GENETIC DIVERSITY OF THE GREENBUG APHID, SCHIZAPHIS GRAMINUM, IN THE OLD WORLD
Wheat, Peanut and Other Field Crops Research
2011 Annual Report
1a.Objectives (from AD-416)
The objective of this cooperative research project is to quantify the genetic relatedness and diversity of greenbug aphid (Schizaphis graminum) populations in Europe, the Middle East, North Africa, and the US.
1b.Approach (from AD-416)
Greenbug aphids will be collected from crop and non-crop hosts in three regions of the Old World: Europe, the Middle East, and North Africa. mtDNA and nDNA from each aphid will be sequenced. DNA sequences will be used to determine the degree of relatedness of greenbug populations. This information will be used to determine if the greenbug found in the US and Old World are the same species, and/or how closely related they are. The geographical origin of S. graminum will be determined, i.e., Palearctic or Nearctic.
During 2010 at Rothamsted Research near Harpenden, 19 S. graminum were collected from suction traps and 10 were collected from Holcus lanatus. Life history characteristics were measured, and it was determined that the aphid was S. graminum holci, and not S. graminum s. s. The mtDNA cytochrome oxidase subunit I (COI) gene was sequenced from 37 specimens collected in 2009 and from 25 specimens (11 from H. lanatus and 26 from traps) collected at Rothamsted Research. Introns from the nDNA cytochrome c (CytC) gene were sequenced from four specimens. Based on COI and CytC sequences, only two specimens collected at Rothamsted Research near Harpenden were determined to be S. graminum and constituted the first record of S. graminum s. s. in the UK. The COI sequences from the remaining 60 S. graminum were subjected to maximum parsimony analysis with 11 S. graminum s. s. biotypes from the USA. This analysis showed that S. graminum from the UK is very closely related to USA biotypes; however, they formed separate and distinct clades.
The ADODR monitored activities via periodic phone calls, e-mails, and brief written reports from the collaborator.