Toxicity and repellent effects of wood extractives of five Malaysian wood species on Asian subterranean termiteCoptotermes gestroiWasmann

Antitermitic potential of heartwood extractives of five Malaysian wood species against the subterranean termite,Coptotermes gestroiwas investigated in laboratory experiments. Heartwood extractives of the wood species,Cinnamomumsp.,Canarium littoraleBlume,Cynometra malaccensisMeeuwen,Eugenia griffithiiDuthie andScorodocarpus 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 usingHevea brasiliensistest 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 ofC. littoraleprepared using EtOH as a solvent was least toxic to termite. Acetone extractive ofS. borneensisshowed significantly higher repellent activity againstC. gestroiat 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.