Repellent, insecticidal and phytotoxic activities of isoalantolactone from Inula racemosa

 Isoalantolactone, a natural product isolated from traditional Chinese medicinal herb roots of Inula racemosa Hook. f. (Fam. Compositae), has been shown to possess strong antifungal activities. The present investigation showed that isoalantolactone also exhibited repellent and toxic activities against rice weevil [Sitophilus oryzae (L.) (Coleoptera: Curculionidae)] based on a food preference apparatus and a poisoned food technique. The toxicity of isoalantolactone to rice weevil was dose dependent, whereas the repellency was not. Isoalantolactone showed strong phytotoxic effects on seed germination and seedling growth of wheat at a concentration of 500 μg ml−1 for 60 h; however, this side effect could be reduced markedly by shortening the treating time at this concentration. Results indicate that isoalantolactone might be considered for wheat seeds preservation in control of storage weevils.