Contact and fumigant activities of constituents of Foeniculum vulgare fruit against three coleopteran stored-product insects.

The insecticidal activities of materials derived from the fruit of fennel, Foeniculum vulgare, against adults of Sitophilus oryzae, Callosobruchus chinensis and Lasioderma serricorne were examined using direct contact application and fumigation methods. The biologically active constituents of the Foeniculum fruits were characterized as the phenylpropenes (E)-anethole and estragole, and the monoterpene (+)-fenchone, by spectroscopic analysis. Responses varied with insect species, compound, dose and exposure time. In a filter paper diffusion test, estragole at 0.168 mg cm-2 caused 91% mortality to S oryzae adults within 1 day after treatment (DAT), whereas (+)-fenchone and (E)-anethole gave over 90% mortality at 2 and 4 DAT, respectively. Against C chinensis adults, all test compounds revealed potent insecticidal activities at 0.021 mg cm-2 at 2 DAT. Against L serricorne adults at 0.105 mg cm-2, (E)-anethole gave 100% mortality at 1 DAT, whereas 90 and 60% mortality at 4 DAT was achieved with estragole and (+)-fenchone, respectively. In a fumigation test, the compounds were much more effective against adults of S oryzae, C chinensis and L serricorne in closed cups than in open ones, indicating that the insecticidal activity of test compounds was largely attributable to fumigant action. As naturally occurring insect-control agents, the F vulgare fruit-derived materials described could be useful for managing field populations of S oryzae, C chinensis and L serricorne.