RESTRICTED HOST-RANGE OF THE WEEVIL AUBEONYMUS-MARIAEFRANCISCAE, A NEW SUGAR-BEET PEST

The extent of feeding, fecundity and fertility of a new sugar beet pes t, Aubeonymus mariaefranciscae Roudier (Coleoptera: Curculionidae), on a range of plants from different families was determined. We have fou nd that the adult weevils were only able to feed and oviposit on two c losely related cultivated plants, beet and sugar beet, both subspecies of Bera vulgaris L., suggesting a restricted host range for this curc ulionid. None of 16 secondary metabolites (widely distributed among pl ants, and representative of different chemical groups), nor any of 19 non-host extracts from 13 different families, deterred the adults of t his curculionid from feeding on sugar beet. We found a phagostimulator y effect when beet and sugar beet homogenates from various plant tissu es were supplied to adult weevils on weeds that they do not feed on. C onversely, no effect was observed when sucrose was provided. These fin dings suggest that host selection by A. mariaefranciscae adults is due to the presence of an undetermined phagostimulant compound(s) in beet and sugar beet, instead of the recognition of deterrent substances am ong the non-host plants.