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Rice virus alert in Vietnam

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A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases

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: Sun 6 Jun 2009
Source: Viet Nam News (VNS) [edited]
<http://vietnamnews.vnagency.com.vn/showarticle.php?num=01AGR060609>

Agriculture officials have warned farmers not to panic over the appearance of small brown plant hoppers in the northern provinces of Hung Yen, Hai Duong, Thai Binh, and Bac Ninh. According to the Ministry of Agriculture and Rural Development, the new planthopper, known as _Laodelphax striatellus_, was found densely scattered over
35 hectares [86.5 acres] of rice fields, sometimes up to 6000 insects per square metre. The highest density in some areas is 18 000 to 20 000 insects per square metre.

The insect has infested several other countries like mainland China, Japan, and South Korea, according to Ngo Tien Dung, head of the Plant Protection Division of the Department of Plant Protection.

Another type of plant hopper is multiplying in northern provinces, damaging some 20 000 ha [49 400 acres] of winter-spring rice crop, of which some 3000 ha [7400 acres] is seriously affected. More than 30 000 ha [74 000 acres] of summer-autumn crop in southern areas have also been affected by this insect.

The brown plant hoppers are the most serious of rice pests. They suck rice plant sap and transmit rice diseases, leaving fields susceptible to the ragged stunt rice disease, rice stripe virus, and maize rough dwarf disease. Brown plant hoppers have destroyed 730 ha [1800 acres] of paddy fields in the central province of Phu Yen.

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Communicated by:
ProMED-mail
<promed@promedmail.org>

[The small brown planthopper, _Laodelphax striatellus_ is an important vector of virus diseases of graminaceous plants and is the most important vector of _Rice stripe virus_ (RSV; genus _Tenuivirus_). It is often responsible for epidemics of rice stripe disease, which causes severe losses in many rice-growing regions. RSV detection in this vector is used for disease forecasting since the virus is transmitted in a persistent manner (propagative in the insects, passed on to progeny through eggs). _L. striatellus_ also transmits _Rice black streaked dwarf virus_ (RBSDV; genus_Fijivirus_) and _Maize rough dwarf virus_ (MRDV; genus _Fijivirus_).
Besides rice, all 3 viruses can also affect wheat and other cereal crops.

The other virus mentioned above, _Rice ragged stunt virus_ (RRSV; genus _Oryzavirus_), is transmitted by the brown planthopper _Nilaparvata lugens_, which is also a vector of several other rice viruses. Additional rice viruses are transmitted by green rice leafhoppers (_Nephotettix_ species). Disease management of rice viruses generally includes cultural techniques (for example planting time, reduction of inoculum), vector control, and use of resistant crop cultivars.

_N. lugens_ and _Nephotettix_ spp. have been reported to be associated with rice virus epidemics in Viet Nam before, and either of these may be the 'other' plant hopper referred to above. However, it appears from this news report that _L. striatellus_ is considered a new incursion in the country. RSV epidemics and southward spread of the disease and its vector have been reported from China in recent years (ProMED-mail post 20080825.2650). The presence of _L. striatellus_ carries an extremely high risk of rice stripe for Viet Nam and further increases the virus disease pressure on national rice crops.

Maps
Map of Viet Nam and neighbours:
<http://www.lib.utexas.edu/maps/middle_east_and_asia/vietnam_pol01.jpg>
<http://healthmap.org/r/008c>
Viet Nam provinces:
<http://www.angelfire.com/co/hongnam/vnmap.html>

Pictures
RSV symptoms:
<http://www.pref.aichi.jp/byogaichu/seitaitoboujyo/0-ine/simahakare-higai1.jpg>
_L. striatellus_:
<http://www.last.gov.cn/oa/upload/other/2007919114515838.bmp>
_N. lugens_:
<http://www.dpvweb.net/dpv/showfig.php?dpvno=320&figno=03>

Links
RSV and _L. striatellus_ in China:
<http://ricehoppers.net/2009/01/01/ricehopper-problems-intensify-in-china/>  and <http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=014054>
RSV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.069.0.01.001.htm>
Information on RBSDV and MRDV:
<http://www.riceblast.snu.ac.kr/file/44/43200_17(3)-4.pdf>
RBSDV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.060.0.07.007.htm>
MRDV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.060.0.07.003.htm>
Information on _L. striatellus_:
<http://popgen.unimaas.nl/~jlindsey/commanster/Insects/Bugs/SuBugs/Laodelphax.striatellus.html>
and
<http://www.cabicompendium.org/NamesLists/CPC/Full/CALGMA.htm>
_L. striatellus_ taxonomy:
<http://www.uniprot.org/taxonomy/195883>
RRSV description and taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.060.0.09.003.htm>
Additional information on rice hoppers and viruses via:
<http://www.knowledgebank.irri.org/RiceDoctor/Welcome_to_Rice_Doctor.htm>
Research on hopper resistance:
<http://www.shigen.nig.ac.jp/rice/rgn/vol21/b23.html>
Review of rice viruses, biology and epidemiology:
<http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.phyto.34.1.249?journalCode=phyto>. 
- Mod.DHA]

[see also in the archive:
Tungro disease, rice - Philippines: (AK) 20090430.1634
2008
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Rice diseases - Viet Nam 20081017.3291
Tungro disease, rice - Philippines: (SCO) 20080902.2744 Rice stripe virus - China: (ZJ), spread 20080825.2650 Virus diseases, rice - Viet Nam: update (02) 20080322.1093 Virus & blast diseases, rice - Viet Nam (Mekong Delta) 20080204.0454 Virus diseases, rice - Viet Nam: update 20080118.0221
2007
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Rice grassy stunt virus - Viet Nam (Mekong Delta) 20070725.2382 Virus disease, rice - Viet Nam (02) 20070614.1939 Virus disease, rice - Viet Nam 20070611.1899
2006
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Ragged and grassy stunt, brown planthopper, rice - Viet Nam 20061103.3157
2003
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Maize rough dwarf virus, maize - Greece: 1st report 20031115.2840
1997
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Rice hoja blanca & rice stripe viruses: RFA 19971015.2132]

 

 

 

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