The calcium precipitating agent NHA has been shown to protect southern yellow pine (SYP) from wood decay and termite damage comparable to CCA in field tests (Gulfport, MS) for two years (Crawford and Green, 1999). In a collaborative study, SYP wood blocks were vacuum treated with three concentrations of aqueous NHA and exposed in a no-choice test to Eastern subterranean termites (FPL, USA) and Formosan subterranean termites (WRI, Japan) to determine protection against termite damage. Individual blocks (leached and unleached) were exposed to R. flavipes (AWPA) or C. formosanus (JWPA) for 3-4 weeks. Mean weight loss of wood blocks after termite exposure ranged from 0.0 to 18.0% for R. flavipes and 6.0 to 20% for C. formosanus. Wood blocks exposed to R. flavipes were completely protected by 0.5 and 1.0% NHA, but weight loss in similar blocks challenged by C. formosanus were 6.0% and 6.2% respectively at the same concentrations. NHA acted as an effective termiticide for R. flavipes with 100% mortality after 3 weeks, but only soldiers were preferentially killed in C. formosanus. Formosan subterranean termite workers showed enhanced resistance to NHA treatment when compared to Eastern subterranean termites.

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