Life–histories and host specificities of Ceutorhynchus geographicus (Goeze) and C. larvatus Schultze (Coleoptera: Curculionidae), potential biological control agents for Echium

Abstract

AbstractThe two weevils Ceutorhynchus geographicus (Goeze) and C. larvatus Schultze, which live and develop on Echium plantagineum (Boraginaceae) in the western Mediterranean regions, are potential biological control agents for this plant, which is an important weed in Australia. Adults bite holes in the leaves and petioles, but this damage is not great in comparison with that caused by their larvae, which mine the collar and root, causing massive necrosis and often the death of the plant. C. larvatus larvae are found especially in the aerial parts of the collar of the plant, while those of C. geographicus attack principally the rootstocks. Quarantine safety testing was based on plants selected by the criteria already used for the Echium leaf–miner Dialectica scalariella (Zell.), and it was confirmed that the two weevils would be safe and effective agents for the biological control of E. plantagineum in Australia.