Field and laboratory host ranges of the Australian weevil, Oxyops vitiosa (Coleoptera: Curculionidae), a potential biological control agent for the paperbark tree, Melaleuca quinquenervia

While some woody weeds have been targets for classical biological control, only a few of these reach a size large enough to be considered trees. In 1986, a long-term project was initiated to develop biological control agents for Melaleuca quinquenervia (paperbark tree; melaleuca), a large tree species which has become a serious pest in southern and central Florida. The paperbark tree is native to Australia, where we studied the host range of the weevil Oxyops vitiosa, a potential biological control candidate for M. quinquenervia, in the field as well as the laboratory. During 7 years, we collected 1077 specimens of this weevil from 644 quantitative collections of M. quinquenervia. It was never found in 371 quantitative collections from other (mostly closely related) tree species. In 10 of 12 intensive evaluations at six sites containing numerous tree species, 0. vitiosa was found only on M. quinquenervia. In the laboratory, high feeding by 0. vitiosa larvae was observed only on M. quinquenervia and two other closely related Melaleuca species, while moderate feeding was recorded on Psidium guajava. Eggs were laid on six plant species in adult oviposition trials, but of the resulting larvae, only on those on M. quinquenervia completed their development. This weevil's potential efficacy as a biological control agent is estimated using the Goeden-Harris scoring system. We also briefly review the success of similar agents, as well as other projects against large woody weeds. As in its native range, this weevil's impact on M. quinquenervia in Florida would most likely be the suppression of growth and stunting of saplings. The high degree of host specificity shown by this weevil species allowed its exportation in July 1992 to quarantine facilities in Florida for further evaluation.