A new article in the Journal of Medical Entomology describes the increased effectiveness of silica aerogel (a synthetic desiccant dust) when combined with a blend of bed bug alarm pheromones.
Joshua B. Benoit, Seth A. Phillips, Travis J. Croxall, Brady S. Christensen, Jay A. Yoder, David L. Denlinger. 2009. Addition of Alarm Pheromone Components Improves the Effectiveness of Desiccant Dusts Against Cimex lectularius. Journal of Medical Entomology 46:3, 572-579 doi: 10.1603/033.046.0323
First-instar nymphs and adult female bed bugs that crawled over a silica gel- and pheromone-treated surface for a short 10-minute exposure were later observed at 0% RH conditions. First-instar nymphs survived 2.6 days when exposed to silica gel alone and 1.2 days when exposed to silica gel plus a specific bed bug alarm pheromone blend. Adult female bed bugs survived 17 days when exposed to silica gel alone and 6.5 days when exposed to silica gel plus the bed bug alarm pheromone blend.
Survival is based on 50% mortality. The 0% RH conditions were necessary to calculate water loss. I’m not sure I understand how long they would survive in natural conditions.
As for diatomaceous earth (DE):
DE was effective only if supplemented with pheromone, resulting in a 50% increase in water loss over controls with the (E)-2-hexenal:(E)-2-octenal blend, and a survival decrease from 4 to 2 d in first-instar nymphs.
A second test was designed to see if bed bugs would leave their harborage sites and cross a silica gel-treated surface if the blend of bed bug alarm pheromone was released in an artificial microhabitat; they did and, again, lost water at a higher rate than when the silica gel was used alone:
Applying a desiccant such as Dri-die and using the alarm pheromone to evoke increased bed bug movement may be a useful technique for controlling bed bugs, including pesticide-resistant strains. It is important to note that, even though the desiccating conditions in this study seem to be severe, possibly because the bugs are adapted to dry human comfort standards (30-50% RH), these experimental conditions are similar to the environment in their habitat.
The pheromone blend was more effective than pheromone components tested separately, and there are interesting remarks about the bed bug alarm response:
In response to 0.01 M (E)-2-hexenal and (E)-2-octenal, bed bugs showed an excited, continuous searching behavior, crawling rapidly over the bottom of the petri dish and failing to settle into clusters at the edge of the dish. Response to 0.1 M was not as high in most cases and may result from the complete saturation of pheromones, possibly leading to a lower response.
As far as this goes, pretty neat, and perhaps we will see an application in the near future.
However, we have to return to DE for a moment.
The authors underscore this point so we may as well start there:
A 10-min exposure to diatomaceous earth had no appreciable effect on net transpiration rates of first-instar nymphs or adult females.
Well, 10 minutes, you say.
But things get serious when you start to realize that, basically, you don’t know much about DE and moreover that DE appears to suck:
The efficacy of diatomaceous earth seems to depend somewhat on the formulation; sometimes it works and sometimes it does not (Allan and Patrican 1994). Resistance also seems to be an issue with diatomaceous earth (Korunic and Ormesher 2000, Rigaux et al. 2001). Previous studies concluded that Dri-die seems to be superior to diatomaceous earths (Allan and Patrican 1994, Appel et al. 1999), and that is what we observed in this study during short-term exposure. Two key points that may alter the effectiveness of Dri-die and DE are the duration of bed bug exposure and the residual effects. Indeed, future studies are needed to test these two aspects for C. lectularius.
Did you know any of that?
The only thing I did know was, sometimes it works, sometimes it does not, clearly, but I thought the problem was with application and the difficulty of ensuring exposure, not resistance. Resistance never crossed my mind. In fact, I’m pretty sure I’ve heard “bed bugs cannot develop resistance to DE” more than once.
So, resistance? Resistance to DE? Seems to be an issue?
The insects that have shown they can develop resistance to DE are stored-products pests, not bed bugs, but I’m not sure that there are studies with bed bugs, and if there are, I could not find them.
So, if anyone wants to point me towards useful sources on this resistance-to-DE suggestion, please, please do. I’ve found some but I don’t have access to half of them and don’t really understand the other half — just a civilian. Genetic? Ebeling said it was not happening; I’m pretty sure we have that from Quarles somewhere. So, are these stored product pests (confused flour beetles, for example, that can definitely develop resistance to DE, doi:10.1016/j.jspr.2007.09.001) what? Weird?
More useful would be the knowledge that someone somewhere is looking into this. DE is the everyman pesticide for bed bugs. Does it or doesn’t it? Which formulations? Why is this so difficult?
These pages may be of related interest:
I haven’t read the whole thing but I can understand this reasoning to some degree:
What they are really establishing here is a maximum effect. The driving force behind mass transfer is the concentration gradient. It’s a little different when you’re looking at mass transfer between two different states (moisture on the surface of the bedbug and moisture in the air), but for conceptual purposes you can think of 0% RH as being the lowest possible water concentration in the air. This is a lot like the air in the desert around noon. So when you decrease the concentration of moisture in the air to 0% RH, you are effectively maximizing the rate of water loss from the bedbug. Now when they say the following:
I don’t know if I would really agree with that. If someone said: Sitting in the desert is equivalent to sitting in your living room in upstate NY. If I spent enough time in the desert, my skin would start to crack. In NY during the summer, I’m fine.
What they really should have done is run the experiment at 0% RH to establish maximum possible effect (this represents a theoretical upper bound). Then run it at 30 and 50% RH to establish what might be a more realistic result in the field.
Pheromones are like any intoxicating substance. At lower concentrations (.01M) people are happy (think one or two beers), at higher concentrations (.1M) people get wasted (perhaps a bottle of vodka).
DE resistance would make sense just like any resistance. Say you have a batch of bed bugs and they are exposed to DE. Say some of them have stronger exoskeletons than others that confer some resistance to DE. Those with the weaker exoskeletons will die off and those with the stronger will survive. This will concentrate the genes in the population which confer resistance. In people this kind of thing can take decades, but in bugs I would imagine the process would be much faster.
Thanks, John, that is kind of you. I’m sort of pissed I didn’t know about DE resistance.
Perhaps at higher alarm pheromone concentrations they start to feel defeated and become aware of their mortality. (Sorry, freaking bugs.)
Wow. I am annoyed too. Especially when pest professionals who seem to know a lot about bed bugs do not know this.
We have been encouraged to think “mechanical killer = no resistance.” What John’s saying makes sense. But I am not sure how to change Bedbugger’s FAQ on DE, for example. For now, and for want of a better plan, will link to this.
Would love to see more on DE resistance.
Perhaps “annoyed” was the wrong word. I am more “confused.” Like a confused flour beetle.
Renee, I know you’re on a much needed break, so please rest and feel better and don’t feel like you need to respond to this at this time!
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I think all that can be said for now is that stored products pests have developed resistance but there are no studies with bed bugs. But at the very least the impossibility of resistance, that idea, needs to be retired.
I was under the impression an article about DE was forthcoming from someone. Didn’t someone present on DE efficacy at the last ESA meeting? Surely, hopefully, they will publish soon and we will finally have some good guidance.
I will add for anyone reading this, just because sometimes I can be opaque although I think in this instance mostly I was distracted by the resistance thing, that dispersal is not a desirable outcome when it comes to bed bug management, so very intriguing of course but any application of this pheromones-plus idea would hopefully be carefully tested and weighed.
When i first read this in regard to resistance to DE, i was a bit perplexed knowing that the effect of DE is mechanical, but of course in terms of the speed of turnover of generations and selection for more durable exoskeletons as noted, it does make sense… Amazing really.
I would love to see alarm pheromones as a major tool, but i remember when there was development of pheromone attraction traps for roaches, and really never took off.. perhaps because at the time the baits were working so well, there was little need to catch in monitor traps.
More use of growth hormone mimics with the effect of preventing nymphs from becoming reproductive adults as mentioned elsewhere on this site shows a lot of promise. These products have negligible mammalian toxicity and if used properly could help loads in the bigger picture..
Your attention to the current research is really astounding Renee… If i were an academic in the new york area, i would hire you… but i am not an academic,, just a struggling IPM practictioner entomologist.
Ok, now I read the abstract and took something completely different from it, I will explain but bear with me its a long one.
Firstly it is difficult to comment fully on a paper where you only see the abstract, its a bit like reading the juicy summary on the back of a book and being disappointed that all the pages are not as hot and steamy. It is meant to entice you to wade through the rest of the report and see how they came to that conclusion.
In this case the key things are that the study was done in a controlled micro climate. Without looking at the full paper it would be impossible to say exactly what they mean by this but it is likely to be some form of controlled and contained environment such as an empty fish tank or large smooth sided plastic box.
In which case as we all know from bed bug behavior in an un-occupied area they will find a place they are comfortable with a bed down until food or a stimuli to get up and move about comes along.
Now this is the key factor here, stimuli. The alarm pheromone is a stimuli or trigger for bed bugs to move because they either perceive the area as dangerous enough that a bed bug(s) has/have produced an alarm response. I am sure you would all agree that if in building when the fire alarm goes off we will all start to vacate the area, it is the same principle. You would observe similar effects if you sprayed the test area with raid or an aerosol based product, you keep the bed bugs moving and they will therefore come into contact with more shards of DE. We all know that using aerosols is not a sensible idea.
Bed Bugs will be more active in an area with a stimuli and will therefore come into more contact with DE and therefore become more cut and ergo loose more water.
The mechanisms of action for DE is physical, it cuts the waxy cuticles and causes the bed bugs to dehydrate. There is no biochemical aspect to it so bed bugs can not simple evolve or mutate to become resistant to it. Yes it is possible that the use of DE will create a selective pressure that could make it preferential for bed bugs with thicker cuticles to remain alive and breed but this is not a process that usually happens quickly (often over 100′s of years in humans and usually as a result of serious pressures).
My great fear from this paper is actually that someone will decide that mixing DE and alarm pheromone will make a new great product and that old DE will fall from flavour to be replaced with the new version. The reason I am worried about this is partly because with an active aromatic compound such as a pheromone the manufacturer can rightly claim that it needs to be reapplied on a monthly basis to remain at peak efficiency. This would in my mind be another shameful example of people parasitising on bed bug sufferers in the same way that the dust mite industry did at the start of the BB resurgence.
If this happens shame on them, I will name and shame if needed and I will certainly not lay down this time and let people miss-sell and miss inform on the way that products should be used.
If they are going to put this theory into test in the field then I sincerely hope that they closely monitor all adjoining properties because an excess of alarm pheromone may induce more spread of infestations between adjoining units and lets face it this is never a good idea.
If anyone has access to the full paper please let me know, I will try and request a copy but it is likely to take weeks to arrive. I could of course be wrong with my analysis of the study and the situation but frankly that is unlikely.
David Cain
Bed Bugs Limited
I don’t understand why this stuff isn’t open access for the duration our our little “epidemic” — I have to probably delete this later in order to not get sued:
[deleted --RC.]
Hi,
Its not open access because these science journals are big money in the publishing world, some of them will be over $1,000 per year as subscription. They make the abstract publicly available but the detail is in the methods and results.
In all fairness though there are very few people with enough field knowledge to fully appreciate the subtle difference between bed bugs in a stimulated environment versus a non stimulated environment.
Hope it helps clarify, as I said stand back if someone launches DE with alert pheromone and claims it to be better I will have them, its almost as ludicrous as saying that mattress protectors help prevent bed bugs when they clearly don’t care what type of bed you have when they hitch a lift with you.
David
Well David we could take all day to discuss your assorted mattress ‘heresies’ but at this point I am more inclined to agree with you than disagree when it comes to encasements. It is well to consider whether for some people mattress encasements will merely prolong an infestation, because they will not be aware of or simply will not be able to find the holes. They don’t tell you about the tears.
The authors of this paper mention that there is disagreement on the mode of action of DE and the synthetic dusts. The synthetic stuff is adsorptive and the DE is generally believed to be abrasive. That could account for much of the performance difference. One might hope they really could find a way to get bed bugs to expend energy in unoccupied rooms without increasing the risk of emigration, since motion + starved status = death (I could add ‘seems to’ but let’s be bold). There may just be no application for this.
Further, I think the lives of bed bugs are probably short in natural conditions. If it takes 30 days, for example, to kill a bed bug with dusts and they’ve laid numerous eggs before they die. Well.
Hi Renee,
I have been working on ways to treat unoccupied areas of recent and hope to have some data to share soon.
I also wanted to say that encasement’s encase they don’t cure it a bit like putting a bag on the issue, its still there just contained. Short of rips and holes they should not be able to get out. I do however have an issue with isolation of the sleeping area during treatment which our comparative studies have shown can increase the duration of the infestation by a few weeks and may cause the bed bugs to find new homes further from the main sleeping area.
The problem is however finding people who are prepared to allow you to “experiment” with an infestation is difficult at best, lets face it most people just want them gone as quickly as possible so they can get back on with their lives.
David
After re-reading the posts here, i am not so confident of an alarm pheromone. In terms of treatment, I don’t think that dispersal is useful. We want to treat them where they are concentrated and in early infestations that is at the sleeping areas. I have heard anecdotal reports of dispersal by local treatment (such as a homeowner using a “Raid” style product – killing the visible bugs, but actually causing dispersal. I think that aggregation pheromones would be much more useful as well as the insect horomone mimicker (sp) products. Regarding micro=environments, the simple reality is that bed bugs, like roaches, thrive in human created interior environments. I agree with the comment about the discomfort of sitting in the sun. Even desert creatures hide from the sun during the day and most of them are active at night when it is cooler.
Regarding mattress/box spring encasements, i am sometimes truly amazed at the misconceptions about what they do or don’t do. Mattress encasements protect mattresses from the soiling caused by bed bugs. I would not expect any live bed bugs on most mattresses after a proper treatment, though i must admit i have seen some designs with tiny openings with metal vents — and in that case, the encasement would shut any bed bugs inside till they died of dessication or starvation. But most mattresses do not have vent. And I would hope that vacuuming, steaming and treatment killed any bed bug stages , so the encasement also serves to protect the mattress because for some people soiling is so aesthetically revulsive that they would discard the mattress on the fact of the soiling alone. A good mattress can cost $800 – $1500 and more, so this is not a frivolous benefit of the encasements. Some mattress retailers base their return policies on use of encasements. Box springs are a different story as treatment of the interior of the box spring is very difficult no matter how done.. whether with spray or with steam… time consuming.. So an ecasement locks in all stages. The other benefit is that the ideal refugias near the host are now gone. An encaseed mattress with no edged seam or an encased box spring, without exposure of the plastic corner guards, or even the harborage between the mattress and the box that is presented by the stitched contour of a mattress resting on a box spring ( a most marvellous refugia — i have seen hundreds of bed bugs concentrated in that very location). so the encasements serve multi-functions and are really a must for bedding for all the noted reasons. The encasements are not a solution of course, but they are part of that “integrated” aspect of measures to enable control that is Integrated Pest Management. Renee, you should laugh at the predictable way i end with IPM as the focus.
Hi Sam,
I agree with you on the use of mattress protectors for sanitation and good hygiene, as you say a good mattress is a serious investment and needs to be protected.
We have more box spring type beds in the UK than almost any other type, yes they are a pain to deal with but its not impossible.
The real shocker is that in over 9,000 cases I have not used a single mattress encasement, so I have to say they are not an essential part of IPM.
If you want something that really helps with detecting an infestation early and therefore making it easier to clear get a passive monitor and set the spare money to one side in case its needed.
If you don’t have an infestation a normal mattress protector will suffice and will give exactly the same benefits as one with a more expensive sealing system on it.
I would also say that the one failing of most current alleged IPM approaches is that they lack sufficient education to assist the occupant of the property to identify and avoid future infestations, I would agree with seeing that before I am ever likely to endorse the current mattress encasement technologies.
David Cain
Hi Sam,
In fact that ;last post spurred me on to look at an advert I saw the other week that claims:
Mattress encasement’s:
Increases time between re-infestations
Decreases the scope of a re-infestation
The ad is also peppered with images of dust mites when it is clearly sold on a page about bed bugs.
Now from my point of view I cant see how a bed bug that you encounter away from home knows its you have a mattress protector or not. The answer is they don’t, they don’t care and if you have one installed it has no bearing on if you will be infected again or not.
If anyone wants to try and explain how it reduces your risk of re infestations please let me know. Until then I think I am more than justified as viewing this as an expensive add on sale that adds little or no value to a bed bug treatment in terms of speed of eradication.
David
Hi David..
good to read your posts.. I did see your passive detection monitor when i was in Washington in April. Your colleague from UK – the managing director of that large firm that handles light traps and air sterilization equipment (his name escapes me at day’s end) = showed it to me. I thought this was a most elegant design using readily available materials. I will certainly order some of those..
I do understand your concern about wild claims by some retailers about mattress encasements, and i have always been shocked by the outrageous pricing which i simply do not believe it justified. $150 for a single bed encasements is ludicrous. I hope that the market place will result in lower priced units of good quality. I know from my research that fairly good encasements exported from China cost less than $30 landed for a single and less than $40 for a queen or a double, so a markup of 500% is really horrible. I am also familiar with the scare tactics of some of the same firms when they were selling pillow nad mattress encasesments as defense against dust mites, conveniently invisible, but certainly visible in scare videos showing the critters in their full scanning electron microscope glory. Though dust mites are recognized as a significant pest in relation to allergies and asthma, i believe that a combination of good climate control and housekeeping eliminates most of these, and only in extreme cases of allergy or asthmatic individuals would the encasements really be merited in most cases. Having said that i disagree with your reluctance to include these as an IPM tool. I know that not every service provider would be as meticulous as you are David, as I know from reading your comments and interview with Renee, that you are committed to do an excellent job,, but in many many cases, the treatment of box springs would not succeed, and the protective encasement is an excellent IPM tool to be used AFTER treatment. Keeping them out of the box spring structure is a huge benefit. And these encasements last for years.. so the overall benefit is huge in my view..
Of course, the claims are ridiculous.. and i put such claims into the garbage heap where they belong, but the claims should not devalue the usefulness of the encasements and I believe that these are becoming a standard to not only protect the beds from soiling, but to keep the bed bugs out of ideal harborages in box springs, and certainly to reduce harborage on mattresses.. I have seen mattresses with tiny holes for air that would enable adults and nymphs to get inside the mattress, and for these, the encasements are invaluable..
IPM has many tools and I support the encasements as a valuable IPM tool in the case of bed bug management..
but i do appreciate your reflections David…
lots for us to learn…
best regards
Sam
Hi David,
i had written a response a few days ago, but then it disappeared into cyberspace because of an impatient ISP.. oh Dear.. and damn as they say..
Regarding the mattress encasements, while I agree with you David about the nonsense of ridiculous claims and I have seen plenty of those over the years for a variety of products, I don’t agree about excluding mattress encasements as part of an IPM strategy. These are not, strictly speaking, control devices as such nor do they prevent infestations however, they do contribute to the total picture. Not all service providers are as meticulous as you are David, and it is altogether too easy to miss some aspect inside a box spring.. further, in consideration of a chemical treatment of a sleeping area, the encasements lock in freshly hatched nymphs from eggs resistant to spray, and that alone is a great benefit. Apart from the protection of the bedding, both the matttress and the box encasesments REDUCE harborage by significant proportions and make it easier to control bed bugs in the long term. The typical hiding places such as seams of mattresses, corner plastic guards of box springs in additon to the undersurface of hte box springs, and for matresses with vent openings ( I recently saw a style that had a very dozen vent holes through which adults and nymphs could easily travel… So the bottom line is that encasesments are very valuable for so many reasons and in my view, in bed bug management they are an ESSENTIAL element of IPM of bed bugs.
As for claims, this was raised at the EPA summit in terms of pr;oducts not registered as pesticides due to low toxicity, such as Cedar Oil and Limoneme oil . I read these ridiculous statements about “not toxic ” and natural. Time magazine had an article last year about the green charlatans using the “green” label to make all sort of ridiculous claims. If it were not toxic, then how can it kill bed bugs and natural does not mean non-toxic.. Some of the most toxic substances are natural… We have a product in North America, a device that the manufacturer claims will control everything under the sun by just plugging into a wall.. (Riddex), and really all it accomplishes is stealing people’s money and doing nothing at all, but it is shown in slick informercials on cable. I met a rep of a firm selling cedar oil at the EPA summit and of course, their main promotion was “buy this, and you can do it yourself without paying someone else” targeted at the property management market, and of course, this is ludicrous as mostly it will fail …………. Some of these products may have a use ultimately, but not until proper studies of efficacy have been undertaken, and even at that, the average person would not want to go through the meticulous effort needed.. enough that they have to go through preparartion.
I did see you passive monitor device in Washington. Mathew Kaye of Brandenburg showed it to me.. Wonderful innovative device.. Do you have field data and images showing its effectiveness?
Renee recently shared Clive Boase perspective on the bigger problem and the meta-population model, and my response to this is that without IPM approaches being mandatory requirements through legislation, the problem is will continue to get worse much as Michael Potter predicts. I don’t agree with him about no solution until an equivalent to DDT is found in the 21st Century. I focus more of the practice of IPM than on any single product. Sadly, this is not done much as it should be, and I face this reality almost every day when I hear of complaints about unresolved infestations and some of the people in charge just not seeing that they need professionals to implement and manage these programs. Too many still live in the misconception that control can be achieved by amateurs…. Of course, people can be trained ot understand the overall concept .. it is not rocket science, but until there is enforcement at the municipal level of standards of program and of service delivery, it is going to continue to get worse. The benefit of professionals is that they keep up to date and look at best practices. Citizen advocates like Renee who has made herself expert in the area.. knowing more about this now than most pest control service people, are very very rare…
Kudoes to Renee for creating this web blog…
Hi Sam,
We will agree to disagree ont he encasements other than the claims which I am getting close to naming and shaming.
Yes we do have some data on the field use of the monitors including one hotel that caught a infestation after just 2 or 3 days and managed to treat the room by removing it and a close inspection to ensure that there was no more activity.
When the monitors was examined it contained a single female adult and 3 or 4 eggs. It has need checked every few days and after 14 it is still clear.
I am not a big fan of searching for the holy grail because any single tool or product is a weak point that biology will always adapt to and over come.
If you want to chat in more detail drop me an email and we can skype.
David .
love to chat with you David…. the more colleagues who can discuss this intelligently and share experiences and thoughts, the better chance we have to get ahead with solving the problem. I certainly agree with you 100% about not depending on some magic bullet solution. I just received a forwarded message today from another one of those medicine men style of marketers promoting a one product magic bullet. I never presume a product is not good until i have seen good solid data, but you know the way it goes… claims of miraculous cures…. i don’t have your e-mail but mine at work is [sam dot bryks at hsisolutions dot ca --Ed.] .. look forward to hearing from you, i don’t have skype but perahps we can chat on MSN messenger or i can learn skype.
take care,
Sam
Sam
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