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by Dr. Oneida Cramer
Termites are not all bad?after all.
If it were not for termites, the earth would be totally different, according to Roger Gold Ph.D., Professor and Endowed Chair, Department of Entomology, Texas A & M University. Imagine how messy the earth would be if we couldn?t get rid of old trees and shrubs. Termites are among the few organisms with the ability to break down cellulose and recycle it. In addition, termites create nitrogen, which is important in making the atmosphere habitable for life. In fact, termites have existed for millions of years and are found everywhere in the soil, especially in the rainy tropics.
?If you were to weigh all the termites, their biomass is greater than all the higher animals,? Gold said. ?The reason they are all over the earth is because they occupy a unique niche?basically unchallenged in terms of their ability to take all the cellulose they need.?
But it just so happens that people like to build wood houses. And because termites prefer dead wood to live wood, they are a menace to homes. In warm climates like Texas, if a structure is not protected from termites, it?s just a matter of time before termite infestation begins. In fact, wooden structures in Texas have more than a 70% chance of being attacked by termites within 10 to 20 years of construction?even soon after construction, according to the Texas Agricultural Extension Service of the Texas A&M University System web page (termites.tamu.edu). So, homeowners need to understand termite control procedures and know what they are purchasing, obtain bids from several companies, and compare warranties.
?This is not a do-it-yourself project,? Gold said. ?We?re talking about a family?s major investment. And I think you need the best advice and treatment that you can afford.?
But consumers are confused, according to Director of Orkin Training Center, Ron Harrison Ph.D. Part of that confusion stems from governmental withdrawal of the pesticide, chlordane, a chemical barrier used for many years until about 1988, when it was phased out because of it?s long-lasting effectiveness (30-50 years), which was thought by some environmentalists to be too long and, hence, had to be bad for the environment, according to Gold. The first pesticides that replaced chlordane were designed for agriculture, and they lasted only one season. By increasing the concentrations, it was possible to get a few more years out of the next generation liquid termiticides. Today, liquid termiticides are effective for about 5 years average (18 months to 7 years range), and new pesticides are being developed. For instance, fipronil, trade name Termidor, is a new product with very good efficacy in controlling termites in the four years it?s been studied. Question is how long does fipronil remain effective?
Liquid termiticides work by establishing a chemical barrier in the soil around the house. As termites forge in soil trying to find wood, they accidentally come upon the chemical barrier, where they are killed or repelled.
?Either way they are kept from feeding on the house,? Gold said. And the barrier is always present until it breaks down or is disturbed. Chemical break down is good because it prevents the compounds from getting into the environment for indeterminate periods of time just in case the chemicals turn out toxic and there were no other way to remove them.
There is, however, a system that uses less pesticide?termite baits?which became available about seven years ago, according to Gold. Termite bait systems depend on the social behavioral characteristic of termites to forge (look in soil for wood and cellulose) and, once they find a food source, to take the food back to the colony where it is shared.
The bait system works as follows. First, the pest control operator establishes a monitoring station, which is basically a piece of wood in plastic inserted in the ground. Every three months, the technician comes out to check stations, and if the wood begins to disappear, the technician replaces the wood with cellulose containing an active pesticide that acts either as a direct killing termiticide or an insect growth regulator (IGR) to inhibit the development of the adult stage. Both compounds depend upon the termite workers transporting the agents back to the colony and passing it around.
Being social insects, termites in one colony can metamorphose into workers or reproductive males and females (swarmers) or become soldiers and provides defense for the colony. Termite metamorphosis is a gradual process (opposed to complete metamorphosis in butterflies) according to Harrison, and its coined The Princess Theory by Gold. The process begins with the eggs hatching into larvae, which molt (shed exoskeletons) three times before the larvae become pseudogates (workers). Basically, the worker is an immature stage that can remain always a worker, or it can develop into a soldier, if the colony needs protection, or into a nymph with little wing pads that eventually becomes a swarmer.
?When they become princesses on the way to becoming a queen, they quit working,? said Gold describing the development of the winged nymphs into swarmers, which, along with soldiers, represent terminal adult stages. The strategy in using baits is to prevent the termites from developing winged nymphs, the princesses, and forming new colonies.
Homeowners are likely to spot swarmers venturing out in search of new locations, according to Harrison. But workers always stay in the dark, and note that the worker getting food is the only termite that does damage to wood.
The advantage of the bait system, which puts pesticides in the ground only when workers demonstrate that they are actively eating, keeps pesticides out of the environment unless they are needed, according to Gold. So, instead of hundreds of gallons of liquid termiticide in a barrier treatment around the house, the bait system relies on a few grams of termiticide active ingredient. The problem with baits, however, is its five step-process beginning with the termite having to find the monitor, then to find the bait and to live long enough to transport the bait back to the colony and to share the bait with the colony, all of which lowers the probability of success. Two years of data on 75 homes using bait systems show that 50% of the time, the bait worked effectively in the first year. In the second year, the baits were effective 80% of the time, provided they were properly maintained.
?We?re trying to protect the structure,? Gold said. We can?t lose site of the goal. Our goal is not to kill termites or put bait in the ground or put a barrier in the ground. Our goal is to protect the structure. The other things are merely technologies that we use to accomplish the goal. The bottom line is that ?either the liquid barrier treatment or the baits can be very effective in controlling termite populations. And one of the most important factors in making these techniques effective is the technician and the company?s philosophy of doing the best work possible to solve the problem.?
Dr. Oneida Cramer
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