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International Society for Infectious Diseases
http://www.isid.org

Date: July 2021
Source: European Plant Protection Organisation (EPPO) Reporting Service 07/2021/160 [abridged, edited]
https://gd.eppo.int/reporting/article-7099


The National Plant Protection Organisation of Spain recently informed of the first finding of _Lettuce infectious yellows virus_ (_Crinivirus_, LIYV - EPPO A1 List) on its territory, in a greenhouse in Biscay province [Basque Country]. This is the 1st record of this virus in the EPPO region. The identity of the virus was confirmed by the National Reference Laboratory.

In January 2021, batavia variety lettuce plants (_Lactuca sativa_) grown hydroponically in a cold tunnel showed symptoms of a possible viral infection: poor development, bunchy aspect, variegation, light green mosaic, and chlorosis mainly of the outer leaves. The infected plants were destroyed. 3 more cycles of lettuce production were carried out and no symptoms were observed. The insect vector (_Bemisia tabaci_) was not detected in the crops.

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ProMED
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[_Lettuce infectious yellows virus_ (LIYV; genus _Crinivirus_) infects lettuces (_Lactuca_ spp., family Asteraceae), as well as some crops in other families, such as cucurbits, sunflower, or carrot. It has been reported from the Americas where it can cause significant yield losses in susceptible crops. Symptoms on lettuces may include interveinal leaf yellowing or reddening; leaf mottling, distortion, and necrosis; overall yellowing and stunting of plants.

The virus is transmitted specifically by whiteflies (_Bemisia tabaci_) in a semipersistent manner. Outbreaks are usually associated with high vector populations. Weed hosts may serve as virus and/or vector reservoirs. Control of whitefly transmitted viruses is particularly difficult in open field crops due to the widespread presence and wide host range of whiteflies. Disease management of these viruses is difficult and includes vector control, removal of reservoirs of both virus and vectors, use of crop varieties with increased pathogen tolerance, and clean planting material.

Criniviruses are transmitted exclusively by their insect vectors, they cannot be spread with seed or by mechanical means. Therefore, although it is claimed that no whiteflies were present in the affected glasshouse, the plants must nevertheless have been exposed to infectious insects at some point, to be able to acquire the virus. Even though eradication of LIYV has been claimed in that particular establishment, the outbreak above would suggest the presence of LIYV in the region. Potential LIYV sources would need to be clarified urgently.

Maps
Spain:
http://www.map-of-spain.co.uk/maps-of-spain/spain/large_map-of-spain2.jpg,
http://healthmap.org/promed/p/5924, and
http://www.venamicasa.com/wp-content/uploads/2012/03/spain_map3.gif (provinces)
Europe, overview:
https://mapofeurope.com/wp-content/uploads/2018/03/europe-political-map.jpg

Pictures
LIYV symptoms on lettuce varieties:
https://bugwoodcloud.org/images/768x512/0162078.jpg,
https://www.cabi.org/isc/portfolio/compendia/normal/16178.img,
https://gd.eppo.int/media/data/taxon/L/LIYV00/pics/1024x0/988.jpg,
https://gd.eppo.int/media/data/taxon/L/LIYV00/pics/1024x0/986.jpg, and
http://www.bitkisagligi.net/Marul/marulresim/LettuceInfectiousYellowsVirus.jpg
LIYV symptoms on melons:
http://bugwoodcloud.org/images/768x512/0162076.jpg and
https://bugwoodcloud.org/images/768x512/0162077.jpg
Whiteflies:
https://www.planetnatural.com/wp-content/uploads/2012/12/whitefly.jpg and
https://www.pinpointpestcontrol.com/images/whitefly-on-plant.jpg

Links
Information on LIYV:
https://gd.eppo.int/taxon/LIYV00,
https://www.plantwise.org/knowledgebank/datasheet/30238,
https://www.genome.jp/virushostdb/31713,
https://www.cabi.org/isc/datasheet/30238,
https://www.fdacs.gov/content/download/11342/file/pp335.pdf,
https://pubmed.ncbi.nlm.nih.gov/19409943/, and
https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-80-5-1111
Information on criniviruses:
https://talk.ictvonline.org/ictv-reports/ictv_online_report/positive-sense-rna-viruses/w/closteroviridae/1293/genus-crinivirus,
https://viralzone.expasy.org/287, and
https://www.frontiersin.org/articles/10.3389/fmicb.2013.00099/full
Virus taxonomy via:
https://talk.ictvonline.org/taxonomy/
Information on whitefly vectors:
http://www.ipm.ucdavis.edu/PMG/r783301211.html and
http://www.issg.org/database/species/ecology.asp?fr=1&si=106
EPPO A1 quarantine list:
https://www.eppo.int/QUARANTINE/listA1.htm
- Mod.DHA]

See Also

2020
----
Tomato chlorosis virus: 1st reports, new hosts 20200607.7428940
2018
----
Tomato chlorosis virus - Netherlands 20180719.5914214
2017
----
Cucurbit yellow stunting disorder virus - Italy: 1st rep (Sardinia) 20170111.4753360
2014
----
Tomato chlorosis virus - Tunisia: 1st rep (KR) 20140808.2671012
and additional items on criniviruses in the archives

Website: http://www.isid.org

Published: August 20, 2021