Amauromyza karli: an emerging pest of quinoa in the USA
Amauromyza karli (Diptera: Agromyzidae) is considered to be a Palaearctic and oligophagous species, feeding on Chenopodium spp. (Amaranthaceae). Very little information is available about the biology and ecology of A. karli. Its host range remained unknown for many years, but so far, the weeds C. album and C. vulvaria, as well as quinoa (C. quinoa) have been recorded as host plants. Until recently, A. karli was not known to cause any particular economic damage to plants.
In North America, A. karli was first recorded in Canada in 1969 in Ontario, and later recorded in other provinces (Alberta, British Columbia, Manitoba, Nova Scotia, Québec, Saskatchewan). Most specimens collected from Canada have been trapped, but some have been collected from C. album and quinoa fields without any indication of damage. The first report of economic damage came from the USA, where A. karli was observed in 2021 severely damaging quinoa crops in the San Louis Valley in Colorado. Damage is caused by larvae which feed extensively in the stems of C. quinoa, thus disrupting nutrient transport, causing lodging, reduced yield, and even plant mortality. As a consequence, the area grown with quinoa in Colorado decreased from 3 000 acres (1 200 ha) in 2021 to 900 acres (360 ha) in 2022. In addition, 100% of quinoa fields in Colorado were affected by A. karli in 2022 and farmers suffered significant crop and economic losses. In the USA, quinoa is largely imported from South America (Bolivia, Peru), but is a developing crop that is mainly grown in Idaho, Oregon and Washington. Research will be carried out to develop management strategies against this emerging pest of quinoa.
In the EPPO region, quinoa is also an expanding crop due to a rising demand from consumers for nutritious, plant-based proteins, and gluten-free food. In addition, quinoa is adapted to high elevations, poor soil conditions, high temperature fluctuations, low water resources and is perceived as an interesting alternative crop in the context of climate change. For the moment, it is very difficult to predict if A. karli has the potential to become a pest of quinoa in the EPPO region. However, attention should be paid to this insect which is already present in the natural environment.
According to the literature, the geographical distribution and host range of A. karli are as follows:
EPPO region: Croatia, Czech Republic, Finland, France, Germany, Greece, Hungary, Poland, Romania, Slovakia, Spain, Sweden, Switzerland.
Asia: Korea (Republic of), Mongolia.
North America: Canada (Alberta, British Columbia, Manitoba, Nova Scotia, Ontario, Québec, Saskatchewan), USA (Colorado, Maryland).
Host range: Chenopodium album, C. quinoa, C. vulvaria.
Pictures of A. karli can be viewed on the Internet: https://entomologytoday.org/2023/04/20/united-states-quinoa-fly-pest-amauromyza-karli/
Sources
Boucher S (2012) Revision of the Canadian species of Amauromyza Hendel (Diptera: Agromyzidae). Canadian Entomologist 144, 733–757. Černý M, von Tschirnhaus M, Winqvist K (2021) First records of Palaearctic Agromyzidae (Diptera) from 40 countries and major islands. Acta Musei Silesiae, Scientiae Naturales 69, 193-229. Gil-Ortiz R, Falcó-Garí JV, Oltra-Moscardó MT, Martinez M, Moreno-Marí J, Jiménez-Peydró R (2009) New host-plants for Agromyzidae (Diptera) from Eastern Spain. Bollettino di Zoologia Agraria e di Bachicoltura 41(2), 71–86. Lonsdale O (2021) Manual of North American Agromyzidae (Diptera, Schizophora), with revision of the fauna of the “Delmarva” states. ZooKeys 1051, 1–481. https://doi.org/10.3897/zookeys.1051.64603 Szczepaniec A, Alnajjar G (2023) New stem boring pest of quinoa in the United States. Journal of Integrated Pest Management 14(1), 1–7. https://doi.org/10.1093/jipm/pmad004 |