title: Evidence for gene flow and local clonal selection in field populations of the grain aphid (Sitobion avenae) in Britain revealed using microsatellites.
abstract: Samples of the grain aphid, Sitobion avenae (F.), a major European pest of cereals, were collected in June and July 1997 from fields sown with winter wheat in a rough transect south-west of Rothamsted, UK. These aphids were genotyped at four microsatellite loci known from previous studies to be highly polymorphic. Allelic frequencies were similar between samples collected in the fields and in the 12.2 m high suction trap at Rothamsted, and there were many widespread genotypes (clones), providing evidence that the species is highly migratory. However, field samples were found to display a high level of genotypic heterogeneity (= variable clonal composition), most probably the result of clonal selection. The suction trap genotypes sample were slightly different from the field samples, indicative of the inclusion of genotypes from plant hosts (cereals and grasses, Poaceae) other than winter wheat and/or genotype-biased emigration from the field. The relevance of these data to modelling of aphid outbreaks is briefly discussed.
authors.affiliation: Plant and Invertebrate Ecology Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Llewellyn
authors.forename: H D
authors.initials: HD
authors.lastname: Loxdale
authors.forename: R
authors.initials: R
authors.lastname: Harrington
authors.forename: S J
authors.initials: SJ
authors.lastname: Clark
authors.forename: P
authors.initials: P
authors.lastname: Sunnucks
mesh_terms: D000818:Animals; D001042:Aphids / Q000235:genetics*; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D018895:Microsatellite Repeats / Q000235:genetics; D006109:Poaceae; D011157:Population Dynamics; D012641:Selection, Genetic; D006113:United Kingdom