STUDIES ON THE REPELLENT AND TOXICOLOGICAL ACTIVITIES OF THE AQUEOUS LEAF EXTRACT OF AN INVASIVE ALIEN SHRUB, CHROMOLAENA ODORATA (L.) (ASTERACEAE) AGAINST THE WORKER CASTE OF MACROTERMES SPP. (TERMITES)

ABSTRACT

Although, several studies have demonstrated the repellent and toxicological activities of the leaf, stem, and root powders and/or extracts of C. odorata against insect pests, studies focusing on the repellent and toxicological activities of the aqueous leaf extract of this same plant against Macrotermes speciesare scarce. Therefore, this study investigated the repellent and toxicological activities of C. odorata leaf extract against Macrotermes species. Five concentrations (0, 2.5, 5.0, 7.5, 10.0% (w/v)) of the aqueous leaf extract of C. odorata plant were tested on the worker caste of Macrotermes species using the filter paper impregnation technique after which percentage repellency was monitored for 30 minutes and mortality for 12, 24, and 36 hours. Results from this study revealed that the leaf extract of C. odorata significantly repelled 95% of Macrotermes species at the highest concentration (10% (w/v)) after a 30 – minute exposure period. Mortality of Macrotermes species caused by the leaf extract of C. odorata was observed to be independent of the concentration, but dependent on the duration of exposure. Following a 36 – hour exposure period, all concentrations (0, 2.5, 5.0, 7.5, 10.0% (w/v)) demonstrated significant toxicological activity against Macrotermes species with percentage mortality ranging between 94% and 98%. In summary, this study demonstrated the potential for the use of C. odorata leaf extract against Macrotermes species for the first time and further suggest the use of this plant in reducing or ameliorating the damages caused by this insect pest in Nigeria and elsewhere.