Repellent and toxic effects of plant extracts on subterranean termites (Isoptera: Rhinotermitidae).

The effects of four plant extract formulations on the orientation and survival of subterranean termites were tested. In choice experiments, extract-treated filter paper had a significantly repellent effect on groups of Reticulitermes santonensis De Feytaud, R. virginicus (Banks), Coptotermes formosanus Shiraki, and Schedorhinotermes intermedius Breinli. There was no species-specific difference in avoidance behavior toward the tested concentrations. No-choice experiments revealed toxic properties of all investigated extracts by contact or airborne compounds against R. santonensis. However, high termite mortality was only achieved by forced direct or forced indirect exposure to the plant material, Feeding deterrence or digestive toxicity could not be judged in these experiments. One of the extracts was efficiently used for soil treatments to protect a food substrate against R. santonenis infestation. Extract-treated barriers in the experiments did not affect mortality compared with control trials but prevented termites from penetrating treated soil.