This is sort of a yes and no answer. Yes, table salt or sodium chloride technically will kill a lot of things including humans if taken in a high enough quantity. The toxicity of products are measured by the LD50 number. If sodium chloride is mixed at the right quantity then it could become toxic to many insects. The issue, however, is not that simple. Delivery of the product, in this case salt, in such a quantity and in such an area, as to control the termites is the problem. The best termiticides have been developed to not kill the termites too quickly, as killing the target pest too quickly will eliminate the spread throughout the colony. All in all, salt would not be a good choice as termiticide or pesticide.