UK researchers: Kidney bean leaves may eradicate bedbugs

ctruman@herald-leader.comApril 9, 2013 

Until now, getting rid of bedbugs involved an army of technologies — extreme heating, freezing, vacuuming and pesticides.

But scientists from the University of Kentucky and University of California-Irvine think they've found an ingenious and natural method to eradicate bedbugs — using kidney bean leaves, which have a unique design in their hairs that ensnares the pests.

The findings are being published in an online article in the Journal of the Royal Society Interface.

So far, the design has not yet been duplicated synthetically, so don't expect to find a line of bug-repellent sheets or sofa fabrics on sale soon. Still, scientists are pleased to have found a way that nature stops the pests.

"The folk remedy had been documented ages ago," said UK entomologist Mike Potter, an expert on the pests, which are about the size of an apple seed and bedevil areas where people sit or sleep.

"They used this folk remedy of sprinkling bean leaves on the floors. The bugs would be caught up in the leaves, and then the leaves would be collected and thrown away."

The leaves work not by being a repellent to the bugs, but rather by their trichomes — the hooked hairs on the leaves — that effectively impale the bugs.

"We were not the first ones to find that these plant hairs serendipitously capture these bedbugs," Potter said. "But the light bulbs went off in our heads. We thought maybe we can reproduce nature synthetically. ... That would serve as a solution to the global bedbug challenge."

Potter had seen the virtues of the hooked hairs before. As an undergraduate at Cornell, he worked on a project in which trichomes were used to capture "leaf hoppers," a plant-eating insect. The hooked hairs served as a natural defense against insect invasion.

The plant mechanism is not like Velcro, Potter said. Instead, picture a fish hook turned upward.

Potter and his colleague Ken Haynes, another UK entomologist, bought samples of various fabrics to try to see if any of them came close to duplicating the texture of the bean leaf. None did.

"Nature is a tough act to follow," Potter said.

Donnie Blake, president of OPC Pest Control, which brought in huge heat machines in 2011 when several rooms at the UK student center were treated for bedbugs, said that such technology could be valuable in the early stages of a bedbug infestation, when control is easier to accomplish.

After the bedbugs have gained a foothold, he said, control is more difficult.

"Bedbugs don't just live in the beds, they live throughout the room," Blake said. "The question is, where do you stop? What if they're in a recliner or a chair? ... We see many times with people who have a lot of stuff, that they (bedbugs) will get in the dressers, behind chairs, behind picture frames."

Kevin Hall, a spokesman for the Fayette County health department, said that the organization gets about 30 complaints a month about bedbugs. Even if bedbugs are eliminated from many surfaces through development of bedbug-trapping fabric, he said, it might not be possible to totally eliminate exposure to the critters which, although irritating, do not transmit disease.

He advised travelers to examine the mattresses, box springs and baseboards of their accommodations before letting their luggage touch the floor.

"Anything that can be developed to eradicate the problem, we would want to look at," Hall said. "One of the most common misconceptions is that bedbugs affect people of low income only. We have them in all zip codes."


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Cheryl Truman: (859)231-3202. Twitter: @CherylTruman.

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