Traiettorie evolutive e diagnostica di specie criptiche in coleotteri fitofagi specializzati

A short synthesis of the main evolutionary processes involving host-plants use by their specialized phytophagous insects,associated with use of prospective biological control agents of weeds, is presented. Several case studies are discussed, bothfrom literature and from experiences carried out by the authors on different beetle groups (e.g., Chrysomelidae, Nitidulidae,Apionidae). Most available data suggest to use with extreme care even apparently highly specialized beetles in biologicalcontrol of weeds, due to the widespread occurrence of host-shift in short - or medium- time perspectives, and to thefrequently undetected presence of cryptic species. This combination of events makes the evolutionary pathways of eachphytophagous beetle species and group extremely difficult to foresee.