THE MISSION of the Wood Products Insect Research Unit (SRS-4552) is to improve the protection of wood products against subterranean termite damage, define the role of termites in forest ecosystems, and understand their impact on forest health. To accomplish this mission, research is organized into four problem areas: (1) develop, refine, and assess new, improved, and alternative compounds, materials, and treatment techniques for effective protection against damage caused by termites; (2) investigate the biology, ecology, and behavior of termites in forest ecosystems to promote the development and efficacy of protection techniques; (3) investigate the role of termites in nutrient cycling to promote an understanding of forest, soil, and watershed health and productivity; and (4) investigate factors that allow the Formosan termite to survive standard termiticide treatments.
Research is formulated with an understanding that termites play dual roles as pests in urban environments and, conversely, as contributors to forest health and productivity. Their role in forest ecosystems as wood decomposers contributes to nutrient cycling, soil fertility and stability, forest productivity, and water quality -- aspects that are little studied and poorly understood. Their role as wood-product pests is better understood, yet increasing restrictions on insecticides make their control less certain and more costly. These divergent issues are important in light of the increasing demands placed on the decreasing forest acreage worldwide. As providers of forest-related research, it is critical that the U.S. Forest Service address the challenges placed on forest resources and associated industries. These challenges include regulation of forest health, timber production, and preservation of wood products to lessen the demands on existing forests and reduce the costs to American homeowners and businesses.
Problem Area 1: Develop, Refine and Assess Treatment Techniques
The cost of controlling termites and repairing their damage is estimated at $2 billion annually in the United States. These losses do not include those incurred by the military or the growing impact from the Formosan termite. Termite control also carries the highest risk for the pest control industry of all categories in urban pest management, and increasing restrictions on insecticides make their control less reliable and more costly. For these reasons, this problem area is a high priority. It can be divided into research originating from scientists within the unit and research originating from outside the unit through agreements with industry. Internal studies conducted during 2000 included research on the distribution and fate of termiticides in soils, the temporal and spatial effects of insecticides on foraging behavior, and the effects of sub-lethal dosages of chemicals on gut protozoa of termites. We found that boric acid negatively affected symbiotic protozoa in termites, and native termites were more susceptible to boric acid than Formosan termites. These results support the finding that borate wood preservatives suppress termite damage. An ongoing cooperative study conducted in the U.S., Australia, and Thialand found that the type and concentration of wood preservative affected the ability to protect against termites. Compound success was consistent across sites.
Problem Area 2: Biology, Ecology and Behavior
Conditions regulating native subterranean termites in natural habitats are poorly understood, and in 1999, research was initiated to investigate the biological, ecological, and physical parameters associated with the diversity and distribution of termites in forest ecosystems. This research will provide an understanding of the habitat requirements supporting and promoting each species. It will furnish insights required to initiate more complex studies on termite colony, population, and community dynamics, which will support the development and implementation of improved integrated treatment strategies directed against termites. Knowledge from these studies may be used to develop risk assessment tools for individual termite species in residential areas. To this end, termites were collected and mapped along with other site information from 370 diverse locations during 1999-2000. Identifications of termites are proceeding, with a possible new species found. A graduate student will begin work this year on termite identification (species, colony, and population). Wood decay fungi were also collected and cultured for assessment of behavioral or foraging affects on termites. In another study, a direct relationship was found between temperature and respiration rates in worker termites, with workers exhibiting higher respiration rates than nymphs and soldiers.
Problem Area 3: Role of Termites in Nutrient Cycling
In response to the changing mission of the Forest Service, the project has initiated cooperative research to investigate the role of coarse woody debris decomposition in sustaining long-term soil productivity of managed loblolly pine in Mississippi and Texas. Coarse woody debris is important in soil transport, sediment storage, energy nets, and nutrient cycles in forest ecosystems. Our understanding of the processes governing sustainable productivity is rudimentary, and our knowledge of the role of woody debris decomposition in maintaining long-term carbon and nutrient capital of the soil is minimal. Few studies on wood decomposition have been carried out in managed southern pines. A long-term study has been installed that will examine the decomposition rates of loblolly pine and the biotic and abiotic factors affecting the decomposition process, including the role of termites. This study will produce guidelines for managing woody debris in the context of sustaining enhanced productivity of managed loblolly pine. Cooperative research in young loblolly pine plantations continued with a long-term soil productivity study at the same sites. The relationships among termite species, soil compaction, and organic matter removal are being examined. More termites were found in Mississippi than Texas. In Mississippi, more termites were found at monitoring stations in plots with highly compacted soils compared to plots with no compaction. Organic matter removal did not influence termite numbers. Fewer termites were found in the control plot (mature pine stand) compared to the treated plots. Although not statistically significant, more termites in Texas were found in plots with the most organic matter removal compared to plots with the least, and soil compaction did not influence termite numbers. A greater number of termites were found in the control plot compared to the treated. These contrasting results are under investigation. In general, termite numbers increased during the late winter and spring, whereas damage lagged slightly behind and was greatest during the spring and summer.
Problem Area 4: Formosan Subterranean Termite
This is an emerging area of importance to the Forest Service. The Formosan subterranean termite is an exotic pest causing about $1 billion damage in the U.S. Unlike native species, this aggressive termite attacks living trees, potentially threatening southern forests and the urban/forest interface. Potential damage to forests is twofold: direct damage or death to trees and indirect disruption or displacement of native termite species which promote wood decomposition and nutrient cycling and, thus, forest ecosystem health and productivity. Demand for product testing aimed at this pest has increased. Unfortunately, no new research has been initiated on Formosan termites due to the lack of funding. we are continuing physical barrier and termiticide research on this pest in cooperation with the U.S. Fish and Wildlife Service on Midway Island. We have also investigated opportunities to secure funding to develop contacts with foreign investigators.
Wood Products Insect Research
201 Lincoln Green
Starkville, MS 39759