SeedQuest - Central information website for the global seed industry

News Page

The news
and
beyond the news

Index of news sources

Topics

Species

Archives

News archive 1997-2008

Reoccurrence of tomato leaf curl New Delhi virus on cucurbits in France

A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

Date: January 2023
Source: European Plant Protection Organisation (EPPO) Reporting Service 01/2023/021 [summ. Mod.DHA, edited]
https://gd.eppo.int/reporting/article-7503

In France, _Tomato leaf curl New Delhi virus_ (_Begomovirus_, ToLCNDV - EPPO A2 List) was first found in 2020 on _Cucurbita pepo_ (zucchini) [ProMED post 20201029.7898960] and later declared eradicated (EPPO RS 2020/250, RS 2021/119). The NPPO (National Plant Protection Organisation) of France recently informed EPPO of new detections of ToLCNDV on its territory. The virus was detected in 5 locations in Provence-Alpes-Côte d'Azur region in September and October 2022:

- in 3 companies producing and trading seeds of _C. pepo_, _Cucumis sativus_ (cucumber) and _Cucumis melo_ (melon). Phytosanitary measures were implemented (destruction and incineration of plants, treatments against the virus vector, _Bemisia tabaci_);

- in 2 sites for fruit production of _C. pepo_ (1 ha outdoor plot and a 640 m² growing tunnel). All plants in the affected plots were uprooted and destroyed after harvest. In 2023, the growers will have to carry out crop rotation and apply treatments against the vector.

--
Communicated by:
ProMED

[_Tomato leaf curl New Delhi virus_ (ToLCNDV; genus _Begomovirus_) was first identified as causing severe yield losses on tomato and watermelon crops on the Indian subcontinent. It belongs to the tomato leaf curl and yellow leaf curl clades of the genus. Known species in these clades cause similar diseases on solanaceous and other hosts and are considered to be the biggest constraint to solanaceous and cucurbit crops, both in terms of yield losses (up to 100% in tomato) and loss of fruit quality.

Begomoviruses are transmitted by different whitefly vectors (such as _Bemisia tabaci_ biotypes). Many can also be transmitted by mechanical means and grafting; they are generally not considered to be capable of true seed transmission (i.e., via the embryo). Whiteflies in themselves are serious pests of many vegetable crops. If virus sources are available locally, high vector numbers are often reflected in high levels of the viral diseases they transmit. Begomovirus control is particularly difficult in open field crops due to the widespread presence and wide host range of whiteflies. Disease management may include pathogen exclusion, vector control, as well as elimination of possible pathogen and/or vector reservoirs. In some cases, crop cultivars with increased virus resistance are available.

ToLCNDV was limited to Asia until it was reported from Europe for the 1st time in 2013 on cucurbits in Spain (ProMED post 20131223.2131729). It has since also been reported from several other countries in the Mediterranean region. Severe potato leaf curl disease caused by a ToLCNDV is currently emerging as a global threat.

Novel viruses have been shown to emerge from recombination events during co-infections of ToLCNDV and other begomoviruses (see links below).The recombinant viruses are often more aggressive and have a widened host range, compared to each of the partners. Examples are new viruses identified in the Mediterranean region causing severe damage to cucurbit crops but poorly infecting tomatoes; or the new potato strain of ToLCNDV having acquired an extraneous betasatellite (small circular DNA in addition to the viral genome), which is considered responsible for its host preference and severity of symptoms. Such new hybrid viruses pose an increased risk to solanaceous, cucurbit, and potentially other crops worldwide.

For the report above, it is not clear if a source of the new detections is being investigated. Both new incursions with plant material or via infectious insects, and reinfection from local plant reservoirs would be possible, since eradication of established pathogens has rarely been successful anywhere in the past (see ProMED post 20230105.8707630 and multiple previous ProMED posts in the archives).

Maps
France (with regions):
https://www.worldometers.info/img/maps/france_physical_map.gif
Europe, overview:
https://mapofeurope.com/wp-content/uploads/2018/03/europe-political-map.jpg

Pictures
Leaf curl disease on tomato:
https://www.agric.wa.gov.au/sites/gateway/files/TYLCV%203%20bush.jpg,
https://c8.alamy.com/comp/ACGAME/tomato-yellow-leaf-curl-virus-symptoms-on-tomato-leaves-on-plants-ACGAME.jpg,
https://www.plantmanagementnetwork.org/pub/php/research/2008/TYLCV/image/TYLCV2.jpg and
https://vegcropshotline.org/wp-content/uploads/2018/06/IMG_20180616_103634.jpg
ToLCNDV symptoms:
http://cienciacebas.files.wordpress.com/2013/09/aranda-1.jpg (zucchini) and
http://cienciacebas.files.wordpress.com/2013/09/aranda-2.jpg (cucumber and melon)
Photo gallery of symptoms of different begomoviruses:
http://www.forestryimages.org/browse/TaxImages.cfm?fam=651&genus=Begomovirus
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 ToLCNDV:
https://gd.eppo.int/taxon/TOLCND (with distribution),
https://doi.org/10.1079/cabicompendium.118179,
https://doi.org/10.2903/j.efsa.2020.6179,
https://doi.org/10.1111/ppa.12978,
https://doi.org/10.3389/fmicb.2019.00140,
https://doi.org/10.1007/s41348-021-00463-w (potato strain) and
https://doi.org/10.3390/v9100264 (review)
Novel ToLCNDV recombinant viruses:
https://doi.org/10.3390/v8110307 and
https://doi.org/10.1007/s10327-019-00849-7
Information on viral betasatellites:
https://doi.org/10.1007/s11262-019-01716-5,
https://viralzone.expasy.org/7777,
https://www.ncbi.nlm.nih.gov/genomes/GenomesGroup.cgi?taxid=190729 and via
https://www.sciencedirect.com/topics/immunology-and-microbiology/betasatellite
Information on leaf curl viral diseases on different hosts:
http://www.oisat.org/pests/diseases/viral/leaf_curl__virus.html and via
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/tomato-leaf-curl-virus
Virus ans betasatellite taxonomy via:
https://ictv.global/taxonomy
_B. tabaci_ whiteflies, taxonomy, and biotypes:
http://www.iucngisd.org/gisd/species.php?sc=106 (with pictures)
EPPO A2 list:
https://www.eppo.int/ACTIVITIES/plant_quarantine/A2_list
- Mod.DHA]