Rubbing alcohol not a good option for bed bug control, says researcher

Improper application of an insecticide dust to a
mattress and pillows by a non-professional. Dusts are
designed for light application to crevices and
voids, out of reach of  people.

The quest for home remedies for bed bugs appears to be never-ending. However, according to the latest reports, it seems that very few over-the-counter insecticides, or home remedies, are worth the time or trouble when battling bed bugs.

A recent article in Science News gloomily summarized some of the most current information about DIY bed bug control, based on papers presented last month at the annual conference of the Entomological Society of America in Austin, TX.

It will come of little surprise to most PMPs that rubbing alcohol, bug bombs and other products just don't work that well. And some products, like ultrasonic repellers, are completely ineffective. Science News reported that rubbing alcohol killed only about half of the bed bugs that were sprayed directly, in work conducted by Changlu Wang, of Rutger's University. Bed bugs confined in a plastic bag for seven days with mothballs (a much higher exposure than you would expect in a clothes closet or storage chest) had about the same survival rate.

I recently had the opportunity to attend the Global Bed Bug Summit in Denver, CO.  One of the debates at that meeting was over the effectiveness of diatomaceous earth (both a professional and DIY product). Despite the fact that PMPs have reported success with d.e. over the years as part of an IPM program for bed bugs, some researchers question its effectiveness in the field.

Despite the fact that no resistance to d.e. among bed bugs has ever been documented, it is never been hailed as a miracle product. Appropriate application sites for d.e. are limited. It is not really designed for broadcast use, and few applicators, especially non-professionals, know how to apply dusts correctly (see image). To liven the debate, one recent field study  by Michael Potter's lab in Kentucky found that professional applications of d.e. provided inconsistent, or only marginal, bed bug control when used by itself, without sprays or other supplemental treatments. Field studies like these are much more difficult to conduct, but usually provide a better estimate of how a product is likely to perform in real life, compared to laboratory tests in a Petri dish (Potter, by the way, contends that silica aerogel, found in professional products Drione® and TriDie®, is a more effective desiccant than diatomaceous earth).

Why the conflicting results? No one knows for sure. But d.e. is an abrasive that scrapes away some of the protective waxes that keep bed bugs from drying out (desiccating) in the dry indoor environments of homes. The effectiveness or ineffectiveness of d.e. may have something to do with the source or form of the diatomaceous earth (the various d.e. products are mined from different geological deposits and thus may vary in abrasiveness), or it may have to do with the ambient humidity or availability of food. Many insects compensate for water leakage cause by desiccant dusts by taking in more water from feeding. Perhaps bed bugs in the field are able to compensate for moisture loss by taking in more moisture through more blood feeding. Not a pleasant thought if you're the one being fed on.

All of this, of course, supports the idea that professional pest control is the best option for bed bug eradication. As a professional, your training and expertise can provide a lifeline for the public in desperate search of a bed bug solution. The professional products at your disposal are superior to most over the counter products, and your ability to problem-solve gives you a big edge over weekend bug-killing warriors.

There will always be do-it-yourselfers. But there is also a great need for trained professionals to get the job done safely and effectively. Let's get out there and show them how it's done.

Plague, prairie dogs and pesticide policy

Urban pest control encompasses an incredibly wide range of organisms including insects, arachnids, birds, bats and a smorgasbord of urban wildlife. I was reminded of this yesterday with a call from a PMP seeking help with flea control in prairie dog towns. It seems there is a plague epidemic among the prairie dogs living in and around Santa Fe, New Mexico.

Since plague is not a common phenomenon in the United States, a little background might be helpful. Plague is a disease caused by a bacterium called Yersinia pestis. The bacterium can be transmitted through the bite of an infected flea, through handling or skinning an infected animal or through the air from an infected human (or more frequently, cat) similar to flu. The term "plague" stirs most people because of its association with the black death of Europe, when dozens of millions died over a 300 year period starting in the 14th century.

There are two ecological forms of plague: urban plague, spread largely by commensal rats; and sylvatic plague, which is spread largely by wild rodents in rural areas. Both forms of plague remain a threat in this country, though the last outbreak of urban plague occurred in Los Angeles in the 1920s. Most recent U.S. cases of plague, 10-15 a year, are sylvatically transmitted and occur over scattered sites in the western states, including a few in Texas.

Rodent control by PMPs has, without a doubt, helped keep urban forms of plague rare over the past century. But effective pest control for public health is still needed to control of sylvatic plague in some areas. In the current Santa Fe epidemic, for example, one of the affected prairie dog colonies is adjacent to a school playground in an urban neighborhood.

Unfortunately, some citizens and politicians appear not to appreciate the seriousness of arthropod-borne disease. Perhaps this is because of our success in keeping arthropod-borne disease rare. Maybe it's a need for better public health education or a lack of understanding of science and medicine. Whatever the reason, in recent years I see more instances where vague health and environmental concerns seem to be trumping well-documented and real concerns about insect-vectored disease.

In Santa Fe, citizen pressure in recent years has led to schools and the city replacing effective conventional pesticides with generally untested, organic alternatives. One specific consequence of this approach is that city workers are being encouraged to use diatomaceous earth for control of Xenopsylla cheopsis, oriental rat flea, in prairie dog burrows. In a cursory review of the literature I could find no information to justify use of diatomaceous earth for flea control in prairie dog burrows. I was, however, able to quickly find peer-reviewed research on the effectiveness of field applications to prairie dog burrows of several other insecticides including carbaryl, DDVP, permethrin, deltamethrin, and pyriproxifen.

While it can be argued that none of these products provide an ideal, long-lasting or inexpensive solution to plague-bearing fleas, they do provide significant, quick control of fleas. They can also rapidly prevent or eliminate plague outbreaks in prairie dog towns. And at least some of these tested products should be acceptable to the staunchest pesticide critics. Pyriproxifen, in particular, is a low toxicity insect growth regulator that has shown excellent flea control in prairie dog burrows with minimal ecological disruption. Highly specific oral vaccines for prairie dogs are also being tested with promise for providing a longer-term solution to plague outbreaks.

On the other hand, my own work several years ago with cat fleas showed that although diatomaceous earth can control fleas under dry laboratory conditions, the addition of moisture to treated soil quickly renders treatments ineffective for control of adult and larval fleas. This casts serious doubt on the effectiveness of field applications of diatomaceous earth dust into damp underground burrows. At the very least it points out the need for field testing before recommending such treatments.

So why would a respectable community persist in requiring an untested, most-likely ineffective pesticide to control plague-bearing fleas? In this case it seems to be because anti-pesticide advocates, armed with little more than an easily-transmitted fear of technology, are able to persuade policy makers that "natural" is always better and safer. The same strategy is being used in my community to spread fear about the responsible, professional use of mosquito spray campaigns in areas of high West Nile virus risk. The big problem here is that untested recommendations are being taken seriously by government and public health.

It is one thing to choose to use untested home recipes in a backyard garden, where the worst that can happen is for the gardener to lose a few of his or her own plants. It's another thing to pressure communities to stop using proven pest control technology against pests that threaten community health. It make sense that before a community switches from a proven technology, advocates should provide (1) proof that the current technology poses an environmental or health cost that exceeds the value of the benefits provided, and (2) evidence that alternatives are both safer and equally effective as the current technology.

Decision-makers at the school, local and state level need to understand both the science and the stakes involved before restricting the kinds of pesticides that can be used by pest management professionals. This is what I believe is wrong with the growing crop of local ordinances banning municipal governments from using certain classes of pesticides in parks and schools and other public places.

You will get little argument from me that pesticides pose their own share of unique environmental and health challenges, but the problem is often less than the public is led to believe. And in many cases, the negative impacts of pesticides can be blunted by keeping them in the hands of professionals and using them in the context of a well thought-out IPM program. Our ability to control pests quickly at reasonable cost, often with a high degree of selectivity and environmental compatibility, means that pesticides will continue to be a valuable part of pest control in the foreseeable future.

I do not live in Santa Fe, and cannot speak to all the issues and circumstances of their plague management program there. But if I were a parent with a child in school next to a prairie dog town with a known plague outbreak, I know I would want a control option that had been tested and shown effective.