Attached
Wood destroying insects and their attack on eight
commercial timber species were studied through a survey in
different climatic zones in sri Lanka, field experiments
and laboratory experiments. Eight commercial timber species
used for this study are Jak (Artocarpus heterophyllus),
Eucalypts (Eucalyptus grandis) , Rubber (Hevea
brasiliensis), Tualang (Koompassia excelsa), Lunumidilla
(Melia dubia), Pine (Pinus caribaea), Mahogany (Swietenia
macrophylla) and Teak (Tectona grandis).
Common wood destroying insects were
collected and identified as Longhorn beetle (Batocera
rubus), Powder - post beetle (Heterostrychus brunneus),
Subterranean termite (Odontotermes redemanni), Carpenter
ant (Camponotus abdominalis), carpenter bee (Xylocopa
latipes), Pinhole borer and weevil. Subterranean termite,
Powder - post beetle and Longhorn beetle were found as the
most important insects according to their damage.
Subterranean termite attack was studied in the
field under natural condition using grave yard trials.
Attacks of termite, powder post beetle and longhorn beetle were studied in laboratory experiments. These
laboratory experiments were carried out according to the
techniques developed by earlier authors, and using new
techniques developed by the author.
Ants and Cunningimella fungus were observed as a
biological control for termites in the field as well as in
the laboratory experiment.
Results show that loss of weight due to insect
attack was significant different between different timber
species. Mortality of insects also significantly differ in
different timber species. Based on these findings timber
species were categorised into three groups: insect
resistant species, moderately resistant species and
susceptible species. Eucalyptus, teak and tualang were the
most resistant species while freshly felled jak was highly
susceptible to larvae of Batacera (Longhorn beetle).
Mahogany was susceptible to powder - post beetle. Rubber
was the most susceptible species, and it is recommended to
use preservative treatment for the effective utilization af
these species.
Wood parameters, density and moisture content of
wood were determined under air dried condition. Moisture
content of wood was positively correlated to the termite
attack and the density was negatively corre·lated to the
termite attack.
