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Molecular Entomology 2013, Vol.4, No.2, 6-12
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8
Table 2 shows the mean absorption value of different
treatments of CEB (Test yard specimens). Minimum
absorption of 2.39 kg/m
3
of CEB was found at CEB
2.5% concentration level. Rate of absorption increased
with the increase in concentration of CEB. Absorption
was maximum (3.36 kg/m
3
) at 5% concentration level.
3.28 kg/m
3
of absorption was found in CEB at 3%
concentration.
Table 2 Absorption of CEB (10% w/v) in veneer and solid
wood of rubber wood
CEB (10%w/v)
concentration (%)
*Mean absorption in rubber wood
(kg/m
3
)
2.5
2.39
3
3.28
5
3.36
Table 3 shows the percentage of damage by
subterranean termite in treated and untreated solid
wood samples exposed in the test yard. Observations
were taken periodically for a period of 6, 12, 24 and
30 months. The untreated control samples were
damaged up to 50% within 12 months and nearly 92%
within 30 months of exposure. It can be seen from the
figure 2 that treated samples are almost sound upto 24
months of exposure at all the treated concentrations.
CEB at 5% concentration level resulted as the best
treatment in arresting the attack of subterranean termite.
Even at the end of the study, CEB at 2.5% and 3%
concentration shows slight damage of 4% and 3.11%
respectively. At the end of the test i.e. after 30 months,
the treated solid wood samples recorded the attack in the
range of 2 to 4 average percent attack which is rated as
trace attack as per IS 4833 (Anonymous, 1993).
Figure 2 Solid wood samples after exposure study against
subterranean termite
Note: A: CEB 2.5%; B: CEB 3%: C: CEB 5%
In case of glue line poison treated plywood samples,
the untreated panels were damaged up to 89.84%
within twelve months and 100% in 24 months of
exposure (Table 5 and Figure 3). Whereas, the panels
treated with CEB at all concentrations i.e. 2.5%, 3.0%
and 5.0% resisted the attack till 24 months. At the end
of the study period, lowest studied concentration rate
of 2.5% showed trace average attack of 4.91%. CEB
at 3% concentration rate also recorded the trace attack
(4.22%). 3.41% of attack was recorded in 5%
concentration.
Figure 3 Plywood samples after exposure study against
subterranean termite
Note: A: CEB 2.5%; B: CEB 3%; C: CEB 5%
Table 3 Efficacy of CEB against subterranean termite on solid wood
*Average percentage damage/attack (%)
CEB (10%w/v)
concentration (%)
6 MAE
12 MAE
24 MAE
30 MAE
2.5% CEB
0
0
0
4
3% CEB
0
0
0
3.11
5% CEB
0
0
0
2
Control
4.33
50
80.18
91.67
* Average of six samples