On the phenology of postembrional stages of Stereonychus fraxini (De Geer, 1775) (Coleoptera: Curculionidae) and on its parasitoids in Sicily

Abstract

The phenology of the stages of Stereonychus fraxini (De Geer) in some olive orchards, for about two years (2001-2002) in Sicily, has been observed; at the same time observations, either on the life-cycle, or on the ethology, as well as on the natural enemies of the Curculionid have been carried out. This insect attacks the young leaves of the host plant and its larva! trophic activity has had no negative impact on the foliage development of fully grown plants. This Curculionid develops in the field from March to July and during this time, it completes only a generation; after that the new born adults are diapausing unti! about the second decade of March of the next year. Eigth species of Chalcidoidea and three of Braconidae have represented his natural enemies. In both two years of observations the average percentage of parasitism played against the mature larvae and pupae together by this complex has been 32% about.