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.
--
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
----
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
----
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
----
Ragged and grassy stunt, brown planthopper, rice - Viet Nam
20061103.3157
2003
----
Maize rough dwarf virus, maize - Greece: 1st report
20031115.2840
1997
----
Rice hoja blanca & rice stripe viruses: RFA 19971015.2132] |
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