Biocontrol Science and Technology (2007) 17, 809-822

Julie Grandgirard, Mark S. Hoddle, Jerome N. Petit, Diana M. Percy, George K. Roderick and Neil Davies (2007)
Pre-introductory risk assessment studies of Gonatocerus ashmeadi (Hymenoptera: Mymaridae) for use as a classical biological control agent against Homalodisca vitripennis (Hemiptera: Cicadellidae) in the Society Islands of French Polynesia
Biocontrol Science and Technology 17 (8), 809-822
Abstract: Homalodisca vitripennis (Germar) (=H. coagulata [Say]) (Hemiptera: Cicadellidae) invaded French Polynesia in 1999. A classical biological control program against H. vitripennis was initiated in 2004 aiming to introduce the exotic egg parasitoid Gonatocerus ashmeadi (Girault) (Hymenoptera: Mymaridae) to the Society Islands archipelago. Prior to any release, two risks were assessed: (a) continued uncontrolled H. vitripennis spread and proliferation in French Polynesia, and (b) non-target impacts by G. ashmeadi on indigenous French Polynesian cicadellids. The primary risk of H. vitripennis is its potential to vector the lethal plant bacterium, Xylella fastidiosa. While the presence of X. fastidiosa in French Polynesia has not yet been demonstrated, the presence of uncontrolled H. vitripennis greatly elevates the risk of a disease outbreak and thus represents a major threat for numerous plant species. Assessing the risk of G. ashmeadi introduction for native cicadellids first required an inventory of the Cicadellidae of the Society Islands, resulting in at least 14 cicadellid species (nine not previously recorded). The risk to these species of attack by G. ashmeadi was assessed using four criteria: (1) their phylogenetic relationships to known hosts of G. ashmeadi, and their similarity in (2) body size, (3) egg laying biology, and (4) ecology. All indigenous cicadellid species found were considered to be at low risk of attack because they differed greatly from all known hosts for G. ashmeadi: (1) none of the indigenous species are in the tribe Proconiini, (2) all were very small and, when possible to determine, (3) lay tiny single eggs, which (4) are deposited on the undersides of leaves of trees. These results persuaded the French Polynesian Government that the benefits of establishing G. ashmeadi for H. vitripennis control outweighed the serious potential risks associated with either delaying release or not releasing G. ashmeadi in French Polynesia. Releases of G. ashmeadi in Tahiti began in May 2005.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): George Roderick, Mark S. Hoddle, Jerome N. Petit, Julie Grandgirard

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
classical biocontrol/new introduction
non-target effects/fate in environm.

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Homalodisca vitripennis		French Polynesia
Cosmocomoidea ashmeadi (parasitoid)	Homalodisca vitripennis