Evaluation of polyphenols-rich natural compounds as treatments to prevent attacks by subterranean and drywood termites: preliminary results

In the view to find sustainable methods to prevent termite attacks to wooden objects and structural timbers, this study represents a preliminary step in the evaluation of some natural substances considered as effective by some African popular traditions. Dark shea cake, obtained from the kernels of Vitellaria paradoxa (Sapotaceae), is the phase just before the extraction of shea (= karitè) butter. In some West African regions, by-products from this extraction are traditionally believed to protect houses from termites. To verify if this practice has scientific basis, shea cake was used in experiments with both subterranean and drywood termites, respectively Reticulitermes lucifugus (Rossi) (Rhinotermitidae) and Kalotermes flavicollis (Fabricius) (Kalotermitidae). As shea nuts are extremely rich in polyphenols, the trials included a comparison with tannins from chestnut (Castanea sativa). Short-term experiments to evaluate repellency and feeding deterrence of the two compounds were performed. Results showed differences in the behavior of the two termites species and that shea cake is significantly more repellent than chestnut tannins, especially for K. flavicollis. No feeding deterrence activity was detected for either substance for either termite species. Further investigation is currently being performed to better clarify how these compounds affect termite biology.