bean leaves and the bedbugs evolved to work together, the leaves are fiendishly clever in exploiting the insects’ anatomy. Like the armour covering knights in medieval times, the bedbug’s exoskeleton has thinner areas where its legs flex and its tiny claws protrude – like the spot where a greave, or piece of leg armour, ends.
“The areas where they appear to be pierceable,” Loudon said, “are not the legs themselves. It’s where they bend, where it’s thin. That’s where they get pierced.”
This folk remedy from the Balkans was never entirely forgotten. A German entomologist wrote about it in 1927, a scientist at the U.S. Department of Agriculture mentioned it in a paper in 1943, and it can be found in Web searches about bedbugs and bean plants.
But the commercial availability of pesticides like DDT in the 1940s temporarily halted the legions of biting bugs. As their pesticide-resistant descendants began to multiply from Manhattan to Moscow, though, changing everything from leases to liability laws, the hunt for a solution was on.
The first task was to determine exactly how the hooks – the technical name is trichomes – worked. The process was viewed through an electron microscope, Loudon said.
“The foot comes down onto the surface, but as it’s lifting up, it’s catching on these hooks,” she said. “The point is pointing down. So all of their legs get impaled.”
“And as soon as one leg gets caught,” she added, “they are rapidly moving legs around and try to get away on the surface. That’s when they get multiply impaled.”
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