Observations on the life cycle of Pissodes castaneus in central Italy

Field and cage studies on the life cycle of Pissodes castaneus (De Geer) (Coleoptera Curculionidae) and on its larval parasitoids were carried out in central Italy. Oviposition occurred in the spring and in the late summer/early autumn; the larvae were present throughout the year, with the exception of a few summer months; P. castaneus mainly overwintered as third and fourth instar larvae, as well as adults of previous generations. This study also provides evidence that a part of adults which emerged in the spring, at beginning of the emergence period, may lay eggs which give rise to new adults within July. In conclusion, in central Italy two generations of the weevil were observed, of which one had a slow development, originating from eggs laid in autumn, and the other had a very rapid preimaginal development, originating from eggs laid in the spring. The most common larval parasitoids of P. castaneus were Metacolus unifasciatus Foerster (Hymenoptera Pteromalidae) and Coeloides sordidator (Ratzeburg) (Hymenoptera Braconidae); which are parasitoids of species belonging to the genus Pissodes, as well as many bark beetles.