Screening of some weed extracts activities against dengue vector Culex spp. (Diptera: Culicidae) under laboratory conditions in Kolkata, West Bengal

The use of plant-based formulations offers a simple and cost-effective approach for controlling insect pests. The study aimed to assess the larvicidal effects of five weed extracts- Lemna minor, Elodea canadensis, Ludwigia hyssopifolia, Alternanthera philoxeroides Eichhornia crassipes, against qulex larvae using four solvents: acetone, 70%alcohol, chloroform and benzene. The objectives were to determine the most effective plant-solvent combination for larval mortality. The percentage of mortality of Culex larvae was calculated after 24, 48, 72 and 96hrs of exposure in different concentrations (50,100,150, 200, 250 and 300ppm). Among them the Lemna minor shows highest larvicidal activity (LC50 value was 58.34823984, 57.79808592, 24.59814031 and 51.95713872). The results highlight the influence of solvent polarity on the extraction of activity larvicidal compounds. This study suggests that common aquatic weeds could serve as promising, eco-friendly sources for mosquito control agents, offering an alternative to synthetic pesticides.