Reconstruction of a windborne insect invasion using a particle dispersal model, historical wind data, andBayesian 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.

Spatial synchrony in sub‐arctic geometrid moth outbreaks reflects dispersal in larval and adult life cycle stages

“…Our current results show that this topic can be explored using relatively simple methods, but more sophisticated approaches could provide even stronger inference about wind‐driven synchrony. For example, higher resolution wind models could be coupled with models of particle spread (Lander et al., ) to predict detailed dispersal patterns and thus help formulate more precise predictions about the directionality of synchrony.…”

The ecology of predispersal insect herbivory on tree reproductive structures in natural forest ecosystems

“…Adult western conifer seed bugs ( L. occidentalis ) display impressively active flight capacities that partly allowed this invasive species to spread over Europe within a decade (Rabitsch, ), while chestnut weevils ( C. pellitus and C. venosus ) have very limited abilities for active dispersal flights (Pélisson et al ., ). Highly host‐specialized seed wasps use prevailing winds for long‐distance dispersal in a landscape fragmentation context in which their incapacity to use alternative habitats is a natural barrier to simple diffusion (Jarry et al ., ; Lander et al ., ). The demography of highly mobile seed predators may depend less of the previous seed crops than that of species with low mobility (Hulme & Benkman, ).…”

The first record of subtropical insects (Thysanoptera) in central Europe: long‐distance transport of airborne thrips, applying three‐dimensional backward trajectories

“…A joint search in Web of Science with keywords ‘insect’ and ‘long‐distance transport’ produced 90 papers. Many of them include a trajectory analysis of the transport processes (Carlson et al ., ; Westbrook et al ., ; Dantart et al ., ; McLaren et al ., ; Sturtevant et al ., ; Lander et al ., ). Carlson et al .…”

“…Lander et al . () investigated the explanatory power of a regional‐scale wind‐dispersed particle trajectory model for the invasive seed chalcid wasp Megastigmus schimitscheki (Hymenoptera: Torymidae) in France. However, so far, only one paper has dealt with the long‐distance transport of thrips using trajectory calculations (McLaren et al ., ), in which probable trajectories were computed for New Zealand flower thrips ( Thrips obscuratus Crawford) transported to Central Otago in the Spring using wind speed, wind direction and air temperature data collected at several meteorological stations, and then the departure conditions were characterized.…”

“…Applying dispersion trajectories of HYSPLIT, Lander et al . () proposed that wind is the most probable vector for the passive long‐distance dispersion of the invasive seed wasp. Their findings confirmed that long‐distance dispersion from source areas is a likely driver of the secondary expansion of invasive species.…”