Bed bug Resistance to Insecticides Might Give Clues About How They Evolved

If you live in New York, this may have happened to you. You find a small bug crawling on your mattress or on the floor of your bathroom and you go into panic mode–bed bugs!! // It’s the quintessential urban nightmare and it’s about to become scarier. According to a new study that came out last week from Purdue University, bed bugs are becoming resistant to two chemicals that are commonly used in pesticides nowadays. This might sound terrifying but it’s helping scientists understand how bed bugs are evolving . Sushmita Pathak reports.

 

Pathak 1

I’m in the office basement of Standard Pest, an exterminator in Astoria, Queens. Gil Bloom is the resident insect expert. He’s giving me a tour of the supply  room. There have all kinds of insecticides–aerosols, liquids, gels and powders You name it? There are also traps–small plastic square containers that go under beds and in corners.

 

Bloom 1

Bloom: Bed bugs will climb into them, it’s a pitfall trap and then they can’t get out. We can also add an attractant to it which smells kind of like human sweat. Which is one of the lovely odors that they’re attracted to.

 

Pathak: That’s absolutely gross.

 

Bloom: That and carbon dioxide. Well, yeah.

 

PATHAK 3

Bloom says one of the most effective insecticides is a liquid called Temprid.

 

Bloom 3

And it’s a combination of imidacloprid and cyfluthrin.

 

PATHAK 4

Cyfluthrin is a common ingredient in insecticides. It’s from a class of chemicals called pyrethroids which attacks the insect’s nervous system. But about ten years ago, scientists found out bed bugs were developing resistance to pyrethroids. So, exterminators started using alternatives. Like chlorfenapyr, which belongs to a different class of chemicals that attacks the insect’s mitochondria.

 

Gondhalekar 1

I wanted to see how bed bugs’ resistance profile was to this particular insecticide.

 

PATHAK 5

That’s Ameya Gondhalekar. He studies urban insects at Purdue University. And it’s his new study which shows bed bugs are developing resistance to some of those chemicals used as alternatives.

 

Gondhalekar 2

It’s kind of a arms race between the chemicals that we use and the ability of insects to develop resistance to these chemicals.

 

ow, the arms race is neck and neck. In the 1950s, when we started using DDT, bed bugs almost disappeared, until.. the mid nineties when they came back, stronger than ever. Insecticide resistance played a huge role in this comeback. Insecticides work by targeting proteins in the nervous system. But when bedbugs develop resistance, their genes mutate – the protein structure changes.

 

Gondhalekar 3

The structure of the protein is modified in a certain way that the insecticides are not able to bind to that protein. And if insecticides are not able to bind to their target protein then basically they are ineffective.

Booth 1

InAnd insecticide resistance associated genes are of a lot of interest.

 

PATHAK 7

That’s Warren Booth. He’s currently studying insecticide resistant genes in bed bugs at the University of Tulsa.

 

Booth 2

Now what’s very interesting, if we look at the population of bed bugs in the U.S. and we look at the population of bed bugs in Europe and the population of bedbugs in Israel and Australia, for example, those in the U.S. show a very different profile in relation to the knockdown resistant mutations.

 

PATHAK 8

Knock down resistance means insecticide resistance. And Booth says, this led to another finding–American bed bugs and European bed bugs don’t mate.

 

Booth 3

The bed bugs in the United States did not originate from those in Europe or at least there is not a huge amount of gene flow occurring which we had somewhat predicted there to be.

 

PATHAK 9

What’s more, Booth says, some bed bugs could be on the way to becoming a different species. Thousands of years ago, bedbugs lived in caves. They only fed on bats – not us, humans.  But when our ancestors moved into these caves, we came their food. According to Booth, bed bugs that feed on humans are becoming more different, genetically, from those feeding on bats. He says, eventually, they could become a whole new species. Another branch in Darwin’s tree of life. For now, these pests will probably continue to become stronger. But don’t panic. We can still kill them with old fashioned heat . Scientists say, there’s no way they’ll become resistant to that. Sushmita Pathak, Columbia Radio News.

 

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