ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective: To select chemical substances with attractive effects on Aedes albopictus for on-field assessment, and to explore the preference of Ae. albopictus to six human odors. Methods: Under laboratory conditions, six chemical substances (1-octen-3-ol, lactic acid, myristic acid, ammonia, acetone, and ethyl acetate) were separately tested for their individual attracting effects on female Ae. albopictus at concentrations of 0.1, 1.0, and 10.0 mg/ml. The six substances were mixed in pairs (1∶1) at certain concentrations, and then the pairs were tested for attracting effects on female Ae. albopictus. The pair with good attractive effects was combined with lactic acid for testing. The attractant combination selected by laboratory experiments was tested for attractive action for Ae. albopictus in the field. The attracting effects of the substances or combinations on Ae. albopictus were compared using the t test and one-way analysis of variance. Results: Ae. albopictus mosquitoes were attracted to 1-octen-3-ol at 0.1, 1.0, and 10.0 mg/ml, myristic acid at 1.0 and 10.0 mg/ml, and ethyl acetate at 0.1 mg/ml, but not to the other three substances at any concentration. The pairs of 1-octen-3-ol+myristic acid, lactic acid+myristic acid, and lactic acid+1-octen-3-ol statistically attracted Ae. albopictus compared with the control group (t=8.102, P=0.001; t=4.696, P=0.009; t=5.127, P=0.007). The combination of lactic acid+1-octen-3-ol+myristic acid statistically attracted Ae. albopictus compared with the control group (F=86.841, P < 0.001). Field testing showed significant differences in the attracting effect between lactic acid+1-octen-3-ol+myristic acid and the control (day 1: t=7.462, P=0.014; day 2: t=20.500, P < 0.001; day3: t=9.383, P=0.001). Conclusion: The combination of lactic acid, 1-octen-3-ol, and myristic acid has attractive action for Ae. albopictus, which should be further researched in the field.
Objective: To investigate knockdown resistance (kdr) genotypes of Aedes albopictus which is the major vector of dengue in Nanning, so as to understand their insecticide resistance levels and provide evidence for scientific control of Ae. albopictus. Methods: Ae. albopictus larvae were collected using the dip method in Nanning and raised to adults in the laboratory. After morphological identification, Ae. albopictus mosquitoes were soaked in 75% ethanol and stored at -20 ℃. DNA was extracted from individual mosquitoes using the magnetic bead-based method. The partial fragments of the voltage-gated sodium channel (VGSC) gene were amplified by PCR and sequenced for alignment with the Basic Local Alignment Search Tool on the platform of National Center for Biotechnology Information. DNAStar 7.1 was used to analyze single-site and multiple-site mutations in the confirmed VGSC gene of Ae. albopictus mosquitoes. Results: A total of 175 Ae. albopictus mosquitoes were examined in 2022, obtaining 350 sequences (about 400 bp in length). Mutations were detected at the 1016 and 1534 loci but not at the 1532 locus of the VGSC gene. At the 1016 locus, there were two alleles (wild-type V [148, 78.28%] and mutant G [49, 21.72%]) and three genotypes (wild-type homozygote V/V [126, 72.00%], mutant homozygote G/G [27, 15.43%], and wild-type/mutant heterozygote V/G [22, 12.57%]). At the 1532 locus, there was one allele (wild-type I [175, 100%]) and one genotype (wild-type homozygote I/I [175, 100%]). At the 1534 locus, there were three alleles (wild-type F [51, 16.86%], mutant S [116, 36.29%], and mutant C [135, 46.85%]) and six genotypes (wild-type homozygote F/F [8, 4.57%], wild/mutant heterozygotes F/S [21, 12.00%] and F/C [22, 12.57%], mutant heterozygote S/C [64, 36.57%], and mutant homozygotes S/S [21, 12.00%] and C/C [39, 22.29%]). Conclusion: VGSC gene mutations are frequent in Ae. albopictus in Nanning. Attention should be paid to the insecticide resistance levels of Ae. albopictus for scientific, standardized, and efficient use of insecticides.
Objective: To investigate the density distribution of Aedes mosquitoes in different habitats and seasonal fluctuation in Hangzhou, Zhejiang Province, China from 2017 to 2021, so as to provide a scientific basis for effective prevention and control, risk assessment, and early warning of dengue fever. Methods: According to the National Vector Surveillance Implementation Plan and the Zhejiang Provincial Vector Surveillance Plan, Aedes mosquitoes were monitored in 15 districts (counties and cities) in Hangzhou. Adult mosquitoes were monitored using the double-layered mosquito net method, and larvae were monitored using the Breteau index (BI) method. The surveillance time was set during April to November. The mosquito surveillance data of the 15 districts (counties and cities) were collected. Excel 2019 software was used for data analysis. The net trap index, BI, and container index (CI) were calculated. Categorical data were compared using the Chi-squared test. One-way analysis of variance was used for quantitative data. Results: From 2017 to 2021, the density of Ae. albopictus in Hangzhou by the double-layered mosquito net method was 2.54 mosquitoes/net·h, and no Ae. aegypti mosquitoes were captured. The density of adult mosquitoes was lowest in 2017 and highest in 2020. There was a statistical difference in the net trap index between different years (F=5.117, P=0.017). The seasonal distribution generally presented a bimodal pattern, with the peaks of mosquito densities mainly in July and October. The average BI from 2017 to 2021 was 9.18, and the peak period of the BI was during May to October. The CI showed that Ae. albopictus larvae were distributed in all kinds of water bodies. The CI differed statistically between different water bodies in the same year (all P < 0.001) and between different years in the same water body (all P < 0.001). Conclusions: Ae. albopictus density was high in Hangzhou, indicating a risk of dengue fever outbreaks and regional epidemics. It is recommended that the counties (cities, districts) take timely mosquito control measures according to the density, distribution, and seasonal fluctuation of mosquitoes.
Objective: To analyze the species, composition, density, distribution, and seasonal fluctuation of flies in Fengxian District, Shanghai, China, so as to provide a basis for the prevention and control of flies in Fengxian District. Methods: The fly surveillance data in Fengxian District, Shanghai from 2011 to 2021 were collected, and Excel 2013 was used to summarize and analyze of the data. The Kolmogorov-Smirnov test was used to compare the density of flies in different habitats. Results: From 2011 to 2016, there was no significant change in the population density of flies in Fengxian District, ranging from 0.50 to 1.02 flies per cage of average annual density. In 2017 and 2018, the density of flies (1.76 and 5.25 flies per cage, respectively) increased significantly, by 70.87% and 409.71%, respectively, compared with 1.03 flies per cage in 2015. The fly density decreased year by year in 2019 and 2020, and increased in 2021, second only to the peak density in 2018. A total of 2 996 adult flies were captured, with an average density of 2.02 flies per cage. Muscina stabulans was the main species (accounting for 31.38%), followed by Boettcherisca peregrina (accounting for 28.64%). The flies density in large-scale green belts was highest with 2.32 flies per cage. The density of flies reached its peak in June, dropped sharply from July to August, and steadily decreased from September to November. Conclusions: There are more flies in large-scale green belts of Fengxian District, and the fly density peaks in June. The critical period to prevent fly-borne diseases is before June. Relevant departments in Fengxian District should raise and strengthen awareness of fly control. The environment management of large-scale green belt should be strengthened to reduce the breeding environment of flies.
Objective: To analyze the situation of vector control in the 7th Military World Games in 2019, so as to provide a scientific basis for vector control in similar major events in the future. Methods: The surveillance results of major vectors in different types of places (venues, hotels, designated hospitals, etc.) in urban areas of Wuhan, China from June to September 2019 were analyzed. Excel 2007 and SPSS 23.0 softwares were used for data processing. The Chi-squared test and Fisher's exact test were used for data analysis. Results: In June, the positive rate of fly breeding sites, the infestation rate of nymph and adult cockroaches, and the detection rate of cockroach eggs were highest, which were 3.88%, 1.69%, and 0.06%, respectively. In July, the positive rate of indoor rodent trace, mosquito larval route index and dip index, and indoor fly density were highest, which were 2.91%, 1.31 stagnant waters per km, 4.20%, and 4.81%, respectively; the qualified rates of rodent-proof and fly-proof facilities were lowest, which were 85.97% and 87.84%, respectively. In August, the outdoor rodent density route index and adult mosquito landing index were highest, which were 1.04 rodents and 1.63 mosquitoes per person, respectively. Conclusions: Authorities should continuously monitor vector infestation and control effects in key places of Wuhan Military World Games, scientifically and effectively evaluate the implementation of vector control, and timely detect relevant problems and adjust response strategies to prevent the occurrence of emergencies.
Objective: To investigate the rodents species, density, and pathogens they carry in Zunyi, Guizhou Province, China. Methods: A total of 70 sampling points were set in 14 counties/districts of Zunyi, with five points in the east, south, west, north, and center of each county/district. Small mammals were monitored through night trapping in Zunyi from October 2021 to October 2022, followed by species identification and pathogen detection. Excel 2021 was used for data organization. SPSS 26.0 was used to analyze the density, species, and pathogen-carrying status of small mammals through rate or constituent ratio comparison with the Chi-square test (P < 0.05 indicates a statistically significant difference). Results: A total of 9 969 effective traps were placed at all the surveillance points, capturing 549 small mammals in total, of which 522 were rodents. The total density of small mammals was 5.51%. The total density of rodents was 5.24%. The rodent density was highest in Honghuagang District (12.94%), followed by Fenggang County (12.34%), and lowest in Chishui City (1.80%). There was a statistical difference in rodent density between the counties/districts (χ2=195.619, P < 0.001). Rattus norvegicus was the dominant rodent species in urban residential areas, rural residential areas, and key industries, while Apodemus agrarius was the dominant species in farming areas. The composition of rodent species statistically differed in different regions (the center, north, east, and west) of Zunyi (χ2=117.357, P < 0.001). Each small mammal was examined for Leptospira interrogans and Orientia tsutsugamushi in the liver, spleen, and kidney; Dabie bandavirus in the liver, spleen, and lung; and Hantavirus in the lung. Among 343 samples tested, 27 were positive, all for L. interrogans, with a pathogen detection rate of 7.87%. Shrews had the highest detection rate (16.00%), followed by A. agrarius (12.35%), and R. norvegicus had the lowest detection rate (1.64%). There was a significant difference in the detection rates of different species of small mammals (χ2=14.372, P=0.002). The detection rate was 9.66% (26/269) in farming areas, which was highest, and 2.94% (1/34) in key industries, with negative detection results in urban and rural residential areas. There were no differences in detection rates between different habitats (χ2=5.171, P=0.160). The detection rate was 27.03% in Meitan County, followed by 25.00% in Suiyang County, and zero in Renhuai City, Fenggang County, and Yuqing County, with a statistical difference between different counties/cities/districts (χ2=35.409, P=0.001). Conclusions: The density of rodents was relatively high in Zunyi. The detection of L. interrogans should be a warning of the possibility of related diseases. Local authorities should strengthen rodent control in spring and autumn and take comprehensive control measures according to actual situation and dominant rodent species and pathogen detection status in different habitats, so as to reduce the density of rodents and prevent the occurrence of rodent-borne diseases.
Objective: To analyze the species, density, distribution, and variation of flies in Shanghai, China, to carry out risk assessment, prediction, and early warning of fly-borne diseases in a timely manner, so as to provide scientific reference for fly control. Methods: Using the cage trap method, fly traps were placed in farmers' markets, residential areas, external environment of restaurants, and large green belts. Fly surveillance data were collected every ten days from March to November in 2016-2021 in Shanghai. The data were processed and analyzed using Excel 2019 and SPSS 20.0. Results: From 2016 to 2021, 18 052 flies were caught with an average density of 1.52 flies/cage. The identified fly species belonged to 5 families, 9 genera, and 14 species. The dominant species were Muscina stabulans, Boettcherisca peregrina, Chrysomya megacephala, Lucilia sericata, and Musca domestica. M. stabulans showed the highest density of 0.28 flies/cage, followed by B. peregrina (0.24 flies/cage). In large green belts, the density of B. peregrina was higher than that of M. stabulans, and in all other habitats, the density of M. stabulans was the highest. There was a significant difference in density between B. peregrina and M. stabulans in the farmers' market (t=-2.674, P=0.023). The proportion of Mu. domestica decreased year by year, and the proportion of M. stabulans increased. The fly density was the highest in 2018 (1.82 flies/cage) and the lowest in 2016 (1.04 flies/cage). Fly density peaked from June to August, with the monthly average densities of 2.65, 2.49, and 2.28 flies/cage, respectively. In 2016-2021, the fly density in different habitats was in the order of farmers' markets > large green belts > residential areas > external environment of restaurants. Conclusions: The fly species are diverse in Shanghai. M. stabulans has the highest density. Fly density peaks from June to August, and farmer's market is a key place for targeted fly control. Fly density rose again after decline in 2019, suggesting that comprehensive control of flies should be continuously strengthened.
Objective: To explore the factors affecting Aedes surveillance by the mosquito ovitrap method in a grid mode, so as to provide a scientific basis for the surveillance and control of Aedes mosquitoes and related mosquito-borne infectious diseases. Methods: Three adjacent residential areas with similar areas, building ages, and greenery ratios were selected as surveillance points in Jing'an District, Shanghai, China. Each residential area was divided into secondary surveillance blocks (about 90 m × 60 m) in a 3×3-grid mode. On-site monitoring was conducted in each surveillance block using the mosquito ovitrap method and the human landing catch method, three times one month from July to September 2021. By comparing the surveillance results of different residential areas, different surveillance blocks, and different environmental characteristics, the factors influencing the positive rate of the mosquito ovitrap method were determined. Excel 2016 and SPSS 16.0 were used to process the data. The Kruskal-Wallis rank sum test, tow-way analysis of variance, and Spearman correlation analysis were performed. Results: A total of 30 secondary surveillance blocks were designated. Eight times of surveillance were completed, and 131 mosquito ovitraps were set each time. The mosquito ovitrap index (MOI) in residential areas 1, 2, and 3 were 8.71, 12.38, and 11.97, respectively, with no significant difference (χ2=2.750, P=0.253). There were significant differences in the MOI among different blocks of residential areas 1 and 2 (F=2.135, P=0.047; F=2.168, P=0.044). In residential areas, the positive rate was 12.24 in living areas and 5.76 in community school areas, with a significant difference (χ2=6.657, P=0.010). The MOI was 14.10 for green areas on the house side, 8.87 for concentrated green areas, and 7.98 for green areas on the road side, with a significant difference (χ2=8.372, P=0.015). During the surveillance period, the MOI was 13.28 when the days of rainfall was < 2 d, and 8.79 when the days of rainfall was ≥2 d, with a significant difference (χ2=4.218, P=0.047). In residential area 1, the average MOI was 8.69, and the average landing index was 3.33 mosquitoes/person·h. In residential area 2, the average MOI was 12.45, and the average landing index was 8.58 mosquitoes/person·h. In residential area 3, the average MOI was 11.88, and the average landing index was 6.50 mosquitoes/person·h. The ratio of the MOI to the landing index was distributed between 1∶1 and 3∶1. Pearson correlation analysis showed that the MOI was highly correlated with the human landing index in each block (r=0.549, P=0.005). Conclusions: The density of Aedes mosquitoes may differ greatly in different areas of large residential areas due to differences in greening types, functional zoning, and other factors. The mosquito ovitrap method has the advantages of simple operation and high specificity compared with other surveillance methods for Aedes mosquitoes, and it is highly consistent with the human landing catch method. The mosquito ovitrap method with grid-based surveillance point distribution can be used in actual practice, which can effectively avoid deviations caused by point selection and fully reflect the density of Aedes mosquitoes.
Objective: To analyze cockroach infestation and its intestinal pathogen infection status in catering places in Pudong New Area, Shanghai, China, so as to provide scientific suggestions for cockroach control and the prevention and control of infectious diarrhea in catering places. Methods: From April 2021 to March 2022, cockroach infestation survey and sampling were conducted using cockroach traps in five types of catering places in 12 subdistricts and towns of Pudong New Area in the middle of each month. The captured cockroaches were examined for intestinal pathogens. Excel 2019 and SPSS 22.0 were used for data collation and statistical analysis. Results: In the catering places of Pudong New Area, the cockroach infestation rate was 20.83%, and the cockroach density was 0.74 cockroaches/trap. Blattella germanica (65.79%) and Periplaneta fuliginosa (34.21%) were captured, with a statistical difference in the constituent ratio in various types of places (χ2=126.509, P < 0.001). The cafeterias of enterprises and public institutions had the highest cockroach infestation rate and density, which were 29.03% and 1.32 cockroaches/trap, respectively. The pathogen detection rate of the cockroach samples was 28.13%. A total of 53 groups of 7 categories of pathogens were detected, including Sapovirus, Norovirus, Astrovirus, Shiga toxin-producing Escherichia coli (STEC), Aeromonas hydrophila, Blastocystis hominis, and Cryptosporidium. The dominant pathogens carried by B. germanica were Sapovirus, B. hominis, and STEC, and those carried by P. fuliginosa were Sapovirus, STEC, and A. hydrophila. Conclusion: Cockroaches in catering places in Pudong New Area carried various human intestinal pathogens, so attention should be paid to targeted cockroach control strategies in catering places.
This paper describes a new species collected from Cangyuan Wa Autonomus County, Yunnan Province, China, in July 2020: Heizmannia (Heizmannia) cangyuanensis sp. nov.. The main distinguishing features of the new species are as follows: white scales on the ventral side of the basal proboscis; anterior pronotums with all white scales; ventral plates Ⅲ-Ⅵ are all white; the middle lobe of the ventral plate of segment Ⅸ has no scales, with numerous and large the ventral middle teeth in the aedeagus, as well as a finger-like protrusion on the lateral apex of gonostylus. There was no significant difference between the morphology of its larvae and that of Hz. menglianensis larvae. All specimens were preserved in the Mosquito Collection of Yunnan Institute of Parasitic Diseases.