Termite Infestation Control: Prevention Versus Treatment.
What works better: baits or barriers?
There are at least 45 different termite species in the U.S., and around 30 of them are pests (Su and Scheffrahn 1990). These insects cause $2 billion worth of damage each year (Su 2003ab; Su 2002), most of which is due to subterranean termites and structural infestations that subsequently require treatment.
Although none of the available treatments are 100% effective, different conditions can lead to various results (Peterson et al. 2006). The treatment options are termite barriers, termite baits and wood treatment. Barriers are established by adding liquid termicide to the soil, thus creating a barrier between termites and the structure. Chemical barriers comprise about 70% of the subterranean termite treatment market (Kard 2003; Curl 2004; Saran and Rust 2007). Termite baits have a low environmental impact and can have long-term success through a maintenance contract but, they work slowly and are not always fully reliable. Treated wood can be combined with baits or barriers. The idea is simply that the termites do not like to eat or tunnel over treated wood (Quarles 1998; Kard 2003).
As with most things, the best approach with termites is prevention over treatment. Keeping these pests out of a building is far more cost efficient than eliminating an infestation. There are building construction techniques that specifically bear in mind prevention of termites, such as no contact between soil and wood, proper drainage and construction standards for foundations.
How Chemical Barriers are Used to Fight Termites.
Chemical barriers have dominated the industry for more than 50 years (Peterson et al. 2006). Trenches are dug around a structure and filled with gallons of liquid termicides. Another method is to pump chemicals into the soil underneath concrete slabs (Peterson et al. 2006). The onus is on applying the active ingredient uniformly so that there are no gaps, otherwise termites will find their way through and attack the structure (Potter 1994; Kuriachan and Gold 1998). New constructions tend to incorporate chemical soil treatments and they can also include barriers of sand or mesh, although these do not offer corrective protection (French 1994; Kard 2003; Ebeling and Pence 1957).
Most liquid termicides use neurotoxins as the active ingredients. The newest one is Altriset, which uses chloranthranilipole as its active ingredient. This binds to ryanodine receptors leading to calcium ion depletion and muscular paralysis. This makes the product a muscle toxicant rather than a neurotoxin and means it is virtually nontoxic to mammals. Termites exposed to it stop eating, slow down and then die of muscular paralysis. Studies have shown that only 14% of a large oral does is absorbed by rats and it has no effect on rat reproduction and is also not carcinogenic. Added to that, the environmental profile is practically benign (Cordova et al. 2006). This may find favor with environmentalists but, termite baits are also renowned for their low impact on the environment. As the ingredients are targeted only against termites and are contained within a bait station, there is a low possibility of exposure to other animals (Quarles 2003b; MSDS 2009).
How to Properly Use Bait Stations Against Termites.
The baiting technique begins by installing underground monitoring stations around a building perimeter. If feeding termites are detected, then active baits are installed. Termite companies measure activity at bait stations, and the amount of bait consumed. The monitoring carried out is not as in depth as research studies, which will analyze foraging activity, foraging ranges and number of foragers (Grace et al. 1989; Grace 1990; Su and Scheffrahn 1996ab).
In the commercial world, this level of monitoring is not viable, instead, if termites start feeding on an active bait, there is a good chance of success. Also, monitoring stations are checked periodically for termites. The manufacturer of Exterra termite baits states this as a measure of determining success: 'If all termite feeding and activity in an area has been absent from the area for six consecutive months and termites fed on the bait for three months prior to the cessation of feeding and activity, we presume that colony elimination has occurred,' (Quarles 2003b). There are numerous studies cited by bait manufacturers to demonstrate success rates. Su (2003a) cites 33 studies involving 159 baited termite colonies, and 152 of them were eliminated. This is an efficacy rate of 96% if we use the measure of colony elimination.
Both baiting and barrier methods have their pros and cons. Baits may take 3 months to eliminate termites and they are not always 100% reliable. In fact commercial research show success rates of 85-98%. Barriers should be initially effective in most (90%) of cases and should last five years, depending on favorable weather conditions and existing termite numbers.
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