Contrasting population structure and demographic history of cereal aphids in different environmental and agricultural landscapes
Genetic diversity of populations has important ecological and evolutionary consequences, which are fundamental to improve the sustainability of agricultural production. Studies of how differences in agricultural management and environment influence the population structure of insect pests are fundamental to predict outbreaks and optimise control programmes. Here, we have studied the population genetic diversity and evolution of Sitobion avenae and Sitobion miscanthi (previously mistaken for S. avenae), which are among the most relevant aphid pests of cereals across Europe and China, respectively. We have used a genomic approach that allows the identification of weak geographic structure and migration patterns at scales that were previously not discernible. In the present study, we show that the population structure in present day populations are different from that described in previous studies, which suggests that they have evolved recently possibly as a response to human-induced changes in agriculture. In the UK, S. avenae is predominantly anholocyclic and, as a result of the evolution of insecticide resistance, a superclone is now dominant across the geographic distribution in the country and the genetic diversity is low. In China, S. miscanthi populations are mostly holocyclic, with one sexual stage in autumn to produce overwintering eggs, and there are six genetically differentiated subpopulations and high genetic differentiation between geographic locations, which suggests that further taxonomical research is needed. Unlike in the case of S. avenae in England, there is no evidence for insecticide resistance and there is no predominance of a single lineage in S. miscanthi in China.