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Molecular Entomology 2013, Vol.4, No.2, 6-12
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10
tested concentration of CEB at 5% was excellent in
controlling PPB and subterranean termite. But on the
background of better bioefficacy obtained at the lower
dose of CEB 2.5%, its use would be relatively safe to
the workers and the end users. Hence, CEB at 2.5%
has been recommended as the lethal dose to control
the wood destroying insects. The insecticidal property
of Boron is widely proven and in the present study the
Boron has been fixed in the treated wood and this may
be the reason for the excellent activity of the CEB
chemical against PPB and subterranean termite.
Borates like boric acid, borax or disodium octaborate
tetrahydrate have proved their efficacy as wood
preservatives for many years. The insecticidal
properties of CEB found in this study may be due the
presence of Boron. These are in consistent with Su
and Scheffrahn, 1991 and Ahmed et al., 2004. These
compounds have shown to be highly toxic to insects
including termites, and fungi (Lloyd, 1997; Drysdale,
1994).
Copper sulphate and Boric acid have multi spectrum
biocide activity but none of them have efficient
fixation capacity in wood. Thus, present formulation
has an advantage that an appreciable amount of
individual metal ion could be fixed. Efficient
protection of rubber wood at all concentrations was
achieved against PPB and subterranean termite. On
the basis of results and discussion of present
investigation it can be concluded that CEB (10% w/v)
at 2.5% may be adopted as the lethal dose to control
PPB and subterranean termite.
3 Materials and Methods
The experiments were conducted during 2009 to 2012.
The laboratory and field experiments were conducted
at laboratory and test yard of Indian Plywood
Industries Research&Training Institute (IPIRTI),
Bangalore, Karnataka respectively. The experiment to
evaluate the efficacy of CEB against PPB and
subterranean termite was as per IS 4873 (Part 2)
(Anonymous, 2008) and IS 401 (Anonymous, 2001)
respectively.
3.1 Wood specimens
Specimens were made of Rubber wood (Hevea
brasiliensis). Rubber wood has a density of 560~640
kg/m
3
(16% M.C.). Seasoned rubber wood is being
used for making furniture in India. It comes under
non-durable class of timber as per IS: 401
(Anonymous, 2001). The samples selected for the
study were free from visual defects.
3.2 Treatment solutions
CEB composition consisted of Copper sulphate,
Mononethanolamine (MEA), Boric acid, Octanoic
acid and co-biocide based aqueous solution. The stalk
solution of CEB (10% w/v) was made by mixing
Copper sulphate, MEA, Boric acid, Octanoic
acid/Caprylic acid and Propiconazole in tap water. The
molar ratio of the mentioned chemicals was kept as
follow:
Ethanolamine: Octanoic acid: Copper sulphate: Boric
acid: Propiconazole=1
:
0.083 8
:
0.223
:
0.158
:
0.0045
The above mentioned chemicals were mixed in tap
water to make solution. The chemicals were added in
the water (stock solution) as shown below in Figure 4.
Figure 4 Flow chart to make CEB solution
The pH of the CEB solution was 10 at the time of
preparation and did not change even after one month
of storage in the laboratory.
3.3 Treatment of Solid wood planks by dipping
method
Solid wood of rubber wood was treated with CEB
(10% w/v) by dipping method for half an hour. The
concentrations used for the treatment were 2.5%, 3%
and 5% made from the stalk solution. The moisture
content of the wood before dipping was in the range of
25~30%. The samples were of size 30 cm × 30 cm ×
2.5 cm. After getting maximum absorption in 30
minutes the planks were removed. The blocks were
blotted off to remove free liquid and were reweighed.