Caractérisation et évaluation au laboratoire de l’effet de l’huile essentielle de piper nigrum sur les stades aquatiques de anopheles gambiae giles, 1902 (diptera : culicidae) vecteur du paludisme

Abstract

Malaria remains by far the most important parasitosis in the intertropical world, particularly in Africa South of the Sahara (Tchoumbougnang et al., 2009). Behavioral change and the emergence of resistance to synthetic insecticides in natural vector populations has led researchers to consider the use of natural molecules, that is, those of plant-based. In this work ovicidal, larvicidal and "nymphocidal" activities of the essential oil of Piper nigrum seeds were evaluated on Anopheles gambiae ss. Adults mosquitoes were supplied from OCEAC and were reared in the insectarium of the Laboratory of zoology of the Trachers Training College of Yaoundé. Piper nigrum essential oil was extracted by hydrodistillation and a chemical analysis was carried out by gas chromatography (GC) and by gas chromatography-mass spectrometry (GC / MS) coupling. Eggs, larvae and nymphs were exposed to essential oil and tested in laboratory according to the protocol of the WHO 2005. The essential oil was tested at 0.025% ; 0.05% ; 0.1% ; 0.3% ; 0.5% ; 0.6% ; 0.7% ; 0.9% ; 1% ; 1.5% ; 2% ; 2.5% et 3%. The extraction yield of the Piper nigrum HE was 0.26%. This essential oil has revealed the presence of 30 terpenes compounds ; Monoterpenes were the main group of compounds found with limonene (9.74%), (+) - camphene (8.44%) and β-pinene (8.00%) as the main ingredients. Biological tests showed a very low egg hatching rate (5%) after 72 hours of exposure at a concentration of 3% of essential oil was obtained; after 48 hours of exposure, 100% mortalities in 1 and instar 2 larvae at a concentrations of 0.5% were observed; 3 and 4 instar larvae to have a total mortality required concentration of 0.7% and 0.9% respectively. With nymphs, we have a very low emergence rate (3%) for a 3% oil concentration after 72 hours of exposure. From these results, it appears that the essential oil of Piper nigrum has ovicidal, larvicidal and "nymphocidal" properties on the aquatic stages of Anopheles gambiae.