Abstract:

Mosquitoes are factors in several parasitic diseases that are dangerous for humans. Culex pipiens is one of the mosquito species, which causes many of the health problems in Algeria. The chemical fight against these mosquitoes causes several environmental problems. Biological control is an alternative considered by the use of secondary plant substances. Saharan plants can provide toxic secondary metabolites against these mosquitoes. With the objective of valuing plants from southern Algeria, the Oudneya africana plant collected from the Ghardaïa region was used as a natural insecticide. Acetone, ethanol and methanol were used to prepare the plant extract using cold maceration method. The larvicidal power of the three extracts against Culex pipiens larvae was studied. Qualitative phytochemical screening of organic extracts is studied. The mortality rates varied considerably and significantly with the concentrations of extract, solvent used and the time of exposure. The acetone extract exhibits the highest larvicidal effect and present the lower LC50 (0.10 g/L) and LT50 (10 h) values while the methanolic extract have a less toxic (LC50=0.36 g/L, LT50=77 h). The phytochemical screening confirms that Alkaloids, Tannin and Steroids were responsible for larvicidal activity. This study shows that the extracts of Oudneya africana can be used as a natural larvicidal against mosquitoes instead of using chemical insecticidal that has negative effects on the environment and health because this natural insecticide is biodegradable. LC-MS analysis suggested that rutin, caffeoylquinic acid and chlorogenic acid are responsible for larvicidal activity of acetonic extract of Oudneya africana.

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