Objective To assess the effect of the EP-1 on the population reproduction of the desert hamster Phodopus roborovskii. Methods Baiting bags containing a mixture of wheat and contraceptive compound EP-1 were placed in the field of Hunshandake Sandland, Xilin Gol League, Inner Mongolia, in late April, 2003. Monthly live-trapping survey were conducted from June to October to investigate the impact of EP-1 on the reproductive parameters and structure of the P. roborovskii population. Results EP-1 did not influence the sex ratio of the P. roborovskii population during the breeding season. In the baited area, EP-1 resulted in a 70%-80% decline in the proportion of juvenile hamsters, which lasted over 4 months. EP-1 profoundly damaged the uteri of approximately 80% of adult female hamsters within 2 months and such impact lasted more than 5 months. In addition, EP-1 significantly reduced the average litter size, which was 1-3 times smaller in the baited area than in the control area. Conclusion In Hunshandake Sandland, a single delivery of EP-1 in spring is effective in controlling the population of P. roborovskii during the breeding season. However, the impact of EP-1 on the reproduction of P. roborovskii population declines over time, which may be explained by the dispersal behavior of P. roborovskii.

Objective To investigate the distribution patterns of mosquito-borne viruses in Mile county, Honghe prefecture, Yunnan province, China, and to provide evidence for prevention and control of mosquito-borne diseases. Methods Mosquito samples were collected in Mile county during July 2009. Viruses were isolated from the samples through cell culture and then identified by molecular biology techniques. Results Nine virus strains were isolated from the mosquito samples including 4400 individuals of Culex tritaeniorhynchus and 2200 individuals of Anopheles sinensis. Seven strains, which were from Cx. tritaeniorhynchus, were identified as Japanese encephalitis virus (JEV), and 2 strains, which were from Cx. tritaeniorhynchus and An. sinensis, were identified as Cx. pipiens pallens densovirus (CppDNV). Conclusion JEV was first isolated from Mile county, Honghe prefecture, demonstrating that Mile county is an endemic area of JE from the etiological aspect. The prevalent JEV strain was confirmed to be genotypeⅠ, according to homology and phylogenetic analysis, and was first isolated in the southeast area in Yunnan province, China.

Objective To investigate the distribution profiles of arboviruses in Jiangxi province, China. Methods Mosquito samples were collected using mosquito lamps at 8 sites in Jiangxi in the summers of 2008 and 2009 and then used for virus isolation by tissue culture. The obtained virus isolates were identified by serological and molecular biological methods. Homology and phylogenetic analysis was performed on the sequences of the isolates by bioinformatics. Results A total of 11 916 mosquitoes (3 species, 3 genera) were collected in 2008, and 5905 mosquitoes (5 species, 4 genera) were collected in 2009. Four virus strains were isolated from the mosquitoes and were all identified as Japanese encephalitis virus (JEV). All the JEV strains belong to genotypeⅠ, according to the homology and phylogenetic analysis. Conclusion GenotypeⅠ JEV strains were isolated from mosquitoes collected in Jiangxi province, China. And they have a close phylogenetic association with JEV strains from Shanghai and Zhejiang province, China.

Objective To investigate the distribution patterns of mosquitoes and mosquito-borne viruses in Yunnan province to provide evidence for prevention and control of mosquito-borne diseases. Methods In 2009, mosquito samples were collected from 6 counties of Yunnan province. Mosquitoes were first classified, followed by cell culturing for viral isolation for molecular identification. Positive isolates were identified using SDS-PAGE and RT-PCR. The genomes of isolates were also, sequenced for phylogenetic analysis. Results A total of 18 562 mosquitos of 4 genera (Culex, Anopheles, Armigeres, Aedes) and 24 species were collected. Cx. tritaeniorhynchus and An. sinensis were the major species, comprising 58.37% and 28.45% of the total population, respectively. Fifteen strains of viruses were isolated from the mosquito pools. RT-PCR and phylogenetic analysis revealed two viral strains from Cx. tritaeniorhynchus, identified as Japanese encephalitis virus (JEV, GenotypeⅠ). One strain isolated from An. sinensis was identified as Banna virus. Twelve vrial strains were identified as Cx. pipiens pallens densovirus (CppDNV), of these, nine strains were isolated from Cx. tritaeniorhynchus, and three strains from An. sinensis. Conclusion Cx. tritaeniorhynchus and An. sinensis were the predominant species in the investigated areas. JEV, Banna virus and CppDNV were isolated. In northeast Yunnan, JEV was isolated for the first time.

【Abstract】 Objective To understand the population composition and seasonal fluctuation of fleas parasitized on Rattus tanezumi in Leizhou city. Methods R.tanezumi were captured in selected districts of Leizhou city from 1985 to 2004. Fleas were collected from their body surface and identified to count the flea index and its  composition  proportion.  Results A total of  1721 R.tanezumi were caught, and about 2345 fleas belonged to 4 species were collected. Among them, Xenopsylla cheopis and Leplopsylla segnis were the dominant species, the average index of them were 1.24 and 0.12, and the proportion of them were 91.13% and 8.66%, respectively. The index and composition proportion of  Pulex irritans and Ctenocephalides felis felis were very low. Conclusion R.tanezumi was the dominant host of X.cheopis and L.segnis. The number of X.cheopis increased year by year, but that of L.segnis decreased year after year.