Larvicidal Activity of Momordica foetida (Cucurbitaceae), Gnidia glauca (Thymelaeaceae) and Vepris soyauxii (Rutaceae) Extracts on Anopheles gambiae Mosquitoes and their Acute Toxicity on Rats

Author(s): Metoh Theresia Njuabe, Chi Tchampo Fru, Soh Desire, Herman Parfait Awono- Ambene

Background: The need to apply alternative strategies to control African malaria vectors such as Anopheles gambiae s.l. is extremely relevant. This study aimed at determining the larvicidal activity of 03 plants against Anopheles gambiae s.l and their acute oral toxicity.

Methods: Bioassays were carried out with third-instar larvae of Anopheles gambiae and Anopheles coluzzii mosquitoes adapted to laboratory to check for LC50 and LC90 and mortality rates, 24 and 48 hours post- exposure to aqueous and methanol extracts from Momordica foetida, Gnidia glauca and Vepris soyauxii plants. The testing concentrations ranged from 100 to 450 ppm. The toxicity of their methanol extracts was also evaluated using Wistar rats.

Results: Methanol extracts showed high lethal activity against Anopheles gambiae and Anopheles coluzzii larvae as compared to aqueous extracts, with variations by plant and Anopheles species as well as duration of exposure. LC50 and LC90 values recorded upon 24h exposure to Vepris soyauxii methanol-based extracts were 203.92 ppm and 241.46 ppm in Anopheles gambiae and 215.01 ppm and 270.87 ppm in Anopheles coluzzii, respectively. These respective LC50 and LC90 values increased with Gnidia glauca and Momordica foetida extracts. As for the toxicity, the highest concentrations of 750 ppm did not show any symptoms of toxicities and death on Wistar rats.

Conclusion: V. soyauxii and other study plant extracts showed promising biological responses against malaria vector species, Anopheles gambiae and Anopheles coluzzii, and may serve as potential alternative and eco-friendly tool for larval control in African endemic countries.