LONG-TERM EFFECTS ON FOOD CHOICE OF LAND SNAIL ARIANTA-ARBUSTORUM MEDIATED BY PETASIN AND FURANOPETASIN, 2 SESQUITERPENES FROM PETASITES-HYBRIDUS

Sesquiterpenes (STs) from the Senecioneae have been found to be potent snail repellents. We investigated the range of activity of the STs pe tasin, isopetasin, furanopetasin, kablicin, and cacalol, which were is olated from Petasites hybridus, P. kablikianus, and Adenostyles alpina . We found the petasin content of leaves of P. hybridus to lie within the range of deterrence of the isolated compound. Furthermore, leaf ex tracts containing petasin proved to be deterrent, and leaf discs with low petasin content were preferred over discs with higher petasin cont ent. The cacalol-containing fraction of a leaf extract of A. alpina wa s not deterrent to the snails. When the snails had experience with the relevant ST one week before a choice test, their sensitivity towards petasine and furanopetasine increased whereas for the other ST it rema ined at the same level. We speculate that this sensitivity increase co uld be the result of a rapid long-term associative learning process, b ut there is also the possibility that these STs are directly interferi ng with the feeding motor program of the snails, thereby eliciting a d irect neurophysiological sensitization reaction which prevents them fr om further feeding.