Toxicity threshold of chitosan for the subterranean termite, Reticulitermes flavipes

Abstract

Chitosan is a hydrophilic and biodegradable polysaccharide with antimicrobial properties. It has low toxicity to non-target organisms and is considered an environmentally friendly preservative. In this study, the efficacy of chitosan polymer (> 50 kDa) as a wood preservative was evaluated against the subterranean termites Reticulitermes flavipes (Isoptera: Rhinotermitidae). The treatability and leachability of chitosan from wood was also studied. Visual ratings and mass losses were used to assess the degree of termite damage to the wood blocks, while percent termite mortality after two weeks was measured for determining the effect of chitosan on the termites. In addition, the mass of chitosan per gram of dried wood before and after leaching was used to determine the stability of the preservative for five different treatment concentrations. High termite mortality was observed in termites exposed to wood treated with 3%, 4% and 5% chitosan solution-treated samples, while only 10% mortality was shown in wood treated with 1% and 2% chitosan solutions. Mass loss of treated wood samples due to termite attack decreased with higher chitosan concentration. Leached samples did not contain enough chitosan to protect wood from termite attack. The results of this study indicate that treating solutions with chitosan concentrations greater than 3% could protect wood under dry conditions.

Citation

Raji, Olanrewaju; Telmadarrehei, Telmah; Tang, Juliet D.; Jeremic, Dragica. 2015. Toxicity threshold of chitosan for the subterranean termite, Reticulitermes flavipes. In: Proceedings of the Canadian Wood Preservation Association 36th Annual Meeting. Ottawa, Ontario. 27-28 October 2015. pp. 128-136.