Phytochemical Composition and Larvicidal Activity of Ocimum canum (L.) Essential Oil against Anopheles gambiae (Diptera: Culicidae)

Background: Malaria is a serious health problem in many countries of the world especially sub-Saharan African. Anopheles mosquito which is the vector of this disease has developed resistance against synthetic pyrethroids which are the main stay of insecticide treated bed nets. The development of insecticide resistance and side effects associated with synthetic pesticides has triggered intense research efforts towards natural products.

Aim: This study aimed at investigating quality and quantity of phytochemical constituents of Ocimum canum leaf extract and determined larvicidal effect of essential oil component of this plant extract on 3rd instar larvae stage of Anopheles gambiae.

Methods: The essential oil was extracted by hydro-distillation using Clevenger type apparatus. Standard methods previously described by other authors were used to determine the quality and quantity of phytochemical components of the plant and larvicidal bioassay method was used to determine the effect of essential oil of O. canum on the mosquito larva.

Results: The analysis of the phytochemical revealed the presence of the following compounds: Tannin, phenol, saponin, trepenoid, alkaloid, steroid, and flavonoid, with the following quantities 22.14, 19.83, 14.08, 10.97, 8.16, 3.40 and 5.29 mg/g respectively. The mosquito larvicidal bioassay showed LC50 and LC90 values of 49.51 and 103.54×10-3 mg/ml respectively after 24 hours exposure to essential oil extract.

Conclusion: The results obtained showed that the essential oil of O. canum is a promising mosquito larvicidal compound.