Nerium oleander leaf extract causes midgut damage and interferes with the survival of Culex pipiens L. larvae

Diseases vectored by mosquitoes are one of the major causes of diseases and death worldwide. Insecticide resistance of Cx. pipiens increased the suffering of the people. Plants are a promising source of secondary metabolites that could provide valuable insights in the search for effective insecticidal agents and help address the issue of insecticidal resistance.

This study investigated the larvicidal potential of N. oleander methanol aqueous extract against Cx. pipiens.

Post 24 h, 48 h and 72 h of exposure, the LC₅₀ value was 4.94 mg/mL and the LC₉₀ value was 8.01 mg/mL. After 72 h of exposure, the values were 2.93 mg/mL and 4.79 mg/mL, respectively. Larvae treated with N. oleander leaf extract displayed degraded microvilli, degenerating peritrophic membrane and degenerating nuclei with blebbing compared to the control. The GC-MS analysis revealed the presence of eleven phytoconstituents in the leaf extract. 1-Methyl-1H-Tetrazol-5-yl) thioacetic acid (80.67%), 2-Furancarboxaldehyde, 5^-1 (hydroxymethyl)- (8.10%) and 9,12-Octadecadienoic acid (Z, Z)- (4.33%) were the main secondary metabolites found in the leaf extract.