Larvicidal Efficacy of Cassia singueana methanol leaf extract against Aedes aegypti and Culex quinquefasciatus

Abstract

Despite the persistent control measures, mosquitoes remain abundant and the disease they transmit persists globally posing significant health challenges. There is increasing enthusiasm for exploring botanical solutions as substitutes for conventional chemical insecticides, driven by their broad insecticidal attributes, eco-friendly nature and compatibility with various ecological settings. As such, the study was designed to assess the larvicidal properties of methanol leaf extract of Cassia singueana against Aedes aegypti and Culex quinquefasciatus. The plant was subjected to preliminary and GC-MS phytochemicals screening. Larvicidal bioassay was conducted using six different concentrations (0.10-3.20 mg/ml) and 31.25mg/l temphos and distilled water were used as positive and negative control respectively. The experimental set up was observed after 24 h and the lethal concentrations (LC₅₀ and LC₉₉) were determined using Probit analysis. Preliminary phytochemical screening of C. singueana methanol leaf extract revealed the presence of alkaloids, cardiac glycosides saponins, phenolic compounds, tannins, steroid carbohydrates, flavonoids, and terpenoids. Eighteen (18) bioactive compounds were identified in the methanol leaf extract of C. singueana which includes 1,5-Heptadien-3-yne, 2-Hydroxy-3-methylbenzaldehyde, 2-Butenoic acid, Acetonitrile, 2,2'-iminobis-, 7,11-Hexadecadienal,2-Hexyne, among others. The extract had larvicidal activity against A. aegypti and C. quinquefasciatus with LD₉₉ of 5.44 mg/ml and 15.85 mg/ml respectively at 24 h post-treatment. This study offers valuable perspectives on the possible application and advancement of C. singueana leaf extract as a potential bioinsecticide against A. aegypti and C. quinquefasciatus and consequently control the diseases transmitted by them.