[Technically Speaking] Termite Research - Pest Management Implications

Following is a review of several published research reports that may help pest management professionals with their termite control practices.

In this laboratory study the effects of a lignin-degrading basidiomycete fungus on the feeding preferences of Formosan termites was measured using five species of commercial lumber (yellow cedar, yellow birch, northern red oak, redwood and spruce). When compared to untreated wood sawdust the termites preferred the fungus-inoculated wood vs. un-inoculated wood, with the exception of Alaskan yellow cedar. Formosan termites also had a preference for inoculated redwood over red oak. This research indicates that fungal decay affects the feeding preference of termites.

When encountering termite infestations it is not uncommon to see decay as well. The question then becomes, what was first, the decay or the termites? Based on this research it might be generally concluded that decay could attract termites. Technicians who have worked with baiting systems that utilize wood stakes as an attractant have found that modest decay may in fact attract termites.

Termite predilection for wood affected by decay is frequently encountered in EIFS structures where there has been significant water intrusion and subsequent decay. Fungal decay and its stimulatory effect on termite feeding may explain why termite activity in EIFS structures is typically very widespread. Several years ago we attempted to mitigate an EIFS structure using Sentricon® AGs and could not get any feeding in the AGs despite placing the AGs on top of active galleries. This was one of the very few times I found termites that would not feed on the AGs. It was readily apparent that the termites were feeding on fungal-decayed wood because their galleries and swarm tubes, which were very abundant, were black from the residue produced by the fungus.

In this case the homeowners refused to mitigate the moisture problem because of an ongoing lawsuit with their builder, thus both fungal decay and termite damage progressed. This research points out the need to incorporate moisture control as part of the remediation program for termites. In addition, the use of borate solutions to treat fungi-affected wood may help to suppress termite damage.

Two of the most perplexing questions regarding termite behavior is why they tunnel over or between perfectly good pieces of wood and what determines the length, branching and direction of exploratory and feeding tunnels.

As termites forage through their secretive world they encounter many objects, pipes, boards, tree roots, wires, etc., and products made of equally diverse materials, such as wood, plastic, steel, etc. One of the questions is how do these items factor into their foraging behavior and their quest for food? This research examines the effects of some structural guidelines on termite foraging and feeding behavior.

Termites built significantly longer tunnels along wood guidelines than they did those constructed of plastic or plastic-wood matrixes. In addition, the probability of discovering bait was significantly greater when the baits were connected by wood guidelines. Bait consumption was not significantly affected by the guidelines connecting them.

This certainly reinforces the need to more thoroughly inspect properties for the presence of tree roots and other wood materials, such as landscape timbers, form boards, etc., that can direct termites without interruption to the structure. For those using baiting programs, the use of these landscape elements may help in station placement.

One of the most interesting comments I encounter performing termite litigation work is from plaintiff’s experts who attempt to use the length of tunneling to establish timelines regarding how long an infestation was present. While this article does not specifically address the use of this information it provides insight into how industrious termites can be and how rapidly they can explore an area.

These studies were conducted in arenas that restricted termite activity and perhaps the tunneling activity was somewhat limited by the confinement of the arena and if given more space the termites would have tunneled further and more aggressively. Despite this limitation, in one day the termites tunneled approximately 87 inches in low compaction soil compared to 67 and 71 inches for moderately and highly compacted soil respectively. Most of the tunneling activity occurred within the first day and total distance declined over a 14- day period due to backfilling of seldom-used tunnels. Soil compaction did not affect the number of primary and secondary tunnels nor did it affect the diameter of secondary tunnels.

This information could also help to explain the difference reported in colony size and distribution reported by various researchers throughout the country who certainly deal with different soil types and degree of compaction. This should also cause us to rethink how we use in-ground bait stations in soils that are moderately heavily compacted than how we use them in less compacted soils, i.e., in moderate to heavily compacted soils there should be more bait station placements and they should be closer together. Likewise, the spacing of holes for liquid soil treatments should be closer together to increase the distribution of the product and contact with termite tunneling activity.

When I met with Syngenta many years ago the company was in the formative stages of developing its Impasse® barrier film. At that time it was my understanding that the film actually would release some lambda-cyhalothrin into the soil, thus creating a sub-slab barrier treatment.

When the product was recently released into the marketplace the people I spoke with from Syngenta insisted that the product would not migrate into the soil and would only affect termites if they attempted to penetrate the membrane. Honestly, I did not have much confidence in the product if the termites actually had to penetrate the barrier to be affected because once the film was breached the question remained whether termites could take advantage of the breach.

This study demonstrated that the lambda-cyhalothrin actually is released in sufficient quantity from the film to provide an effective barrier to prevent termite penetration for at least five to five-and-a-half years (the time tested to date). This research has restored my confidence in attempting to sell this product as a termite and moisture barrier in the preconstruction housing market.

CONCLUSION. The pest management industry has the luxury of having a group of user-friendly researchers. Many of them have spent many years and others their entire adult lives benefiting our industry by providing us answers to the practical pest management problems we face every day. As an industry we need to do two things: take advantage of the research they do for us and support their many efforts in the field and in the lab.

To all of them say thank you!