Correcting some mistakes and revisiting my strategy

When I first started this Blog, I never expected that I would spend so much time on it. Since the support and information that I received from others helped me tremendously during the worst period of my ordeal, I figured that maybe it was my turn to help others by writing down some of my experience and knowledge. But somewhere along the line I noticed that some people were so desperate that they would blindly follow any advice given by others without hesitation, which made me quite nervous because any inaccurate information could potentially cause adverse effects. This is the reason why I have gradually got into the habit of doing research before writing my Blog or giving advice to others. And this is also the reason why I often appear to be challenging others', including the experts' views, even though I may not be always correct. Since apparently we still have very limited knowledge about bedbugs, I think it should be agreed that what's important is not to argue who is right or wrong, but to find the accurate information, reach the correct conclusion, and find the best way to defeat the bedbugs.

Although I have been trying hard to ensure the accuracy of the information that I give to others, mistakes still happen. Some of the mistakes that I have made in my previous articles include that,

- I mentioned that all pesticides registered before 1984 were required to be re-registered under the Pesticide Registration Improvement Act. This was a mistake since this legislation only established pesticide registration services fees. It's the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) that requires the EPA to review the pesticides registered prior to Nov 1984 to ensure they meet current scientific and regulatory standards. All registered pesticides also must meet the safety standard of the Food Quality Protection Act (FQPA). It's the FQPA that has resulted in the cancellation or restriction of many organophosphate and carbamate pesticides, some of which are believed to be more effective than pyrethoids in controlling bedbugs. The cancellation and restriction of these pesticides are likely one of the several main factors that have led to the recent resurgence of bedbugs.

- I cited combined pyrethroid and carbamate two-in-one treated bed nets as an example of tank-mixing, and suggested that it might not be the best approach since both pyrethroid and carbamate affect the nervous system. Although this is not wrong, strictly speaking, this strategy may not be considered as tank-mixing, since pyrethroid and carbamate are not mixed, but rather are applied to different parts of a bed net. The typical tank-mixing strategy would actually mix two or more pesticides, which could have some undesirable consequences such as incompatibility between pesticides, and reduced overall effectiveness if one of the tank-mixing partners has any repellency action. But I don't think that there is a specific term for applying multiple pesticides at the same time without mixing them. Furthermore, although it is true that both pyrethroids and carbamates affect the nervous system, resistance to pyrethroids is mainly caused by sodium channel gene mutations, whereas carbamates work by binding to an enzyme in the synapse called acetylcholinesterase, or simply put, they have different site of action than pyrethroids do, therefore, it does make sense to rotate or combine these two classes of pesticides.

- I also suggested that insects would try to avoid chemicals in general. This too may not be accurate. It may be possible for some chemicals to have very low repellency to certain insects, because, firstly, although behavioral resistance is common, it takes time to develop, secondly, if the insect population has already developed high degree of physiological resistance, then it may not be necessary to develop behavioral resistance. Correct me if I am wrong here, but my thinking is that, an insect population that has developed behavioral resistance to an insecticide would have less exposure to it, which would lead to reduced selection pressure, and would in turn delay the development of physiological resistance, and vice versa. Although behavioral resistance may be less important than physiological resistance, it seems to be more complicated.

With all due respect to the experts on bedbugs in different fields, I think it's also important to realize that even the experts may make mistakes from time to time, since everyone only specializes in one or several fields. The only know-it-all expert is probably the web, although it also contains misinformation. In my opinion, the bedbug sufferers are also the experts, since they live with bedbugs everyday and they live with the real bedbugs (I call them real bedbugs because researchers often work with lab strain bedbugs, which can be quite different than field strain ones in many aspects), they know a lot of things that the experts may not know. For example, Parakeets, a Yahoo Bedbugger Group member, once gave me very detailed answer to my question about bloodstains on pillow and sheet, that I considered very valuable and that I didn't think the experts could provide, since they simply didn't get bitten everyday. Also, we know that thoroughness is the key to successful treatment of many pests. Some responsible and experienced PCOs know how and where to find the harborage sites. But this is you home, you live in it everyday whereas a PCO will only spend from a few minutes to several hours on a treatment job, depending on the size of your residence as well as his work ethic. There might be some hidden cracks and crevices that you know of but the PCOs may easily miss. My point is that, while it's necessary to follow experts' advice, it is also important to use your own judgement.

Similarly, last time I suggested caulking as an important alternative control measure, and in fact it has been recommended by quite a few experts as a long term control measure, and believe it or not, some pest control companies even provide caulking and sealing as an add-on service. But it does not necessarily mean that caulking is the only solution to our problem. There are many, many smart people out there, and sometimes all it takes is just one smart idea to have a tough problem solved. I also mentioned the use of boiling water in my last article, but it does not mean that you should start pouring it on everything, since it can potentially harm yourself, damage the item, and lead to other problems such as dust mite and mold growth, and provide hospitable environment to many pests. Again, whether you take advice from an expert or from an amateur like me, it is important to use your own judgement.

I've already discussed the causes of failure of extermination in my previous article, but I would like to get into more details this time.

The failure of a treatment can be caused by a number of factors, and here are a few common ones:

1. The eggs survived the treatment and hatched afterwards.

2. The PCO did not do a thorough job and missed some harborage sites.

3. Some bedbugs were hiding in wall voids during the treatment and survived.

4. Your neighbors also had bedbugs, which invaded your home after treatment and caused re-infestation.

5. The bedbugs were resistant to the pesticide used.

Let's take a look at them one by one.

1. The eggs survived the treatment and hatched afterwards

We know that with a few exceptions, insecticides are not capable of killing eggs since they are protected by eggshells from mechanical injury, desiccation, as well as insecticide application, and this is the reason why eggs can often survive treatment. Although I always suggest that one of the best ways to prevent egg-laying is to cut off the food supply by protecting ourselves, it may be difficult for some people to do so effectively, in which case it becomes necessary to repeat treatment. A few experts have suggested repeating treatment every two weeks until the bedbugs are gone. My question then is, if eggs hatch in two weeks, why don't the hatchling bedbugs get killed by the residual effect of the insecticide? And why is it necessary to repeat treatment every two weeks instead of one, or three weeks?

I believe that the failure of residual control can be caused by one or several of the following reasons.

The length of the residual control is too short.

The bedbugs did not come into contact with the pesticide, either because the PCO did not apply the insecticide to the areas en route to where bedbugs live or feed, or the bedbugs avoided the insecticide, whether intentionally or not.

The bedbugs were resistant to the insecticide applied.

Most residual insecticides for bedbugs have three months of residual control according to the labels, but it could be a lot shorter in reality. The length of residual action depends on many factors, such as the dosage applied, the type of surface treated, temperature and humidity, and the presence of dirt and dust on the surface. But for pyrethroids, researchers have discovered that the UV rays in sunlight are the primary cause of breakdown. Pyrethroids may break down in a matter of several hours under direct sunlight, but can persist for months in areas with limited sunlight. Under normal situation, they last from a few days to several weeks, although different generations of pyrethroids can have different lengths of residual action. Harvard University Operations Services web site also suggests that most residual insecticides last for one month. So I guess it's safe to say that, for indoor application, the residual action of pyrethroids lasts from a few weeks to a month under normal circumstances.

If the above hypothesis is valid, then the failure of residual control is likely due to the bedbugs' avoidance of or resistance to the insecticide. Either way, I think it's safe to conclude that residual action is not a guaranteed way to eliminate the bedbugs.

To find the answer to my second question, I compared the data from 20 sources. The data are mostly from the entomology web site of some major universities, since I believe that universities not only have the most talented people, but also provide the most unbiased information. Other sources include some most reputable experts on bedbugs such as Dr. Harold Harlan and Cooper Pest Solutions.

These are the sources that I used in case you want to do your own investigation, all links are valid as of the time of writing:

University of Kentucky, Virginia Tech, Harvard University, University of Sydney, Cornell University, University of Florida, Pennsylvania State University, Institue of Clinical Pathology and Medical Research (PDF), Utah State University (PDF), Ohio State University, University of Arizona, North Carolina State University, Purdue University, University of Minnesota, Health Canada, WHO (PDF), Michigan Department of Community Health (PDF), The Best Control II (PDF), Armed Forces (by Dr. Harold Harlan), Cooper Pest Solutions

Here are the things that I can see from these data:

- The hatching time (incubation period) is temperature dependant, and most sources agree that it takes 6 to 17 days, or one to three weeks, to hatch at room temperature (above 21^oC), and up to 28 days at lower temperatures. Eggs are not laid at temperatures lower than 50^oF.

- The development time depends on both temperature and food supply. There seems to be more disagreement on the exact length of the development time. Most sources indicate that under ideal conditions, bedbugs can complete development in one or two months. Dr. Harold Harlan suggests that a full cycle (from egg to egg) could take as little as five weeks to complete at a temperature between 28^oC and 32^oC, and a relative humidity between 75% and 80%. Ohio State University Extension's web site suggests 21 days at 86^oF, and 120 days at 65^oF. Considering that our room temperatures are a few degrees lower than the ideal temperature range and that bedbugs normally have 3 to 4 generations a year, I would say that under normal conditions, the total development time is at least 2 to 3 months. (Note that some of these sources give the full egg-to-adult development time, while others give the length of the nympal period instead.)

- Although the numbers are from some most reliable sources on the Internet, they are quite different from each other, particularly on the development time, and I don't know how many of them have been obtained through independent research. At the time of writing, Wikipedia, the free encyclopedia written by volunteers and apparently one of the most popular information sources on bedbugs, also states that "the eggs hatch in one to two weeks", and that "at room temperature, it takes about 5 weeks for a bedbug to pass from hatching, through the stages, to maturity", which obviously differs from the numbers provided by most experts. This just shows how little we know about bedbugs at this point and how easily mistakes can be made.

If egg-hatching is the only cause of treatment failure, then the best time to re-treat should be after all eggs have hatched and before any nymph reaches maturity, which is about three weeks after the first treatment, based on the arguments above. But if other factors are involved, for example, if some adult bedbugs have survived the treatment, than it may be necessary to repeat treatment at a shorter interval.

2. The PCO did not do a thorough job and missed some harborage sites.

Although it is easy to miss a few harborage sites during treatment, if you keep seeing bedbugs or getting bitten after treatment, and if you have done thorough preparation, especially have eliminated the clutters before treatment, then it is possible that your PCO did not do a good job (it is also possible that the bedbugs were resistant to the insecticide applied). As we have concluded above, residual control is not guaranteed to eliminate these survivors, and even if they do get killed, they may lay eggs, which will even survive the next treatment. Thoroughness is the key to the success of a treatment, if your PCO cannot do a thorough job, consider switching to a better PCO.

3. Some bedbugs were hiding in wall voids during the treatment and survived.

Whether your PCO use chemical treatment or structural heat treatment, it is possible to cause the bedbugs to disperse to other rooms of your home or even your neighbors' homes. You definitely don't want this to happen since the matter will be out of your control and the bedbugs can come back to haunt you again in the future. Some PCOs apply insecticide dust along the baseboard to prevent the bedbugs from escaping, others drill holes in the walls to apply chemical to kill the bedbugs inside, or apply insecticide dust for long term control. While these methods are all good, I believe that the most effective and long-term solution is to caulk all the entrances to the wall voids in all directions.

4. Your neighbors also had bedbugs, which invaded your home after treatment and caused re-infestation.

The solution to this is the same as above.

5. The bedbugs were resistant to the insecticide used.

Although quite a few recent researches have found significant pyrethroid resistance in bedbugs, the pest control industry still claims that they are in control, which is something that I am not able to explain. Nevertheless, if you see bedbugs in recently treated areas and don't seem to be affected, then it is possible that they are resistant to the pesticide applied. To eliminate these resistant bedbugs, your PCO will have to either increase the dosage (within the certified limit) or switch to another pesticide with different mode of action, although even these measures may not always work. Again, the best way to handle resistance is to adopt an integrated approach and use as many weapons as possible.

There's no doubt that repeated treatment is necessary at this point. However, if it is costing hundreds or even thousands of dollars to remove an infestation now, as more of our neighbors have bedbugs and as pesticide resistance becomes widespread, the required number of treatments will only go up, and this bedbug epidemic will potentially make many people bankrupt. The EPA constantly faces pressure and even lawsuits from various interest groups to cancel or continue the registration of many pesticides, and its decision is often not purely based on scientific facts. As this epidemic starts to cause people serious financial crisis, and as public opinion starts to weigh in, the EPA may be under pressure to reverse some of its earlier actions, or the government may be forced to amend the related legislations. But we don't know if and when this will happen. What we do know is that the pesticides we have are not effective, nor are the treatments, yet we don't have other choices. Besides taking an integrated approach, the best thing we can do at this point is to alleviate the stress and financial losses by improving the effectiveness of treatment, which in turn, can be achieved by eliminating or at least reducing the possible causes of failure, as I suggested above.