Insect feeding deterrent activity of lignans and related phenylpropanoids with a methylenedioxyphenyl (piperonyl) structure moiety

The antifeedant activity of a series of lignan lactones, hemiacetals, ethers, and alcohols derived from yatein and cubebin, together with structurally related phenylpropanoids and phenolics possessing a methylenedioxyphenyl (piperonyl) moiety, was tested against selected stored products pests: Sitophilus granarius L. (Coleoptera: Curculionidae), Tribolium confusum Duv. (Coleoptera: Tenebrionideae), and Trogoderma granarium Ev. (Coleoptera: Dermestridae). The relation between molecular structure and antifeedant activity was examined and implication of the piperonyl moiety is assessed. The compounds represent either natural substances isolated from plants (Libocedrus yateensis Guillaumin and Piper cubeba L.) or their structural analogues prepared by simple chemical transformations as well as compounds selected from commercially available sources. Natural lignan lactones with methoxy and/or methylenedioxy substituents showed significant activity that is strong enough to affect plant - insect interactions. Presence of polar substituents, especially hydroxy or glycosyl groups, often reduce the activity. Non-polar substituents, such as methoxy or methylenedioxy groups, enhance the activity not only in lignans but also in simple phenylpropanoids. The most active compound was synthetic piperonylbutoxide.