TITLE:
Toxicity of the Methanol Extract and the Fractions of the Leaves of Lippia adoensis Hochst (Verbenaceae) against the Larvae of Anopheles gambiae Giles and Culex quinquefasciatus Say (Diptera: Culicidae)
AUTHORS:
Andre Sieumeni, Kary Mallam Oumarou, Lame Younoussa, Kalayam Kalayam Moutsina, Theodora Kopa Kowa, Elias Nchiwan Nukenine
KEYWORDS:
Larvicidal, Phytochemical, Extract, Fraction, Lippia adoensis, Anopheles gambiae, Culex quinquefasciatus
JOURNAL NAME:
Advances in Entomology,
Vol.14 No.3,
July
6,
2026
ABSTRACT: Nowadays, the control of mosquitoes using phyto-insecticide products is strongly encouraged to the detriment of synthetic insecticides that are not biodegradable and are also toxic to humans and animals, as well as non-target living beings. The present study aimed to evaluate the efficacy of the methanolic crude extract of Lippia adoensis leaves and its fractions against Anopheles gambiae and Culex quinquefasciatus larvae under laboratory conditions. After the phytochemical analysis of each plant product, the methanolic crude extract and its five (5) fractions were diluted in 1 mL of methanol, and different concentrations of 125, 250, 500, and 1000 ppm were prepared in 100 mL of distilled water in 250 mL plastic cups. The commercial insecticide Bi-One (49% dichlorvos) was used as the positive control, while methanol (1 mL) was added to distilled water (99 mL) to constitute a negative control. Twenty-five (25) 4th instar larvae of each mosquito species were transferred into each prepared concentration solution and control. Mortality of the mosquito larvae was recorded 24 h post-treatment. Phytochemical analysis revealed the presence of alkaloids, phenolic compounds, terpenoids, flavonoids, tannins, and saponins in the methanolic extract and fractions of L. adoensis. Among the products tested, the methanolic crude extract was the most toxic to An. gambiae (LC50 = 18.23 ppm) and Cx. quinquefasciatus (LC50 = 75.44 ppm), followed by fraction 1 with CL50 values of 70.04 and 75.88 ppm on An. gambiae and Cx. quinquefasciatus, respectively. Due to their significant larvicidal activity, the methanolic crude extract and its fraction 1 might be considered as a promising candidate in the discovery of a novel botanical larvicide to reduce the mosquito larvae density.