Canadian Forest Service Publications
Reconstruction of a windborne insect invasion using a particle dispersal model, historical wind data, and Bayesian analysis of genetic data. 2014. Lander, T.A.; Klein, E.K.; Oddou-Muratorio, S.; Candau, J.-N.; Gidoin, C.; Chalon, A.; Roig, A.; Fallour, D.; Auger-Rozenberg, M.-A.; Boivin, T. Ecology and Evolution 4: 4609-4625.
Issued by: Great Lakes Forestry Centre
Catalog ID: 36546
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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.
Plain Language Summary
We reconstructed the dispersal history of the invasive seed wasp Megastigmus schimitscheki in France, using local-scale wind data and a regional trajectory model. We found that initial invasion across the range was the result of long-distance dispersal from the longest established sites. Wind is the most probable vector for passive long-distance dispersal from introduction areas, which drives secondary expansion. We suggest that management programs for this and other windborne invasive species focus efforts at the longest established sites and also monitor outlying populations due to their influence on rates of spread. Understanding the establishment and spread of invasive species is vital for developing effective management strategies for invaded areas and identifying new areas where the risk of invasion is highest. There is also a need for new analysis methods for dispersal and invasion that can combine data from field observations with genetic and environmental data.