Evaluating the natural durability of a number of lesser known species of Ghanaian hardwoods using a short term laboratory assay
J R Williams, S M Cragg, L M S Borges, B Shayler
Resistance of a number of Ghanaian hardwoods to attack by the crustacean Limnoria quadripunctata was assessed by measuring the production of faecal pellets under forced feeding conditions over a two week period. Small sticks of commercially available, lesser known timber species, were leached in seawater for one week then placed in a cell culture chamber with one animal and 4 ml of seawater. At intervals, the number of faecal pellets per chamber was counted. The number of pellets produced by animals feeding on Scots pine sapwood, which is non-durable, and on greeheart or ekki, timbers with a reputation for resistance to marine borer attack, were used as a basis for comparison. Mortality rates were also compared. Lower pellet production rates and higher mortality rates were taken as measures of natural durability. Feeding on ekki (Lophira alata), kusia (Nauclea trillesii) and ananta (Cynometra ananta) was about one tenth of that on Scots pine. Mortality of animals with wonton (Morus mesozygia) was 90%, but high mortality did not occur with any of the other species.