Chemical Composition and Control Potential of Melia azedarach Extracts Against Culex pipiens

Culex pipiens (Diptera: Culicidae) poses a persistent global health challenge. The overuse of synthetic insecticides has led to resistance and environmental damage, underscoring the need for sustainable alternatives. Melia azedarach (Meliaceae) represents a promising source of bioactive compounds. This study aimed to comprehensively evaluate the potential of alkaloid extracts from M. azedarach against all life stages of Cx. pipiens and to characterize their phytochemical composition.

Crude alkaloid extracts were prepared from both plant parts. Ovicidal, larvicidal, pupicidal and adult repellent effects, were assessed through laboratory bioassays. The chemical profile of the extracts was determined using Gas Chromatography-Mass Spectrometry (GC-MS).

Bioassays demonstrated significant ovicidal activity, with 100% egg mortality at 1% (w/v) concentration. Larvicidal activity was also notable at 1% (w/v). The fruit extract caused 100% mortality across the first three larval instars, while the leaf extract caused 100% mortality in the first two instars and 96.6% in the third. In the fourth instar, larvae showed 93.33 and 91.67% mortality with the fruit and leaf extracts, respectively. The extracts exhibited significant repellent effects, with rates of 63.00% and 60.00% at 1% (w/v) and consistently negative equilibrium ratios. GC-MS analysis showed the fruit extract was rich in insecticidal fatty acid esters, while the leaf extract contained repellent terpenoids like Piperitenone Oxide. Linoleic acid was a major shared compound, potentially underpinning the broad-stage efficacy.

These findings support the use of M. azedarach extracts as a promising, locally accessible and environmentally responsible strategy for integrated Cx. pipiens mosquito management.