Nutritive Supplement Method to Evaluate Resistance of Natural or Preservative-Treated Wood to Subterranean Termites1

Abstract

A bioassay for determining resistance of wood samples to Reticulitermes flavipes (Kollar) and R. virginicus Banks uses a small, measured amount of aspen wood sawdust as a nutritional supplement. Trials of this sawdust supplement method resulted in generally high termite survival (>75%) which, in turn, produced greater attack on resistance samples than normally occurs in termite assays. Block weight loss data thus could be used as the sole criterion for comparison of the relative resistance of different wood samples. Antitermitic properties were assessed with the supplement method for 2 oilborne and 2 waterborne preservatives and 21 different timbers. Except for a toxic effect by one of the oilborne preservatives, antitermitic properties of the preservatives and the natural woods were due primarily to repellency or feeding deterrency factors. The sawdust supplement method appears adaptable to any subterranean termite for assessment of wood resistance.