Limited genetic structure and demographic expansion of the Brassicogethes aeneus populations in France and in Europe

International audienceThe pollen beetles, Brassicogethes aeneus (Fabricius, 1775), is one of the most significant pests of oilseed rape. To shed light on past and present pollen beetle demography (dispersal, population size), twelve microsatellite markers were developed and population genetic diversity and structure were analyzed at different spatial scales in France and in Europe from 433 individuals collected in 18 winter oilseed rape fields. RESULTS: The genetic differentiation among the population samples was low but significant between the Estonian sample and the rest of Europe. Isolation by distance was only significant at the European scale. The genetic variability was similar among the 18 population samples. Demographic inferences suggested a recent expansion of B. aeneus population size over Europe, possibly corresponding to an increase of oilseed rape crop’s area during the last decades. CONCLUSION: Current population size and dispersal are not straightforward to estimate from the distribution of genetic variability in B. aeneus over Europe because of the complexity of the demographic history of the pests. Nevertheless, as gene flow was important enough to prevent strong genetic differentiation at large geographical scales, the management of pollen beetle populations should likely be thought at the European continental level