Objective To investigate the susceptibility of Blattella germanica to commonly used insecticides and optimize future application of insecticides. Methods The surface contact method was used, calculating the medium knock-down time(KT ₅₀) and obtaining resistance ratios by comparing with susceptible strain from 2015 to 2016. Results The resistance index of field-collected strains of B. germanica to beta-cypermethrin, deltamethrin, cypermethrin, acephate, DDVP, ehlorpyrifos, and propoxur were 13.76-32.93, 5.26-15.25, 4.81-21.02, 1.01-2.11, 1.05-7.38, 1.00-1.20, and 1.02-2.12. The average mortality of B. germanica in different areas of Chongqing after 72 h of contacting to acephate, ehlorpyrifos, DDVP, deltamethrin, cypermethrin, propoxur, and beta-cypermethrin were 100%, 100%, 94.0%, 92.0%, 81.0%, 79.0% and 78.0%. Conclusion Field collected strains of B. germanica in Chongqing have already developed different resistance to seven kinds of insecticides. Insecticides should be applied strategically to manage the insecticide resistance of B. germanica effectively.

Objective To investigate the susceptibility of Aedes albopictus larvae to four insecticides in some areas of Chongqing. Methods To determine the median lethal concentration (LC⁵⁰) of the field population of Ae. albopictus larvae of Yuzhong district and Wanzhou district located in the hinterland of the Three Gorges Reservoir, by immersing them with pesticide in 2014-2015. Results In comparison with the susceptible strain, the resistance ratios of Ae. albopictus larvae to beta-cypermethrin, deltamethrin, permethrin, and temephos were 7.59-, 4.50-, 9.88-, and 3.18-fold respectively in Yuzhong district, and 12.82-, 7.50-, 13.29-, and 2.00-fold respectively in Wanzhou. Conclusion Aedes albopictus larvae of Yuzhong had a low level resistance to beta-cypermethrin, deltamethrin, permethrin, and temephos; that of Wanzhou had a moderate resistance to beta-cypermethrin and permethrin, but a low level resistance to deltamethrin. Therefore, it is important to rotate pesticides and choose appropriate doses in mosquito control.

Objective Master the species, seasonal dynamics, and distribution of Aedes mosquito vectors, and incidence of dengue in Wanzhou district, to assess the risk of dengue fever, provide the basis for the prevention and control of dengue fever. Methods Monitoring the density of Aedes larva by Breteau index method, investigating the density of mosquito population by double stack method, analyzing the case data using the method of comparative analysis of epidemiology. Results There was 1 imported case of dengue fever in Wanzhou area in 2015, the incidence was 0.62/100 000, there was no case of epidemic spread due to the imported case. Monitoring the mosquito vectors density in 4 sites in the May through October in 2015, Aedes Breteau index fluctuated between 3.74-7.54. Fifteen mosquitoes were caught in 6 rounds of trapping with double stack method, of which 1 was the Anopheles sinensis, 14 were the Armigeres obturbans. The 6-round of trapping in the monitoring did not capture the vectors of dengue fever, the Aedes mosquito bite index was zero. Conclusion The human population flow in this area is frequent, there are many migrant workers in Burma, Guangdong, Yunnan and the other places, this is a high possibility of imported case, but a low risk of local outbreaks of dengue fever, suggesting to strengthen the monitoring to prevent epidemic.

Objective To understand the species composition and quantitative distribution of the dominant host animals and plague vector fleas, and the infections of host animals with Yersinia pestis in Wanzhou and Fuling sections of the Three Gorges Reservoir Area to determine whether there existed plague foci or not. Methods Rodents captured by cages and fleas collected with sticky papers, were identified with the flea-carrying rate and flea index calculated. The plague F1 antibody from host animals was detected with IHA. Results (1)Host animals: one hundred and seventy rodents were captured in Wanzhou with a rodent density of 3.20% and 303 rodents in Fuling with a density of 5.95%.(2)Flea index: one hundred fifty-one fleas were caught in Wanzhou with a flea-carrying rate of 22.94% on rodents, the total flea index being 0.888. Sixty-four fleas were caught in Fuling with a flea- carrying rate of 7.59%, the total flea index being 0.211.(3)The free flea index: three thousand sticky papers were placed and 6 fleas were captured in Wanzhou with a total flea index of 0.002. No fleas were captured in Fuling with the same method.(4)The plague serological examination: in Wanzhou and Fuling sections, no plague F1 antibody was detected. Conclusion Wanzhou and Fuling sections are not plague foci where no plague has occurred, but based on the information of geographical landscape, host animals, vector insects and epidemiological investigation, it is likely that the plague epidemic may occur in the sections.

Objective To determine the density dynamics and species composition of mosquitoes in Wanzhou agricultural areas of the Three Gorges Reservoir region, providing the basis for prevention and control of mosquito-borne diseases and mosquito hazard prediction. Methods The labor hour and light trap methods were employed to capture mosquitoes in different areas for taxonomic identification and statistical analysis. Results A total of 229 561 mosquitoes were captured using the two methods in the two years. Identification results showed that the mosquitoes were in 5 species, 4 genera, 2 subfamilies, 1 family and 1 order. The predominant species was Armigeres subalbatus, accounting for 69.80% of the total captives, followed by Culex pipiens quinquefasciatus (15.59%), Anopheles sinensis (8.56%) and Cx. tritaeniorhynchus (6.00%). The average density of adult mosquitoes in 2008 and 2009 was 247.3 and 145.8/(light·night) in residential areas, 933.5 and 1166.1/(light·night) in pigpens, and 1835.2 and 1203.3/(light·night) in cowsheds, respectively. According to the labor hour method, the average adult mosquito density was 94.03/ labor-hour in residential areas and 254.46/labor-hour in pigpens. Conclusion The density dynamics and species composition of mosquitoes obtained by the labor hour and light trap methods are the first-hand indicators of mosquitoes in Wanzhou agricultural areas and even the Yangtze River Three Gorges Reservoir region. These will be of great importance and value for the prevention and control of mosquito-borne diseases as well as vector mosquitoes in the region.

【Abstract】 Objective To grasp the population constitution of the rat-shape animals and its density fluctuation at the Three Gorges district, prevent the damage of the rodent and the rodent-borne diseases to the human, and to provide the science evidence for its forecast. Methods The investigation was preformed at four habitats by night trapping at 5 meters intervals. Results There were 79 rat-shape animals captured at Wanzhou district, belonging to 6 species, 2 families and 2 orders, and the average rodent density was 2.76%. Of which, that in the north of the Yangze River was 2.32% and 3.06% in the south of the Yangze River. The common species in the resident room were Rattus norvegicus, Mus musculus and R.flavipectusye. And the dominant species were Mus musculus and R.flavipectusye. In the wild rural areas, the dominant species were Apodemus agrarius and Anourosorex squamipes. Conclusion The average rodent density was 2.76% (79/2863) in this district on April 2008. For the rodent density in the resident room, it in the north of the Yangze River was higher than that in the south, and that in the dry land neighboring the water area was also higher than other dry land.

Objective Investigating the variation of mosquito density with temperature,humidity and rainfall.Methods According to "the surveying project about the social health in the Three Gorges area"(modified in 2002),we collected datum of mosquito density and weather and made correlation and regression analysis between them by SPEM software.Results The correlation of temperature and mosquito density was positive,coefficient was 0.690 5( P< 0.05).Standard partial regression coefficients between mosquito density and temperature,humidity were respectively 0.851 7( P<0.05) and 0.382 1( P< 0.05),which is of statistic significance.Conclusion Temperature and humidity can influence mosquito density,especially temperature.