Deciphering the routes of invasion of Drosophila suzukii by means of ABC random forest

Abstract

Deciphering invasion routes from molecular data is crucial to understanding biological invasions, including identifying bottlenecks in population size and admixture among distinct populations. Here, we unravel the invasion routes of the invasive pest Drosophila suzukii using a multi-locus microsatellite dataset (25 loci on 23 worldwide sampling locations). To do this, we use approximate Bayesian computation (ABC), which has improved the reconstruction of invasion routes, but can be computationally expensive. We use our study to illustrate the use of a new, more efficient, ABC method, ABC random forest (ABC-RF) and compare it to a standard ABC method (ABC-LDA). We find that Japan emerges as the most probable source of the earliest recorded invasion into Hawaii. Southeast China and Hawaii together are the most probable sources of populations in western North America, which then in turn served as sources for those in eastern North America. European populations are genetically more homogeneous than North American populations, and their most probable source is northeast China, with evidence of limited gene flow from the eastern US as well. All introduced populations passed through bottlenecks, and analyses reveal five distinct admixture events. These findings can inform hypotheses concerning how this species evolved between different and independent source and invasive populations. Methodological comparisons indicate that ABC-RF and ABC-LDA show concordant results if ABC-LDA is based on a large number of simulated datasets but that ABC-RF out-performs ABC-LDA when using a comparable and more manageable number of simulated datasets, especially when analyzing complex introduction scenarios.

Deciphering the worldwide invasion of the Asian long‐horned beetle: A recurrent invasion process from the native area together with a bridgehead effect

“…Six nested sets of invasion scenarios were analysed sequentially: after each analysis, a new population was added to the most likely scenario (Supporting information Figure ), following the methodology described by Fraimout et al (). The scenario topologies were based on the dates of first observation.…”

Development of Asian parasitoids in larvae Of Drosophila Suzukii feeding on blueberry and artificial diet

“…Among these, Drosophila suzukii Matsumura (Diptera, Drosophilidae), or spotted wing drosophila, a fly of East Asian origin, was first found in 2008 in Europe and North America, from where it invaded several other regions (Fraimout et al, 2017). This fly quickly became a serious pest of small and stone fruits in the invaded regions because, in contrast to the majority of Drosophila species, which feed on rotting fruits and other organic matters, D. suzukii is able to lay eggs in fresh fruits (Asplen et al, 2015).…”

Evolution of Multiple Sensory Systems Drives Novel Egg-Laying Behavior in the Fruit Pest Drosophila suzukii

“…We address this question by studying the egg-laying behavior of Drosophila suzukii , an invasive agricultural pest species that has spread from Southeast Asia to Europe and North America in the last decade [2]. While most closely related Drosophila species lay their eggs on decaying plant substrates, D. suzukii oviposits on ripening fruit, thereby causing substantial economic losses to the fruit industry [3, 4, 5, 6, 7, 8].…”