Hi Greg- termites are a valid concern any where in the tropics. Most homes in Panama are built with cinder blocks, concrete and tile, and for good reason. Your person in Las Lajas is correct to warn you of these concerns.
If I were building a home in Las Lajas (I live in David, Chiriquí) I would not use wood. If your heart and mind are set on a wooden home, then I suggest you research the best type of materials and processes before you begin. I know that treated lumber is available here in Chiriquí, but I do not know the specifics. Learning about the local hardwoods may be very helpful also.
Perhaps doing a broader online search for construction techniques in the tropics and prevention of termite infestation might bring you some useful information.