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Molecular Entomology 2013, Vol.4, No.2, 6-12
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11
The percentage of intake of preservative or the amount
of preservative absorbed by the sample was calculated
in kg/m
3
as per IS 4873 (Anonymous, 2008). The
samples were conditioned and subjected in the test
yard to assess the bioefficacy of CEB against
subterranean termite.
3.4 Glue line treatment of plywood
Three concentration levels viz., 2.5, 3 and 5% of CEB
respectively were mixed with PF resin as glue additive
on the weight of solid content of resin. Control
samples were also prepared in which preservative
chemical was not added in glue. The veneers were
dried to a moisture content of 6~8% and then coated
with above adhesive mixed. The glue coated veneer
were given an open assembly time of 1.5 to 2 hours to
attain moisture content of 12~14%.
The veneers were then assembled to 4 mm thickness
and loaded into the hot press. The assembly was hot
pressed at a temperature of 145
±
5
℃
with a
specific pressure of 14~16 kgs/cm
2
. Curing time of
thickness + 3 minutes was provided. The hot pressed
panel was downloaded and stacked for about 24~48
hours for stabilisation. The panels were then
dimensioned to required size for further evaluation.
3.5 Toxicity of CEB against Lyctus
The toxicity test was carried out as per IS 4873 (Part 2)
(Anonymous, 2008). Adults of the powder post beetle
i.e.
Lyctus africanus
were used for the test which were
obtained from the laboratory cultures. Toxicity test
Plywood made from Rubber wood veneers were cut
into test samples of 10 cm × 4 cm size. Six
replications were used in each treatment. The treated
along with untreated control samples were kept with
material infested with powder post beetles (
Lyctus
africanus
) in culture tubs. Monthly observations were
made and recorded as IS 4873 (Part 2) (Anonymous,
2008), covering a total exposure period of eighteen
months. Results are presented in Table 1. Photographs
of plywood samples after exposure of thirty months
are depicted in Figure 1.
3.6 Field test/ test yard/ grave yard test
Toxicity test was performed according to IS 4833
(Anonymous, 1993). Treated and untreated solid wood
and plywood samples were randomly installed in test
yard. Six replications were made for each treatment
with control stakes in rows at test yard. Termite
activity and percentage of damage to the test panels
were recorded at the intervals of three months.
Observations were made covering a total exposure
period of thirty months. Specimens were reinstalled in
their respective positions after each inspection. The
knife test or sound test was carried out as and when
necessary to determine the extent of decay or
destruction due to termite attack till the sample was
destroyed. The visual observations and ratings were
done according to the IS 4833 (Anonymous, 1993).
Results of toxicity studies on CEB against
subterranean termite on solid wood and plywood
against termites are presented in Table 3 and Table 5
respectively.
Author’s Contribution
The new chemical has been developed by the author. Bioefficacy study,
statistical analysis and manuscript preparation has also been done by the
author.
Acknowledgement
This paper is published with kind permission of Director, IPIRTI, Bangalore,
Karnataka, India.
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