title: Reconstruction of a windborne insect invasion using a particle dispersal model, historical wind data, and Bayesian analysis of genetic data.
abstract: Understanding how invasive species establish and spread is vital for developing effective management strategies for invaded areas and identifying new areas where the risk of invasion is highest. We investigated the explanatory power of dispersal histories reconstructed based on local-scale wind data and a regional-scale wind-dispersed particle trajectory model for the invasive seed chalcid wasp Megastigmus schimitscheki (Hymenoptera: Torymidae) in France. The explanatory power was tested by: (1) survival analysis of empirical data on M. schimitscheki presence, absence and year of arrival at 52 stands of the wasp's obligate hosts, Cedrus (true cedar trees); and (2) Approximate Bayesian analysis of M. schimitscheki genetic data using a coalescence model. The Bayesian demographic modeling and traditional population genetic analysis suggested that initial invasion across the range was the result of long-distance dispersal from the longest established sites. The survival analyses of the windborne expansion patterns derived from a particle dispersal model indicated that there was an informative correlation between the M. schimitscheki presence/absence data from the annual surveys and the scenarios based on regional-scale wind data. These three very different analyses produced highly congruent results supporting our proposal that wind is the most probable vector for passive long-distance dispersal of this invasive seed wasp. This result confirms that long-distance dispersal from introduction areas is a likely driver of secondary expansion of alien invasive species. Based on our results, management programs for this and other windborne invasive species may consider (1) focusing effort at the longest established sites and (2) monitoring outlying populations remains critically important due to their influence on rates of spread. We also suggest that there is a distinct need for new analysis methods that have the capacity to combine empirical spatiotemporal field data, genetic data, and environmental data to investigate dispersal and invasion.
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Tonya A
authors.initials: TA
authors.lastname: Lander
authors.affiliation: INRA, UR546 Unité de Biostatistique et Processus Spatiaux F-84914, Avignon, France.
authors.forename: Etienne K
authors.initials: EK
authors.lastname: Klein
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Oddou-Muratorio
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France ; National Resources Canada, Canadian Forest Service, Great Lakes Forestry Ctr Sault Ste Marie, Ontario, P6A 2E5, Canada.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Candau
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Cindy
authors.initials: C
authors.lastname: Gidoin
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Chalon
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Roig
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Fallour
authors.affiliation: INRA, UR633 Unité de Recherche de Zoologie Forestière F-45075, Orléans, France.
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Auger-Rozenberg
authors.affiliation: INRA, UR629 Ecologie des Forêts Méditerranéennes F-84914, Avignon, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boivin
keywords: Cedrus; HYSPLIT; Megastigmus; invasion; long-distance dispersal; microsatellite; wind