Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2008
Publication Date: 7/14/2008
Publication URL: http://dx.doi.org/10.1080/09583150802344902
Citation: Wright, S.A., Center, T.D. 2008. Nonselective oviposition by a fastidious insect: the laboratory host range of the melaleuca gall midge Lophodiplosis trifida (Diptera: Cecidomyiidae). Biocontrol Science and Technology. 18(8):793-807. 2008. Interpretive Summary: Florida’s wetlands, such as the Everglades, have been invaded, colonized, and degraded by the Australian paperbark tree, Melaleuca quinquenervia. Federal and state agencies have developed a plan to restore these wetlands. Expansive stands of melaleuca are removed and new stands are prevented from developing. The latter goal is being accomplished through the use of biological control. Two biocontrol control agents, a leaf feeding weevil and a sap sucking psyllid, are well established and reducing flowering, seeding, and growth and causing mortality of seedlings and saplings. However, they are not present in all habitats at all times. Thus, additional agents are needed. A bud galling fly has been released but is resisting establishment. The release of a fourth species, a stem galling fly, has been proposed. When tested on 64 relevant plant species in the laboratory, it exhibited a narrow host range, completing its life cycle only on the paperbark tree. Moreover, it impeded growth and killed small plants. The gall stem fly is likely to establish and contribute to the management of the invasive paperbark tree.
Technical Abstract: Invasion by the Australian paperbark, Melaleuca quinquenervia, has degraded large expanses of south Florida wetlands. Restoration of these wetlands requires the removal of expansive monocultures of this large tree while simultaneously curtailing its spread. Management strategies developed by federal and state agencies include biological control as a measure to halt the spread of this species as well as a means to prevent reinfestation of cleared areas. This requires biological agents able to reduce flowering, seed production, and growth while increasing mortality of seedlings and saplings. Two of the three introduced agents (Oxyops vitiosa Pascoe and Boreioglycaspis melaleucae Moore) partially meet these needs but outcomes are not spatially or temporally consistent. Thus, additional agents are needed. The bud-gall fly Fergusonina turneri Taylor, with its mutualistic nematode Fergusobia quinquenerviae Davies and Giblin-Davis, is actively being released but is resisting establishment. A fourth very promising agent, the gall midge Lophodiplosis trifida Gagné, manifested an extremely narrow host range during laboratory testing. Oviposition was indiscriminant in caged environments and small, incipient, unilocular galls initiated on Melaleuca viminalis, but larval development ensued only on M. quinquenervia. The unilocular galls on Melaleuca viminalis did not grow and produced no adult flies. As a result, M. viminalis test plants suffered only minor cosmetic damage. Observations from both Australia and Florida attest to the ability of this midge to impede M. quinquenervia growth and kill small plants. Thus, L. trifida is safe to release and will likely contribute to management objectives for control of this pernicious wetland invader.