Biocontrol potential of <i>Flemingia wightiana</i>: A natural weapon against <i>Culex quinquefasciatus</i>

Globally, mosquito-borne diseases, particlulalry those transmitted by Culex quincquefasciatus pose a significant public health challenge. Traditional methods of eradication using synthetic insecticides pose environmental concerns and a risk of developing insecticide-resistant varieties. Here, the use of plant-based biopesticides offers a safer and sustainable alternative. The study aimed to investigate the insecticidal properties of Flemingia wightiana (FW) leaves by synthesising leaf extracts and silver nanoparticles. The toxicity of the test samples was tested on Oreochromis niloticus at concentrations of 0.1, 0.5, and 1 mg/L. Furthermore, the test samples were subjected to lethality assay on C. quinquefasciatus. Laboratory bioassays were conducted to evaluate the efficacy of crude extract and silver nanoparticles of F. wightiana at varying concentrations, specifically 0.5, 1, 2, and 4 mg/L. Ovicidal, emergency and larvicidal activity were studied. The results indicated significant larvicidal activity and exhibited better potential for toxicity against Culex larvae treated with AgNPs. FW-AgNPs have substantial effect in delaying the hatching of mosquito eggs. Moulting of larvae from one instar to the next was also delayed by treatment with AgNPs. The findings demonstrated that FW-AgNPs play a significant role in controlling C. quinquefasciatus populations.