Friday, August 5, 2016

Comparing dusts for bed bug control

For several years PMPs have known that dusts can be useful tools in the management of bed bugs, but a new paper in the Journal of Economic Entomology by Narinderpal Singh and colleagues at Rutgers University shows just how powerful they can be.

Singh et al. used four different lab assays and two strains of bed bugs to probe the efficacy of eight insecticide dusts.  Each assay showed a different aspect of how these dusts perform.  Together, I think, they do a pretty good job of evaluating how you can reasonably expect these products to perform in the real world.

Four experimental assays used to study the toxicity of
various dusts and predict their effectiveness in the field.
Clockwise from upper left (1) brief exposure assay, (2)
choice assay, (3) assay where CimeXa-treated bugs are
allowed to mingle with untreated bugs, and (4) continual
exposure assay with treated paper . (Singh et al. 2015,
J. Econ. Entomol.)
One of the problems with doing lab assays is that they can be highly unrealistic.  Sure, you can put an insect on a treated surface and watch them until they die (a continuous exposure assay).  Certainly this kind of assay can tell you whether there is potential for a product to work; but in a customer's home do your bed bugs have nothing better to do but sit on the insecticides you put out?  Probably not.

More often than not in the real world, insects run quickly across an insecticide barrier and then spend most of their time resting on untreated surfaces. Insecticide exposure may be only a matter of seconds. At other times, insects that move back to a treated harborage may be able to sense when they are on insecticide residues.  They may then choose to move to a clean spot that has not been sprayed or dusted (a sign of repellency).  Continuous exposure assays may overestimate the effectiveness of insecticide applications, especially when applications do not reach key harborage areas, or when residues are repellent to the pest.

On the flip side, insects may inadvertently pick up insecticide residue from a treated surface and carry that insecticide on their cuticle back to a harborage area. When this occurs they may transfer it via contact to other bed bugs clustered in the same harborage.  Failure to account for this in lab assays might end up underestimating the effectiveness of your treatment.  

Singh and colleagues tried to account for all of these possibilities in their research. One assay required the bugs to sit on treated paper for the length of the study.  A second assay had the bed bugs walk across a treated one-inch barrier.  And a third test gave the bugs the choice to visit and rest on either dust-treated or untreated surfaces.
Bed bug dusts included in the trial were Tempo, DeltaDust, Cynoff, Pyganic, EcoPCO D.X, Alpine, MotherEarth, and CimeXa. 

As you might expect, all products killed bed bugs when they sat continuously on the treated surfaces. After five days there was 100% mortality for all bed bugs in the treated dishes. When bed bugs were allowed to choose freely to rest on either treated and untreated surfaces, CimeXa and Tempo gave 80-95% control after one day; however after 10 days MotherEarth (diatomaceous earth) and Cynoff were close behind.  

The clear champion of the toughest test, the brief exposure test, was CimeXa Dust. CimeXa provided 95-100% mortality (at 1 and 10 days after exposure) to bed bugs crossing a one inch barrier of the dust.  Tempo was the next most effective product in the brief exposure trial, providing 40-60% mortality against the two bed bug strains. This ability to kill bed bugs with very short contact can be a game changer. It suggests that CimeXa may be capable of providing decent barrier protection on bed and furniture legs, in dressers or even along door thresholds (though unprotected deposits will likely be quickly rubbed or swept away). 

Singh and his team then went on to see whether CimeXa might also have the ability to transfer from exposed to unexposed bed bugs. It did. Clean bed bugs, that had not been previously exposed to CimeXa, when placed with CimeXa-treated bugs also had significantly higher (80-100%) mortality after 10 days compared to untreated controls.

Singh's work backs up previous work done by Mike Potter's lab in Kentucky.  Potter's group found that CimeXa was more effective than liquid Temprid residues against resistant bed bug strains in continuous exposure assays. He also found that as a stand alone treatment in infested apartments it provided rapid and marked control, superior to diatomaceous earth, and similar to that provided by the top liquid insecticide sprays. 

What these studies tell me is that insecticide dusts should definitely be part of your bed bug control program, especially in accounts with insecticide resistant bed bugs.  Silica aerogel, the active ingredient in CimeXa, performed better than the other commonly used desiccant (MotherEarth, i.e., diatomaceous earth), and even out performed the other pyrethroid dusts.  It should be noted, however, in settings where harborages can be fully dusted, these other products may still provide good control. And laboratory tests cannot fully duplicate what happens in the field--your real world accounts.

But my real reason to single out this study is that it provides a true low-risk option for bed bug control.  Because the mode of action of desiccant dusts is based on abrading the cuticle of the insect, and not on any mechanism that would potentially affect human health, it's a no-brainer to make these products a mainstay of your dust arsenal.  Used inside furniture, behind drawers and baseboards, in cracks and crevices of bed frames, these products make excellent, safe to use, treatments. Even if heat treatment is your tactic of choice, insecticide dusts can provide a long-term supplemental treatment to kill any bed bugs that might re-infest an apartment, hotel room or other bed room.

If dusts are not an important part of your chemical or heat treatment protocols, you may be missing out on a relatively economical, effective and safe option to improve your success rate against these adaptable and tough-to-kill pests.  


Monday, August 1, 2016

Zika the real deal for Texas PMP

More than 1600 cases of Zika have been reported in the U.S. so far, but until last week all of these had been in travelers--people who caught the virus somewhere else and brought it here.  As of last week, however, the picture is changing.  Last week four cases among people who had not traveled outside of their town were reported from north Miami in south Florida.  In an alarming development for Miamians this morning, 10 new locally acquired cases were reported today, likely signalling the first home grown epidemic of Zika infection in the U.S. All cases so far have been restricted to the north Miami neighborhood of Wynwood.

Jackie Thornton's Zika rash appeared about ten
days after he became infected.  It itched like
measles, he said.
Could this happen in Texas, or other states?  Absolutely.

When Jackie Thornton volunteered at his church to go on  a summer mission trip to the island of Dominica in the eastern Caribbean, the last thing on his mind was Zika virus.  Jackie is the owner of Alvin Pest Control in Alvin, TX, and long-time PMP.  "I was more worried about bed bugs," he admitted.

But when he arrived on Dominica (pronounced doe men NEE kah), someone mentioned that Zika and Chikungunya cases had been reported on the island.

Life in Dominica is a world away from a Texas suburban town like Alvin. Nighttime temperatures this time of year typically hover around 85 degrees F. Not so hot that air conditioning is a necessity, and besides few could afford such luxury.  The home where Jackie and his team slept was typical for the area.  Keeping cool at night depended on a nice breeze coming through one of the unscreened windows.

Knowing that Zika was around, and being an Associate Certified Entomologist, Jackie got interested in what was flying in his window.  Each night he would catch a few mosquitoes that looked more like house mosquitoes than the yellow fever mosquito, believed to be the primary Zika carrier.  Maybe things wouldn't be that bad after all.

But he got worried again about Zika about a week after arriving. "I developed a low grade headache that seemed to be behind my eyes," he said.  "It was worse when I woke up and lessened as the day progressed."  Eventually four others on his team also got sick, but not enough to keep any of them from working their shifts at vacation Bible school and helping repair homes damaged by Hurricane Erica.

After returning to Texas on July 24 the headaches persisted.  Two days later he woke up with joint pain in his hands, elbows, knees and feet, he said.  The next day, about a week and a half after the first headaches started, he went to the doctor for his joint pain.  On the way to the clinic, an itchy rash broke out "head to toe".  It was like having measles, he said.

Red itchy eyes was the only classic symptom of Zika that Jackie didn't have.  But he says he saw plenty of folks with red eyes while he was there.

Today, two and a half weeks after the first headache, he still itches, but the headache and joint pain is not as bad.  In typical PMP trouper fashion Jackie said he never felt like he had to be bedridden, but that it's been an "uncomfortable nuisance".  Indeed Jackie worked at his pest control company all last week, albeit while wearing long sleeves and lots of insect repellent to reduce the chance of starting his own Alvin, TX epidemic (an important community health precaution for any returning traveler, sick or not).

He now says, with a little bit of irony, "I may be the first U.S. PMP to come down with Zika."

I tell Jackie's story to remind us all that the risk from Zika virus is real... especially for anyone traveling to an area where Zika infections are active.

To see a map showing cities at highest risk for Zika this summer, click  http://www.cbsnews.com/news/zika-virus-mosquitoes-us-cities-most-at-risk/

To learn more about "Zika precautions for Women", see http://citybugs.tamu.edu/files/2016/06/Ento-053-Zika-Precautions-for-Women.pdf  and "What Texans Need to Know About Zika" see http://citybugs.tamu.edu/files/2016/06/ENTO-052-What-Texans-Need-to-Know-about-Zika.pdf




Tuesday, July 26, 2016

The OTHER clothes moths

This week I received reports of two insects that are sometimes confused with clothes moths or pantry pests. The brown house moth, Hofmannophila pseudospretella, is a common moth pest in the United Kingdom, but much less so in the U.S.  In a paper written in the 1950s, one researcher noted that it probably occurred in small numbers in every private home in Britain, and that few stores or warehouses in Britain were without at least a small population.  The brown house moth specimens I saw on a sticky card this week, however, were the first ones of this moth I've ever encountered in Texas.

Brown house moth on sticky card.  Head to tail, these  
small moths are between 4 and 7 mm long. 
The BHM could easily be mistaken for Indian meal moth based on size.  But wing patterns are different.  Wings are bronzy brown with dark flecks on the forewings.  It is a slow grower with about one generation per year, but capable of becoming abundant under the right conditions.  It appears to require high relative humidity of 80% or more, perhaps accounting for the fact that it is not so common in climate controlled homes here in the U.S.

The diet of BHM is varied, ranging from cereal products to wool and dead insects.  It is readily capable of developing in wheat germ, whole wheat, damaged beans, macaroni, fish meal.  When yeasts were present, it could also develop on feathers and flannel wool.

Woodroofe, a British entomologist who studied the moth over 60 years ago, felt that the importance of this moth in homes was more as a fabric pest than a pest of stored grains.  If this moth is found in a home the most likely source of infestation would likely be in a basement or garage with higher humidity.  Check for pet food, woolen clothing, furs or feathers being stored under damp conditions. Also look in light fixtures with dead insect accumulations, or old bird nests in chimneys or soffits. Sticky traps may be useful in catching some of the moths for identification. If the suspected site of infestation is in an inaccessible void, consider dusting the area with Cimexa or Tri-Die, or other dessicant dust. If given a chance, these little moths can become very abundant.

Household casebearer cases collected from a
home in east Texas.  Note the caterpillar head
emerging from the case on the far right, and the
flattened cases widest in the middle. Photo by
Randy Reeves.
Another interesting insect that I encounter more frequently in samples is the plaster bagworm or household casebearer, Phereoeca uterella.  A close cousin to the clothes moth, household casebearers live inside a spindle-shaped silken case.  University of Florida provides a nice article on this moth, which feeds largely on spider webs.  If that sounds like an odd thing to eat, remember that spider webs are a type of proteinaceous silk, and probably just as nourishing to a clothes moth as silk clothing made from silkworm silk.

Like the BHM, household casebearers thrive in higher humidity conditions.  The cases, like a silk purse, are usually flat in later life stages.  It is most likely to be confused with the casemaking clothes moth, a more frequently encountered pest; but the spindle shape, and flattened case are distinctive.  According to the Florida fact sheet these cases may be found "under spiderwebs, in bathrooms, bedrooms and garages... on wool rugs and wool carpets, hanging on curtains, or underneath buildings, hanging from subflooring, joists, sills and foundations; on the exterior of buildings in shaded places, under farm sheds, under lawn furniture, on stored farm machinery and on tree trunks."  Besides spider silk, the caterpillars have been observed to feed on wool, human hair and dead insects.

I've not heard of any infestations severe enough to require insecticide use with household casebearer. In most cases they seem to be a curiosity more than anything; but a vacuum cleaner to get rid of spider webs would be a good idea to make sure that your casebearers don't decide to nosh on something a little more valuable in the home.

Friday, July 22, 2016

Webinar on mosquito control Monday

Drs. Grayson Brown (top) and
Nicky Gallagher are featured
speakers at next week's Webinar.
Just a short post today about a webinar on mosquito control for PMPs on Monday, July 25.  It's sponsored by PCT magazine and will be held at 1 pm CDT (that's Texas time).  Free signup is available here.  Speakers are Drs. Nicky Gallagher with Syngenta, and Grayson Brown with the University of Kentucky, both excellent speakers and knowledgable in mosquito control technology.

My reason for plugging this particular webinar is its timeliness, in combination with the surprising growth of the mosquito control portion of the pest control industry over the past couple of years.  I was shocked to learn at this spring's National Conference on Urban Entomology that mosquitoes are now big player Orkin's #1 annual residential service offering.  And I was amazed to hear that Arrow Exterminating's mosquito annual revenue went from $39,000 in 2004 to $6.5 million in 2015,with mosquito control customers among their most loyal customers.

So if you service residential accounts and are not yet providing mosquito control services, you might want to check out this offering. All you need is a computer and connection to the Internet. What could be an easier way to grow your business?


Thursday, July 14, 2016

West Nile virus risk high in north Texas

Residual insecticides applied via backpack mist blower
sprayer can provide 3-4 weeks of mosquito control  during
times of peak mosquito activity.
July and August are typically the months of highest risk from west Nile virus, and true to form the past few weeks Dallas and Tarrant counties have seen a major increase in not only mosquitoes themselves, but infections within the mosquitoes.

After the major outbreak of WNV in 2012 in north Texas, some health officials made a decision to use something called the Vector Index (VI) as a form of threshold to ramp up mosquito control efforts.  Based on when human cases started to soar in 2012, and on suggestion from the CDC, a VI of 0.5 was determined to be a good threshold to consider going from ground based spray efforts to aerial spraying.

Two weeks ago the VI exceeded that threshold in both Dallas and Tarrant counties.  Both counties publish very interesting reports, available to the public, that include graphs to show  the latest mosquito counts and VI numbers.  To see the trends in Dallas and Fort Worth areas, check out the graphs below.  In the first graph, the Vector Index is the heavy red line.  Last week it exceeded the 0.50 threshold, although there was a drop this week. Note also the numbers of mosquitoes this summer (red bars) compared to average trap catches in 2012 (for the past four weeks, higher than 2012 averages shown by the blue bars). In Tarrant County (Fort Worth and surrounding communities) the VI (green line with triangle points) was likewise up last week, over 0.60 (new data is not yet published).  Note that the most recent 1-2 data points are preliminary estimates and may change as all the data is calculated.


These data are why there is discussion about aerial spraying this week.  In 2012 the number of human cases of WNV in Dallas county reached almost 400, and there were 19 deaths attributed to WNV. Serious business. Last week DCHHS issued a health advisory to the public, and this week the Dallas County commissioners voted to authorize the health department to prepare for possible aerial spray operations should conditions warrant.  

Where does all this leave the PMP who provides residential mosquito control service?  Municipal mosquito spraying actually complements, rather than replaces, mosquito control work on the ground done by professionals.  Aerial spraying generally provides better coverage of the tree canopy where WNV carrying mosquitoes (Culex quinquefasciatus in north Texas) live and mostly feed. Municipal truck mounted ULV sprays provide some control of lower level mosquitoes (Aedes mosquitoes that potentially transmit Zika and dengue fever, among other diseases), but they typically do not provide high level control in backyards or areas protected from spray coverage.  In that sense, the best control of Aedes mosquitoes is accomplished by your boots on the ground, looking for and treating or eliminating mosquito breeding sites, treating doorways, and treating shrubbery and other mosquito resting sites that are difficult to reach from the street.

As you and your technicians visit mosquito control customers this summer, keep in mind that you carry some of the most effective tools in the war against mosquitoes.  This summer, with Zika fears and WNV threats, what you do is more important than ever.

New Zika Resources for the Public

Hiring a professional is one way that the public
can help reduce mosquito biting risk around the home.
I was asked a few weeks ago if the collective "we" (meaning the whole state of Texas) were going to be ready for Zika.  My answer was a cautious, "I think so".  If we're not, it at least it won't be for lack of trying.

Zika is a much different disease than West Nile virus. It has different vectors, mosquitoes that prefer to feed on humans over any other animal (unlike WNV mosquitoes, which mostly feed on birds).  It is also very difficult to detect in wild mosquito populations.  The mosquitoes are more difficult to control with spray trucks, so responding to local cases is going to depend more on public cooperation.

Unlike WNV, Zika is virtually undetectable in the blood supply, as there is no approved way to screen newly donated blood to see whether it has the Zika virus in it. If Zika does make it into the country, it will also potentially affects more people.  Any family with members of childbearing age will need to be on high alert. The CDC recently released its response plan for Zika.  It's assumptions are sobering:
  • Travel-associated and sexually-transmitted cases will continue to occur and are likely to increase. (we just don't know how much!)
  • Local transmission (spread) of Zika virus in US territories and affiliated Pacific Island countries is ongoing.
  • Neither vaccines nor proven clinical treatments are expected to be available to treat or prevent Zika virus infections before local transmission begins nationwide.
  • The ability for mosquito control efforts to reduce infection risks may be limited, as has been the case with similar viruses, such as dengue and chikungunya.
The entomology department, and especially my colleague Extension entomologist Dr. Sonja Swiger, has been busy in recent weeks trying to figure out how to best arm everyone with the best information on how to prepare for the "Summer of Zika".

As part of the effort, some new fact sheets from Texas A&M AgriLife Extension are now available to answer some of the more common Zika questions. These may be useful for your customers who are worried about mosquitoes and how to protect themselves.  The DIY fact sheet talks about the different consumer-oriented treatment options, including hiring a professional.

Wednesday, June 29, 2016

The Exam Experience

It's been a long time since I've had to take an exam that meant anything. This morning, however, as I sat waiting to be processed to take my pesticide applicator's exam I felt a familiar, almost forgotten feeling. Test anxiety. Can I do this? Sweaty palms. What if I don't pass?

After all, I worry, I've been doing pest control and pesticide application for more years than I care to count. If I flub the exam, my research technician, who is taking the exam today too, will know. How embarrassing would that be? I'm supposed to know this stuff. I teach CEU classes for goodness sake.

So why after 27 years as an Extension specialist am I taking my applicator's exam? Well truth is that I did have a TDA non-commercial applicator's license for most of these years; but several years ago, amidst the busy-ness of life, I let my license expire. Then I discovered that it was kind of nice not having a license.  I go to plenty of CEU classes every year, so the education requirement wasn't the problem. It was just the minor but annoying process of keeping track of certificates, and sending in renewal forms (and money) every year. Also, my job doesn't really require that I maintain a license.  When doing research, all the compounds I've worked with recently are already registered, and so don't need a Research and Demonstration license, which TDA requires for researchers working with unregistered (numbered) compounds. When I do put out insecticides for trials, I have worked with other licensed applicators, so it didn't seem necessary to retest and re-establish my license (in Texas, folks can work under the supervision of non-commercial certified applicators).

So why go through the trouble of re-upping now? I guess it felt like the right thing to do. I don't like relying on other people for my licensing credentials. And it didn't seem right for me to be an instructor of pesticide applicators and not have a license myself. And the part of me wanted to remember what it was like to go through the study manuals and take the test like a raw recruit.

So this morning I sat in the sixth floor, PSI Services exam office of the Empire Central Building off of Stemmon's Freeway in Dallas. Even though the employees there were very nice, a kind of static anxiety hovered over the room and the testing center.  PSI has provided testing services for TDA since June 2014, and serves other industries as well.  The nervous young man next to me was sitting for his electrician journeyman's license. The test takers I saw were not a talkative bunch.  Sort of like sprinters at the Olympics, focused inward, centered... thinking "help me, God."

So for me the anticipation for me was much worse than the test. The test itself would be challenging without study or good familiarity with pesticides and the law.  It's definitely not a "no-brainer". But once the clock starts ticking and the questions start flashing I knew I could do this. I was signed up for three exams: General Standards, Landscape Maintenance, and Demonstration and Research.

The testing room was silent with a half dozen test takers sitting quietly, focused on their screens.  I found the quiet relaxing, but also noticed that the testing center provides ear plugs for those who want them.  I guess they are needed by some for our protection against "sighers" or "groaners" in the room.  Everything, by the way, is under video surveillance--so security is high.

If you haven't taken a "final" in awhile, and the thought of a test scares you, you're not alone.  I think the longer it's been since high school or college, the scarier the thought of sitting for an exam. This is normal, especially for us adults who have a lot of pride on the line. So here is my personal set of advice for pesticide exam test takers:
  • Relax.  If you've studied, you've retained a lot more stuff than you probably realize.  It's all in there; you just have to relax and let it flow.
  • Read the instruction screen explaining all the available buttons.  There is some interesting stuff there that can help you be a better test taker. 
  • Take the test one question at a time.  If you come to a question you're not sure about, the PSI test allows you to mark it.  Put the answer you think is right, then tag the question with the Mark button.  When you get to the end of the test, you can use the GO TO button to go back and view all the questions that you've marked.  It's a nice testing feature, and it's also amazing how those questions sometimes clarify themselves after you've had a few minutes to reflect and think about something else.
  • Read all the choices. Carefully.  Eliminate the obviously wrong ones (called "distractors" in test writing jargon), and focus on the remaining choices.  The tests, by the way, are all multiple choice with only 3-4 choices.
         BTW, another nice feature of the exam is that you can Comment on questions.  If you think a question is poorly worded or unclear, hit the comment button and explain why you think the question isn't fair or how it could be improved.  As you write, you may actually develop a clearer idea of what the best answer is.  I did this on several questions.  I didn't know if anyone would actually read my comments, but at least I felt a lot better getting it off my chest.
  • Don't be surprised to see math problems on the exams.  If math is not your strong suite, be sure to work and rework the problems in the AgriLife Pesticide Applicator License Exam Study Materials ahead of time.  Learn the formula "Gal/Min=((Gal/Acre) x Speed x nozzle width)/5940".  And learn how to convert milliliters and fluid ounces to gallons, and how to estimate square feet and convert to acres. Trust me, you'll need this.  The study materials I would say are essential.  In my testing center the staff did not allow writing tools (I guess so you can't write down questions), though they said we could have scratch paper if requested...???  
  • When you get to the end of the test hit GO TO all your marked questions.  Review them, choose your final answer, and Unmark them one by one.  If you have time, GO TO all test questions.  Quickly scan through all the question and reassure yourself you did a decent job. 
  • Don't leave any question unanswered. If you do, you will get the question wrong.  If you have to guess at least you've got a one-in-three chance or better of getting the answer right. At the top of the test screen it will tell you how many questions are unanswered.  Check it to make sure you didn't forget to answer a question.
  • Once you finish your test, you'll fill out a short feedback form and then receive your results on the screen.  No waiting for days or weeks to find out how you did.  Passing score is 70%, an achievable score for most people who study. The software also shows you how you performed on the various kinds of questions (calibration, legal, pests, etc.), but this will be the only time you see that data, so look at it closely and see where you went wrong and right (especially if you didn't pass, this will tell you what to study).  As I left the Center I was given a printout showing my final score for the three tests I took (passed them all!), but this sheet did not show the score breakdown.
I communicated with Allison Cuellar of TDA about the Commenting feature of the exams.  She said that staff at TDA do have access to the comments, but most of the comments they see are the ones sent via email directly to their offices. She seemed genuinely interested in feedback about the testing process.  So if you feel moved to provide positive or constructive feedback about your exam experience, contact Allison Cuellar (on the Structural Pest Control Service side) or Perry Cervantes (on the Ag side).

If you or someone in your company is preparing for the exam, being a little nervous is normal (as I was reminded this morning). But for most of us the anticipation is worse than the event. As for me, I had so much fun this morning, I'm thinking that maybe I need to go next for the Structural Pest Control non-commercial applicators license. I wonder if there's a loyal customer discount?