ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Mosquito larvicides derived from microbial organisms and insect growth regulators(IGR)have been increasinglyused to control mosquito larvae. Their relative target specificity, non?target safety and environmentally friendly profile have beenwell documented. The current paper was intended to review and analyze the relevant information regarding resistancedevelopment and management strategies and measures. The biorational larvicides discussed include Bacillus thuringiensisisraelensis de Bajac(B.t.i.), Bacillus sphaericus Neide, spinosad derived from Saccharopolyspora spinosa Mertz and Yao, as wellas IGRs such as methoprene, pyriproxyfen and diflubenzuron. The prevention of resistance and restoration of susceptibility inmosquitoes to these biorational larvicides are crucial to the success of sustainable integrated mosquito management.
Objective To investigate the species composition and population dynamics of mosquitoes in Lhasa, Tibet, China, so as to provide scientific evidence for the surveillance, prevention, and control of mosquitoes and mosquito?borne diseases in this city. Methods Representative research sites were selected based on geographical distributions in Chengguan District in Lhasa. Adult mosquitoes were collected by bed net traps, labor hour method, and light traps in 2009, 2012, and 2013. The trapped mosquitoes were initially identified according to morphological criteria. A proportion of them were examined using a multiplex PCR assay for species confirmation. Results Mosquitoes in Lhasa comprised the subspecies of Culex pipiens complex and Armigeres subalbatus, with subspecies of Cx. pipiens complex as the dominant species. The mean mosquito density monitored by bed net traps was 19.57 mosquitoes per net?hour in 2009 and 3.06 mosquitoes per net?hour in 2012; there was no significant difference in mosquito density between research sites in different years (F1, 1＝0.934, P＞0.05). The mean mosquito density monitored by labor hour method was 62.10 mosquitoes per person?hour in 2009 and 7.90 mosquitoes per person?hour in 2012; there was no significant difference in mosquito density between research sites in different years (F1, 1＝0.874, P＞0.05). The mean mosquito density monitored by light traps was 1.47 mosquitoes per trap?hour in 2012 and 0.20 mosquitoes per trap?hour in 2013; there was no significant difference in mosquito density between research sites in different years (F1, 3＝1.503, P＞0.05). A hundred and five mosquitoes captured in 2012 were identified by multiplex PCR, of which 36 (34.29%) were homozygous subspecies of Cx. pipiens complex, while 69 (65.71%) were hybrids. Conclusion Mosquitoes of Cx. pipiens complex subspecies are established in Lhasa, and the population density was relatively low in recent years, indicating that the risk of mosquitoes and mosquito?borne diseases exists in Lhasa. Therefore, surveillance and risk assessment should be conducted to provide a basis for decision?making in the control of mosquitoes and mosquito?borne diseases in this region.
Objective To identify CYP6P5 gene of Anopheles sinensis and to analyze its bioinformatic characteristics for further research on its role in insecticide resistance. Methods We searched the transcriptome dataset of An. sinensis for CYP6P5 cDNA sequence with bidirectional Blast, using the sequence of An. funestus CYP6P5 gene as query. The primary structure, hydrophobic region, transmembrane region, structural domain, and 3D structure of translated protein of the resultant sequence were analyzed using bioinformatic software. The phylogenetic relationship of CYP6P5 sequences of An. sinensis and representative mosquito species was constructed using maximum likelihood methods. Results A complete cDNA sequence of An. sinensis CYP6P5 was obtained by BLAST searching. The whole sequence was 1583 bp long with an open reading frame of 1527 bp, encoding 508 amino acids. The deduced amino acid sequence was found with characteristic conserved regions of superfamily P450 family 6 (CYP6). The gene was designated as CYP6P5 (GenBank No. KF358704). Bioinformatic prediction indicated that the molecular weight of CYP6P5 protein was 58.32×103, and the isoelectric point was 7.17. The sequence contained a predicted hydrophobic region spanning from locus 5 to 21, a transmembrane region from 5 to 22, a P450 domain from 36 to 505, and multiple enzyme active sites. Phylogenetic and similarity analyses of amino acid sequences showed that An. sinensis CYP6P5 had the closest phylogenetic relationship with CYP6P5s of An. funestus and An. gambiae, with similarity values of 89.4% and 89.0%, respectively. They formed a monophyletic group. Conclusion This study laid a foundation for further study on the molecular mechanism of An. sinensis CPY6P5s role in pyrethroid resistance.
Objective To investigate the population dynamics, temporal distribution, and stinging indices of mosquito population in the downtown Shanghai, China. Methods Five mosquito?lmonitoring sites were set up in Shanghai Peoples Square and Peoples Park areas, where mosquitoes were frequently encountered. A 194-day continuous dynamic monitoring of adult mosquitoes was conducted by human landing catch. Results During the 194-day surveillance from late April to late October, 2012, a total of 1666 adult mosquitoes of 5 species and 3 genera were collected. The proportions of Aedes albopictus and Culex pipiens pallens were 71.1% and 27.7%, respectively. The high daily fluctuation of adult mosquitoes was observed. Most of the mosquitoes were captured during July to September, with a peak of 52 mosquitoes per day. Cx. pipiens pallens peaked in early June, and its population density was significantly higher than that of Ae. albopictus in May and June (P＜0.05). Ae. albopictus peaked in late July, and its population density was significantly higher than that of Cx. pipiens pallens during July to September (P＜0.05), so it was the predominant species during that period. Conclusion This is the first report on mosquito infestations in downtown area as the results of 194-day continuous surveillance based on human landing catch. The results suggested that routine mosquito monitoring methods have limitations and inaccuracy. Targeted and efficient measures with special focus on the two predominant mosquito species, Ae. albopictus and Cx. pipiens pallens, should be introduced into the prevention and control of mosquitoes in downtown Shanghai. Furthermore, the study suggested that the increasing suitable sites for overwintering mosquitoes are more likely to cause an earlier arrival of Cx. pipiens pallens peak in the studied areas.
Objective To determine the sensitivity of Anopheles sinensis to DDT, deltamethrin, cyfluthrin, and malathion in Zibo, Qingdao, and Jining of Shandong province, China. Methods Anopheles sinensis collected were selected and exposed to insecticide?impregnated papers with discriminating concentrations of DDT, deltamethrin, cyfluthrin, and malathion using WHO standard assays. Knock?down rates were recorded at 10, 20, 30, 40, 50, and 60 min of exposure. Mortality resulted from 24 h of exposure was recorded. Resistance was graded according to adjusted mortality rate. Results After exposure to 4% DTT for 60 min, the knock?down rates of An. sinensis in Zibo, Qingdao, and Jining were 31.78%, 22.32%, and 25.66%, respectively. The mortality rates at 24 h after exposure were 34.58%, 30.40%, and 24.67%, respectively. The resistance level of An. sinensis to DDT in the three areas was evaluated as “R”. After exposure to 0.05% deltamethrin for 60 min, the knock?down rates of An. sinensis in Zibo, Qingdao, and Jining were 40.20%, 42.16%, and 22.73%, respectively. The mortality rates at 24 h after exposure were 86.58%, 61.85%, and 31.94%, respectively. The resistance level of An. sinensis to deltamethrin was evaluated as “M” in Zibo and “R” in Qingdao and Jining. After exposure to cyfluthrin for 60 min, the knock?down rates of An. sinensis in Zibo, Qingdao, and Jining were 14.29%, 30.10%, and 13.00%, respectively. The mortality rates at 24 h after exposure were 66.39%, 42.77%, and 22.05%, respectively. The resistance level of An. sinensis to cyfluthrin in the three areas was evaluated as “R”. After exposure to malathion for 60 min, the knock?down rates of An. sinensis in Zibo, Qingdao, and Jining were 31.19%, 49.53%, and 29.52%, respectively. The mortality rates at 24 h after exposure were 75.09%, 87.18%, and 81.47%, respectively. The resistance level of An. sinensis to malathion was evaluated as “R” in Zibo and “M” in Qingdao and Jining. Conclusion The resistance of An. sinensis to DDT and cyfluthrin remains high in some areas of Shandong. The resistance and anti?knockdown potential of An. sinensis to deltamethrin and malathion are also high. The status of insecticide resistance in different areas of Shandong province should be further studied in order to optimize surveillance and management programs.
Objective To investigate the mosquito species composition and activity rhythm in the lower reaches of Ertix River on the Sino?Kazakhstan border and their relationship with the habitat. Methods The species, density, seasonal rhythm, and circadian rhythm of mosquitoes in different habitats were investigated by human?baited net traps. Biting cycles were determined through biting indices. Results Eight species of four genera of mosquitoes were found in the lower reaches of Ertix River on the Sino?Kazakhstan border. Aedes vexans was the predominant species, with a proportion between 82.22% and 96.09% among all captured mosquitoes in different habitats. The seasonal activity of Ae. vexans started in mid?April, ended in early September, and reached the peak between mid?June and late July. The circadian rhythm of activity was in a double?peak pattern, with the morning peak appearing at 1-2 h after sunrise and the evening peak at 1 h after sunset; the evening peak was higher than the morning peak. The biting circadian rhythm was dawn type; biting activity started around sunset and ended after sunrise. The biting circadian rhythm was also double?peaked; the morning peak appeared at 1 h before sunrise, and the evening peak appeared at 1 h after sunset. The species diversity index ranged from 0.1912 to 0.7227, indicating that mosquito species were not abundant in the lower reaches of Ertix River on the Sino?Kazakhstan border. The habitat had significant impacts on the species distribution and number of mosquitoes. The numbers of Ae. vexans, Anopheles messeae, and Culex modestus in riparian forest were significantly higher than those in saline regions. Biting of Ae. vexans was the severest in riparian forest. However, seasonal activity, circadian activity, and biting cycle were similar for Ae. vexans in different habitats. Conclusion The habitat has a significant impact on the population size of Ae. vexans. In integrated prevention and control of Ae. vexans, special focus should be placed on microhabitats where mosquitoes propagate.
Objective To investigate the chromosome number of ground squirrels in the delta at the intersection of Luo River and Wei River (Wei?Luo Delta) in Shaanxi province, China and to provide a basis for the classification and identification of Spermophilus alashanicus. Methods The chromosome karyotype of ground squirrels was studied by microscopic counting of bone marrow cell chromosomes. Results Forty?seven cells of two ground squirrels were investigated, of which 45 (95.74%) were observed with chromosome number 2n＝38. Conclusion The ground squirrels in the Wei?Luo Delta of Shaanxi are Spermophilus alashanicus.
Objective To investigate the relationship between diversity of farmland small rodents and environmental factors in different regions of Shanxi province, China and to provide a foundation for regional integrated management for farmland small rodents in Shanxi province. Methods The study areas were established in Xi county of Linfen, Loufan county of Taiyuan, and Wutai county of Xinzhou in Shanxi province. The snap?trap method was used to investigate the diversity of farmland small rodents in each study area from March to November. The vegetation heterogeneity index in the middle ten days of July was used to determine the habitat complexity in study area. The impact of farmland habitat complexity on diversity of small rodents in Shanxi province was evaluated. Results There was a significant positive correlation between the richness and diversity indices of farmland small rodents and vegetation heterogeneity index in Shanxi province, with a correlation coefficient of 0.998. On the other hand, the species dominance index was negatively correlated with the vegetation heterogeneity index, with a correlation coefficient of -1.000. However, the capture rate and evenness index showed no significant correlation with the vegetation heterogeneity index, with correlation coefficients of 0.404 and 0.994, respectively. Conclusion The complexity of habitat environment is a key factor influencing the richness and diversity of small rodent community. The uniformity of vegetation coverage in farmland is probably correlated with the evenness index of small rodent community.
Objective To evaluate the application of autoregressive integrated moving average (ARIMA) model in the prediction of monthly incidence of hemorrhagic fever with renal syndrome (HFRS). Methods The database of monthly epidemic situation of HFRS in Hebei province, China from 1986 to 2011 was constructed with SPSS 16.0. A mathematic model was constructed using ARIMA of SPSS 16.0 and used to predict the epidemic situation in 2012. Results The HFRS incidence presented obvious seasonal periodicity during 1986 to 2011 in Hebei province. ARIMA (0, 1, 1)×(0, 1, 2)12 model best fitted the incidence of HFRS from January 1986 to December 2011. The actual average incidence of HFRS in 2012 fell within the 95% confidence interval of prediction. Conclusion ARIMA model fits well in the prediction of HFRS incidence, and is suitable for use in epidemiological prediction to provide a basis for the prevention and control of HFRS.
Objective To determine the chemical property and attractive activity of volatiles from Blattella germanica. Methods Volatiles from B. germanica were collected by headspace SPME method in purge flow. GC?MS was used to identify the main components in SPME extracts. GC?EAD was used to identify electrophysiologically active components. Active components were used for trapping test. Results Analysis of the extracts after SPME revealed that there were at least 19 components in the volatiles, with 13 volatile C2-C5 carboxylic acids and alcohols as main components. GC?EAD test with standard chemicals showed that only 6 volatile carboxylic acids elicited electroantennogram responses. Field trapping test showed that the mixture of 6 volatile carboxylic acids were effective in attracting B. germanica. Conclusion Attractive volatiles emitted by B. germanica play a role in colony aggregation.
Objective To evaluate the feasibility of applying Google Earth software to spatial epidemiological analysis of new autochthonous malaria cases. Methods The epidemic data of all new autochthonous malaria cases during 2007-2011 in Shanxian county of Shandong province, China were collected and used as underlying data. Patients’ residences and the major river systems where malaria vector mosquitoes bred in Shanxian county were positioned via a GIS data collector. An integral database of malaria was constructed by batch inputting or importing of above data into Google Earth Free 7.1 software. Results The map database of new autochthonous cases in Shanxian county was constructed on the background of Google Earth satellite imagery. The spatio?temporal distribution of malaria cases was clearly shown in the 3D window. Zooming in and out at special epidemic foci and display of the foci were supported. Landforms surrounding the epidemic spots and distribution of river systems where mosquito vectors bred could be directly exhibited. Conclusion Based on precise positioning with global positioning system and visual display with Google Earth, the satellite imagery map database of malaria can be used in the analysis of spatial distribution of infectious diseases such as malaria and its relationship with the surrounding geographical factors.
Objective To evaluate the efficacy of ultra?low?volume (ULV) spraying and residual spraying, and the combined application of the two, in control of mosquitoes. Methods We used ULV spraying and residual spraying, alone or combined, to control mosquitoes. Mosquito density was monitored using animal?baited net traps, light traps, and labor hour method before and after application of the controlling methods. Results Residual spraying reduced indoor mosquito density, but had no significant effect on outdoor mosquito density. ULV spraying reduced indoor mosquito density too. However, mosquito density monitoring using light traps showed increased density after ULV spraying, while monitoring using animal?baited net traps showed decreased density. Conclusion Combined use of residual spraying and ULV spraying can improve mosquito control efficacy. Mosquito density monitoring using goat?baited net trap is a reliable method in evaluating the mosquito control effect of ULV spraying.
Objective To investigate the effects of several metallic ions on the activity of phenoloxidase (PO) from Oncomelania hupensis of different ages such as adult snails, young snails, and snail eggs. Methods PO from O. hupensis of different ages was partially purified. PO activity was determined with different concentrations of NaCl, KCl, Na2SO4, K2SO4, MgSO4, CaSO4, ZnSO4, and CuSO4. Catechol was used as a substrate. Results Na+ and K+ had no effects on the activity of PO from O. hupensis of any age. Mg2+ and Ca2+ showed enhancing effects in all age groups, while Zn2+ had an inhibitory effect. For O. hupensis of different ages, Cu2+ enhanced the enzyme activity at low concentrations, but inhibited the enzyme activity at high concentrations. Conclusion Several metallic ions such as Mg2+, Ca2+, Zn2+, and Cu2+ can affect the activity of PO from O. hupensis of different ages. These findings provide a rationale for developing novel methods in chemically eliminating snails.
Objective To evaluate the application of 5S-23S rRNA and outer ospA genes in PCR?based detection of Borrelia burgdorferi and to investigate the infection with B. burgdorferi in rodents of Zhejiang province, China. Methods PCR was used to amplify 5S-23S rRNA and ospA gene fragments from 100 mice collected from different areas of Pan’an county. PCR products were purified and sequenced. Results Of the 100 mice investigated, 3 were positive for 5S-23S rRNA gene of B. burgdorferi and 5 for ospA gene of B. burgdorferi. The sequences of PCR products were found with high homology to the reference genes. Conclusion B. burgdorferi can be detected from rodent samples by PCR amplification of 5S-23S rRNA and ospA genes.
Objective To classify the subfamily Phaoniinae in Shanxi province, China. Methods The principles and methods of entomological classification were used in this study. Samples were collected extensively in this region. Microscopic classification was performed according to relevant literature. Related data were sorted and analyzed. Results Ninety?two species of Phaoniinae, which belonged to 4 genera and 2 tribes, were identified in Shanxi province. Five species of the genus Brontaea, one species of the genus Dichaetomyia, 40 species of the genus Helina, and 46 species of the genus Phaonia were found, of which 39 were type species in Shanxi province, and 11 were new record species in this province. Conclusion These results indicated that the species of Phaoniinae in Shanxi province are abundant, diversified, and specific.
Objective To perform a fundamental research on the classification and geographic distribution of Ceratopogonidae in Guangxi Zhuang Autonomous Region, China. Methods Based on the relevant literature on biting midges, 10 collecting sites were set in north, south, east, west, and central areas of Guangxi. Insects of Ceratopogonidae were collected by insect net, human?baited net trap, baited trap, and light trap. Insects were finally identified and classified. Results About ten thousand insects of Ceratopogonidae were collected from Guangxi in this study. Classification of insects covered 4 subfamilies, 12 genera, and 91 species, including 1 species of Leptoconops, 14 species of Dasyhelea, 10 species of Atrichopogon, 13 species of Forcipomyia, 12 species of Lasiohelea, 31 species of Culicoides, 7 species of Alluaudomyia, 1 species of Downeshelea, 3 species of Stilobezzia, 1 species of Guihelea, 1 species of Mackerrasomyia, and 5 species of Bezzia. Conclusion The classification and geographic distribution of Ceratopogonidae in Guangxi Zhuang Autonomous Region have basically been determined by this study. This study also provides a scientific basis for further studies of zoogeography and integrated control.
Objective To analyze the epidemic features and trends of plague in Manzhouli, China during 2001-2013, and to provide a basis for the development of plague prevention and control strategies and early warning. Methods Epidemiological methods were used to analyze plague surveillance data in Manzhouli during 2001-2013. Results A total of 1764 sera (including 1327 sera from Spermophilus dauricus) collected from 2001 to 2013 were examined, with special focus on 2004, 2005, 2007, 2008, 2010 and 2012 samples, of which 34 F1 antibody?positive S. dauricus sera were identified. Bacteriological tests of 2131 rodents and 1884 fleas found no signs of Yersinia pestis. Conclusion No signs of human plague were found in Manzhouli during 2001-2013, while indication of animal plague epidemic was discovered. There were substitution of plague host and invasion of Mongolian gerbil at the same time. The monitoring and precaution in the key areas should be strengthened to prevent the occurrence and epidemic of plague among humans.
Objective To analyze the epidemiological features of dengue fever from 2005 to 2012 in Ningbo, China and to assess the risk of dengue fever epidemic in Ningbo given the vector monitoring data. Methods The data of reported dengue fever cases in Ningbo were collected to analyze the epidemiological features using Excel 2003. The CO2 trapping lamp method was used to determine the population structure and density of mosquitoes. Results A total of 11 dengue fever cases, all of which were imported, were reported in Ningbo from 2005 to 2012. Eight of the 11 cases were aged 25-50 years. The male?to?female ratio was 1.75∶1. Businessmen constituted the largest group (36.37%) of these cases. Aedes albopictus was the main mosquito vector of dengue fever in Ningbo. Conclusion In Ningbo, Ae. albopictus is prevalent, and imported cases increase year by year; there is risk of dengue fever epidemic. We should continue to enhance mosquito surveillance to prevent dengue fever epidemic.
Objective To determine the species composition, ecological habits, and seasonality of flies in the urban area of Xi’an, China, and to provide a scientific basis for the prevention and control of flies and fly?borne diseases. Methods Cage traps with sugar and vinegar baits were used to capture flies. Monthly statistical analysis of surveillance data for the diversity of flies was performed from March to November each year. Results A total of 2378 adult flies were captured from 2009 to 2012 and classified into 15 species, 10 genera, and 3 families. The general average density was 2.65 flies/cage. The highest density was found in 2009 (3.00 flies/cage), and the lowest density in 2012 (2.47 flies/cage). Musca domestica (54.71%), Muscina stabulans (10.26%), Helicophagella melanura (10.13%), and Lucilia sericata (9.04%) were the predominant species. Conclusion The population density and seasonality of flies are related to the habitat, climate, and seasons. Integrated control measures with chemical and physical methods before activity climax will substantially reduce fly population density and the incidence of fly?borne diseases.
Objective To investigate differentiated rodent control standards based on difference between new afforestation and secondary forest in north China. Methods In each of secondary forest and new afforestation in the Manhan Mountain Forest Farm, 3 sample areas and 3 control areas were selected. In the sample areas, a three?day investigation was performed using poison bait box, followed by live trap capture for four days. Capture rate was calculated accordingly. In the control areas, community composition and quantity of rodents were investigated. Control efficacy was evaluated according to the changes in capture rate after deratization. Results Cricetulus longicaudatus was the predominant species in the new afforestation of Manhan Mountain. Apodemus speciosus was the predominant species in the secondary forest. With the use of PVC box containing type C botulinum toxin as poison bait, the population density of rats in sample areas was significantly decreased as compared with that in control areas (F＝6.46, P＜0.05). Conclusion Type C botulinum toxin shows good palatability and rodent control efficacy in the new afforestation and secondary forest, and it can be widely used in the forest region for rodent control.
Blattella germanica is one of the prevailing pests that are most difficult to manage in urban China. Gel bait has been extensively used in the control of B. germanica. This study reviews the current situation and research development of gel bait application in controlling B. germanica, including its main active ingredients, dosage, protocol, on?site killing effect, palatability, and chain killing efficacy, in order to find a more scientific and practical way in gel bait?based control of B. germanica.
As the primary component of biomass, cellulase is the richest renewable resource on the earth. Enzymatic hydrolysis of cellulose plays an important role in producing bioethanol by efficient conversion of lignocellulosic biomass. Termites, living on lignocellulose, possess the highest digestive efficiency for cellulose. Cellulases are secreted from termites’ salivary glands and midgut. This paper describes the secretion of termites’ endogenous cellulases, endo-β-1, 4-glucanase (EG) and β-glucosidase (BG), and reviews the research advances in heterologous expression of the corresponding encoding genes, EG (GHF9) and BG (GHF1). This will provide beneficial information and new insights into further discovery and study on the rich cellulase genes in termites.
Bacteria of the genus Bartonella are Gram?negative, fastidious, aerobic, intracellular parasitic, and pleiomorphic bacillus. It is considered as an emerging pathogen with increasing importance and worldwide distribution. Since it is hard to culture, and the phenotypic characteristics are not clear, identification mainly relies on results of gene amplification. Therefore, suitable primers are particularly important. In detection, identification, and phylogenetic study of Bartonella, many primes are designed and used, mainly based on 16S rDNA, 16S-23S rRNA ITS, gltA, rpoB, ribC, groEL, and ftsZ, etc. In this paper, we review several commonly used genes and primers used in studies of Bartonella.
