Efficacy of Some Selected Edible Essential Plant Oils in the Management of Subterranean Termites Infestation on Wood-in-Service in Lafia, Nigeria.

This study evaluated the efficacy of three edible essential plant oils (Clove, West African black pepper (WABP) and Ginger) and one commercially produced termiticide (Termiguard®) for the control of subterranean termite infestation on Gmelina arborea as a servicing wood. The study was conducted at the Faculty of Agriculture (Shabu-Lafia Campus), Nasarawa State University Keffi, Nigeria. The wood test samples measured 4x4x40 cm and the study was laid in a 5 x 3 x 2 factorial experiment in a Completely Randomized Design (CRD) with a total of 30 treatment combinations replicated 10 times making a population of 300 test samples. Each wood test sample was staked at 1 x 0.5 m with 20 cm of the test samples planted into the soil while the other half (20 cm) was exposed to natural environmental conditions for a period of 20 months. Dry weight, %moisture content was taken prior to staking and at 4 months interval of exposure to subterranean termites. The results showed that the susceptibility of Gmelina exposed to subterranean termites in the Graveyard site had final %weight loss of (21.12±8.25%) while samples buried at the termitaria had (19.55±19.69%). It further revealed that the final %weight loss in Gmelina treated with Ginger (17.43±23.78%), WABP (17.78±10.46%), Clove (20.42±13.68%) were not significantly different (p≥0.05) but significantly different (p≤0.05) from the final %weight loss observed in Gmelina treated with Termiguard® (Treated check) (13.76±6.12%) and the %weight loss of (24.78±15.39%) in non treated samples at (p≤0.05). Thus, the susceptibility of Gmelina exposed to subterranean termites at the Graveyard site treated with edible essential plant on oils can be ranked as follows: Control>Clove>WABP> Ginger>Termiguard® (Treated check). The results also showed that the final %weight loss in Gmelina treated at 0.5 dosage rate had (24.78±15.39%) and 1.0 dosage rate had (26.34±21.79%) were not significantly different (p≥0.05) but significantly different (p≤0.05) from the final %weight loss in samples treated at 1.5 g/640 cm3 application rate with %weight loss of (18.55±11.82%). Thus, the susceptibility of samples exposed to subterranean termites at the Graveyard site treated with edible essential plant oils can be ranked as follows: 1.5>0.5>1.0 rate of application and these were significantly different (p≤0.05) from each other. Based on the results of theis study, ginger at an application rate of 1.5 g recorded the least weight loss among the three edible essential plant oils and this compared favourably with the treated check, Termiguard®; it is therefore, recommended for use as a wood preserver.