The web is buzzing about a new pyrethroid-resistance study of New York City bed bugs by researchers at the University of Massachusetts and Seoul National University. Pyrethroid-resistance is just one reason it is often so hard to get rid of bed bugs.

Two of the many articles picking up on the study’s results included this item in the U.S. News and World Report Health Blog today, and this article from Monday’s LiveScience.

As the U.S. News Health blogger reported,

Bed bugs in New York City, where infestations have grown in recent years, appear to have developed nerve cell mutations that weaken the effect of the pyrethroid toxins, such as deltamethrin, commonly used against them, according to a report in the current issue of the Journal of Medical Entomology. Such nervous system poisons normally would paralyze and kill the nocturnal blood suckers.

Toxicologists at the University of Massachusetts Amherst and Korea’s Seoul National University found that the New York City bed bugs are now as much as 264 times more resistant to deltamethrin than an easier-to-kill type of bed bug found in Florida.

Pyrethroid-resistance is no surprise to us, since it has been found elsewhere.

Unfortunately, the current round of press coverage of the U Mass-Amherst / Seoul National U study may give those not in the know about pyrethroid-resistance the sense that this is a “New York City” problem, which it isn’t.

This 2007 article in PCT Online from Alvero Romero, Michael Potter and Kenneth F. Haynes outlines a study comparing pyrethroid-resistance found in populations from around the US:

Further testing of third-to-fifth instar nymphs from 16 different field populations indicated that pyrethroid resistance in bed bugs, while not universal, may be widespread (see accompanying map and table on pages 44 and 48). Using a “discriminating” dose equivalent to 10 times the labeled rate of deltamethrin (0.6 percent), 14 of 16 populations collected in Kentucky, Ohio, Michigan, New York, Massachusetts, Virginia, Florida and California were resistant (0 percent mortality), one field population from New Jersey was deemed “intermediate” (45 percent mortality), and one of the two populations collected from the same building in California was relatively susceptible (100 percent mortality).

(Information on getting a copy of this study follows at the bottom of the post.)

The Livescience article helps put the new pyrethroid-resistance data in perspective, with the help of Dr. Lou Sorkin, a friend to Bedbuggers everywhere:

Unless the researchers sampled every population of bed bugs in New York, it is unlikely that all NYC bed bugs are resistant to the insecticide, said Louis Sorkin, an entomologist at the American Museum of Natural History in New York.

Also, most pest control companies rely on more than one insecticide to combat bed bugs, he said. The ideal is to use a combination of chemicals that have different modes of action — perhaps one is good at killing the adults and nymphal stages immediately while another is better at lingering and killing bugs days later — and come from different chemical families, not just pyrethroids, Sorkin said.

Exterminators also have different ways to administer insecticides, which can make a difference — foams, powders, aerosols. However, over-the-counter aerosol bombs are not recommended. They just cause the bugs to scatter, Sorkin said, and fail to get inside cracks where bugs can hide.

“Some people don’t like to say they have bed bugs. They try to take care of it themselves,” Sorkin said. But amateur attempts often just push the bugs away for a while and spread them into neighboring properties.

Lou reminds us not to take an infestation lightly. If you’re using traditional treatments for bed bugs, a multi-pronged approach is best. The article notes that Integrated Pest Management (IPM) solutions go beyond sprays and dusts:

Techniques include caulking, spackling and using other sealants to fill cracks and crevices, refinishing and sealing floors, injecting frozen carbon dioxide “snow” into electronics to freeze pests, re-painting walls and other surfaces, using low-moisture steam and clothes dryer heat to kill bugs, and injecting bug-killing dust into electrical outlets and switches.

Commodity fumigation (usually done by sulfuryl fluoride gas, including Vikane TM) is also mentioned by Lou in the article. (The home itself obviously must be treated thoroughly if items are to be gassed and returned to it.)

Thermal heat is not specifically mentioned, but is now an option which can be effective.

If done properly, no bed bug is resistant to sulfuryl fluoride (Vikane TM) or thermal heat. However, these options can be more expensive, and are not available everywhere.

Pyrethroid-resistance is a good reason for the pest control industry to keep seeking alternative solutions to bed bugs and for all pest professionals, landlords, tenants, and property owners to get serious about an aggrerssive, multi-pronged approach to fighting bed bugs.

The new research study referred to in these articles is:

Yoon, K. S., Kown, D. H., Strycharz, J. P., Hollingsworth, C. S., Lee, S. H., and Clark, J. M. 2008. Biochemical and Molecular Analysis of Deltamethrin Resistance in the Common Bed Bug (Hemiptera: Cimicidae). J. Med. Entomol. 45(6): 1092-1101.

(Use accession number 185379 to get a PDF of this item from the Armed Forces Pest Management Board Literature Retrieval System! Accession numbers for items below are also noted where available.)

Also see the study referenced in the PCT Online article above:

Romero, A., M.F. Potter, D.A. Potter and K.F. Haynes. 2007. Insecticide resistance in the bed bug: a factor in the pest’s sudden resurgence? J. Med. Entomol. 44 (2):175-178. Accession number 183531.

The PCT Online article linked to above also suggests the following articles:

Myamba, J, C.A. Maxwell, A. Asidi and C.F. Curtis. 2002. Pyrethroid resistance in tropical bed bugs, Cimex hemipterus, associated with use of treated bednets. Med. and Vet. Entomol. 16, 448-451. Accession number 175921.

Boase, C.J., G. Small, and R. Naylor. 2006. Interim report on insecticide susceptibility status of UK bedbugs. Professional Pest Controller. Summer 2006:6-7.

Karunaratne, S.H.P.P., B.T. Damayanthi, M.H.J. Fareena, V. Imbuldeniya, and J. Hemingway. 2007. Insecticide resistance in the tropical bed bug Cimex hemipterus. Pestic. Bochem. Physiol. 88, 102-107. Abstract.

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by hopelessnomo

Bedbugger has been following the fascinating genetic research on bed bugs, a collaboration between the University of Arkansas at Fayetteville’s Insect Genetics Laboratory and Texas A&M’s Center for Urban & Structural Entomology, that illuminates a new perspective on the bed bug resurgence: the possibility that bed bugs were continuously present in the United States throughout the period when they were presumed to have been nearly eradicated.

Present and enjoying well-fed lives in chicken coops across the land.

This research has several interesting components and includes the successful isolation of human DNA from bed bugs, evaluations of pesticide resistance and population genetics.

Texas A&M associate research scientist Dr. James W. Austin was exceedingly kind to answer our questions via email.

Bedbugger: News reports about the research indicate the possibility that bed bugs are spreading or have spread in the past via chickens from breeder houses to poultry workers and to the community, is that correct? How significant a factor could this be in the bed bug resurgence in this country and others? And do New Yorkers, who live in a city of seventy or more viveros need to be concerned that urban live poultry markets may also be a conduit, not just via chickens but also via the business next door (structurally, the markets can be in the ground level of apartment buildings) and its employees and even customers?

James Austin: Yes, we have found significant populations of bed bugs in poultry facilities and given their unique ability to phoretically transfer (hitching rides on other organisms), bed bugs are very likely using alternate hosts (such as chickens) to fulfill their dietary needs. This could be a significant factor in the resurgence of bed bugs globally…not just in the USA. To suggest that all bed bug occurrences have emanated from international travel is unrealistic. There are undoubtedly endemic occurrences that are contributing to the resurgence phenomenon.

As for New Yorkers being concerned about live chicken markets…I would be concerned. You have to put bed bug history into context here. Likely, bed bugs were first associated with bats, moved onto humans that probably dwelled in caves, and then onto poultry. When you look at other Cimicids there is a significant number that have direct relationships to various domestic and wild birds, so it isn’t a stretch to see how bed bugs have utilized chickens (and other galliformes) as their food source.

Bedbugger: You have isolated human DNA from bed bugs. Do bed bugs have the potential of becoming a common and significant forensic indicator? Have they already been used in criminal cases?

James Austin: Bed bugs have tremendous potential for assisting forensic experts in criminal investigations, because unlike other obligate blood feeders both male and female bugs must consume a blood meal prior to molting. Bed bugs won’t stray too far away from their hosts if they are consistently available. This means that if you wanted to link a suspect in a criminal investigation to an exact location, you could get pretty darn close. Besides demonstrating that the recovery of human blood from bed bugs is possible, we have also conducted time course analyses and have demonstrated that we can recover mitochondrial DNA (mtDNA) up to 7 days after feeding and short tandem repeat DNA (or STRs) up to 60 days. This offers a significant time window of opportunity for forensic investigators to possibly recover blood samples from bugs that were in proximity to a location of interest. There were no specific differences between male and females in terms of recovering human DNA. To our knowledge, there has not been a criminal investigation where human DNA recovered from bed bugs has been used, but this offers another view to forensic experts if all the right pieces of the jigsaw puzzle are there.

Bedbugger: What is the relevance of genetic population studies of bed bugs to the issues of pesticide resistance and what are the findings so far?

James Austin: If you contextualize genetics and resistance together an alarming (and not too unfamiliar) picture emerges. Based on our use of both mtDNA and nuclear DNA (nDNA) we find significant variation without population structure and support recency of the whole resurgence phenomenon. In other words, we genetically demonstrate no variation in nDNA (which supports recency of resurgence scenarios) and the lack of population structure with mtDNA suggests rapid movement of populations. Basically, this research supports what a lot of researchers believed was true without supporting it empirically.

Bedbugger: We want to make sure we understand the findings. You tested samples from chicken breeding facilities and also from field collections elsewhere in the U.S., is that correct? The genetic variation and population structure you found point to a) populations of bed bugs surviving over a continuous period (presumably on alternate hosts like the poor chickens), and b) a recent expansion of these bed bug populations. Or can we speak of a single, genetically simple population of bed bugs?

James Austin: Yes…we looked at populations collected from numerous locations in addition to poultry facilities. We employed two classes of genetic markers, mtDNA and nDNA. mtDNA provides a glimpse at the maternal lineage of any successive population since this is maternally inherited. nDNA share both parental contributions so you can at least get some perspective of the paternal input as well. In most cases it encodes more of the genome than the mtDNA and is passed sexually rather than matrilineally. Both genes can coevolve within the same populations at different rates. It takes significantly longer to observe changes in nDNA sequences than in mtDNA sequences.

By applying both to these disjunct populations, we are able to definitely support that bed bug resurgence is more recent (if there was significant variation here you would imply that change was going on and continued to go on for some time) and that the absence of population structure from mtDNA sequences supports large scale mixing of populations (if populations were isolated, you would likely detect geographic correlations with where certain haplotypes (of mtDNA) occur). I think it would be too simplistic to believe that all our bed bug problems originated from a single founding population. If this were so, you would have essentially no mtDNA variation because they would all be related. No…in this case there have been several points of origination and likely mixing of several populations which have culminated into the situation we have at hand.

Bedbugger: And the U.S. bed bug population genetic picture with regard to pesticide resistance? What is a “genetic bottleneck” and what are the implications?

James Austin: While screening multiple populations of bed bugs against various insecticides we have found virtually all populations were 100% resistant to DDT. This is not a surprise given that the first observances of DDT resistance were noted almost 50 years ago. It is a little surprising that they continue to be so completely resistant to DDT. This fact would support a “genetic bottleneck” where DDT susceptible populations were so aggressively challenged to DDT that it wiped them all out…only the highly resistant populations might have survived (a bottleneck), hence the relative freedom we have had from bed bugs for so many years. There are examples from other organisms that demonstrate cross resistance from one insecticide to another insecticide (largely because they have similar modes of action), but this doesn’t seem to be as common in bed bugs that we have evaluated from poultry facilities. Without doubt, we find resistant populations that have been challenged with organophosphates (OPs) and the like, so it is too early to assume anything yet. The bottom line here is that when it comes to treating bed bug infestations, careful lessons learned from cockroach management apply (rotate chemicals, good sanitation, applying push and pull techniques, etc.).

Bedbugger: But that is a tall order when it comes to bed bugs, isn’t it? Rotating chemical classes and push-pull (which, and please correct us if we’re wrong, we understand is a strategy to move insects towards treated surfaces via the use of attractants) is going to be hard because, well, we got nothing at present. Or is there hope in any of these areas? Can their aggregating habits favoring feces-marked locations be turned against them?

James Austin: You are correct in that the strategy of push-pull applications focuses movement to a desired area. However, it doesn’t necessarily mean towards a treated area. It is relatively clear that bed bugs favor warm foci for obvious reasons (if you are an obligate blood feeder, you can only find blood from a warm blooded animal…heat=possible meal). Push and pull techniques might employ non-repellent chemistries and heated target zones (or possibly traps). There is good evidence that bed bugs do prefer harboring in areas where feces is deposited. Studies on C. lectularius and other cimicids appear consistent in that they prefer these areas. Your last inquiry about turning their preferred roosting areas against them is one that you will see a lot more of in the near future.

Bedbugger: Can we hope that bed bugs will one day have the research footprint of termites or other economically important pests?

James Austin: In the short run they very well may already have that footprint. One of the reasons termites get people’s ire up so much is the thought of an unseen invader eating one of their most valued possessions, their home. Like termites, nothing would get my ire up a lot more than being fed on while I sleep or thinking about them on my children. This will take a little time, but I think there will be significant interest in bed bug research in the years to come.

Bedbugger: We want to end with a thought about the chickens. What is being done to alleviate their condition? It pains us to think of chickens suffering bed bug bites. Are current control methods having an effect?

James Austin: Unfortunately, no. Many large-scale poultry producers do not even have entomologists on staff to consider ways to manage resistance in these insects. Until producers change their ways, they are more likely to contribute to the problem than assist with correcting it. Now, to be fair to them, it isn’t their fault either. These insects have been around many, many years and they are doing what they do best, surviving at all costs. So, we needn’t be too alarmed that this has occurred, but we can’t just sit on our duffs hoping for better days either.

Heartfelt thanks to Dr. Austin for his generosity and this wonderful discussion.

You can access the bed bug human DNA forensics paper on the publications page at the Insect Genetics Lab and while you’re there, check out the video and photo resources.

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Update 9/09/08: North Carolina State University researchers have been awarded a USDA-NRI grant to, ambitiously, use bed bug population genetics to determine the source and movement of bed bugs, within buildings, cities and surrounding areas, and even between countries… and between poultry farms/urban environments, to determine whether poultry farms are important sources of the spread.  We look forward to hearing more from the researchers on the project, Warren Booth, Ed Vargo, and Coby Schal.Similar Posts:

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Hungry bedbugs a rising problem in some areas : Ventura County Star

Rene Laraine of Thousand Oaks, California, has bed bugs.

Laraine said that after nine treatments performed by two pest control companies, the bedbugs are still there.

A representative for Essex Properties, the company that manages the complex, said the company is doing what it can to try to treat the problem in Laraine’s apartment.

What?

No. I am sorry.

If you have had nine treatments and still have bed bugs, I would seriously question whether someone–landlord, pest control operator, tenant, or neighboring tenant– is not doing what they should to eliminate those bed bugs.

Let’s just go through some things that might be going wrong:

1. The landlord has not had a qualified and knowledgeable pest control operator inspect every adjacent unit (top, bottom, and all sides) and treat them properly if necessary.
2. Treatment is not being repeated by the PCO at appropriate intervals (hint: PCOs who know bed bugs tell us they treat every 10-14 days; at least one in Denver treats at 3-week intervals instead, due to low humidity). Treatment must continue without a gap, until all bed bugs and signs of bed bugs are completely gone.
3. The residents in every infested unit are not getting the same treatment, at the same times.
4. The residents in every infested unit are not cooperating 100% with treatment, and following preparations as instructed by a PCO (who has such guidelines)– these often include washing and drying all clothes and linens on hot, and keeping them in sealed bags, and encasing the mattress. They may be much more extensive.
5. Tenants or building employees are unknowingly re-infesting the unit. (This can happen if you got bed bugs from somewhere and you are getting them again, and again.)

Some of these things can happen due to simple ignorance about how bed bugs operate. For example, a landlord might ask neighbors if they had itchy bites or saw bed bugs. If they say no, it might be assumed they are not being bitten. (Not necessarily true!) PCOs may have treated bed bugs a number of times and may still not understand that fact.

Likewise, PCOs might have difficulty finding visual evidence, or may only count actual bed bugs as visual evidence. (But not seeing these, or not seeing them easily, does not mean a tenant is bed bug-free.)

Landlords may suspect or know neighbors are infested but may be allowing them to refuse treatment (based on anything from religious to medical objections to pesticides). While people may be concerned about the actions of pesticides on children, people with illnesses, and pets, bed bugs must nevertheless be remedied somehow. Neighbors who refuse traditional pesticides must be treated somehow. There are other options.

PCOs may refuse to treat infested units that are not properly prepped. Or may treat un-prepped units without success.  Landlords might simply ignore those tenants’ units. This is a big mistake. Even if Rene is prepped, if his neighbor isn’t, the bed bugs can keep coming.

Other issues may be happening to make bed bugs hard to eradicate: pesticide resistance is real. However, good PCOs are aware of it and have options in their arsenal like dusts which have a mechanical action, and steam: neither of these can be resisted if the bed bug is in contact with them. Combined with pesticides, PCOs should be able to eliminate even pyrethroid-resistant strains of bed bugs, which do exist.

Some of these factors may be the tenant’s fault, make no mistake. Or they may be another tenant’s fault. Many of these factors mean landlords are mismanaging treatment, or hiring PCOs who mismanage treatment. I would put my money on adjacent units being infested and either overlooked or not treated properly.

Whatever the cause, landlords and tenants should be trying to avoid the above situations.

And if you have bed bugs after even four treatments, let alone nine, something is terribly wrong.Similar Posts:

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