Larvicidal efficacy of Quassin against Culex quinquefasciatus.

Crushed aqueous extracts of leaf, wood, bark and flowers of Quassia amara showed antilarval activity against C quinquefasciatus. Quassin has been identified to be the antilarval principle present in this plant and was effective against mosquito larvae at a concentration of 6 ppm. Quassin was present to the extent of 0.1 to 0.14 per cent (average 0.12%) on a dry weight basis in wood of Q. amara. This compound is an unsaturated lactone and it gave a positive response to the Legal test, characteristic of unsaturated lactones. Quassin lost its antilarval activity on treatment with strong alkalies. Quassin was over five times as active as carbaryl, a synthetic antilarval agent.