ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective To investigate the resistance status of Aedes albopictus to used insecticides in the late stage of dengue fever emergency control of Guangdong province in 2014, and learn how to prevent the development of resistance. Methods From the end of October to the beginning of November 2014, larve of Ae. albopictus were collected in epidemic regions in Haizhu and Baiyun district of Guangzhou city, Chancheng and Nanhai district of Foshan city, Chaoyang district of Shantou city, Chao'an district of Chaozhou and Rongcheng district of Jieyang city, and were reared about 1 to 2 generations in the lab, then were tested along with the susceptible larvae according to the methods of national standard “Test Methods of mosquito resistance to insecticides-bioassay methods”(GB/T 26347-2010) to calculate LC50 and resistance index. Results Aedes albopictus of all tested regions had low resistance to temephos and propoxur, the resistant index was 4.92-8.33 and 2.35-6.23 fold respectively. The resistantce to permethrin, beta cypermethrin, deltamethrin resistance were 3.53-31.29 fold, 8.35-38.69 fold, and 2.63-37.04 fold respectively. Of pyrethroid insecticides, Guangzhou city have reached the high level resistance mostly, Foshan city, Chaozhou city mostly low level of resistance, Jieyang city for low level of resistance, Shantou city mostly above the moderate level of resistance against cypermethrin. Aedes albopictus from some cities also have developed resistance to other insecticides in different levels. Conclusion Resistance of Ae. albopictus in the dengue epidemic cities in Guangdong increased very quick to the used insecticides. The control of Ae. albopictus should adhere to the principle of sustainable and integrated management to prevent or delay the development of resistance.
Objective To study the community structure, dynamic and West Nile virus (WNV) carried of mosquito vectors in Guangdong, and provide scientific evidence for further development of control and prevention strategies. Methods Mosquito density was monitored by Light-trap from May 2013 to April 2014. One-step reverse-transcript PCR was applied. Results The average density of mosquito was 11.80/light. The seasonal peak of density was from May to July. Of all habitats the density in the barn was the highest. Culex pipiens quinquefasciatus accounts for 89.90%, the largest proportion of mosquitoes. No positive was found by RT-PCR. Conclusion Culex pipiens quinquefasciatus was the predominant species, the monitoring data could provide scientific basis for the control strategies and warning and forecasting of WNV, but the vectors species of West Nile fever in Guangdong province and its spread risk needs to be further studied.
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 study the resistance of Rattus rattus sladeni to anticoagulant rodenticide. Methods No?choice food test was used in this study according to the method of national rodent resistance surveillance group. Results The rodents caught in nine districts of Guangzhou were tested. The survival rate was 3.8%. The total average dosage was 30.31 mg/kg, and survival average dosage was 58.29 mg/kg. The result showed that its sensitivity to anticoagulant rodenticide was between R.tanezumi and R.norvegicus. Conclusion The anticoagulant rodenticide can be still used to the control of R.rattus sladeni. But it should strengthen the resistance surveillance, and the chemicals should be used scientifically and rationally.
【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.