Comparative lethal effects of three Ocimum plants species against Culex quinquefasciatus mosquito larvae

Abstract :

Successes have been reported from studies involving the use of botanical derivatives as larvicides, repellents or insecticides. The toxicity of the aqueous, methanolic and oil extracts of the three plants: Ocimum gratissimum L., O. canum Sims and O. basilicum L. (family: Labiacae) were tested on the 3rd instars larvae of Culex mosquitoes which is an important vector for filariasis, encephalitis to humans. This approach is meant to find a safer and cheaper alternative for vector control. The extracts were graded into concentrations and the larvae were exposed to test for 3 and 24 hours with percentage mortality of 74.17% at LC50 value of 0.95g/ml in methanolic extract of O. basilicum being the most potent after 24 hours followed by O. canum (methanol) with 71.83%, O. basilicum aqueous (68.33%) and O. gratissimum methanol extract (65%). However, the oil extract of O. canum was most potent after 3hours with 57.33% mortality (LC50 = 1.0g/ml), followed by O. basilicum 49.33% (LC50 = 1.0mg/ml) while O. gratissimum was the least toxic at 42.00% mortality (LC50 = 2.0g/ml). Invariably, these plants can be incorporated as botanical larvicides to inhibit the growth of mosquito vectors in order to prevent transmission of the mosquito borne diseases.

Keyword :

Toxicity, extracts, Ocimum gratissimum L., Ocimum canum Sims, Ocimum basilicum L.

Author(s) : Aina, S. A., Onajobi, I. B., Salisu, T. F., Owagboriaye, F. O., Olasupo, A. O., Sanusi, A. S., Samson, O. J., Adeoye, A. T.
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Published Issue : 2023 Vol. 18 Number 1

2023 Vol. 18 Number 1