ABSTRACT

Whiteflies are problematic to several crops including citrus. Hence this study was aimed at evaluating the insecticidal properties of aqueous extracts of Chromolaena odorata against whiteflies and its associated non-target (ant) species. Aqueous extracts of 50 g C. odorata (in 50ml of water) was prepared as stock concentration, from which other concentrations (10%, 1%, 0.1% and 0.01%) were obtained through serial dilution technique. Ten unsexed whiteflies and five ants, replicated five times, were separately treated with the different concentrations and they were monitored for mortality after 24 and 48 hours. The percentage mortality encountered in the trials were corrected using Abbott’s formula. It was observed that percentage mortality on the 100% w/v was significantly higher than that caused by the 1% dilution but not others. For whiteflies, percentage mortality after 24 hours in units treated with 100% w/v had (37.50 ± 7.36%) which was not higher than 10% w/v (29.17 ± 3.89%), 0.01% w/v (22.92 ± 5.3%) and 0.1% w/v (14.58 ± 5.10%), but was significantly higher than 1% w/v (12.50 ± 6.25%). Percentage mortality in treatments of 100% w/v after exposure of 48 hours had (76.47 ± 7.49%) which was higher than treatment 10% w/v (35.29 ±3.60%), 0.1% w/v (26.47 ±5.50), 0.01% w/v (20.58 ± 8.05%) and 1% w/v (8.82 ± 7.49%). Following exposure period and concentration of aqueous extracts of Chromolaena odorata it was observed that no treatment caused significant harm to the predatory ants. Conclusively, the insecticidal activities of C. odorata in this study suggests that the leave extracts of plants can be used in the control of the pest Bemisia tabaci with no significant harm on a non-target organism.