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Date: February 2024
Source: European and Mediterranean Plant Protection Organisation (EPPO) Reporting Service 02/2024/044 [summ. Mod.DHA, edited]
https://gd.eppo.int/reporting/article-7794


Cucurbit chlorotic yellows virus (_Crinivirus_, CCYV) is an emerging virus of cucurbits [ProMED post 20220318.8702057] transmitted by _Bemisia tabaci_ (EPPO RS 2022/043). It was previously known to cause damage to cucurbit plants, but is more recently being reported from crops in other families:

[1] CCYV is reported infecting and damaging lettuce (_Lactuca sativa_) in India. Infected plants were first observed in 2021 and showed blistering, chlorosis, mosaic, rosetting/ excess proliferation and stunting symptoms.

[2] CCYV is reported in cannabis plants (_Cannabis sativa_) grown in farms in Israel. Infected plants showed foliar symptoms of interveinal chlorosis, yellowing, brittleness and occasionally necrosis which were more apparent in older leaves. Severe disease symptoms of yellowing and leaf-edge necrosis were observed in the case of mixed infections with _Lettuce chlorosis virus_ (_Crinivirus_, LCV) and CCYV.

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ProMED

[Cucurbit chlorotic yellows virus (CCYV) is still designated as an unclassified virus related to genus _Crinivirus_ by the International Committee on Taxonomy of Viruses (ICTV; see links below), due to as yet incomplete or unverified sequence information. It was first identified in the early 2000s causing damage to cucurbit crops in Asia and has since spread to Africa and Europe. The whitefly species _Bemisia tabaci_ has so far been shown to be a vector of CCYV; further work is needed to assess other potential whitefly vectors.

CCYV infects a wide range of cucurbit species (Cucurbitaceae, order Cucurbitales; such as melon, watermelon, cucumber, pumpkins). Not all cucurbit species that can become infected by CCYV develop visible symptoms. Species in other families have also been reported as natural or experimental hosts, including some wild species which may serve as virus or vector reservoirs for infection of crops. The two new hosts reported above, i.e., _Lactuca_ (Asteraceae, order Asterales) and _Cannabis_ (Cannabaceae, order Rosales), represent additional taxonomic families in different taxonomic orders and thus expand the known host range of the virus further. The role of the different host and non-host plant families in CCYV epidemics needs further investigation. Even CCYV non-host species may provide preferential feeding sources for the vectors and thus aid in insect reproduction, increased virus transmission and development of CCYV epidemics.

CCYV symptoms on cucurbits include brittleness, thickening and interveinal yellowing of leaves, often resembling nutritional deficiencies. Similar symptoms in crops can also be caused by _Crinivirus_ species such as _Cucurbit yellow stunting disorder virus_, _Beet pseudoyellows virus_; or by _Polerovirus_ species such as _Cucurbit aphid-borne yellows virus_, _Pepo aphid-borne yellows virus_.

Criniviruses are transmitted exclusively by their insect vectors; they cannot be spread with seed or by mechanical means. 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.

Pictures
CCYV symptoms on cucurbit leaves:
https://bugwoodcloud.org/images/1536x1024/5556501.jpg,
https://bugwoodcloud.org/images/768x512/5556502.jpg and
https://bugwoodcloud.org/images/768x512/5556503.jpg
Whiteflies:
https://www.planetnatural.com/wp-content/uploads/2012/12/whitefly.jpg and
https://files.growingproduce.com/growingproduce/wp-content/uploads/2016/05/whiteflies.jpg

Links
Information on CCYV and characterisation:
https://ecucurbitviruses.org/resources/fact-sheets-videos/cucurbit-chlorotic-yellows-virus/,
https://gd.eppo.int/taxon/CCYV00,
https://doi.org/10.1079/cabicompendium.110472,
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=558690,
https://doi.org/10.1094/PDIS-02-17-0164-RE and via
https://doi.org/10.1016/B978-0-12-816030-5.00012-4
CCYV transmission by _B. tabaci_ vector:
https://doi.org/10.1016/j.jviromet.2015.04.014 and
https://doi.org/10.1038/srep36604
Virus taxonomy via:
https://talk.ictvonline.org/taxonomy/
Information on whitefly vectors:
https://ipm.ucanr.edu/agriculture/tomato/whiteflies/ and
https://www.iucngisd.org/gisd/species.php?sc=106
- Mod.DHA

ProMED maps:
India: https://promedmail.org/promed-post?place=8715377,142
Israel: https://promedmail.org/promed-post?place=8715377,90]

Website: http://www.isid.org

Published: March 15, 2024