HOST-PLANT RELATIONSHIPS AND LIFE-HISTORY OF SOME ALEBRA SPECIES IN ITALY (AUCHENORRHYNCHA, CICADELLIDAE)

Four Alebra species, A. albostriella, A. coryli, A. viridis, A. wahlbe rgi and their colour morphs, have been investigated on the following h ost-plants: Corylus avellana, Castanea sativa, Quercus cerris, e. robu r, e. petraea and Acer campestre. Host-plant relationships of Alebra s pecies showed an association between A. coryli and C. avellana, A. alb ostriella and Q. robur, A. wahlbergi and A. campestre. On the contrary on Q. cerris, Q. petraea and C. sativa two different species, A. albo striella and A. viridis, are coexisting. Alebra species showed differe nt phenology and life histories: A. coryli and A. wahlbergi appeared u nivoltine,A. viridis bivoltine, and A. albostriella both uni- and bivo ltine. The oviposition sites have been documented both for overwinteri ng eggs, laid in the branches, and for summer eggs, laid in the main l eaf nervation. Associations between nymphal and adult morphs are repor ted. A new morph, A. albostriella m. atrata,has been found on Q. robur .