Toxicity and repellent effects of wood extractives of five Malaysian wood species on Asian subterranean termite Coptotermes gestroi Wasmann

Antitermitic potential of heartwood extractives of five Malaysian wood species against the subterranean termite, Coptotermes gestroi was investigated in laboratory experiments. Heartwood extractives of the wood species, Cinnamomum sp., Canarium littorale Blume, Cynometra malaccensis Meeuwen, Eugenia griffithii Duthie and Scorodocarpus borneensis (Baill.) Becc. were removed from wood sawdust using the four solvents, methanol (MeOH), ethanol (EtOH), acetone and toluene:industrial methylated spirit (Tol:IMS). Extraction was done using a Soxhlet extractor. Two different tests, toxicity and repellency, were conducted on filter paper treated with different concentrations (0.5, 1, 2, 3 and 4%) of each wood extract to observe the repellents, feeding response and mortality of termites. No-choice bioassay using Hevea brasiliensis test blocks treated with the same concentrations of each wood extract was also carried out to compare the results with the termiticidal activity of extractives. Termite feeding, repellents, and mortality followed a concentration-dependent response. The highest termite mortality occurred at an extractive concentration of 4% of each wood species. Extractive of each wood species prepared using MeOH showed higher termite mortality, feeding inhibition and lower filter paper consumption when treated with 4% of concentration. Extractive of C. littorale prepared using EtOH as a solvent was least toxic to termite. Acetone extractive of S. borneensis showed significantly higher repellent activity against C. gestroi at 2, 3 and 4% of concentrations compared to the rest of treatments. Further characterization of the extractive content is needed to find out which compounds are responsible for termiticidal and antifeedant activity, either singly or jointly.