A study examining termite damage to plastic cabling reveals some surprising findings.
Most pest managers would have seen termite damage to materials other than wood and other cellulose-based products – damage to plastic items, especially cables are not uncommon. Although damage to cabling in buildings is certainly unwanted and has the potential to cause house fires, damage to the extensive network of underground communication and power cabling presents the biggest cause for concern, as damage can be extensive and difficult to locate.
Cables are protected by the outer sheath material, which are typically made from various polymers. The susceptibility of these plastics to termites varies with their chemical structure, hardness and surface finish. Their resistance can be further improved through the inclusion of plasticisers, inert fillers or insecticides, or enclosing them in a physical barrier. To assess the suitability of materials for the cable sheath, cables are challenged by exposing the cables to eld trials in areas of high termite pressure, not dissimilar to the trials used to evaluate chemical soil treatments.
Research has shown that termites in Australia caused more damage to buried plastic cabling than termites in the US (Gulfport, Mississippi, USA), Thailand (Phuket), Malaysia (Penang) or Japan (Kagoshima). Not surprisingly, cables buried in soil in Darwin took the biggest hit, but the other test site in Griffith NSW was not far behind.
Many may assume that most of the damage in Darwin would have been due to the giant northern termites, Mastotermes darwiniensis (pictured above), a known vandal of a wide variety of non-cellulose material. However, in both Darwin and Griffith the main culprit was Coptotermes acinaciformis. In contrast the damage caused by Coptotermes formosanus and Coptotermes gestroi in other locations, also known to damage plastics was significantly lower. This difference in response between the different Coptotermes species could not be explained by the authors but may have been due to inter-specific differences in repellency/attraction to the chemicals in the plastics.
However, this observation caused the authors to conclude that testing for plastic resistance needs to take place in the environment, and against the species the material is likely to encounter when in use. Much like drawing conclusions from foraging behaviour and bait performance from overseas species, information on plastic resistance cannot be determined by using overseas data. For materials used in Australia, they need to be tested in Australia, which means exposure to Coptotermes acinaciformis and Mastotermes darwiniensis.
Reworked extract from: Resistance of polyamide and polyethylene cable sheathings to termites in Australia, Thailand, USA, Malaysia and Japan: A comparison of four field assessment methods/ Lenz et al (2012). International Biodeterioration & Biodegradation 66 (2012) 53-62