[Cover Story] Are You Smarter than a Termite Researcher?

Editor’s note: PCT magazine recently surveyed 10 of the industry’s preeminent experts about all facets of termites and their control: termite biology and behavior, control methods, real-world experiences and more. Following is a question and answer session with university and other researchers from around the country. PCT made efforts to contact several more researchers, so stay tuned for future issues of PCT for additional questions and answers. Readers, if you have a termite question you’d like to have answered by the “best of the best,” e-mail your question to PCT Editor Jodi Dorsch at jdorsch@giemedia.com and we’ll make efforts to get it answered for you. The PCT staff hopes you have as much fun reading this month’s cover story as we did compiling it.

Our experts:

Dr. Gary Bennett, Professor and Urban Center Director, Purdue University

Dr. Ken Brown, Principal Research Entomologist, City
of New Orleans Mosquito and Termite Control Board

Dr. Brian Forschler, Professor, University of Georgia

Ed Freytag, Senior Research Entomologist, The City of New Orleans Mosquito and Termite Control Board

Dr. Roger Gold, Professor and Endowed Chair, Center for Urban and Structural Entomology, Department of Entomology, Texas A&M University

Dr. Gregg Henderson, Paul K. Adams Professor of Urban Entomology, Louisiana State University AgCenter

Dr. Susan Jones, Associate Professor, Ohio State University

Dr. Mike Potter, Professor/Extension Entomologist, University of Kentucky

Dr. Nan-Yao Su, Professor of Entomology, University of Florida

Dr. Barbara L. Thorne, Professor of Entomology, University of Maryland

Is it true that termites were here before the “dinosaur age”?

Dr. Barbara L. Thorne: Dinosaurs evolved during the Triassic period (225+ million years ago) and grew in numbers and species diversity in the Jurassic period. The Cretaceous period (144-65 million years ago) is considered the last portion of the “Age of Dinosaurs.” The earliest known termite fossils are from the early Cretaceous period, but termites probably evolved even earlier because they are already fairly diverse, and show different castes, by the Cretaceous period. In short, the first dinosaurs almost certainly appeared before the first termites, but termites got the last laugh because they persist today while dinosaurs (other than their modern ancestors, birds) disappeared about 65 million years ago.

Speculating on interactions between dinosaurs and termites, the sad truth is that termites likely were a nutritious delicacy in the dinosaur diet. Termites also may have benefited from dinosaurs. Many species of dinosaurs were herbivores, and just as modern termites enjoy the rich resource of a moist, cellulose-rich cow “pie,” dinosaur “pies” probably had similar appeal to Mesozoic period termites.

Do termites drown?
Dr. Gregg Henderson: Termites breathe oxygen through their spiracles. They can’t close off their spiracles to stop movement of air (like some stored product beetles can) but they can stop moving when they are put under water. This is how they survive long durations under water. They simply don’t move and this can go on for at least 15 hours before 50 percent of water-logged termites drown.

Which controls termites more effectively: baits or liquid barrier treatments?
Dr. Roger Gold: Both baits and liquids are effective in termite population management and protecting structures; however, each has advantages and limitations. The best scenario is a combination of both methods when needed. Liquid treatments have the advantage of being relatively fast acting and long lasting (through five years), whereas baits are slower acting, and must be maintained through frequent servicing, but are useful in situations where trenching and drilling are inappropriate.

What’s the simplest answer you can give to a homeowner who asks, “How do I keep termites out of my house?”

Dr. Mike Potter: The best answer is for a homeowner to pay a pest control firm to have the house treated preventively. In addition, minimize termite-conducive conditions such as moisture next to the foundation, wood in contact with soil or mulch, firewood against the house, etc.
 
Why haven’t termites been swarming as much the past few years?
Dr. Susan Jones: Environmental conditions are the key to the termite swarm season. Subterranean termites swarm when there is a specific set of environmental conditions, including temperature, moisture, light, and wind. The eastern subterranean termite, Reticulitermes flavipes, typically swarms during the spring on warm, sunny, calm days that have been preceded by rain. Without the right set of conditions to trigger the emergence of swarmers, colony members will simply cannibalize the unflown alates. (Fly or die!)

The unusual weather conditions that we have experienced during the past few years have influenced termite swarms. Interestingly, on May 1, 2007, we witnessed a large number of termite swarms on the Ohio State University campus in Columbus. This was a warm, sunny, calm day that had been preceded by rain and warm temperatures.

Termites, like all insects, are cold-blooded organisms whose development and activity are controlled by the temperature of their surrounding environment. Events in an insect’s life cycle, such as swarming, are best predicted by tracking temperature over time (accumulated degree days) rather than using the calendar. Alates (swarmers) are produced seasonally, depending on the species and its geographic location.

Why haven’t termites been swarming as much the past few years?
Dr. Gregg Henderson: We have been collecting alate data since 1989 on Formosan termites in New Orleans. What we have seen is a cycling that is related to droughts and natural disasters (like hurricanes). Soon after droughts begin, we start seeing alate numbers drop in our light traps. This goes on for as long as the drought continues. Others have claimed alate drop due to good success with termite control. Our data do not support this relationship since even when alate populations rebound after a drought, the good products continue to be used as before. These flights also can be constricted to just a few major flights over the two-month flight period during difficult times in the weather/climate. This can result in the perception of low numbers since PCOs get fewer calls.

Do termite dogs work?
Dr. Gary Bennett: Properly trained dogs working with a certified handler can add to the inspector’s ability to find hidden, active infestations. The economics of “owning” a trained dog has limited their (widespread) use.

What are carton nests and why are they so effective in protecting a termite colony?

Dr. Ken Brown and Ed Freytag: Carton material is a combination of frass, soil, cellulose and saliva. Large carton structures are formed first as a series of interconnected foraging tunnels. Larger foraging galleries and cells with thickened walls are constructed as termites continue to add to this elaborate gallery system. When the soil used in construction is primarily sand or when lime is incorporated, the carton can take on an almost masonry-like density. Although these structures are commonly referred to as carton “nests,” it is important to note that not all carton material contains reproductives or brood.

Therefore, it should not be presumed that removing a carton “nest” from a structure eliminates the source of the infestation. The thickened walls of the carton help protect termites and the large structures provide areas for termites to retreat to when threatened. However, the primary advantage of the carton is that it provides the capacity to store water, which results in an increased ability to exploit above-ground moisture sources.

What does the termite use to decide where to go next? (or, please explain “random foraging”?)
Dr. Nan-Yao Su: Regarding the movement of termites in existing tunnels, once tunnels are connected to foods, termites have to decide to which foods to go. If conditions of all connected food sources are equal, our study showed that the Formosan subterranean termite did not appear to go back to the same food source. The choice as to which food sources they are heading to appeared to be “random.” Note that this was made on Formosan subterranean termites only and there is no data for other species. This concept has been very much misunderstood with the “termites find food at random” concept (see “How do termites locate wood” question below). How a termite tunnels and intercepts foods is not random, but this does not mean that we know exactly how they locate foods. What we do know is that once they find a food, tunnels “radiate” out of that food source. Knowing all this, we can make a bait station more “attractive” by placing water, sugar waters, wood decay extracts, etc. Or we can install more stations near a station that is intercepted by termites since we know tunnels will “radiate” out of that “hit” station.

Which types of termite control are the most effective?
Dr. Ken Brown and Ed Freytag: The choice of which type of termite remedial treatment to utilize (liquid treatment, spot treatment, bait system, fumigation, etc.) should be made only after considering several factors such as termite species, construction type, customer expectations, location and degree of infestation/damage and any special/unique considerations. For example, homeowner concerns about pesticide use, the time required to achieve control, interior drilling, etc., may help determine which remedial treatment is most appropriate. The specific goals of each treatment also should be thoroughly discussed with the homeowner. The “best” option for termite control, however, is prevention. Preventive strategies include exclusion (i.e., use of termiticide-impregnated vapor barriers, stainless steel mesh or other physical barriers), use of non-cellulose building materials, sanitation and moisture problem remediation. Spending a little time considering these factors during construction or eliminating conducive conditions post-construction may prevent remediation decisions.

How do termites locate wood?
Dr. Nan-Yao Su: Subterranean termites do not “locate” food in the same sense as a terrestrial animal “locates” food since termites live in soil. They construct underground tunnels to “intercept” foods. The geometry and direction of tunnels may be affected by factors such as thermal shadows, moisture, some complex sugars or decayed wood extracts (only at a very short distance). They apparently cannot detect sound wood in soil at any distance. They have to literally “bang into it.” Termite tunnels tend to “radiate” out of the origin (nest, food sources, etc.), and they are constructed in such a way to effectively cover an area for an efficient interception of potential foods in soil. Our modeling work showed termite tunnels may be selected for intercepting food particles in clumped distribution. Beyond these, little is known.

How can you tell if termite evidence found is by subterranean or Formosan termites?
Dr. Ken Brown and Ed Freytag: This brings up a good point. Formosan termites are subterranean termites. Their full common name is the Formosan subterranean termite. Termites commonly are classified by their habitat requirements/preferences (i.e., drywood, dampwood, subterranean). Our native Reticulitermes, Heterotermes and the Formosan are all subterranean termites.

When termite evidence is found without any live foragers, determining the species of subterranean termite is difficult. Attention should be paid when inspecting the evidence. Occasionally, wings or soldier head capsules can be found in or around abandoned feeding sites or foraging galleries. This is really the only time that termite evidence can be considered completely diagnostic (although not up to date, some example ID keys can be seen at www.termitesurvey.com).

However, there are some other factors that can indicate whether the evidence resulted from the activities of the Formosan or other subterranean termite species. The primary characteristic is the presence of carton material. The presence of carton indicates that the damage resulted from Formosan activity. However, occasionally when Reticulitermes infestations go unchecked and are allowed to build up, the gallery system may be mistaken for FST carton. The FST creates distinctive alate dispersal structures — “swarm castles or pads” — on buildings and trees during the swarming season and may remain in place for several years. In contrast, Reticulitermes build small openings with relatively little mudding (pilot holes) from which the winged reproductive take flight. Shelter tubes of FST leading to wooden members in a structure tend to be wider and thicker than those of other species in North America. Free-standing shelter tubes in crawlspaces constructed by Reticulitermes can occasionally be large, resembling stalactites.

Another indicator is the general appearance of the galleries within the damaged wood. FST galleries tend to appear “cleaner” than those of Reticulitermes. This is most likely the result of increased fecal staining in FST galleries and increased “mudding” in Reticulitermes galleries. Experience inspecting properties damaged by FST and other subterranean species increases the likelihood of correctly identifying species by the evidence. However, again, these indicators cannot be considered completely diagnostic.

Why is grooming behavior so critical to the survival of a colony?
Dr. Nan-Yao Su: Grooming behavior is so critical because it promotes colony hygiene. For example, most of the attempts to use fungal spores for biological control failed because termites typically groom the spores off
the body surface of nestmates.

Since there is no “magic bullet” in termite control, what is the best way to decrease termite damage and damage claims?
Dr. Roger Gold: The most efficient method to reduce termite claims is to respond immediately to any concerns that a client has about your termite management practices. By the time a client contacts an attorney, the “minimum” cost to the pest management professional is going to be $10,000. Consider how much work can be re-done for that amount of money. Based on the calls I get at the office, the No. 1 complaint from consumers is that the “pest control company will not return my calls,” or the pest management professional says, “That is not really a problem.” The customer may not always be right, but it is less expensive if you act like they are.

Will there ever be a termite attractant that will “pull” termites a specific distance (either toward a bait or trap) or away from vulnerable areas?
Dr. Brian Forschler: I can foresee the day…then again I think the Cleveland Browns will win a Super Bowl in my lifetime! Seriously, though, for most research scientists, an attractant is something that will “call” termites to a site from some distance. Termites are different than other solitary soil animals because they live in groups and their movements in soil are decided along two distinct tracks.

The first concerns the termites that are digging new galleries through the soil. The second is movement of termites in galleries once they are constructed. An attractant could be used to influence either type of movement by termites to a particular site but it would have to occur by very different mechanisms. The tunnel builders are known to follow soil texture and structures in the soil. Getting termites that are tuned into the tunneling mode (we know only certain termites do that job) to follow a scent in the soil may be possible but not really proven to everyone’s satisfaction. Once a tunnel is built, termites certainly use chemical signals to tell their brothers and sisters where to go when they reach a fork in the road but we have no idea of how that works.

The bottom line is it is a complex story and for the most part science is not able to back up tales told from field observations. Until we decipher termites’ language — and they certainly have one otherwise they would not be living in organized groups — the question of any attractant’s usefulness in termite management scenarios will be a best guess.

Researcher Roundtable, part 1

PCT asked many of the researchers interviewed for this article the same questions to get varying points of view on several important issues. Here’s what our panel of experts had to say when we asked them, “What is the No. 1 misconception PCOs have about termites?”

Dr. Gary Bennett: The No. 1 misconception is that inspections can be done quickly and at no charge to get more termite jobs.

Dr. Ken Brown and Ed Freytag: First, that there is a distinction between Formosan termites and subterranean termites. Another misconception is that an individual Formosan termite consumes more wood than its native subterranean termite counterpart. Research has demonstrated that workers of each species consume relatively equal amounts of wood. The difference is really due to numbers. While Reticulitermes colonies contain up to 200,000 to 300,000 foraging individuals, FST colonies can contain millions.

Dr. Brian Forschler: The No. 1 misconception is that they live in staid colonies.

Dr. Roger Gold: That there are some houses in which the termite population cannot be controlled (as in the “house from hell”). The fact is that any termite problem can be solved, but it may not be in the best interest of the pest management professional to make that offer.

Dr. Susan Jones: I have studied termites for about 30 years, and I think that PCOs generally are more knowledgeable of termite biology than they were years ago. For example, many PCOs now recognize that the termite colony has considerable reproductive flexibility through the production of neotenics that can supplement or replace the king and queen. PCOs also recognize that above-ground colonies may be headed by neotenics.

Dr. Mike Potter: That’s a tough question. There’s been so much information provided on termites in recent years that I think most companies understand them pretty well, at least in respect to what’s most relevant for management. Those old misconceptions like “termites need to return to the soil every 24 hours” or “kill the queen and you kill the colony” have long been disproved, and I think (hope) we’ve wiped those mistaken beliefs from our vocabulary.

Dr. Nan-Yao Su: Many still don’t understand that a colony of subterranean termites may construct an interconnected tunnel system that may extend up to 100 to 300 feet. Despite some claims that we do not know what a “colony” is, a colony can be simply defined as “a group of termites sharing an interconnected gallery system.” Thus, unlike drywood termites, subterranean termites found in a house may travel via their tunnels from outside.

Researcher Roundtable, Part 2

Here’s what they had to say when we asked them, “What is the #1 question researchers would like to have answered about termite behavior?”

Dr. Gary Bennett: Will genetic manipulation ultimately lead to an economically feasible management program?

Dr. Ken Brown and Ed Freytag: What defines a subterranean termite colony?

Dr. Brian Forschler: How can this research make me millions of dollars? (Just kidding!) What is the cycle of signals that cause termites to move from one feeding site to another?

Dr. Roger Gold: How is it that one species of termite can have such wide distributions, but differ so much in food preferences and types of damage done? Also, how is it that the ancient Order Isoptera can have the same social attributes as only expressed in more recent orders?

Dr. Gregg Henderson: What makes termites social? Moreover, how does their sociality make them so well organized and successful? Most important toward this end is working out how they control their caste system, which provides them with their task allocations and makes them a well-oiled machine.

Dr. Susan Jones: There are many questions that remain unanswered, all of which deserve high ranking. One question of considerable interest is, “How do termites recognize other termites as being related or unrelated?” “How often do termites molt and how is this affected by intrinsic and extrinsic factors?” and “Over what distance does a termite queen or king exert an inhibitory effect on reproductive development of immatures?”

Dr. Mike Potter: How do termites find resources, and how we might use this information to design better baits and detection devices?

Dr. Nan-Yao Su: How do they find food?