Contact and repellent effects of essential oils of Chromolaena odorata (L.) and Uvaria chamae (P. Beauv) against Macrotermes bellicosus (Smeathman)
Macrotermes bellicosus, though a beneficial termite species causes serious damage to wood and wood products, fabrics and many agricultural crops and ornamental trees. This study was conducted to assess the potentials of essential oils of the leaves of Chromolaena odorata and roots of Uvaria chamae in the control of M. bellicosus. The repellency, knockdown and insecticidal effects of the oils to M. bellicosus were tested using the filter paper and cotton ball impregnation technique. Each test oil (0.05, 0.075 and 0.10 ml) was separately used in the repellency assay, for an exposure period of 30 and 60 minutes. For the knockdown and toxicity test, termites were exposed to 0.05, 0.075, 0.10, 0.125 and 0.15 ml of each oil for an exposure period of 60 minutes and 6 hours, respectively. Each test and control (untreated) group had three replicates and in each experiment twenty active workers of M. bellicosus were exposed. Repellency results were somewhat irregular and oil volume and exposure, time independent. Knockdown effect of 56.67 and 86.67 % were observed for C. odorata and U. chamae oils (0.15ml), respectively at the 60th minute. Contact toxicity test with 0.15 ml of the oils resulted in 100 % and 86.67 % mortalities for U. chamae and C. odorata, respectively. No knockdown or mortalities were observed in the controls. The difference between the repellency of both oils at 30 and 60 minutes was not significant (p>0.05; p= 0.842 and 0.212 respectively), whereas for knockdown and insecticidal effects of both oils the difference was significant Q3(p<0.05; p= 0.000 and 0.001 respectively).. Essential oils of C. odorata and U. chamae are potential agents for the control of M. bellicosus.
Ubulom PME, Akpan AU, §Umohata IA and Iboyo EA.