Evaluation of the potentials of Jatropha curcas seed oil and in combination with leaf extracts of Cymbopogon citratus, Ocimum basilicum, and Eucalyptus globulus as wood preservatives against Macrotermes bellicosus termites

The preservation of non-durable woods such as Ayous through the use of environment friendly products is nowadays a major concern to many tropical wood researchers. The objective of this work was to assess the potentials of Jatropha curcas oil (JCO) alone and in combination with Cymbopogon citratus (JCO + CC), Ocimim basilicum (JCO + OB), and Eucalyptus globulus (JCO + EG) leaves extracts at different concentrations (1, 2, 4, 8, and 16 mg) as wood preservatives of Ayous (Triplochiton scleroxylon) against Macrotermes bellicosus termites. The extracts were tested for their toxicity and repellency on termites. Subsequently, treated and untreated wood was exposed to termites for four weeks. Termite response to treatùents varied with plant species, concentration, and exposure time. Ocimum basilicum extracts combined with J. curcas oil appeared to be the most effective against termites at 16 mg/l for in-vitro tests. It was also shown that the tested treatments were repellent to termites and therefore their mortality could not result from inhalation. J. curcas oil significantly improved the persistence of the treatments. Finally, a combined treatment of J. curcas oil and methanolic extracts of O. basilicum yielded the best protection of Ayous to termite attack, as shown by an average mass loss of 2%. Further research is needed to improve the longevity of the treatments on wood over time.