Larvicidal activity of a living fossil!

Living fossils” refers to plants that are similar to extinct ones. One classic example –Cycads, prominent in the Jurassic and Cretaceous period but recently the cycads have started to disappear. Cycas circinalis L. commonly known as Queen Sago is an endemic restricted to the Western Ghats, was investigated for larvicidal activity. The fourth instar larvae of Aedes aegypti and Culex quinquefasciatus were exposed to test concentrations of 1000,750, 500,250 μg of hexane, chloroform:methanol [1:2] and ethanol extracts of leaf in dimethyl sulphoxide. The chloroform:methanol [1:2] extract showed 91% mortality after 48 hrs of incubation against the Aedes, LC50 of 0.302 followed by 0.219 and 0.214 for 750,500, and 250 μl concentrations respectively. Hexane extracts exhibited 95% mortality against Culex larvae. The formulations proved to be effective in inhibiting the metamorphosis. This research leads to possible utilization of new phytochemical compounds and their role in the near future as eco-friendly natural pesticides.