Sunan Wititsiri

pp. 349 - 354

Abstract

Coconut shells and coir are considered as wastes of coconut based products that have not been utilized efficiently.
By using these abundant bioresources, which are widely available in Thailand, as raw materials, we were able to produce
wood vinegars that may be alternatives to termiticides and pesticides. The wood vinegars were obtained from carbonization
process using a 200-liter fuel tank as charcoal brazier under temperatures of 300-400°C. In this study, termiticidal and pesticidal activities of wood vinegars were evaluated against termite workers, Odontotermes sp., and striped mealy bugs, Ferrisia
virgata, using direct contact application. Percent mortalities in the experiments were recorded after 24 hours and corrected
for control mortality with Abbott’s formula. Wood vinegars of 850, 696, and 898 milliliters were produced from coconut shell
(wood vinegar A) and the mixture of coconut shell and coir (wood vinegar B) and the mixture of coconut shell, coir and holy
basil (wood vinegar C), respectively. Wood vinegar A exhibited high termiticidal activity against termite workers at a dilution
of 1:50, wood vinegar: sterile water (v/v). By this way, 85% (81.71% corrected mortality) of termite workers were killed after
the 24 hours of test. At a dilution of 1:10, both wood vinegar A and B had exhibited high pesticidal activities against mealy
bugs, 96% (95.12% corrected mortality) of striped mealy bugs were killed by those wood vinegars. In the weakest termiticidal
and pesticidal activities, wood vinegar C was able to kill 60% (51.22% corrected mortality) of termite workers at a dilution of
1:50 within 24 hours. Also it killed 93% (91.89% corrected mortality) of striped mealy bugs with a dilution of 1:10 (v/v) within
the same amount of time. Post-hoc comparisons (Tukey test) revealed that wood vinegar A possessed the most effective
termiticidal activity against termite workers. However, a similarity in high pesticidal activity was found among three wood
vinegars against striped mealy bugs. The termiticidal and pesticidal properties of these wood vinegars can be attributed to the
mode of action of their active components.