Comparison of the feeding deterrent activity of some sesquiterpene lactones and a lignan lactone towards selected insect storage pests

Four sesquiterpene lactones isolated from Eurpatorium cannabinum, Homogyne alpina and Petasites albus (all Compositae), together with two of their adducts, as well as one lignan lactone of dibenzylbutanolide type from Libocedrus yateensis (Cupressaceae), were tested for their feeding deterrent activity against the adults of Sitophilus granarius and Tribolium confusum, as well as against the larvae of Tribolium confusum and Trogoderma granarium. The strongest deterrent activity against all species was exhibited by the lignan lactone yatein and the sesquiterpene spirolactone bakkenolide A. Both may be included to the class of very good insect feeding deterrents. The comparison presented here showed that the conjugated α-exomethylene moiety of the lactone ring was not the decisive factor for the deterrent activity in the investigated test model.