Leaf-like material 'traps bedbugs', say researchers

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Media captionScientist footage: a bedbug gets trapped in the hairs of a kidney bean leaf, and only momentarily caught on the synthetic material which attempts to mimic it

A material designed to mimic the hooked hairs found on leaves could help trap and control bedbugs, the Journal of the Royal Society Interface reports.

The US scientists were inspired by a traditional Balkan remedy that used kidney-bean leaves to combat the pest.

Infestations have increased worldwide, partly due to pesticide resistance. An ensnaring solution could sidestep this.

Sceptics ask if enough insects could be trapped to control numbers but suggest it may help monitor populations.

'Hard act to follow'

Catherine Loudon, an entomologist and lead author of the paper said: "Plants exhibit extraordinary abilities to entrap insects. Modern scientific techniques let us fabricate materials at a microscopic level, with the potential to 'not let the bedbugs bite' without pesticides."

The researchers were inspired by an age-old remedy formerly used in Bulgaria and Serbia where kidney-bean leaves were strewn on the floor next to beds to trap the bugs. The greenery was burned the next day. Bedbugs have no evolutionary link with bean plants - although the general idea that plants have developed to trap insects like aphids and spider mites is known.

Using scanning electron microscopy and videography, the team studied the capture mechanism of the leaves. They found that rather than a Velcro-like mechanism that would only hold the bug momentarily, the leaves impaled the bedbugs' feet.

The scientists carefully studied the microscopic hairs on the kidney-bean leaves, looking at their geometry, orientation, sharpness of tips, density and height. They used this as a template to develop a synthetic material. They found this was able to catch the bedbugs temporarily, but it did not stop them as effectively as the real thing.

Michael Potter, an entomologist from the University of Kentucky who collaborated on the research said: "Nature is a hard act to follow, but the benefits could be enormous. Imagine if every bedbug inadvertently brought into a dwelling was captured before it had a chance to bite and multiply."

'Questionable effectiveness'

Other experts are yet to be convinced on how the material could help stop infestations.

Image caption High magnification: bedbug leg on leaf surrounded by entrapment hairs

Ian Burgess, of the Medical Entomology Centre said: "A bedbug is not small, an adult can be 5-6mm long. You would need an extensive amount of hooky-hairs to capture them. It might be able to catch little ones, but whether it traps big ones is the question.

"In a bedroom there are hundreds of nooks and crannies where bedbugs can hide - they even get into the crevices of the telephone and alarm clock - so how would you apply this material. Do you cover the bedroom with it?

"Bedbugs move around walls, across the ceiling - you could try to create a barrier around the bed - but it is questionable how effective this would be."

Others suggest that rather than a control device, the material might be useful to get a handle on population numbers.

Dr James Logan, an entomologist at the London School of Hygiene and Tropical Medicine said: "Bedbug numbers can explode rapidly from one bug, to hundreds in a week, to thousands a month - it is difficult to trap and remove them all.

"But this material could be useful as a monitoring tool - the idea is similar to the gluey interception traps we already have.

"Monitoring is useful so you know population levels. Hotels, for example, can have traps which are checked daily and give an indication if action needs to be taken.

"At the London School of Hygiene and Tropical Medicine we are working on making traps with pheromones that entice bedbugs to the trap - otherwise you are just waiting for them to stumble across it."

Bedbug infestations have increased over the years and experts say they are likely to continue to rise for a little while longer. The exact reasons are hard to pin down, but resistance to chemicals, more people travelling and an increase in second-hand furniture sales have all been thought to play a part.

As well as pesticides, freezing, heating, vacuuming and even sniffer dogs to root out infestations are all used in the fight against bedbugs.

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