About Aphis spiraecola Patch, 1914
Aphis spiraecola is an aphid species first described in 1914 by Edith Marion Patch. Its common names are green citrus aphid, Spirea aphid, and apple aphid. It is distributed worldwide, and is most abundant in the United States. It has a diploid chromosome number of 2n=8. A. spiraecola occurs globally across temperate and tropical regions, including Asia, Africa, North America, Europe, and Oceania, and is absent from cold regions. It is thought to have originated in the Far East. It has been recorded in North America since at least 1907, in Australia since 1926, in New Zealand since 1931, in the Mediterranean since 1939 (other sources date this introduction to the early 1990s), in Africa in 1961, in Israel in 1970, in Germany in 2000, in Hungary in 2004, in Bulgaria and Serbia in 2007, in the Baltic region in 2015, in Kosovo in 2018 (collected in Llugaxhi on 23 July), in Slovakia in 2018 (collected in Tvrdošovce on 2 May), in the Czech Republic in 2019 (collected in Bílé Podolí on 21 June), in the United Kingdom in 2018 (collected in Ash near Canterbury, England on 13 July, after earlier 1979 and 1996 detections in the UK did not lead to established populations), and in Denmark in 2019 (found in the Pometum of the University of Copenhagen Taastrup campus on 20 July). Today, A. spiraecola is found across the globe in both its native and introduced ranges, and is considered invasive in nearly all areas it inhabits. There are multiple risks and pathways for this species to be introduced to new geographic areas. The movement of fruits or ornamental plants can carry this aphid to new regions; since it can feed on a very wide range of host plants, it can easily survive and reproduce in most environments, allowing it to establish in new areas. A. spiraecola is a holocyclic species: it undergoes sexual reproduction during part of its life cycle, and reproduces exclusively via parthenogenesis across most of its geographic range. In regions where it is holocyclic and produces sexual morphs, its primary hosts are Spiraea or Citrus.
