Objective To investigate the species and distribution of mosquitoes in the residential areas of the Yuanjiang River-Red River basin, Yunnan Province, China, and to analyze their species composition and distribution characteristics, so as to provide reference data for the prevention and control of mosquito-borne diseases in this region. Methods During July to August in 2022 and June in 2023, mosquitoes were collected using light traps at night in nine rural residential areas selected from five counties/cities located in the upstream, midstream,and downstream areas of the Yuanjiang River-Red River basin. Excel 2013 software was used for data pooling and analysis. The Berger-Parker index (I) was calculated to determine the dominant mosquito species. The Kruskal-Wallis H test was used to compare the densities of mosquitoes in different regions. Spearman's rank correlation analysis was performed to analyze the correlation between latitude and the richness and density of mosquitoes. Results A total of 76 710 female mosquitoes belonging to 29 species in 7 genera under 2 subfamilies were captured in the two field surveys. Culex tritaeniorhynchus (I=0.73) and Anopheles sinensis (I=0.21) were the dominant mosquito species in the basin. Among all the mosquito species, the density of Cx. tritaeniorhynchus was highest at 430.57 mosquitoes/night·lamp, followed by An. sinensis at 126.79 mosquitoes/night·lamp. There was no significant difference in mosquito density between different regions (H=3.773, P=0.152). With the decrease in latitude from the north to south of the basin, increasing trends were observed for mosquito species richness (r_s=-0.678, P=0.045) and density (r_s=-0.745, P=0.021). Conclusion The densities of Cx. tritaeniorhynchus and An. sinensis are high in the Yuanjiang River-Red River basin,where health departments should strengthen the surveillance of mosquito density and cases of Japanese encephalitis.

Objective To investigate the distribution of mosquito vectors in Hainan Province, China from 2020 to 2022, so as to provide common mosquito ecological surveillance data for analyzing the risk of transmission of imported mosquito-borne diseases after the initiation of China (Hainan) Pilot Free Trade Zone operations. Methods In 18 cities (counties) across the province throughout the years, adult mosquitoes were monitored using the light trap method and the double-layered mosquito net method, and larval mosquitoes were monitored using the Breteau index (BI) method. With the use of R 4.3.1 software, one-way analysis of variance (ANOVA) was performed to compare the mean values of different mosquito populations in different years and regions, and if the difference was significant, the least significant difference method was used for further pairwise comparison. Results From 2020 to 2022, a total of 12 240 lamps were set across Hainan Province, and 41 087 female mosquitoes were captured. The density of mosquitoes was 3.36 mosquitoes/light·night. The annual density fluctuated between 1.59 and 4.55 mosquitoes/light·night, and was significantly different in different years (F=4.810, P=0.015). The net trap index for Aedes was 0.90 mosquitoes/net·hour. The annual fluctuated between 0.06 and 1.74 mosquitoes/net·hour, and there was no significant difference in the mean net trap index of different years (F=2.697, P=0.082); The BI for Aedes larvae was 4.13. The annual BI fluctuated between 2.13 and 6.60, and the mean BI showed no significant difference between different years (F=2.969, P=0.065). The mosquito density by the light trap method showed an obvious seasonal pattern, which was higher in summer than in winter; the density of Ae. albopictus also showed obvious seasonality, which was lowest during December to next February, and then increased to high levels during June to August, followed by a downward trend after August. There were significant differences in the mean annual values of adult mosquito density (F=7.758, P<0.001) and BI (F=11.630, P<0.001) between different dry and wet climate zones, but the net trap index showed no significant difference (F=1.977, P=0.113). Conclusions The annual mosquito density, net trap index and BI were all at a low level in Hainan Province from 2020 to 2022, but mosquito density were high in some areas. It is necessary to pay close attention to the mosquito vector density after the closure of the free trade port, and strengthen the surveillance of the vector mosquitoes.

Objective To investigate mosquito species and mosquito-borne viruses in some areas of Yunnan Province, China in 2023, so as to provide evidence for the prevention and control of mosquito-borne infectious diseases. Methods Mosquitoes were collected in Kaiyuan City (in Honghe Hani and Yi Autonomous Prefecture) and Huaning County and Yuanjiang Hani, Yi, and Dai Autonomous County (in Yuxi City) of Yunnan Province from July to August 2023. After species identification, the mosquitoes were examined for various viruses by quantitative PCR. The target virus gene was amplified by conventional PCR, and the virus sequences were analyzed using bioinformatics software. Results A total of 9 060 mosquitoes belonging to 5 species of 4 genera were collected, among which Culex tritaeniorhynchus was the dominant mosquito species, accounting for 50.30% of the total number of mosquitoes caught, followed by Anopheles sinensis, accounting for 33.77%, Cx. pipiens quinquefasciatus, Armigeres subalbatus and Aedes vexans were less, accounting for 5.96%,2.98% and 2.98% respectively. Ten strains of Japanese encephalitis virus were detected in mosquitoes from Kaiyuan City and Huaning County, with a positive rate of 3.31%. No other viruses were detected. According to the NS1 gene-based phylogenetic analysis and nucleotide and amino acid homology analysis of 8 strains of Japanese encephalitis virus from Kaiyuan City and Huaning County, they all belonged to Japanese encephalitis virus genotype Ⅰ. Conclusions In this investigation, Kaiyuan city and Huaning County were dominated by Cx. tritaeniorhynchus, Yuanjiang County was dominted by An. sinensis. Japanese encephalitis virus was for the first time isolated from mosquitoes in Kaiyuan City and Huaning County, indicating that the two places are epidemic areas of Japanese encephalitis, so surveillance and control should be strengthened.

Dengue fever, a vector-borne infectious disease caused by Dengue virus and transmitted by the bite of Aedes mosquitoes, has imposed a significant disease, economic, and social burden on both the global and China. Influenced by multi-dimensional driving factors including climate change, globalization, urbanization, and public health insecticide resistance, the risk of dengue transmission and outbreaks are escalating worldwide and in China. Currently, traditional surveillance and control technologies for Aedes vectors have already revealed certain limitations in preventing and controlling dengue. The research and development of innovative surveillance and control tools and products, as well as application technologies for Aedes vectors, are relatively insufficient, making it challenging to meet the demands of dengue prevention and control in the new era. In future, it is imperative to actively implement sustainable Aedes management, control Aedes vectors based on a graded response approach for dengue prevention, and comprehensively utilize various appropriate techniques. This will provide a solid foundation for the risk assessment, early warning, and scientific and precise prevention and control of dengue in China.

Japanese encephalitis virus (JEV) is an important arbovirus that continues to spread in China. Japanese encephalitis (JE) caused by JEV is one of the important public health problems in China. Over the years, despite significant control of JE in China, the geographical distribution of JE cases and the age structure of the affected population have changed due to ecological changes and vaccination. Moreover, JEV has evolved rapidly, and the dominant genotype has changed from GⅢ to GⅠ,which brings challenges to the prevention and control of JE. This paper reviewed the epidemic characteristics of JE and the genotypes of JEV in China, providing reference for the prevention and control of JE.

Objective To investigate the characteristics of dengue fever outbreaks in four cities/counties of Yunnan Province, China, and to provide a reference for the prevention and control of dengue fever. Methods The data about dengue fever cases reported in Yunnan Province in 2023 were collected from the China Information System for Disease Control and Prevention. The circular distribution method was used to analyze the temporal patterns of dengue fever outbreaks in Gengma Dai and Wa Autonomous County, Jinghong City, Ruili City, and Mengla County. Excel 2010 software was used for data collation, and SPSS 19.0 software was used for data analysis. The rate or constituent ratio was compared using the Chi-square test. The correlation of non-normally distributed continuous data was examined through Spearman correlation analysis. Descriptive epidemiological method was used to describe the characteristics of dengue fever outbreaks in the four cities/counties. Results A total of 13 748 cases of dengue fever were reported in Yunnan Province in 2023, with a reported incidence rate of 29.42/100 000. The four cities/counties reported a total of 10 012 cases of dengue fever, accounting for 72.83% (10 012/13 748) of the total number in the province. The peak period was from June 15 to November 11, and the peak day was August 30. The temporal distributions of the imported cases, local cases, and exported cases in the four cities/counties were generally consistent, and they were correlated in different months (r_{simported-local}=0.901, P=0.006; r_{slocal-exported}=0.893, P=0.007; r_{simported-exported}=0.793, P=0.033). In terms of the reported cases distribution, the top five occupations were farmers, homemakers and the unemployed, business employees, freelancers, and students, accounting for 31.25% (2 795/8 945), 16.88% (1 510/8 945), 14.21% (1 271/8 945), 10.90% (975/8 945), and 8.09% (724/8 945), respectively. By age distribution, the group of 20 to <70 years accounted for 80.00% (7 818/9 772), with the highest reported incidence rate in the group of 70 to <80 years (1 244.41/100 000) and lowest in the group of <10 years (306.55/100 000). There was an increasing trend in the reported incidence rate with age (χ²_trend=985.310, P<0.001). By regional distribution, the cases were mainly concentrated in ports or urban townships densely populated and with large numbers of floating people, which were more distributed in the border areas and scattered in the inland and suburban townships. The number of local cases reported in national port townships was largest, with an incidence rate of 1 341.09/100 000, while the lowest incidence rate was 250.60/100 000 in townships without ports or local channels. As the opening level increased, the incidence rate of local cases reported in each township tended to increase (χ²_trend=4 610.937, P<0.001). The incidence rate of each township was positively correlated with the local population density (r_s=0.446, P=0.006). Conclusions In the four cities/counties of Yunnan Province, dengue fever cases are mainly clustered in ports or urban townships, and show specific distribution patterns by region, population, and time. The focus should be on densely populated urban areas and port townships with large floating populations near the border, and high attention should be paid to the long-distance export of infectious sources and vectors to low-risk areas.

Objective To investigate the species composition, density, and seasonal fluctuation of mosquitoes in Yancheng, Jiangsu Province, China, so as to provide a scientific basis for developing effective mosquito control measures and forecasting and early warning of mosquito-borne diseases.Methods Mosquito density was monitored by using the lamp trapping method in five types of habitats (urban residential areas, parks, hospitals, farmers’ houses, and livestock sheds) in Yancheng. The species composition, population density, and seasonal fluctuation of mosquitoes were analyzed. With SPSS 20.0 software, the Chi-square test was performed on the mosquito species composition ratios of different years and different habitats, analysis of variance was performed for different years, different species, and different habitats of mosquito densities, and trend analysis was performed for different years and different species of mosquito densities.Results From 2016 to 2023, a total of 132 432 female mosquitoes were caught in Yancheng, with an average density of 13.59 mosquitoes/light·night. Culex pipiens pallens/quinquefasciatus, Anopheles sinensis, and Cx. tritaeniorhynchus were the top three mosquito species, accounting for 68.62%, 13.95%, and 12.09% of the total catches, respectively. There was a significant difference in the composition of mosquito species between different years (χ²=9 026.399, P<0.001). Mosquito density and trend changes differed significantly in different mosquito species (both P<0.001). By habitat, the highest mosquito density was in livestock sheds (28.37 mosquitoes/light·night), while the lowest mosquito density was in hospitals (7.84 mosquitoes/light·night), with significant differences in the species composition ratio and density of mosquitoes between habitats (both P<0.001). Seasonal fluctuations in mosquito density showed unimodal distributions for all habitats and for all species, peaking during June and September.Conclusions Cx. pipiens pallens/quinquefasciatus, An. sinensis, and Cx. tritaeniorhynchus are the dominant species in Yancheng. Livestock sheds and farmers’ houses are the key places and June to September is the key time for mosquito control. Specific mosquito control measures should be taken based on the population distribution, density change, and seasonal fluctuation of mosquitoes.

Objective To investigate the resistance levels of Blattella germanica to five commonly used insecticides in Zhejiang Province, China, so as to provide a basis for rational use of insecticides and scientific control of cockroaches. Methods From 2017 to 2022, field population of B. germanica were collected in different surveillance areas of Zhejiang Province in different years. The resistance of B. germanica to beta-cypermethrin, deltamethrin, acephate, dichlorvos, and propoxur was measured by using the residual film method with a conical flask. The median knockdown time and resistance ratio (RR) were calculated using a probit regression model. Results From 2017 to 2022, the overall resistance of B. germanica to pyrethroid insecticides was relatively high in Zhejiang Province. The RR for beta-cypermethrin was 11.49 in Jinhua in 2022, 6.48 in Shaoxing in 2021, 16.00 in Wenzhou in 2018, and 6.87 in Lishui in 2018, indicating medium-to-high resistance levels. The RR for deltamethrin was 8.66 in Quzhou in 2020, 10.20 in Wenzhou in 2017, 11.66 in Jinhua in 2018, and 7.58 in Lishui in 2018, showing medium-to-high resistance levels. The RR for dichlorvos was 7.86 in Jinhua in 2022, 7.33 in Shaoxing in 2021, and 7.05 in Wenzhou in 2017, showing medium resistance levels. In general, B. germanica was sensitive or lowly resistant to acephate and propoxur in Zhejiang Province. B. germanica developed from sensitive to lowly resistant to propoxur in Ningbo since 2020, developed moderately resistant to deltamethrin in Quzhou since 2020, and developed from sensitive to moderately or lowly resistant to both pyrethroids and dichlorvos from 2018 to 2021. In 2022, insecticide resistance levels were higher in Jinhua, with high resistance to beta-cypermethrin, medium resistance to deltamethrin (RR=8.87) and dichlorvos (RR=7.86), and low resistance to propoxur (RR=2.36) and acephate (RR=1.16). Conclusions B. germanica cockroaches in Zhejiang Province are highly resistant to pyrethroid insecticides, with certain resistance to other insecticides. Future control strategies should choose appropriate insecticides according to the resistance of B. germanica.

Objective To select palatable rodenticide baits, so as to provide support for reducing time invested and improving rodent control quality in large-scale rodent control activities. Methods Wax block baits, rice baits, corn baits, wheat baits, and peanut baits containing 0.005% brodifacoum were each paired up with a type of bait base (naturally dried peanuts) in a 1∶1 ratio. The baits were placed in a saturated manner. Bait consumption was monitored and recorded consecutively for seven consecutive days. Analysis of variance and bivariate correlation analysis were performed. Results The 7-day cumulative feeding coefficient (FC) was 0.57 for the peanut baits, indicating good palatability; 0.18 for the rice baits, 0.18 for the wax blocks, and 0.17 for the corn baits, indicating moderate palatability; and 0.10 for the wheat baits, indicating poor palatability. There were significant differences in the 7-day cumulative FC of different baits in paddy field (F=25.340, P<0.001), residential area (F=5.667, P=0.002) and forest habitat (F=3.190, P=0.022), and the 7-day cumulative FC of peanut bait was the highest in the three habitats, which was 0.69, 0.54 and 0.49, respectively. The corn baits also showed good palatability in residential areas with a 7-day cumulative FC of 0.41. Conclusion Before starting construction at construction sites in the eastern coastal area of Shanghai, China, peanut baits containing brodifacoum can be used for large-scale rodent control work, which can improve the efficiency of rodent control.

Objective To analyze epidemiological characteristics and outbreak of dengue fever in Yunnan Province, China, so as to provide a scientific basis for formulating effective prevention and control measures. Methods Relevant data on dengue fever cases and outbreaks reported in Yunnan Province during 2013-2022 were collected from the “Infectious Disease Surveillance System” and “Public Health Emergency Management Information System” of “China Disease Control and Prevention Information System”. The concentration method was used to analyze seasonal characteristics. Excel 2007 software was used to sort out the data. MapInfo 7.8 software was used to draw the map. SPSS 26.0 was used to analyze the correlation, and the Chi-square test was used to compare the rate or composition ratio. The descriptive epidemiological method was used to analyze the epidemiological characteristics and outbreak response to dengue fever. Results A total of 16 774 cases of dengue fever were reported in Yunnan Province from 2013 to 2022, including 11 944 local cases, 4 521 overseas imported cases, and 309 domestic imported cases, with an average annual reported incidence of 3.53/100 000. The disease showed a high incidence every other year. The concentration (M) was 0.84, showing strong seasonality. Imported cases mainly occurred from June to October, and local cases mostly from August to November. The male-to-female ratio of imported cases was slightly higher than that of local cases (χ²=37.596, P<0.001). The majority of local cases were 30～<40 years old (20.14%), and the majority of imported cases were 20～<30 years old (27.58%). The local cases were found in 5 border prefectures (cities). The overseas imported cases were mainly from southeast Asian countries and African countries, and Myanmar, Cambodia, and Laos were the main source countries (96.81%). The domestic imported cases were mainly from Xishuangbanna Dai Autonomous Prefecture (85.76%). The majority of cases were farmers, commercial service personnel, cadres/retirees, housekeepers, job-waiting people, and students. Commercial service personnel accounted for the highest proportion in local cases (21.89%), while farmers accounted for the highest proportion in imported cases (39.90%). There was a significant difference in occupational distribution between imported cases and local cases (χ²=1 535.415, P<0.001). A total of 28 dengue fever outbreaks were reported from 2013 to 2022, including 1 major event and 27 general events. The number of reported cases accounted for 83.41% of the total number of cases, and each event involved an average of 499.71 cases. The median time from the onset of the first case to the verification of event occurrence was 7 (5, 9) days, and the median duration of the outbreak was 110 (27, 140) days. Twenty-five outbreaks occurred in villages/communities. Conclusions Dengue fever in Yunnan has obvious seasonal, aggregated, and regional distribution patterns. We need to further strengthen imported case management, disease vector surveillance and control, and the prevention and control of dengue fever in key areas.

Marmota himalayana is an endemic species of the Qinghai-Tibet Plateau and an important part of its ecosystem, which plays a significant role in maintaining the ecological balance of the natural foci of plague. The distribution of marmots is influenced by environmental factors such as climate, soil, and vegetation, thereby determining the distribution and changes of natural plague foci and the risk of associated plague epizootics. In other words, the distribution of geographical landscape elements and the main host animals of plague play a decisive role in the distribution area of natural plague foci. Ecological research on M. himalayana has been widely reported. This paper reviews the research status in China and globally from the aspects of ecological, burrow, and habitat characteristics of M. himalayana, with the aim to improve the understanding of M. himalayana ecology and promote the application of ecology in plague prevention and control.

Objective To investigate the species composition, population density distribution, and seasonal fluctuation of flies in Qingdao, China, and to provide a scientific basis for fly control. Methods Flies were monitored using the cage trap method. Fly species composition was analyzed using the chi-square test, and fly population density was analyzed using the Kruskal-Wallis H test. Results From 2017 to 2022, a total of 10 490 flies were caught, with a mean annual density of 12.14 flies/cage. The dominant fly populations were Sarcophagidae, Musca domestica, and Lucilia sericata, accounting for 22.73%, 17.58%, and 17.45%, respectively. The species composition of fly differed significantly in different years (χ²=4 863.573, P<0.001). The activity of flies spanned a long period from March to November. The seasonal peak of fly population density in different years all occurred in July, at 47.63, 32.13, 33.63, 23.00, 26.75, and 28.50 flies/cage, respectively, and there was a significant difference in the seasonal fluctuations of fly density between different years (H=36.442, P<0.001). For different habitats, fly density was highest in farmers’ markets (15.27 flies/cage) and lowest in restaurant surroundings (7.26 flies/cage), with a significant difference in the density of each fly species between different habitats (H=2.386, P=0.035). Among the dominant species, M. domestica had the highest density in residential areas (3.18 flies/cage), Sarcophagidae had higher densities in farmers’ markets (2.68 flies/cage), green belts (2.73 flies/cage), and residential areas (3.75 flies/cage), and L. sericata had the highest density in farmers’ markets (3.34 flies/cage). Conclusions Flies in Qingdao are mainly infested farmers’ markets and residential areas, peaking in July, and different fly species prefer different habitats. Fly seasonality, dominant species, and breeding characteristics should be considered in formulating targeted control measures to effectively reduce fly population density.

Objective To investigate vector density changes in the flood-stricken areas of Hebei Province, China, so as to provide a basis for vector control and the prevention and control of vector-borne diseases in a scientific and orderly manner. Methods The daily monitoring data on the density of mosquitoes, flies, and rodents were collected at 192 resettlement sites in 21 counties/cities/districts of 7 flood-stricken prefecture-level cities in Hebei Province from August to October 2023. The density of mosquitoes and flies was monitored through visual inspection, and the density of rodents was measured using the footprint tracking method. R 4.2.2 software was used to perform the Wilcoxon signed-rank test, Friedman test, and Pearson correlation analysis. Results The average densities of mosquitoes, flies, and rodents of all the resettlement sites were 1.05 inds/labor hour, 0.45 inds/m², and 0.037 tracks/2 000 m, respectively. The average mosquito density of the resettlement sites showed a slowly fluctuating downward trend, with the highest level on the 1st day of surveillance, reaching 1.97 inds/labor hour, which was lower than the reference level for mosquito control (10 inds/labor hour). The density of flies showed a slowly fluctuating downward trend, with the higher levels on the 1st day (0.71 inds/m²) and the 25th day (1.00 inds/m²) of surveillance, approximating or reaching the reference level for fly control (1 ind/m²). The average rodent density showed a rapidly downward trend, with the peak on the 1 st day at 0.181 tracks/2 000 m, far lower than the rodent control reference level (5 tracks/2 000 m). Pest and rodent control work was completed for a total of 12 586 points covering 1 353 104 m² of three types of habitats, including resettlement sites and their surroundings, toilets, and garbage points. In August 2023, there were 729 cases of vector-borne diseases in the flood-stricken areas, which were more than the cases in the same period of 2022 (t=-1.429, P=0.002) and 2021 (t=-0.929, P=0.119), similar to the number in the same period of 2020 (t=-0.024, P=1.000), and more than the number in September 2023, the late stage of the flood disaster (W=44.500, P=0.013). From August to September 2023, the local reported no case of mosquito-borne infectious diseases, 1 case of rodent-borne typhus, and 1 215 cases of fly-related diseases (can be mechanically carried and transmitted by flies) diseases such as the other infectious diarrhea and bacillary dysentery; and the number of daily cases was not correlated with the density of flies (r=-0.195, P=0.146). Conclusions The density of mosquitoes, flies, and rodents was low at the resettlement sites of flood-stricken areas in Hebei Province in 2023. When the density exceeded the vector and rodent control reference levels, the implementation of emergency vector and rodent control effectively limited the density of vectors and rodents in the flood-stricken areas and prevented the outbreak of the related diseases.

Objective To verify the field efficacy of 0.2% curcumol baits against farmland rodents and determine the optimal dose. Methods A field experiment with 0.2% curcumol baits at three doses 1 500, 3 000, and 4 500 g/hm² was carried out in the plague foci of Lijiang, Yunnan Province, China. The changes in rodent density,uterine development status, pregnancy rate, and litter size were investigated at 30, 60, and 90 days after baiting. The bait efficacy and intake level were calculated with the use of Excel 2010 software. Results The control effects of curcumol baits at 1 500, 3 000, and 4 500 g/hm² groups were 47.06%, 51.87%, and 57.65% at 30 days, respectively; 50.00%, 63.64%, and 60.00% at 60 days, respectively; and 54.55%, 62.81%, and 50.91% at 90 days, respectively. The number of subadults decreased substantially, and the pregnancy rate and average litter size of female adult rodents also decreased. The curcumol bait intake coefficient of rodents was 0.77. No dead rodents or non-target organisms were observed during 15 consecutive days of investigation since the first day after baiting. Conclusion 3 000 g/hm² of 0.2% curcumol baits is recommended for controlling farmland rodents based on the control effects and the economic threshold.

Objective To investigate the rodent species composition, density, and seasonality in different habitats based on the rodent surveillance program in Nanchang, China, so as to provide a basis for scientifically formulating rodent control strategies in Nanchang. Methods Three types of surveillance habitats including urban residential area, rural natural village, and special industry were chosen from 2017 to 2022. Rodent density was investigated by the night snap-trapping method. Descriptive methods were used to perform a statistical analysis of rodent species composition and seasonal variation of rodent density in three different habitats in Nanchang. With SPSS 26.0 and Excel 2021 softwares, descriptive methods were used to perform a statistical analysis of surveillance data, and the Chi-square test was used for comparison of rodent density across different years and habitats. Results A total of 104 121 effective traps were placed in Nanchang from 2017 to 2022, and 548 rodents were captured, with an average rodent density of 0.53%. The overall rodent density in the six years was statistically significant (χ²=34.857, P<0.001). A bimodal distribution with seasonal variation was found in the overall rodent density, the annual density of three dominant rodent species (Rattus norvegicus, Mus musculus, and R. tanezumi), and the rodent density in residential areas and special industry habitats, while the rodent density in rural natural village habitats showed a unimodal trend, with the peak in July. The rodent density in rural natural villages (1.56%) was significantly higher than that in special industries (0.45%) and than that in urban residential areas (0.30%) (χ²=304.340, P<0.001). The dominant rodent species in urban residential areas and rural natural village habitats were R. norvegicus and R. tanezumi, while M. musculus predominated in special industry habitats (47.47%). The composition ratio of R. norvegicus in special industry and rural natural village habitats was decreasing year by year; the composition ratio of R. tanezumi in urban residential areas showed a decrease after increasing, while it was generally increasing in special industry and rural natural village habitats; the composition ratio of M. musculus in three different habitats showed an overall increasing trend. Conclusions The rodent density varies greatly in Nanchang from 2017 to 2022. The rodent density showed a bimodal distribution with seasonal changes and was high in rural areas. Specific control measures should be taken according to the changes in rodent species in different habitats to reduce the rodent density and the risk of rodent-borne diseases.

Objective To investigate mutations in the voltage-gated sodium channel gene (VGSC) responsible for knockdown resistance (kdr) in Aedes aegypti and analyze the prevalence characteristics of the VGSC gene in the key areas of Ae. aegypti distribution in Yunnan Province, China. Methods Wild adult or larval Ae. aegypti samples were collected from 7 counties/cities (Yingjiang County, Ruili City, Zhenkang County, Gengma Dai and Va Autonomous County, Menghai County, Jinghong Municipality, and Mengla County) in Yunnan Province. The gene VGSC was amplified by direct sequencing to analyze the point mutation rate and the composition of combined mutations. The Chi-square test was used to compare the differences in the kdr mutation rate of VGSC gene between different loci and between different sexes of Aedes albopictus. Results The DNA was successfully extracted and VGSC gene were sequenced for a total of 561 Ae. aegypti mosquitoes (276 females, 242 males, and 43 larvae) in 7 counties/cities. Four point mutations were found in the VGSC gene. S989P, V1016G, and F1534C mutations were present in every county/city. The S989P mutation rate ranged from 71.43% to 100%, with a mean of 92.51% (95% confidence interval [CI]: 90.33%- 94.70%). The V1016G mutation rate was 100%. The F1534C mutation rate was 55.81%-100%, with a mean of 85.38% (95%CI: 82.45%-88.32%). The Y1527F mutation was first detected in Ruili Municipality, Gengma and Zhenkang County, and the mutation rate ranged from 0 to 35.45%, with a mean of 8.73% (95%CI: 6.39%-11.08%). There were 4 types of co-occurring mutations: S989P+V1016G, V1016G+F1534C, S989P+V1016G+F1534C, and S989P+V1016G+Y1527F+F1534C. Single point mutations were not found. There were no significant differences in the mutation rates of 989, 1016, 1527, and 1534 loci and the composition ratios of combined mutations in female and male mosquitoes in six counties/cities except Yingjiang County. Conclusions The kdr mutation in the VGSC gene of Ae. aegypti in Yunnan Province is mainly characterized by multiple-point joint mutations, and a new Y1527F mutation appears. Kdr mutations surveillance in Ae. aegypti should be carried out regularly to grasp the changes in its resistance to insecticide targets in time.