Submitted to: Biocontrol News and Information
Publication Type: Research notes
Publication Acceptance Date: 6/1/2005
Publication Date: 6/20/2005
Citation: Blackwood, J.S., Lieurance, D.M., Giblin-Davis, R., Pratt, P.D. 2005. Bud-gall fly release for biocontrol of melaleuca in florida.. Biocontrol News and Information. 26(2):48N. Interpretive Summary: A bud-gall fly recently released as a biological control agent against the Australian melaleuca tree, Melaleuca quinquenervia, is the third insect species to be released as part of an areawide melaleuca management programme in South Florida (USA) [also see: Melapaleuza 2005, Training News, this issue]. An obligate mutualistic relationship between the bud-gall fly and a nematode makes this release a milestone in biological control; this is the first mutualism approved for release as a natural enemy pair in the USA.
Technical Abstract: Since its introduction into South Florida in the late 1800s, melaleuca has invaded more than 200,000 ha of wetlands comprising the Florida Everglades. Efforts to implement classical biological control of the tree began in 1986. The melaleuca weevil (Oxyops vitiosa) and the melaleuca psyllid (Boreioglycapsis melaleucae) were two taxa considered to be top candidates for release as biological control agents. Following intensive host-specificity tests in quarantine, O. vitiosa and B. melaleucae were approved for release in South Florida in 1997 and 2002, respectively. Both insects have since become widely distributed in melaleuca stands throughout South Florida. Laboratory and field studies have indicated that damage caused by the feeding of each insect can inhibit both growth and reproductive capabilities of the plant. A third biological control candidate, the melaleuca bud-gall fly (Fergusonina turneri), has also cleared quarantine-based host specificity testing. This fly deposits its eggs, along with a nematode symbiont (Fergusobia quinquenerviae) in the interior of young melaleuca buds via an elongated ovipositor. The nematode appears to cause a proliferation of cell growth to occur within the bud. The resulting gall prohibits normal growth of leaf or flower tissues from the bud and provides the necessary food source for developing nematodes and fly larvae. Nematodes re-invade the ovaries of female flies during the fly’s pupal stage, and adult flies emerge through ‘windows’ which appear on the gall surface during fly pupation. The US Department of Agriculture - Animal and Plant Health Inspection Service (USDA-APHIS) has issued a permit for the release of F. turneri (+ F. quinquenerviae), and releases have now been made at six sites in South Florida.