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Negative impacts of invasive predators used as biological control agents against the pest snail Lissachatina fulica: the snail Euglandina ‘rosea’ and the flatworm Platydemus manokwari

Gerlach, Justin and Barker, Gary M. and Bick, Cindy S. and Bouchet, Philippe and Brodie, Gilianne D. and Christensen, Carl C. and Collins, Timothy and Coote, Trevor and Cowie, Robert H. and Fiedler, G.C. and Griffiths, Owen L. and Florens, F.B.V. and Hayes, Kenneth A. and Kim, Jaynee and Meyer, J-Y and Meyer III, Wallace M. and Richling, Ira and Slapcinsky, John D. and Winsor, Leigh and Yeung, Norine W. (2020) Negative impacts of invasive predators used as biological control agents against the pest snail Lissachatina fulica: the snail Euglandina ‘rosea’ and the flatworm Platydemus manokwari. Biological Invasions, NA . NA. ISSN 1387-3547

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    Abstract

    Since 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flatworms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L. fulica and native snails. Since 1993 there have been unofficial releases of Euglandina within island groups. Only three official P. manokwari releases took place, but new populations are being recorded at an increasing rate, probably because of accidental introduction. Claims that these predators controlled L. fulica cannot be substantiated; in some cases pest snail declines coincided with predator arrival but concomitant declines occurred elsewhere in the absence of the predator and the declines in some cases were only temporary. In the Hawaiian Islands, although there had been some earlier declines of native snails, the Euglandina impacts on native snails are clear with rapid decline of many endemic Hawaiian Achatinellinae following predator arrival. In the Society Islands, Partulidae tree snail populations remained stable until Euglandina introduction, when declines were extremely rapid with an exact correspondence between predator arrival and tree snail decline. Platydemus manokwari invasion coincides with native snail declines on some islands, notably the Ogasawara Islands of Japan, and its invasion of Florida has led to mass mortality of Liguus spp. tree snails. We conclude that Euglandina and P. manokwari are not effective biocontrol agents, but do have major negative effects on native snail faunas. These predatory snails and flatworms are generalist predators and as such are not suitable for biological control.

    Item Type: Journal Article
    Subjects: Q Science > Q Science (General) > Q1-390 Science (General)
    Q Science > QL Zoology
    S Agriculture > S Agriculture (General)
    Divisions: Faculty of Science, Technology and Environment (FSTE) > Institute of Applied Science
    Depositing User: Gilianne Brodie
    Date Deposited: 05 Jan 2021 16:05
    Last Modified: 05 Jan 2021 16:05
    URI: http://repository.usp.ac.fj/id/eprint/11906
    UNSPECIFIED

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