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Title: Identity of Schizaphis species (Hemiptera: Aphididae) in the United Kingdom: Are they a threat to crops?

Author
item KATI, AMALIA - Rothamsted Research
item SHUFRAN, KEVIN - Retired ARS Employee
item TAYLOR, MARK - Rothamsted Research
item BARJADZE, SHALVA - Georgia State Agricultural University
item EASTOP, VICTOR - Natural History Museum - London
item BLACKMAN, ROGER - Natural History Museum - London
item HARRINGTON, RICHARD - Rothamsted Research

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2012
Publication Date: 8/1/2013
Citation: Kati, A., Shufran, K.A., Taylor, M.S., Barjadze, S., Eastop, V.F., Blackman, R.L., Harrington, R. 2013. Identity of Schizaphis species (Hemiptera: Aphididae) in the United Kingdom: Are they a threat to crops? Bulletin of Entomological Research. 103(4):425-440.

Interpretive Summary: The greenbug aphid, Schizaphis graminum, is a major pest of wheat and other cereal crops in some parts of the world and is of particular concern because it can be resistant to some insecticides and overcome the resistance of crops. In the United Kingdom (UK), it has never been found on crops but an aphid looking like the greenbug has been found in increasing numbers in suction trap samples. DNA barcoding (using DNA sequences to identify insects to species) of greenbug-looking aphids caught from the UK show them to be very similar, and in some cases identical, to greenbugs from the USA. Large numbers of greenbug-like aphids were found on native English grasses the UK. Laboratory colonies of the UK aphids were established and various aspects of their biology were studied to address the questions that have been raised on their identity and damage potential. At present it seems likely that UK specimens correspond with the aphid Schizaphis holci, which poses no threat to crops. Some of the aphid samples from the native English grasses had identical DNA sequences to some of the trap samples, but it seems likely that the trap samples comprised more than one species or subspecies. Aphids identified as greenbug from the UK were very closely related to greenbugs found in the USA. However, they are genetically different. Aphids identified as greenbugs found in the UK are probably a cryptic species and appear to be no threat to crops.

Technical Abstract: The greenbug aphid, Schizaphis graminum (Rondani), is a major pest of cereals in some parts of the world and is of particular concern because it can be resistant to some insecticides and overcome the resistance of crops. In the UK it has never been found on crops but an aphid morphologically like the greenbug has been found in increasing numbers in suction trap samples. COI mtDNA gene sequences from UK specimens show them to be very similar, and in some cases identical, to US specimens and to match the three mtDNA haplotypes reported from the US. Large numbers of a Schizaphis species were found on Holcus lanatus L. (Yorkshire fog grass) in Hertfordshire and Bedfordshire (UK). Laboratory clones were established and various aspects of their biology were studied in order to address the questions that have been raised on the taxonomic status and damage potential. At present it seems likely that UK specimens from H. lanatus correspond with Schizaphis holci, which poses no threat to crops. Some of the field samples from H. lanatus had identical COI sequences to some of the suction trap samples, but it seems likely that the suction trap samples comprised more than one species or subspecies. Schizaphis graminum s.l. from the UK were very closely related to S. graminum s.s.as found in the US. Nuclear DNA sequencing supported this relationship. The possibility of S. graminum from Southern Europe moving to the UK and becoming established as a pest of cereals is discussed.