Chemical Compositions and Preventive Activity of Essential Oils Extracted from the Leaves of two varieties of Tephrosia (Leguminosae-papilionoideae) collected in Benin on Callosobruchus maculatus (Fabricius)

Essential oils extracted by hydrodistillation of Tephrosia vogelii (Hook. f.) And Tephrosia densiflora (Hook. f.) leaves harvested in Benin were analyzed by GC/MS. The essential oil of T. vogelii contains 33 to 38 compounds representing 91.6 to 99.5% of the weight of this volatile extracts. 28 to 36 compounds corresponding respectively at 86.0 to 99.8% of the weight of T. densiflora leaves essential oil were identified. The major compounds (> 3%) identified and recorded independently of the studied variety are β-caryophyllene (4.6 -45.0%), germacrene-B (13.3 -18.0%), (E)nerolidol (8.1 -20.7%), elemol (5.9 -13.0%), 14-hydroxy-9-epi-(E)-caryophyllene (9.8 -11.5%), humulene epoxide II (5.4 -10.8%), phytol (4.3 -9.3%), α-humulene (3.4 -9.2%), carotol (3.2 -7.2%), %), guaia-3,10(14)-dien-11-ol (7.0%), (Z)-β-farnesene (6.9%), cadalene (6.8%), epi-α-bisabolol (3.8 -6.0%), germacrene-D (4.7 -5.8%), α-bisabolol (5.3%), selina-3,7(11)-diene (5.2%), caryophyllene oxide (4.5 -5.2%), 14-hydroxy-α-humulene (4.2 -5.1%), (6S, 7R)bisabolone (4.0 -4.8%), β-acoradiene (4.7%), epi-cedrol (4.1%), epoxide-allo-aroamdendrene (4.1%), 8-muurolene (3.7%), α-acorenol (3.7%), β-farnesene (3.6%), α-muurolol (3.2%), cis-calamenene (3.1%), α-cadinol (3.1%). The doses of each of these essential oils tested on C. maculatus at temperatures between 22°C and 31°C and a relative humidity of 80% are 0, 5, 10, 15 and 20μL/mL. Both essential oils, through their chemical constituents, have different effects (insecticidal, larvicidal and ovicidal) on C. maculatus (Fabricius) adults living on seeds of cowpea (Vigna unguiculata L. Walp.) of local variety "Chawe." In this occasion, the damage caused by C. maculatus and its larvae were evaluated by calculating the percentage of seeds attacked (A) and weight loss of these (B).