Objective To investigate the fly density and its seasonal fluctuation in Dongcheng district of Beijing, China, and to provide a reference for fly control. Methods From 2014 to 2019, fly density was monitored by the cage trapping method at seven surveillance sites in Dongcheng district from April to October. The surveillance data were statistically analyzed by Excel 2007 software. Results From 2014 to 2019, the dominant fly species in Dongcheng district were Sarcophagidae (35.16%), Muscina stabulans (18.92%), Musca domestica (16.83%), and Lucilia sericata (13.19%), accounting for 84.10% of the total fly counts. The overall fly density decreased from 2014 to 2019. The fly density peaked in July. In terms of different habitats, greenbelt had the highest fly density (6.20 flies/cage), followed by hotels (5.49 flies/cage) and residential areas (4.88 flies/cage). The dominant fly species in greenbelt and residential areas were Sarcophagidae and M. domestica, respectively. Conclusion This study reveals the fly density, species composition, and seasonal fluctuation in Dongcheng district. Fly control should focus on greenbelt and hotels. The fly density peaks in July, suggesting that fly control measures should be taken before the peak.

Objective To understand the resistance dynamics of Blattella germanica to commonly used insecticide beta-cypermethrin, and provide the basis for the integrated pest management in different districts. Methods Insecticide resistance of 11 field strains B. germanica collected from hotels, gasthaus, farmer's markets, and small restaurants in Dongcheng, Xicheng, Chaoyang, Changping, Miyun, Huairou, Daxing, Shijingshan, Shunyi, Fangshan, and Mentougou district in 2014 and 2016, during May to July each year, were detected by surface contact method. The resistant ratio (RR) was calculated for each strain. Results The susceptibility of the field B. germanica strains to insecticide tested varied from different districts. The Dongcheng, Miyun, Huairou, Daxing, Xicheng, and Changping strains showed decreasing susceptibility to beta-cypermethrin, but Shijingshan, Chaoyang, Shunyi, Fangshan, and Mentougou strains showed increasing trend. The 11 field strains of B. germanica had low levels of resistance with RRs between 1.01 and 5.14 folds in 2014 and 2016 to beta-cypermethrin, except Shunyi strains with moderate resistance in 2014. The resistance change of Dongcheng and Mentougou stains was the widest, RR increased from 2.39 to 4.44 folds in Dongcheng strain, while RR decreased from 4.58 to 2.73 folds in Mentougou strain. Conclusion Field collected strains of B. germanica in different districts in Beijing had already developed different levels of resistance to beta-cypermethrin in 2014 and 2016. Based on the integrated pest management strategy, insecticides should be applied reasonably according to the local resistance surveillance results to control the cockroach effectively.

Objective To assess the risk of deltamethrin resistance development in Musca domestica and predict the rate of resistance development, and to provide a scientific basis for prolonging the service useful life of insecticides, protecting the effectiveness of existing insecticides, maximizing the potential of insecticides, and properly applying insecticides. Methods The resistant M. domestica strain for resistance risk assessment was obtained by lab resistance selection and bioassay. The resistance realized heritability (h₂) was estimated using Tabashnik method, and then the rates of resistance development under different selection pressures were predicted. Results The resistance ratio was increased to 2197.55-fold in the deltamethrin-resistant M. domestica strain after 21 consecutive generations of lab selection. The h₂ of M. domestica to deltamethrin was 0.1571, indicating a relatively high risk of resistance development. According to the general pattern of resistance development in M. domestica (the deltamethrin resistance development in M. domestica can be divided into three stages: the resistance development is very slow within the first seven generations, becomes fast from the 8th generation, and tends to level off in later generations). The h₂ values in three resistance development stages were 0.1016 (F₀-F₇), 0.2140 (F₈-F₁₇), and 0.0250 (F₁₈-F₂₁). According to the h₂ values in different stages, we predicted that 10-fold resistance increase required 7.2-15.9, 4.9-10.8, and 44.4-98.1 generations under different selection pressures (mortality rates: 50%, 60%, 70%, 80%, and 90%). Conclusion The risk of deltamethrin resistance development is relatively high among M. domestica, so attention should be paid to proper use of insecticides based on the situation of targeted pest.

Objective The species, quantity and distribution of the wintering mosquitoes in Dongcheng district were investigated to provide data basis for early forecast, prediction and handling of emergency events. Methods The wintering mosquitoes were monitored by visual observation. Five observation places were randomly selected from the monitoring sites,1m² for each, to record the number of mosquitoes within 5 min. In the process, priority was given to the monitoring in the major habitats for overwintering mosquitoes such as air-raid shelters, basements and greenhouses. Results Wintering mosquitoes had been observed for two consecutive years, and were identified as Culex pipiens pallens in both years. In 2008, a total of 31 monitoring sites were set up, covering a cumulative monitoring area of 5600 m², resulting in a positive rate of 19.35%. In 2009, 26 monitoring sites were set up with the cumulative area of 2835 m², resulting in a positive rate of 15.38%. The number of winter mosquitoes significantly increased in 2009 as compared to that in 2008, the average mosquito density being 0.88 per m² in the former and 0.41 per m² in the latter. The number of wintering mosquitoes in air-raid shelters remained high for the two consecutive years with the average mosquito density of 3.50 and 6.25 per m², respectively. Conclusion Air-raid shelters were the major habitat for wintering mosquitoes. The monitoring of mosquito and the prevention and control of related infectious diseases in the next summer should be strengthened.

【Abstract】 Objective To know about West Nile virus （WNV） in mosquitoes during 2008 Beijing Olympic Games, and prevent and control West Nile fever. Methods Mosquitoes were collected by  CO2  lamp  trapping  method.  Two  methods, ADAPCO’s Ramp System and MAS’s VecTest Kits, were used to detect WNV in mosquitoes. Results Compared with 2006 and 2007, the density of main vectors decreased significantly in 2008. Culex pipiens pallens was the dominant specie of mosquito, which constituted ratio reached 96.94% in Beijing Olympic venues. There were 22 275 mosquitoes captured in Beijing Olympic venues that all were negative by detection. Conclusion Mosquitoes were controlled effectively in 2008 Olympic Games. No WNV?positive mosquitoes were detected.

Objective To study the role of carboxylesterase in the development of organophosphate resistance and the activity variance of carboxylesterase in different strains of German cockroach( Blattella germanica).Methods Relationship between carboxylesterase and organophosphate resistance in German cockroach was studied with bioassay,biochemical analysis and synergistic test.The cockroaches from the susceptible strain(SS) of laboratory and field strains of different areas in Beijing [Xuanwu(XW) district,Changping(CP) district,Shunyi(SY) district and Shijingshan(SJS) district] were used as test insects. Results The synergistic test showed that synergistic ratio of TPP to malathion and dichlorvos were 1.86 and 1.51 fold in susceptible strain,respectively.And in field strains(XW,CP,SY and SJS),they were 5.79,20.08,15.26 and 4.74 fold for malathion,respectively and 2.00,1.67,2.16 and 4.81 fold for dichlorvos,respectively.There was significant difference between the Michaelis-Menten constants( K _m) and the maximum velocity( V _max) of carboxylesterase from two strains of German cockroach.The K _m and V _max of caboxylesterase in susceptible strain were 0.1580 mmol/L and 58.4225 μmol/(mg pro·min),respectively.And in field strains(XW,CP,SY and SJS),the K _m and V _max of carboxylesterase were 0.1279,0.1071,0.1080,0.1095 mmol/L and 307.2550,338.5755,340.3300,212.4570 μmol/(mg pro·min),respectively.The inhibition medium concentration(I ₅₀) of malathion and dichlorvos to caroxylesterase from SS strain were 17.64 mmol/L and 0.91 μmol/L,respectively.For field strains,the I ₅₀ of malathion were 80.48,35.49,83.24 and 82.29 mmol/L,respectively,and that of dichlorvos were 15.35,7.89,11.52 and 8.60 μmol/L respectively.The inhibition of malathion and dichlorvos to caroxylesterase from SS strain(I ₅₀ were) was much lower than from field strains strain(XW,CP,SY and SJS).Conclusion The enhancement of detoxification activity was one of resistance mechanism to organophosphate in German cockroach.

Objective To confirm the resistance status of Blattella germanica through studying its carboxylesterases(CarE) characteristics systemically and establish a quick, accurate and simple detection method. Methods The optimal concentrations of CarE and substrate, pH, temperature and reaction time of the reaction system, were determined by orthogonal matrix methods. And the optimal group was selected in the experiment. The data was analyzed with range analysis and analysis of variance. Results The results revealed that there were significant difference among various levels of the selected five factors which affected specific activity of CarE from Blattella germanica. The optimal levels of A (CarE concentration), B (substrate concentration), C (reation time), D (reation temperature) and E (pH of reation system) were A ₄ (0.35 head/ml), B ₃ (0.6 mmol/L), C ₁ (5 minutes), D ₄ (40 ℃) and E ₂ (pH 6.5), respectively. The results of range analysis and variance analysis indicated that the optimal combination was A ₄B ₃C ₁D ₄E ₂, and the maximum specific activity of CarE was 37.286 μmol/(mg pro·min) determined under the optimal conditions. The effect of factors on CarE specific activity were in the order of temperature>time>substrate>enzyme concentration>pH. Conclusion The optimal condition were: 0.35 head/ml, 0.6 mmol/L substrate, 5 mintues, 40 ℃, respectively.