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

Abstract

The pollen beetle, Brassicogethes aeneus (Fabricius, 1775), is one of the most significant pests of oilseed rape. To shed light on past and current pollen beetle demography (dispersal, population size), 12 microsatellite markers were developed, and population genetic diversity and structure were analysed at different spatial scales in France and in Europe from 433 individuals collected in 18 winter oilseed rape fields. Genetic differentiation among the population samples was low but was significant between the Estonian sample and the rest of Europe. Isolation by distance was significant only at the European scale. 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 in oilseed rape crop area during past decades. 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 this pest. Nevertheless, because gene flow was important enough to prevent strong genetic differentiation at large geographical scales, the management of pollen beetle populations should likely be thought of at a continental Europe level. © 2018 Society of Chemical Industry.