Evaluation des propriétés insecticides des feuilles de Callistemon viminalis (Myrtaceae) contre les adultes d'Aconthoscelides obtectus (Say) (Coleoptera; Bruchidae)
2009
Ndomo, AF. | Tapondjou, AL. | Tendonkeng, F. | Tchouanguep, FM.
Evaluation of the Insecticidial Effect of Leaves from Callistemon viminalis (Myrtaceae) against a Major Bean Pest: Aconthoscelides obtectus (Say) (Coleoptera; Bruchidae). Efficacy of essential oil, dried leaf powder and acetonic extract from dry leaves of Callistemon viminalis (Myrtaceae) against Acanthoscelides obtectus (Say) (Coleoptera; Bruchidae), a major Phaseolus vulgaris pest of stored beans in Cameroon was evaluated in the Laboratory of Environmental and Applied Chemistry of the University of Dschang from November 2003 to April 2004. Breeding of bruchids and the different tests were carried out in Petri dishes at room temperature (24 ± 1 °C) and at 85 ± 5% relative humidity. Results revealed that at the end of the first day of exposure, the highest concentrations of essential oil applied on grains (0.40 μl/g) and on filter paper discs (0.251 μl/cm2) caused 72.6% and 80% mortality rates, respectively. These rates increased up to 97.5% and 100% respectively after four days of exposure whereas no mortality was recorded in the acetone-treated controls. LD50 values of the essential oil from C. viminalis leaves against adults of A. obtectus calculated after two days of contact through filter paper discs and on grains were 0.103 μl/cm2 and 0.152 μl/g, respectively. In addition, oil repellency average (defined as the average rate of insects repelled by the oil) was amounted to 60.8%. Both powder and acetonic extract showed no activity against the insects at the tested concentrations.
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