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A Report of the Mosquito Host Range of Pythium guiyangense Su
Xiaoqing Su
(Department of Biology, Guiyang Medical College, Guiyang 550004, Guizhou, China)
Summary: Mosquito causes problems on both disease transmission and disturbance to people's
daily life. The controlling methods used now are mainly application of chemical pesticides which
result in serious harm to environment. Biological control of the pest is one of the ideal ways. But,
lack of suitable agent makes it difficult to extend this technique in wider scope. Pythium
guiyangense Su is a newly found fungal pathogen of mosquitoes and is promising for practical use.
Here we summarize a list of mosquitoes that can be infected by the fungus so far, which shows the
potential significance of the application of the fungus in the future.
Mosquitoes not only disturb people, but also transmit serious diseases, such as malaria, filarial,
Dengue fever, and encephalitis B etc
[1]
. Mosquito control is an important part of the battle against
these diseases. Comparing with chemical pesticides that used widely at present, and have caused
serious environmental problems, biological control of mosquito is relatively safe and friendly to
our environment.
Biological control of medical insects is more hysteretic than that of agriculture pests. One of
the facts is the lack of suitable agent.
Pythium guiyangense Su is a fungal pathogen of mosquitoes isolated in Guiyang, China, in
1994
[2]
(China patent No. ZL 200510003027.7), and has been proved has merits of safe to
non-target organisms, strong growth vigor on wide range of media, and high tolerance to adverse
* The research is supported by NATURAL SCIENCE FOUND OF CHINA (No. 30160003)
Nature Precedings : hdl:10101/npre.2008.1875.1 : Posted 10 May 2008
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environmental conditions
[3,4,5]
. In order to explore the fungus for mosquito biocontrol, we have
been keeping on investigation of its mosquito host range. So far, more than 20 species of
mosquitoes were tested and 14 species of them were infected by P. guiyangense. The research is
reported here.
1.
Material and methods
Mosquito larvae were collected in different breeding sites including rice field, bamboo tube,
and holes in rock or trees, and identified in lab morphologically. Then, the larvae were kept in
plastic cups separately and stayed with agar pieces containing mycelia of P. guiyangense.
Observation was made twice a day, and dead larvae were picked out and checked under
microscope for infection. Data were recorded and analyzed.
2.
Results
The list of the mosquito species infected by P. guiyangense is as follows:
Eight species of genus Culex:
Culex pipiens quinquefasciatus Say
Cx. tritaeniorhynchus Giles
Cx. pipiens pallens Coquillett
Cx. mimulus Edwards
Cx. tianpinggensis Chen
Cx. theileri Theobald
Cx. pseudovishnui Colless
Cx. minor Leicester
Five species of genus Aedes :
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Aedes elsiae Barraud
Ae. novoniveus Barraud
Ae. formosensis Yamada
Ae. albopictus Ckuse
Ae. eagypti Linnaeus
One species of genus Anopheles:
Anopheles sinensis Wiedemann
3.
Discussion
Among the hosts confirmed, 6 species are important vectors of diseases. Culex
pipiens quinquefasciatus Say and Cx. pipiens pallens Coquillett are subspecies of Cx.pipiens
and are proved the vector of Filaria bancrofti. C. quinquefasciatus is also vector of yellow
fever virus and encephalitis B virus.
Cx. tritaeniorhynchus is the main vector of encephalitis B virus in many areas of
China. Ae. albopictus is a polyergic vector of viruses, specially those of encephalitis B and
Dengue fever. Ae. eagypti is also a vector of Dengue fever virus in southeast parts of China
along the coast, and southeast Asia countries.
Malaria is the most important mosquito transmitted disease, to which 300 million
people in 104 countries and arers are involved each year, and 1 to 1.5 million die from the
disease. The vectors are mostly members of Anopheles. A. sinensis in the list is also a vector
of malaria in our place
[7]
.
Members in genus Aedes such as Aedes elsiae, Ae. Albopictus and Ae. eagypti are
Nature Precedings : hdl:10101/npre.2008.1875.1 : Posted 10 May 2008
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diumal insects and can disturb travelers in tour regions, which is a big problem to tourism
business.
The application of P. guiyangense in mosquito biocontrol might be one of the
resolvents for the problems of disease control and the mosquito disturbance.
The host investigation is still kept on going, and, along with the extension of the
host list, the application scope of the fungus will be increased further.
REFERENCE
[1] Lu, B., Zhao T. Research of mosquito for 50 years in China [J].
Entomologia Sinica 2000
5(43
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[2]
Su, X. A new species of Pythium isolated from mosquito larvae and its ITS region of rDNA
Mycosystema 25
4523-528 2006-12-11
[3] Liu, P., Su, X. A long-term test on the safety of Pythium guiyangense to rats
Mycosystema 2007 26
3440447
[4] Liu, P., Su, X. An acute test on the safety of Pythium guiyangense to several kinds of animals
Journal of Guiyang Medical College 2007 32
4331336
[5] Huang, S., Su, X. Biological studies on Pythium guiyangense, a fungal
pathogen of mosquito larvae Mycoststema 2007 26
3380388
[6] Zhao, X.., Zuo, L., Shu L. A study of vertical transmission of Dengue virus type 1 in three
Guizhou geographical strains of Aedes albopictus Journal of Guiyang Medical College 2004
29
3189-192
[7] Lu, B. The epidemiology of malaria in our country and the research of its vectors
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Nature Precedings : hdl:10101/npre.2008.1875.1 : Posted 10 May 2008