ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Bacillus sphaericus (Bs) is an aerobic spore?forming bacillus widely distributed in nature, with a sub?terminal swelling capsule and spherical spores. As Bs grows, it produces binary toxin, Mtx and Cry48Aa/Cry49A, which have specific toxic effects on a variety of mosquito larvae. It is hence widely used in biological vector and mosquito control and considered a larvicidal solution that is non?toxic to human, animal, poultry and aquatic life and environmentally friendly. At present, many countries, including China, have developed commercial Bs mosquitocides that are widely used worldwide to control vectors and mosquitoes and good results have been achieved. However, laboratory and field experiments show that mosquitoes can produce binary toxin resistance under a long-term high selective pressure, which compromises Bs products as a biological mosquito larvicide in the comprehensive prevention and control of vectors and mosquitoes. The present article provides introduction to the mosquito-killing mechanisms of Bs agents, the development and application of mosquitocides, the resistance against them and vector and mosquito control.
Objective To determine the seasonal fluctuation and population composition of major vectors by a 3-year surveillance in the Shanghai World Expo area at Luwan district in the early period of construction (2006-2008), providing science evidence for vector control strategies for 2010 Expo. Methods CO2 traps, light traps and ovi-traps were used for mosquito monitoring, cage traps for fly monitoring, and snap traps for rat monitoring. Results Surveillance results indicated that the density of mosquitoes in 2006 was significantly lower than that in 2007 and 2008. The density of flies in 2008 was the lowest, being 18.13/cage, as compared to 39.31/cage in 2006 and 34.17/cage in 2007, respectively. No significant change in rat density was found during the three years. A total of 4781 mosquitoes of 5 species were captured, the dominant species being Culex pipiens pallens (74.75%), followed by Aedes albopictus (24.83%). A total of 11 447 flies of 16 species were captured, Lucilia sericata being the dominant species (44.96%), followed by Chrysomya megacephala (28.98%). About 34 rats of 2 species were captured, among which Rattus tanezumi accounted for 76.47% and R. norvegieus accounted for 23.53%. Conclusion Environmental changes and sanitation management exert great impact on vector density. Potential hazards of vectors shall be noticed in the Expo area.
Objective To evaluate the impact of the earthquake in Wenchuan on vector population and vector-borne diseases, and to track the species, density and pathogen-carrying conditions of vectors in the area, providing basis for risk assessment and development of control and prevention of vector-borne diseases. Methods Visual observation was used to monitor the density of mosquitoes and flies, and rat density was traced through rat trails. Results The density of mosquitoes, flies and rats reached 5.77 per labor hour, 0.46 per square meter and 0.81 positive dot per 2000 m, respectively. Seasonal fluctuation of mosquito and fly density suggested an upward trend from June to July, which peaked in July and declined afterward. The overall density of rats peaked in June followed by a subsequent decline. Conclusion The overall density of mosquitoes, flies and rats was generally low, despite a few districts where the density exceeded reference indexes. Scientific and systematic monitoring of vectors in the earthquake-stricken areas played a guiding role in the control and prevention of vector-borne diseases and epidemic outbreaks of related infectious diseases.
Objective To evaluate the impact Wenchuan earthquake exerted on vectors and vector-borne diseases and identify the species, density dynamics and ecologic patterns, providing scientific basis for the risk assessments of vector-borne diseases. Methods The density of vectors was monitored using such approaches as cage traps, light traps, visual observation and mist net capture, the species of mosquitoes and flies investigated. Results Low density of mosquitoes, flies, mice and fleas in the earthquake-stricken areas was identified, clearly below the reference indexes. However, high positive rates of larvae in stool were found. More than 800 mosquitoes and flies were captured, flies belonging to 42 species, 28 genera and 4 families and mosquitoes belonging to 5 species, 3 genera and 1 family. Helicophagella melanura, Mascina stabulans, Musca domestica, Culex tritaeniorhynchus and Cx. pipiens quinquefasciatus were dominant species there. Conclusion Aggregate analysis revealed that vector control was effective and played a key role in preventing the occurrence of major epidemics after the earthquake. However, redundant and inadequate vector control was still noticed. Therefore, it is necessary to establish a long-term effective mechanism in conjunction with comprehensive responding teams for prompt emergency response.
Objective To present the composition and spatial distribution patterns of small mammals in Hengduan Mountains, a mountainous area in the southwest of China. Methods Based on previous serial investigations of small mammal fauna, the data of the composition and spatial distribution of small mammals were collected and statistically analyzed. The investigated areas covered from north latitude 21° up to 29°, including eight latitude zones which were denoted as Ⅰ-Ⅷ and altitude from 100 to 5000 meters, including nine altitude zones denoted as A-I, in Hengduan Mountains (west of Yunnan province). Results The small mammals identified were composed of 187 species (subspecies), 58 genera, 11 families, 5 orders in Hengduan Mountains of Yunnan. The richness distributions of small mammals in species, genera and families along the latitudinal gradient revealed that there were 44 species, 30 genera, 9 families in zone Ⅰ; 57 species, 33 genera, 9 families in zone Ⅱ; 74 species, 38 genera, 9 families in zone Ⅲ; 93 species, 43 genera, 9 families in zone Ⅳ; 101 species, 43 genera, 10 families, in zone Ⅴ; 91 species, 39 genera, 9 families in zone Ⅵ; 102 species, 40 genera, 11 families in zone Ⅶ; 67 species, 35 genera, 11 families in zone Ⅷ. A gradual increase followed by a gradual decrease was noticed in the species and genera richness distribution as the latitude increased, the peak at 24°N-27°N(the mid-latitude zone). The richness distributions along the altitudinal gradient showed 54 species, 28 genera, 8 families in zone A; 90 species, 41 genera, 9 families in zone B; 102 species, 37 genera, 9 families, in zone C; 101 species, 41 genera, 10 families in zone D; 94 species, 35 genera, 9 families in zone E; 76 species, 33 genera, 9 families in zone F; 58 species, 29 genera, 9 families in zone G; 28 species, 15 genera, 8 families in zone H; 7 species, 5 genera, 4 families in zone I. A U-shaped pattern could be observed in the species and genera richness distribution, with the peak at about 1500-3000 m (mid-altitude zone). Conclusion Varying composition and distribution of small mammals were observed at different latitude and altitude zones in Hengduan Mountains, with relatively greater species richness seen at the mid-latitude and mid-altitude zones.
Objective To analyze the dietary composition of Bandicota indica to unearth the seasonal and annual patterns of the food structure, providing theoretical foundation for the development of scientific control countermeasures and sustainable management. Methods The contents of rat stomachs were analyzed in conjunction with field observation. Results Fibers accounted for (68.68±5.17)% in the gastric contents of the rats, while starch food (23.06±4.32)% and animal food (8.26±1.43)%, respectively. Significant differences were found in the gastric contents of subjects of different age, sex and in different seasons and years (P＜0.01). The proportion of starch and animal food in females was significantly greater than that in males. No significant differences were found in starch and fiber food consumed by the juvenile versus that by the sub-adults and adults, though the juvenile had higher intake of such kind of food (P＞0.05). However, the proportion of animal food consumption in adults was significantly higher than that in sub-adults and juvenile (P＜0.01). Considerable seasonal disparity in the food structure, characterized by higher amount of starch and animal food in summer and autumn and higher amount of fiber food in winter and spring, was also shown in B. indica. Conclusion B. indica were mainly fed on fiber food, as well as starch and animal food, under natural conditions. Diversity of food structure was associated with the reproduction and population growth, growth season of crops and vegetation types of the habitat.
Objective To determine the species and distribution of flies in the living environment of camels in the steppe region, in order to evaluate the possibility of different kinds of flies to be vectors of Parabronema skrjabini. Methods From July to September in 2007 to 2009, species of flies in three desertification grasslands where camels lived were investigated. Net fishing method was used to collect flies and traditional morphological classification to identify the species. Results As a result, 9 families, 17 genera and 25 species were identified in Inner Mongolia, 12 species of flies being new records. A total of 2489 flies were collected from Bayannaoer in Inner Mongolia, the dominant species being Hydrophoria ambigua, up to 37.2%, next, the proportion of Haematobia titillans was high, up to 23.0%. From the 2260 collection in Alaxan region, the dominant species, accounting for about 31.5%, consisted of Coelopidae, followed by Norellia striolata that accounted for 26.5%; the proportion of other fly species was relatively small. A total of 2343 flies were collected from Wulanchabu region. Trixoscelidae accounted for a dominant portion of about 43.4%, followed by Lispe litorea and L. consanguinea (10.6% and 12.4%, respectively). Conclusion The composition of species of flies in camel’s living environment in Inner Mongolia was primarily uncovered, providing essential fundamental data for the investigation of Parabronemosis vectors.
Objective The study was conducted to determine the effects of frozen storage of Lucilia sericata pupae on the prolificacy of Nasonia vitripennis. Methods The length of growth stages, sizes of descendants, life span of the females, parasitic and reproductive ability of descendants of N. vitripennis within L. sericata pupae were documented. Results Two groups of N. vitripennis in L. sericata pupae, frozen at -20 ℃ and -70 ℃, respectively, demonstrated a growth period of approximately 13 days, the body length of female descendants about 1.8 mm and males about 1.2 mm, the life span of female descendants about 11 days, suggesting no significant differences when compared to the control group (P＞0.05). A total of 83% to 90% eclosed N. vitripennis could successfully parasitize natural L. sericata pupae, and 73% to 80% emerged, about 37 from each pupa, with the female to male ratio of about 90%, suggesting no significant differences when compared to the control group (P＞0.05). Conclusion Frozen storage of L. sericata pupae had no effects on the development and prolificacy of N. vitripennis descendants.
Objective To predict the potential distribution of the Western Treehole Mosquitoes, Aedes sierrensis (Ludlow, 1905) in China. Methods Genetic algorithm for rule-set production (GARP) was used for prediction of the potential distribution based on current stable distribution of Ae. sierrensis derived from previous literatures. Results The potential distribution of Ae. sierrensis covered most provinces in China, with the high-risk area located in the north and central part of China, including Xinjiang, Inner Mongolia, Ningxia, Shaanxi, Shanxi, Hebei, Beijing, Tianjin, Henan, Shandong, Liaoning, Jilin and Heilongjiang; the moderate?risk areas including Anhui, south of Hebei, southeast of Shandong, north of Hubei and northwest of Zhejiang; and the low-risk areas including Guizhou, Guangxi, Hunan, Chongqing, Hubei, Jiangxi, Fujian, Hainan and Taiwan. Conclusion Extensive potential distribution of Ae. sierrensis was identified in China with high risk levels, and thus risk management should be developed and deployed to prevent potential invasion of such mosquitoes.
Objective To evaluate the effectiveness and comparability of three methods of cockroach density monitoring in the same unit, providing scientific basis for the standardization of cockroach density monitoring and the assessment of control efficacy. Methods Three commonly used density monitoring and measurement approaches were tested in three units with different infestation rates. For each place, visual observation, glue traps and sprays were concurrently conducted in order. Data statistics was tested using Chi-square, two-sample mean-comparison test and one-way ANOVA. Results （1） Except for three units where no cockroaches were captured, cockroaches were detected in 28 out of 31 experimental units by the three monitoring methods. （2） The detection rates of visual observation, glue traps and sprays were 48.82%, 46.08% and 48.44%, respectively, without statistically significant difference (χ2＝0.556，P≥0.05). The density indexes were 9.65 /room, 7.04 /trap and 13.57 /room, respectively.（3） Regardless of high, intermediate or low infestation rates, no statistical difference was shown in the positive rates and density indexes derived from three approaches. Conclusion The three methods were all useful in density monitoring, investigation and efficacy assessment. However, the sample size, the responsibility of monitors and the adherence to standard procedures determine the accuracy and reliability of positive rates and density indexes whichever approach is taken. Establishment of indexes for glue traps is desired.
Objective To evaluate the sensitivity of the four test methods, hemagglutination test, gold immunochromatographic assay (GICA), enzyme-linked immune sorbent assay (ELISA) and polymerase chain reaction (PCR). Methods The minimal detectable dilution of antiserum of a bacteria?immunity rabbit via serological approaches for F1 antibody detection, the minimal detectable concentration in F1 antigen measurement, and the minimal concentration of template with a detectable gene pair, fra and pla, were evaluated. Results For the F1 antibody test, the minimal dilution detected was 1∶64 through IHA, 1∶1000 through GICA, and 1∶204 800 through ELISA. For F1 antigen test, the minimal detectable concentration was 2 ng/ml by RIHA and 50 ng/ml by GICA. The minimal concentration of template was 0.21 ng/μl when fra and pla were both detected. Conclusion In the serum consisting mainly of antibody IgG, the ELISA method has a higher sensitivity detecting F1 antibodies. The RIHA has higher sensitivity detecting F1 antigens. To minimize misdiagnosis, a minimal concentration of template of 0.21 ng/μl is required to diagnose plague when using PCR.
Objective To histochemically locate the lipid peroxidation induced by photosensitized α-terthienyl(α-T) in Aedes albopictus larvae. Methods Cold-schiff was employed to observe the Ae. albopictus larvae exposed to photosensitized α-T under optical microscope in comparison to the control group to evaluate the histochemical localization of lipid peroxidation. Results Tissues in the control group remaining unstained, the midgut epithelium, the peritrophic membrane, the brush border and the lumen of malpighian tubules were stained purple in the experimental group. Conclusion Photosensitized α-T could induce lipid peroxidation in tissues of Ae. albopictus larvae, involving primarily the midgut and malpighian tubules.
Objective To determine the effectiveness of Japanese encephalitis (JE) mass immunization campaign in Guizhou in 2008, providing evidence for the development of control strategies. Methods Comprehensive analysis was performed based on the reports and investigation results during mass immunization campaign and epidemic information from the National Diseases Reporting System before and after the launch. Results A total of 1 503 052 children were immunized, the reported immunization coverage being 96.72%, the estimated coverage based on the population data 91.82%. The provincial incidence of JE was 0.85/100 000 in 2008, a decrease of 44.08% compared to that in 2007. Sharp decline in the incidence among target population was observed in various areas and counties to a more significant extent than that in non-target population. The incidence also decreased in each age group in 2008, yet the 8?month to 6-year-old group still had the highest incidence. Above average level of incidence was seen in Anshun, Qianxinan, Tongren and Bijie, and an increase of 111.59% was present in Anshun when compared to that in 2007. The incidence rates of 7 to 10-year-old group in Anshun, Qianxinan were both above the provincial average level, which increased by 117.83% and 66.32% when compared to those in 2007. Conclusion The expected goal of the JE mass immunization campaign had been attained. Younger children, especially those aged 8 months to 6 years in the province, were still the key group for prevention and control of this disease. Importance should be attached to the prevention and control of JE in such key areas as Anshun and Qianxinan.
Objective To determine the correlation between the occurrence of Culex tritaeniorhynchus and meteorological factors. Methods Photocatalytic light traps were used to collect mosquitoes in Nanjing suburbs from August in 2006 to December in 2007. Multivariant stepwise regression was conducted using SPSS 16.0 with mosquito density (Y1), female mosquito density (Y2) as the dependent variables and synchronous meteorological factors, including mean temperature (X1), maximum temperature (X2), minimum temperature (X3), precipitation (X4), mean air pressure (X5), mean relative humidity (X6), mean wind velocity (X7) and sunshine hours (X8), as the independent variables. Results Cx. tritaeniorhynchus accounted for over 90% in Nanjing suburbs, and female mosquitoes 95%. High density (＞60 individuals per hour) was observed in the period from June to October. Significant linear correlation was present between X3 and the changing trend in mosquito densities, despite insignificant regression link. Most meterological factors were significantly nonlinear correlated with the density of Cx. tritaeniorhynchus. Favorable results were obtained via the following regression equations: Y1＝10∧［18.645 Lg（X1＋1）－21.403 Lg（X2＋1）－0.930 X7＋0.104 X8＋2.470］－1，Y2＝10∧［19.051 Lg （X1＋1）－21.994 Lg （X2＋1）－0.945 X7＋0.106 X8＋8.675］－1，R2＞0.8. Conclusion The occurrence of Cx. tritaeniorhynchus could be forecasted based on the concurrent meteorological factors. This prediction method could be applied to other vectors and relevant diseases.
Objective To investigate the density of mosquitoes and their population composition in the ares of Shanxi province where Japanese encephalitis（JE） was highly prevalent. Methods Mosquitoes were collected by light trap in pig pens, lakesides and other enviranments. Results It was found that the mosquito density at Wuxing lakeside in Yongji was 2000.0 each trap night, 1352.0 in Chengbei district of Yongji city, more than 500 in Dingxiang county and in the Sushui riverside in Yongji and 100-500 in Linyi county(in Sep. 2006 and in Aug. 2007), Wutai county, Taiyuan city, Changzhi city, the Shengtian lakeside in Ruicheng and Yangquan city, with a density of less than 100 in Ruicheng, Linyi county (in Aug. 2006) and the Sushui riverside in Linyi. Culex tritaeniorhynchus accounted for 77.7 percent of all the mosquitoes collected from pens for livestock in Linyi (in Aug. 2007), however Ruicheng, Linyi county ( in Sep. 2006), Yongji city see a lower percentage in terms of the species. In terms of the density of Cx. pipiens pallens in the sites where the samples were collected, the suburbs were ranked at the top of the list, accounting for 100 percent, followed by Wutai county and Dingxiang county. There were fewer species of mosquetoes in other sites, with Aedes vexans and Ae. dorsalis as the major species. As far as the samples collected from lakesides and riversides were concerned, Cx. tritaeniorhynchus was most heavily populated in Shengtian lakeside in Ruicheng, accouting for 94.4 percent, with Cx. pipiens pallens having a highest in Wuxing lakeside and Sushui riverside in Yongji, being over 99.0%. Conclusion In view of the high mosquito density, Mosquitoe control in pens for livestock and other water-rich areas should be strengthened. Anti?mosquito publicity and promotion of mosquito control infrastructure are to be reinforced in Shengtian Lake scenic spot.
Objective To determine the density fluctuation and population composition of mosquitoes in Anhui, providing scientific evidence for further development of control and prevention strategies. Methods From May to October in 2004 and 2007, man?attracting and net trap approaches were used to monitor the density of mosquitoes, which were then classified, identified and counted. Results The mosquito density peaked in the period from July to September, particularly in early July (641.4/person hour) and late August (824.6/person hour). The highest density was present in late August. The dominant species was Culex tritaeniorhynchus, accounting for 65.36% of the total captures. Conclusion Cx. tritaeniorhynchus was the dominant species in Anhui, to which importance should be attached in further prevention and control process. The development of control strategies should be based on the occurrence patterns derived from the monitoring data.
Objective To determine the mechanisms of development and hereditary patterns of the resistance against pyrethroids in Musca domestica using beta?cypermethrin-resistant strain domestically produced by selective breeding, providing scientific basis for the establishment of practical management strategies to restrain the development of insecticide resistance for effective control of houseflies. Methods Beta-cypermethrin of median lethal concentration applied to each generation of susceptible M. domestica strains, the resistance selective breeding was performed in compliance with the National Standard GB 13917.1-13917.8－92, Laboratory efficacy test methods and criterions of public health insecticides for pesticide registration. Bioassay methods were utilized to determine the LD50 of generations of M. domestica from which the resistance index was generated. Results Continuous affection of beta?cypermethrin on twenty?two generations of selective breeding gave arise to rapid development of strong resistance in susceptible M. domestica strains, resulting in a resistant line with the resistance index of 104.23 folds. Conclusion The occurrence and development of resistance in M. domestica was the result of the directional selection favoring traits of resistance genes exerted by the insecticide. The stronger the selection pressure is, the faster the resistance develops. Different methods of insecticide application pose significant influence on selective breeding for resistance.
Objective Nosopsyllus laeviceps ellobii (Wagner) were reared at different temperatures and relative humidities to determine the biological characteristics, providing basic evidence for the prevention and control of flea. Methods Adults and larvae were separately raised and observed under constant temperature and humidity. Results The growth of fleas ceased at the first larval stage under a relative humidity of (35±3)% and a temperature of (20.5±1)℃ or (22.5±1)℃, and the third stage under a relative humidity of (95±3)% and a temperature of (20.5±1)℃. At (22.5±1)℃, egg?to?adult development was achieved with nevertheless low survival rate. The mean survival time of new eclosed fleas was 11.68 days under starvation conditions, less than 15.07 d (22.5±1)℃, suggesting a sub?optimal temperature of (22.5±1)℃ and an optimum humidity of (75±3)%. Conclusion N. laeviceps ellobii is characterized by short metamorphic period, long adult life and strong reproductive capacity.
Objective To observe the life cycle of Xenopsylla minax Jordan, 1926 under laboratory conditions and whether it could suck in human blood or not. Methods The specimens of X. minax collected from Rhombomys opimus haunting Mayile Mountain valley of Tuli county of Xinjiang were fed on white mice. The life cycle was observed under the conditions of 18-24 ℃ and 70%-90% RH. The two breeding methods, including the common medium method and plate culture of third instar ripe larvae and pupae, were used for the study. The first filial generation adults 1-3 d after emergence with an empty stomach were induced to suck human blood from the anterior arm and ankle skin of 4 volunteeres. Results It was found that the egg stage was at 10-11 d, the larva stage 18-19 d, the pupa stage 10-12 d, and the pregnancy 2-3 d. 40-45 d was needed from oviposition of the adults to that of the first filial generation adults. Of the 34 tested fleas （15♂♂，19♀♀） 18♀♀ showed the behavior of sucking human blood, but 15♂♂ and 1♀did not. Conclusion It took 40-45 d for X. minax to complete a life cycle under laboratory conditions as stated. Almost all of the female first filial generation adults were able to suck human blood but the males were not.
Two new species of Culicoides (Fastus) were reported lately from Jilin province: C. (F.) haerbalingensis Liu et Wang, sp.nov. and C. (F.) subchangbaiensis Liu et Ren, sp.nov. Though C. (F.) haerbalingensis Liu et Wang sp.nov. is alike to Culicoides pallidicornis Kieffer, 1919; the latter is noticeably distinguishable by a large but shallow sensory pit in the third segment of palpus and a small pale spot in the anal cell. C. (F.) subchangbaiensis is somewhat alike to Culicoides（F.） changbaiensis Qu et Ye, 1995, but the latter is distinctly characterized by approximately 90 tubercular spinules in the cibarial armature with a palpal ratio (PR) of 3.45; two spermathecae of the same size. The type speciemens are preserved in the Center for Disease Control and Prevention of Shenyang Command, Shenyang 110034, China.
Objective To identify the clinical manifestations and regional distribution of Lyme disease by analyzing the serological testing for suspected patients, providing scientific evidence for proper management of the disease. Methods The indirect immunofluorescence assay (IFA) and the enzyme-linked immune sorbent assay (ELISA) were employed for the detection of serum antibodies(IgM, IgG) against Borrelia burgdorferi for suspected Lyme disease patients. The results were then comprehensively interpreted combining clinical manifestations. Results From 2007 to 2008, a total of 105 suspected Lyme disease patients were subject to the analysis, resulting in 16 positives (15.24%), including 4 out of 44 patients with neurological disorders; 1 out of 5 patients with cardiovascular conditions, 6 out of 25 patients with skin lesions; 1 out of 10 fever patients; 2 out of 14 arthralgia patients; and 2 out of 7 patients with mental disorders. Of the 16 patients distributed in 9 provinces, 87.50% responded favorably to the application of antibiotics. Most confirmed patients were from Heilongjiang, Jilin and Inner Mongolia. Conclusion Sporadic spirochete infections were observed in Chinese population. Serological testing contributes to the early detection of Lyme disease and the improvement of efficient diagnosis and treatment.
Objective The study was conducted to determine the community structure and seasonal changes of mosquitoes based on light?trap surveillance, providing evidence for the development of prevention and control of mosquito infestation. Methods Adult mosquitoes were captured, classified and identified at surveillance sentinels from April to November in 2007 to 2008. Results A total of 7685 mosquitoes were captured using light traps, including Culex pipiens pollens, Cx. tritaeniorhynchus, Anopheles sinensis, Aedes albopictus and Armigeres subalbatus. The average density was 4.06 in 2007 and 3.46/(light·hour) in 2008, the seasonal peak of density was from May to July according to the light?trap surveillance, with similar pattern by labor hour method. Conclusion The light?trap surveillance was applicable for reflecting the seasonal changes of domestic and semi domestic mosquitoes with the exception of Ae. albopictus. The light?trap capture was recommended to last three or fifteen hours.
Objective To evaluate the resistance of Blattella germanica against seven kinds of commonly used insecticides, providing scientific basis for appropriate application of insecticides. Methods The residual contact method was used to determine the resistance. Results The average resistance of seven wild B. germanica strains in Wuhan against beta-cypermethrin, deltamethrin, propoxur, chlorpyrifos, DDVP, cypermethrin, and permethrin was 2.6-7.7, 3.3-10.7, 1.1-2.0, 2.9-3.8, 2.5-11.2, 3.5-5.3, and 4.0-6.4 times that of susceptible strain, respectively. Conclusion Seven wild B. germanica strains have developed different degrees of resistance to five kinds of insecticides, yet susceptible to propoxur. Domestic strains have developed strong resistance against deltamethrin, and those collected from fair trade markets have been highly resistant to DDVP.
Objective To develop scientific and sustainable approaches of cockroaches control in barracks. Methods Cockroach gluing planks and inquiry survey were utilized to determine the density of cockroaches. An integrated approach combining environmental cleaning-up, density monitoring and deployment of insecticides was employed in conjunction with key point intensified control strategies. Results The cockroach density in the barracks decreased from 22.00% to 0.18% in the past twelve years. From 1998 to 2008, the infestation rate was properly controlled, ranging from 0.34% to 2.93%. Conclusion The combination of routine monitoring of cockroach density, analysis of infestation, and comprehensive prevention and control in key points has resulted in marked effect of time- and labor-saving cockroach control, avoiding blind application of insecticides.
Objective To determine the distribution and fluctuation of vectors at Shunyi Olympic Rowing-Canoeing park of Beijing, providing background data for vector control in the area. Methods The monitoring was performed in accordance with the requirements of Beijing Center for Disease Control and Prevention. Results Mus musculus was found, the annual average density being 0.12%. Collected mosquitoes belonged to 1 family, 2 genus and 2 species, Culex pipiens pallens being the dominant species, and the annual average density being 20.58/(light·hour). Captured flies belonged to 3 family, 7 genus and 7 species, the dominant species being of Sarcophagidae, and the annual average density being 3.11/(trap·h). For cockroaches, Blattella germanica was the only found species, the annual average density being 0.02/(trap·night). Conclusion The monitoring provided an insight into the population composition, density and seasonal fluctuation of rodent, mosquitoes, flies and cockroaches at Shunyi Olympic Rowing?Canoeing park of Beijing, establishing scientific basis for further vector control in Olympic venues.
Objective To assess the course of the first case of human eperythrozoonosis in Huludao city and to determine the current infection situation and influential factors in humans and animals. Methods Blood smears were examined under microscope to determine the infection in humans and animals, blood analyzers employed to detect anemia in humans. Types and density of mosquitoes were analyzed using outdoor light traps. A case-control study followed to identify the influential factors for infection. Results The overall infection rate of eperythrozoon in humans was 30.67% without noticeable significant difference between men and women or among different age groups (χ2＝1.79, P＞0.05; χ2＝1.05, P＞0.05). The infection rate of eperythrozoon in swine was 60.87%. High density of mosquitoes was detected as Aedes vexans and Culex dominated. Anemic symptoms were primarily present in younger children. An excess risk for eperythrozoon infection was noted in swine breeders 2.77 times higher than in others, and the risk in those breeding and delivering swine was 2.97 times higher than pure breeders. Conclusion High prevalence of eperythrozoonosis was found in both humans and animals in the area, children constituting the major victims. Swine were the important reservoir host, breeding swine the risk factor and mosquitoes the transmission medium.
As the genetic basis of Yersinia pestis, chromosomes and plasmids play a determinant role in its biological characteristics and virulence. G＋C?base composition deviation, abundant insertion sequences, substantial pseudogenes and frequent gene recombination in varying types of strains indicate rapid evolution of Y. pestis. The present study employs the genetic approaches such as comparative and evolutional genomics to analyze the virulence and pathogenic mechanisms of Y. pestis, disclose the genetic mechanisms of the pathogenicity and evolution of Y. pestis, and provide scientific basis for the development of epidemiologic surveillance, vaccine deployment and prevention of plague.
This paper reviewed on integrated control of cockroach on chemical, biological, physical and environmental basis, and analyzed the practical prospect and development of insecticide for cockroach control, providing appropriate reference on cockroach control in various areas.
