Quarantine host range studies with Lophyrotoma zonalis, an Australian sawfly of interest for biological control of melaleuca, Melaleuca quinquenervia, in Florida

摘要

The Australian melaleuca tree, Melaleuca quinquenervia (Cav.) S. T. Blake (Myrtaceae), has naturalized in southern Florida, U.S.A., and is now one of that regions most important weeds. Primarily a weed of wetlands, it also infests neighboring drier areas. Current efforts to restore the South Florida ecosystem are threatened by the continuing range expansion of melaleuca and other weeds. In an effort to supplement the current chemical and cultural control methods for melaleuca, a search for potential biological control agents was begun in Australia in 1986. The sawfly, Lophyrotoma zonalis, was determined after extensive field and laboratory studies to have potential as a biological control agent. Larvae of L. zonalis eat leaves and occasionally defoliate large trees in Australia. Host range studies were conducted in a Florida quarantine facility with native and cultivated plant species. Multi-choice and nochoice oviposition tests were conducted with 36 species in the Myrtaceae and with 18 species in other families. Larvae developed to prepupae and adults from the eggs oviposited on 23 species of Myrtaceae only on 3 species of bottlebrushes, Callistemon. Medium-sized larvae were tested for feeding on bouquets of plant cuttings and on potted plants. They are the stage that might wander from defoliated trees. Noticeable feeding, but much less than on melaleuca, was restricted to the Myrtaceae, except for a few individual larvae that fed on wax myrtle, Myrica cerifera. Medium-sized larvae became perpupae only on Melaleuca decora (73%) and on wax myrtle (10%). However, neither species received eggs in the oviposition tests. These studies confirmed the narrow host range of L. zonalis as previously reported from field and laboratory studies in Australia.