ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective To investigate the resistance levels of Musca domestica to four commonly used insecticides in the special places such as landfill and meat processing plant in Guangdong province, China. Methods M. domestica larvae were collected in the wild breeding habitats, and topical application was used to determine the median lethal doses (LD50) of permethrin, deltamethrin, beta-cypermethrin, and DDVP for M. domestica. The experimental data were statistically analyzed by extremum method. Results The LD50 of permethrin, deltamethrin, beta-cypermethrin, and DDVP were 13.7179, 3.5971, 5.5982, and 0.7704 μg/insect, respectively, for M. domestica in the landfill and were 1.0999, 0.7278, 8.3314, and 0.5322 μg/insect, respectively, for M. domestica in the meat processing plant. The resistance ratios were 58-2525, increased 1-103 times compared with those in 1996 and increased 2-1383 times compared with those in 1991. The resistance of M. domestica to permethrin, deltamethrin, and DDVP was higher in the landfill than in the meat processing plant. Conclusion M. domestica develops high resistance to some insecticides in the special places in Guangdong province, and the resistance to pyrethroid increases rapidly. Comprehensive management strategies and proper insecticide use should be adopted to control M. domestica in the special places such as landfill and meat processing plant.
Objective To determine the characteristics and dynamics of mosquito population during the process of rapid urbanization, and to identify the relationships between the dynamic of main vectors and rapid urbanization. Methods The mosquito density was investigated for the past four years using the human-bait method. Results Five species of mosquito were captured, including Culex tritaeniorhynchus, Culex pipiens quinquefasciatus, Anopheles sinensis, Aedes albopictus, and Armigeres subalbatus. Cx. pipiens quinquefasciatus was predominant (92.27%), followed by Ar. subalbatus (3.98%). The proportions of Ae. albopictus and Cx. tritaeniorhynchus were relatively small, accounting for 1.62% each. The smallest was An. sinensis (0.51%). During a four-year study period, significant changes had taken place in the proportions of mosquito populations by comparison among the data in 2006, 2008 and 2009. The population of Cx. pipiens quinquefasciatus decreased while increased of that of Ae. albopictus. An. sinensis gradually disappeared as the time elapsed. The poplation of Cx. tritaeniorhynchus fluctuated largely in the study periods. In the evening, varieties of mosquito species showed distinct activity patterns. The biting time of Cx. pipiens quinquefasciatus and Cx. tritaeniorhynchus was from 19: 00 to 22: 00 in the evening with a peak after 21: 00. Ae. albopictus could be caught all the night with the main peak before 20: 00. A similar activity pattern was observed from Ar. subalbatus and Ae. albopictus. Conclusion During the process of rapid urbanization, the population of the dengue vector, Ae. albopictus, increased gradually. The population of the Japanese encephalitis vector, Cx. tritaeniorhynchus, fluctuated greatly in different years. However, the malaria vector, An. sinensis, eventually was not found. Thus, we propose that the surveillance and control of Ae. albopictus and Cx. tritaeniorhynchus should be strengthened during the process of urbanization.
【Abstract】 Objective To test the efficacy of four kinds of electric liquid repellents (A 0.12% dimefluthrin, B 0.17% dimefluthrin, C 0.86% transfluthrin, D 0.86% prallethrin) for the Japanese encephalitis(JE) vectors in the field. Methods The landing count method was used to the investigation of mosquito density before and after treatment by electric liquid repellent. Results The main species caught in the field were Culex pipiens quinquefasciatus and Cx. tritaeniorhynchus, which were the JE vector. Only sample A reached >80% population reduction of Cx. tritaeniorhynchus. Both sample B, C and D caused <80% population reduction of Cx. tritaeniorhynchus. Both sample A, C and D caused >80% population reduction. However, only sample B led to 70%-80% population reduction. Conclusion The tests suggest that four samples have a good repellent effect on mosquito, but the efficacy of sample B is less than that of sample A, C and D. There are different for the control efficacy of different electric liquid repellent in the lab and the field.
【Abstract】 Objective To evaluate the surveillance effect of Mosq?ovitrap to Aedes in the littoral areas with the high mosquito density. Methods Three or four Mosq?ovitraps were set in each household selected randomly from every 5 families. At the same time, the positive rate of the containers was investigated inside and outside of the household. Results A total of 1027 Mosq?ovitraps were set, and 43 Mosq?ovitraps were positive among 939 Mosq?ovitraps recovered effectively. Mosquito and oviposition positive index(MOI) was 4.6. There were 217 positive standing wasters among 324 households investigated, and the Breteau Index was 67.0, which was much higher than MOI. There was no significant correlation between them (r=0.449,P>0.05). Conclusion The environmental hygiene condition has an important effect on the monitoring results of Mosq?ovitrap. It still needs to further study that how to raise the catching ability of Mosq?ovitrap to mosquitoes and apply it to the mosquitoes surveillance in the areas with high mosquito density.
【Abstract】 Objective To develop a system of stepwise response for risk categories for dengue fever in China. Methods According to ecological features of Aedes albopictus, establish the method of mosquito and oviposition trap and compare the relationship of the mosquito and oviposition positive index (MOI) and the Breteau index (BI) or the Ovitrap index obtained from the traditional dengue fever vectors surveillance. Develop an epidemic forecast and phased response system for dengue fever control and prevention with reference to other correlative grade control system for dengue or other vector?borne disease, combined with the actual application of mosquito and oviposition trap in the vector surveillance. Results The MOI could be classified into 4 levels, below 5, 5-20, 20-40, and >40 respectively. Stepwise response for risk categories for dengue fever were divided into 4 levels according to the levels of MOI, seasonal character, virus infection rates in mosquitoes and the result of human cases surveillance. Conclusion The MOI is less than 5, which suggestes the control of dengue fever is very effective. However, the risk categories and its response index still need further study and verify in the practical application.
【Abstract】 Objective A field study was carried out in a restaurant in the south of China to investigate the blood sources affected Japanese encephalitis (JE) vectors Culex tritaeniorhynchus and Cx.pipiens quinquefasciatus indoor abundance. Methods Vector density was investigated by human?leg capture technique. Results In the dinning room adjacent to deer blood resource, Cx.tritaeniorhynchus was the dominant specie(74.80% of total number) and the minor vector was Cx.pipiens quinquefasciatus (21.14%). However, in the restroom where the mosquitoes could only access to human blood, Cx.pipiens quinquefasciatus accounted for 60.28% and that of Cx.tritaeniorhynchus was 36.62%(n=845). The density of Cx.tritaeniorhynchus in restroom was higher than that in the dinning room (df=1, χ2=5.32,P<0.05, n=676). However, the density of Cx.pipiens quinquefasciatus in the dinning room was higher than that in the restroom(df=1, χ2=268.45, P<0.001, n=611). Conclusion The results showed that the blood resources influenced the JE vector spatial abundance. The abundance of Cx.tritaeniorhynchus or Cx.pipiens quinquefasciatus was affected by the animal blood or the human blood.