Avoid moisture accumulation near the tree. Divert water away as much as possible. Ground near the base needs to be sloped or graded in order for surface water to drain away from the building. Termites and ants are attracted to moisture.
In nationwide field tests, the U.S. Department of Agriculture Forest Service, Gulfport, Mississippi evaluates termiticide soil treatments. In general, termiticides tested under concrete slabs were 100 percent effective for five or more years when applied at the highest rate, but often were less effective when applied at lower rates (Source: Pest Management Magazine, pages 14, 15 & 16 - Feb. 1994, Vol. 13, No. 2). Termiticides tested included bifenthrin (Biflex), cypermethrin (Demon TC), permethrin (Dragnet FT), chlorpyrifos (Dursban TC), chlorpyrifos (Equity), cypermethrin (Prevail), chlorpyrifos (Tenure), permethrin (Prelude) and fenvalerate (Tribute).
I would also bait them out termiticide termite bait and keep the area dry. See if any pesticide companys have any ideas. Malithion might work. Pest company could kill your tree
Darin