Entomology in Knoxville: Bed bugs, Ants and Others

Bed bugs remained one of the most frequent subjects of
new research reports at the annual ESA meetings.

Continuing my earlier report on goings on at the Entomological Society of America's annual conference...

Total release foggers

In addition to health-related papers, urban entomology sessions covered many practical aspects of pest control. North Carolina State's Coby Schal, one of the top guns in urban entomology, reported on the first field study of total release foggers (bug bombs) for cockroach control. You may have heard of a parallel study done this year by Susan Jones at Ohio State University. She conducted a set of laboratory experiments with total release foggers (TRFs) against bed bugs, the results of which she recently spoke about on PCT's multimedia website.  She found that field collected strains of bed bugs were essentially immune to three common over-the-counter pyrethroid TRFs, and that even highly pesticide susceptible lab strains were largely able to survive when give basic cover as simple as a piece of paper.

Schal pointed out that TRFs are frequently misused by the public, causing four to eight home explosions per year in New York City alone. His lab looked at the impact of two TRFs on both naturally occurring cockroach populations and on "sentinel" cockroaches (lab reared cockroaches contained in open, escape-proof containers) placed in multiple locations in the treated apartments.  While the foggers did kill the pesticide-susceptible, lab-reared cockroaches, they provided little to no control of wild cockroaches (with 200-fold resistance to pyrethroids). In some treated apartments wild cockroach populations actually increased during the test. It will be interesting to see if the U.S. reevaluates registrations for TRFs in the next few years given the safety issues and dismal data coming out of university labs around the country concerning their use.

Bed bug repellents?

Conventional wisdom suggests that there are no repellents that can be sprayed on the skin to prevent bed bugs from taking a blood meal. However Changlu Wang, of Rutgers University, says "not so fast". He looked at the problem from a different angle, pointing out that there are two possible uses for repellents. Besides the traditional use of repellents applied to the skin to keep insects from biting, repellents may also be used off-host to keep bed bugs from climbing onto beds, suitcases, or other inanimate objects.  

Wang and colleagues looked at this second use. They chose several repellents including DEET, permethrin, picaridin, isolongifolenone, and other potential repellents. Although several products showed repellency, DEET was the overall winner. At 10% and 25% concentration, bed bugs were repelled from Climbup Interceptors (guarding a table with a CO2 lure) for 9 hours and 2 weeks, respectively.  While the practical use of repellents in the real world needs more experimentation, this is useful information.  DEET could conceivably be used as a repellent on some shoes (it does dissolve some plastics, so user beware) or booties to reduce the risk of hitchhiking bed bugs being picked up by technicians (or researchers!).  I expect that eventually bed bug control will be supplemented by the use of repellents as a quarantine tool or for "push-pull" tactics to get bed bugs to go where we want them to go (say, to treated harborages).  Wang cautioned that bed bug behavior may be different around a host where attraction to a live host may overcome the repellent effects he saw.

Standardized bed bug testing

One of the biggest applied bed bug research challenges today is how to standardize insecticide testing. It is common knowledge that results for nearly any insecticide can be fairly easily manipulated by selecting the right strains and using protocols that show more or less bed bug mortality. The challenge is to find protocols that are more or less predictive of a product's performance in the field. Mark Feldlaufer, with the U.S. Department of Agriculture/ARS, reported on progress being made to verify fair, standardized testing methods. This research will support the EPA in its efforts to develop standardized test protocols.

He noted that there are currently 318 insecticide formulations registered for bed bug control, 90% of which include pyrethroid insecticides. He noted that not all pyrethroids are equal, and cited as an example transfluthrin (currently unregistered in the U.S.). Transfluthrin has a high vapor pressure, which most PMP realize is likely to provide better control in difficult to reach areas like voids and crevices.  He also noted that a new combination product (metofluthrin plus clothianidin) is in the insecticide pipeline for bed bugs.

Among the USDA findings were that male and female bed bugs are approximately equal in insecticide susceptibility. This finding could allow researchers to use only one sex in tests (avoiding mortality problems with  traumatic insemination by males on females) rather than the 50/50 ratio currently recommended. Also, test results did not significantly change after seven days, suggesting that tests could be terminated after this time.

How to classify and handle insecticide exposed bed bugs is an issue for anyone who has conducted bed bug trials. USDA classified insecticide-exposed bed bugs as alive (A), dead (D), or morbid/moribund (M/M).  The latter group consisted of bed bugs that were not completely dead, but did not behave normally or respond normally to probing. They found that if placed on untreated surfaces after exposure, between 7 and 77% of the moribund bed bugs recovered compared to 100% mortality of M/M bed bugs left on treated surfaces. This information should be useful in helping EPA decide how to require M/M to be handled. It is fascinating, and alarming, how slight differences in the way test subjects are handled and classified can dramatically influence test results.

Other interesting reports

• Susan Jones (Ohio State) reported positive results controlling bed bugs with a new neem formulation (CIRKIL), which, PCT magazine reports, will be available in the U.S. this fall.
• Joe DeMark (Dow AgroScience) reported on field testing of a new Recruit AG above ground bait station for termites. This product will carry 254 grams (one pound) of bait matrix per station. Of nine sites on which it was tested, all termite colonies were determined to be eliminated within four months.
• Mike Rust (University of California, Riverside) reported on studies with the Turkestan cockroach, a species spreading throughout the southwestern states (CA to TX). They found that the Turkestan cockroach is better adapted to dry situations than the oriental cockroach, especially at higher temperatures, and may be expected to displace Oriental cockroaches in hot, dry situations.
• Karen Vail (University of Tennessee) tested insecticides on odorous house ant.  She found fipronil provided slightly superior control to Talstar, and she observed 2-4 weeks control with the new Arilon insecticide (indoxacarb).  She also found that sprays applied with backpack sprayers targeting ant trails and structural guidelines (gutters, ledges, etc.) were as effective in controlling ants as high-volume power sprays.
• Dini Miller (Virginia Tech) reported that a 2011 National Apartment Association survey found bed bugs as the number one concern among apartment owners (beating out concerns over property taxes). Besides control expenses, additional costs due to bed bugs include carpet wraps (to contain bed bugs on infested carpets during removal), need for heavier duty paint (to better cover fecal spots on walls), delays in rental payments, increased evictions, more abuse from residents, and loss of reputation in the community. Twenty states now have laws addressing responsibility for treatment costs for bed bugs.
• In a study reported in the May 2012 issue of Infection Control and Hospital Epidemiology, researchers from Nebraska tested the effectiveness of chlorine dioxide gas as a fumigant for bed bugs. You may remember chlorine dioxide as the gas used in US governmental facilities after the 2001 anthrax attacks. It proved to penetrate cracks and crevices well and kill bed bugs effectively. Chlorine dioxide is used in hospitals for germ control and might find a niche use for battling bed bug infestations in medical settings.
• Margie Lehnert, Clemson University, described a simple but (I thought) ingenious technique for studying bed bug population dynamics. She used nylon stockings inside a HEPA vacuum hose attachment to collect small bed bug aggregations in infested apartments. Once an aggregation is sucked up, the stocking can be removed and tied off and returned to the lab for counting. In this way Lehnert has developed a powerful tool to study population patterns and, perhaps, better infer reasons for bed bug dispersal away from beds. 
• Chris Keefer, Texas A&M University, presented some of the first data I've seen on the invasive, and difficult to control, dark rover ant. This ant is thought to have entered the U.S. from Argentina in Louisiana in 1978. It is now common through most of the southern states.  Keefer, after some difficulty,  has figured out how to colonize these ants in the lab. Using his lab ants he was able to compare the effectiveness of three baits: Terro PCO gel (98% control), Advance Ant Gel (88% control) and Advance Granular Bait (large granules) (58.81% control). The best residual insecticide treatments he found during an outdoor field trial were Demand CS and Temprid, which gave 84% and 82% control, respectively. This confirms what I've heard some PMPs say about effective treatments for these ants.

Of course much more went on in Knoxville than I can report (curse those concurrent sessions!). If I've done no more than convey how exhausting it is to sit for 50 paper sessions (my count), I've given you a taste of what it's like to be there.  Next year's meetings are scheduled to be in Austin, TX, so I encourage some of my Texas colleagues to consider attending. This year the ESA planned a special event for PMPs, including an ACE prep class. Stay tuned for PMP programs for 2013.

Swarming rover ants, Batman!

Dallas, TX. If you've been getting higher numbers of calls than normal about swarming insects in customers' homes recently, the culprit may be rover ants.

Last month I posted an entry about two new ant pests for Texas, in which I discussed the true identity of a tiny rover ant that has been growing in importance throughout Texas. Since that post, the identity of the rover ant has been confirmed as the dark rover ant, Brachymyrmex patagonicus. This ant is believed to be a relatively new immigrant from South America, and is one of the latest in a string of exotic pests that seem to have found themselves a new home in the U.S.

The swarmers are similar in size to a Pharoah ant swarmer, about 3/16 inch (4 mm) long and brown in color. Like the workers, they have a 9-segmented antenna and single node (pedicel) between the thorax and gaster. This is the first year I have had so many ant swarmers submitted in mid-summer, and the most likely explanation seems to be the spread of this new ant.

Rover ant swarmers seem to emerge at night and hover weakly around lighted rooms. As with other ant swarmers, there is little that can be done to prevent the swarms, short of finding and sealing the small holes or cracks from which they emerge (an unlikely task). Fortunately, swarmer emergence is relatively short-lived, usually a few days to a week, and are at worst a minor nuisance. The worker ants can be more troublesome because of their persistence in returning to a variety of indoor sites.

Rover ants have been difficult for the industry to control. Janis Reed, of ABC Pest and Termite in Austin, presented her observations of the best control methods for this ant at the recent National Conference of Urban Entomology meetings in Tulsa, OK. She considers rover ants very difficult to control, and a pest for which there is yet no magic bullet.

Technicians at ABC Pest and Termite rely on a combination of baits and sprays. Standard ant sprays reportedly provide little, or inconsistent, control of these ants; however Reed reports that combination sprays, containing both a pyrethroid and a neonicotinoid insecticide (such as the new Transport Insecticide, containing both bifenthrin and acetamiprid), seem to provide improved control. Gel and liquid baits may provide temporary suppression, but continued inspections and baiting are needed to keep ants from returning.

Rover ants are honeydew feeders, often milking scale insects, aphids and other sap-feeding insects for their sweet secretions. Rover ants are even reported to feed off the secretions of subterranean aphids feeding on plant A good IPM approach, therefore, would be to treat nearby trees to eliminate sap feeding insects, in addition to using baits and barrier sprays on the outside of the building. This approach has a better chance of providing long-term ant suppression than either of these tactics used alone.

Two New Ants for Texas: What They Can Teach Us

A version of this article appears the August 2008 issue of Texas Pest Control Association Magazine

by Mike Merchant and Jason Meyers

Just when you think you’ve got the technical side of the pest control business all figured out, things change. New pests emerge, old ones develop bad habits, and familiar pests get harder to control. Texas pests have a way of keeping things interesting. Just when you think you know all the bad characters, new ones show up. In this article we’d like to look at the emergence of two relatively new ant pests and consider what lessons we can take away from our experiences.

Crazy ants

Certainly one of the biggest pest surprises in recent memory is the crazy rasberry ant, Paratrechina sp. nr. pubens (Hymenoptera: Formicidae: Formicinae). Other published names for this ant include the Caribbean crazy ant, hairy crazy ant, and the brown crazy ant. There has been much confusion about the true identity of this recent Texas invader, discovered in 2002 by Houston pest management professional, Tom Rasberry. Originally it was thought that our Houston area-based, crazy rasberry ant might be one of several species that were distinct from, but closely related to, the other Caribbean crazy ant, Paratrechina pubens, established for many years in Florida. The lack of similar reports of densities in Florida also placed into question the validity of the Texas and Florida populations being the same species. However, recent collaborative work using molecular identification suggests that both our Texas and Florida crazy ants came from South America. Whether or not our crazy rasberry ant came from South America, the Caribbean, or an as yet unknown origin, is an important question. The answer could help us prevent further introductions into Texas and other coastal states.

Since the first infestations of the crazy rasberry ant were discovered in Pasadena, TX in 2002, this ant has spread to at least seven known counties along the Texas coastline. Chances are good that there are more undocumented cases of this pest in this part of the state. It’s important that PMPs throughout the state keep alert for this ant.

Crazy ants spread by “budding”, or nest division, rather than the more familiar process of mating flights (like the red imported fire ant). Budding behavior often results in super-colony formation, which, in turn, can produce unusually high foraging populations. Crazy ant nests are often associated with human dwellings and inhabit soil or almost any object on the ground. They move their nests frequently and may infest potted plants, garbage, discarded boxes, and even motor vehicles. This makes it easy for these ants to be unwittingly transported around the state by people. We still don’t know the potential of this ant to spread and thrive in more northern, cooler areas. However, without better quarantine and public education efforts, their spread to new counties will likely continue.

Rover ants

Another ant that has taken PMPs by surprise recently is the so-called rover ant, in the genus Brachymyrmex (Hymenoptera: Formicidae: Formicinae). Brachymyrmex are very small, approaching the size of Pharaoh ants, but generally darker in color. Under magnification, they have only one node between the thorax and abdomen, a small circle of hairs around the anal opening and 9 antennal segments. According to The Common Ant Genera of Texas, a handy field guide to Texas ants published by Texas AgriLife Extension, only two species of Brachymyrmex are considered native to the U.S., and both are found in Texas. The same publication says that these ants are rarely considered pests.

Over approximately the past four years rover ants have been reported as an emerging household pest by PMPs from Dallas to Corpus Christi. At my home (MM) in Plano, TX, this ant has been a nuisance kitchen pest for the past three summers. In contrast to the almost-certainly exotic Caribbean crazy ant, these new rover ant pests were originally assumed to be one of our native species gone bad. But that picture may be changing.

New evidence suggests that sudden emergence of Brachymyrmex as a household pest may actually be the result of invasion by a new species of ant. A South American ant, Brachymyrmex patagonicus, was recently recognized as an emerging household pest in much of the southeastern U.S. (see online paper by MacGown, J. A. J. G. Hill, and M. A. Deyrup. 2007. Florida Entomologist. 90:457-464; at http://www.fcla.edu/FlaEnt/feissues.htm ). Confusing taxonomy and relatively few experts trained to identify these tiny ants are the reasons for slow recognition of this problem. Although no careful collection and analysis of rover ants has yet been undertaken in Texas, patagonicus has been identified from Smith (Tyler, TX) and Val Verde (Del Rio) counties by Dr. Joe MacGown at Mississippi State University.

Should its identity be confirmed, the “dark rover ant” (a name proposed by MacGown et. al) would make an interesting example of how some exotic species can spread very quickly over a wide geographic area. In contrast to the Caribbean or rasberry crazy ant, which has spread over only five counties in approximately the same time period, reports of rover ant problems seemed to appear almost simultaneously from north to south Texas. The reason for this difference is not immediately evident, and may never be known without more basic research into the biology of these two species.

A Lesson to be learned?

The emergence of these two new pests underscores the importance of ongoing urban entomology research, the importance of rapid communications, and the importance of effective training for PMPs. A strong research program is one of our industry’s best tools for quickly recognizing, understanding, and developing solutions for new pests. A rapid communications network is essential for reporting unusual problems to our state experts and for spreading the word about exotic pest threats. Training opportunities, like the Texas A&M winter workshop, the numerous TPCA conferences and industry-sponsored training courses are essential to keep technicians, training directors and owners on the cutting edge of science.

Together, our research, communication and training networks form an infrastructure just as essential to the success of our industry as our highway and road systems are essential to our American way of life. Unless we continue to invest in this infrastructure, through support of university and Extension programs, associations and workshops, this network can not sustain itself. Imagine a working world where new pests arise and become more difficult to control, and where solutions are the product of guesswork. Perhaps that’s the biggest lesson crazy ants and rover ants are trying to teach us.

If you suspect you are having problems with either crazy rasberry ants or dark rover ants, we’d like to know. Send a sample of the suspect ants (up to a dozen, if possible) in a small amount of ethyl or rubbing alcohol to us. Be sure to include the city and county of collection, date collected, your name and phone number or (preferably) email address, and any other information you think important (e.g., whether collected indoors or outdoors, notes on abundance, and whether it was seen as a pest problem by the client).

For crazy ant specimens, mail to: Dr. Jason Meyers, Center for Urban and Structural Entomology, Texas A&M University, MS 2475, College Station, TX 77843-2475

For rover ant specimens, mail to: Dr. Mike Merchant, Texas AgriLife Extension, 17360 Coit Road, Dallas, TX 75252-6599.

Dr. Jason Meyers is a recent graduate from the Department of Entomology, Texas A&M University (jmmeyers@tamu.edu). He can still be reached in College Station at the Center for Urban and Structural Entomology.