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Objective To investigate the infection and genotypes of Wolbachia in common mosquito species in Henan Province, so as to provide insights into management of mosquito-borne diseases. Methods Aedes, Culex and Anopheles samples were collected from cowsheds, sheepfolds and human houses in Puyang, Nanyang City and Xuchang cities of Henan Province from July to September, 2022, and the infection of Wolbachia was detected. The 16S rDNA and wsp genes of Wolbachia were amplified and sequenced. Sequence alignment was performed using the BLAST software, and the obtained 16S rDNA gene sequence was compared with the sequence of the 16S rDNA gene in GenBank database. In addition, the phylogenetic trees were created based on 16S rDNA and wsp gene sequences using the software MEGA 11.0. Results A total 506 female adult mosquitoes were collected from three sampling sites in Nanyang, Xuchang City and Puyang cities from July to September, 2022. The overall detection of Wolbachia was 45.1% (228/506) in mosquitoes, with a higher detection rate in A. albopictus than in Cx. pipiens pallens [97.9% (143/146) vs. 50.6% (85/168); χ2 = 88.064, P < 0.01]. The detection of Wolbachia in Cx. pipiens pallens was higher in Xuchang City (96.8%, 62/64) than in Nanyang (15.6%, 7/45) and Puyang cities (27.1%, 16/59) (χ2 = 89.950, P < 0.01). The homologies of obtained Wolbachia 16S rDNA and wsp gene sequences were 95.3% to 100.0% and 81.7% to 99.8%. Phylogenetic analysis based on wsp gene sequences showed Wolbachia supergroups A and B in mosquito samples, with wAlbA and wMors strains in supergroup A and wPip and wAlbB strains in supergroup B. Wolbachia strain wAlbB infection was detected in A. albopictus in Puyang and Nanyang Cities, while Wolbachia strain wPip infection was identified in A. albopictus in Xuchang City. Wolbachia strain wAlbA infection was detected in Cx. pipiens pallens sampled from three cities, and one Cx. pipiens pallens was found to be infected with Wolbachia strain wMors in Nanyang City. Conclusions Wolbachia infection is commonly prevalent in Ae. albopictus and Cx. pipiens pallens from Henan Province, and Wolbachia strains wAlbB and wAlbA are predominant in Ae. albopictus, while wPip strain is predominant in Cx. pipiens pallens. This is the first report to present Wolbachia wMors strain infection in Cx. pipiens pallens in Henan Province.
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Objective To investigate the role of angiotensin-converting enzyme (ACE) in the reproduction of Culex pipiens pallens, so as to provide insights into selection of targets for controlling mosquito vector populations. Methods Cx. pipiens pallens was collected from Tangkou County, Shandong Province in 2009. Female and male mosquitoes were selected at 72 hours post-eclosion, and quantitative real-time reverse transcription PCR (qPCR) assay was used to detect the expression of ACE gene in the whole body and reproductive tissues of male mosquitoes and fertilized female mosquitoes before (0 h) and after blood meals (24, 48, 72 h), respectively. Then, 150 female and 150 male mosquitoes at 0 to 4 hours post-eclosion were selected and divided into the wild-type group (WT group), small interfering RNA-negative control group (siNC group) and small interfering RNA-ACE group (siACE group), of 50 mosquitoes in each group. Mosquitoes in the WT group were given no treatment, and mosquitoes in the siNC and siACE groups were given microinjection of siNC and siACE into the hemolymph at a dose of 0.3 μg per mosquito. The knockdown efficiency was checked using qPCR assay, and the reproductive phenotype of mosquitoes was observed. Results The relative ACE gene expression was higher in the whole body of male mosquitoes (5.467 ± 1.006) relative to females (1.199 ± 0.241) (t = 5.835, P = 0.004) at 72 h post-eclosion, and the highest ACE expression was seen in reproductive tissues of male mosquitoes (199.100 ± 24.429), which was 188.3 times higher than in remaining tissues (1.057 ± 0.340) (t = 6.602, P = 0.002). Blood meal induced high ACE expression in all body tissues of fertilized female mosquitoes, with peak expression at 24 h after blood meals (14.957 ± 2.815), which was 14.8 times higher than that before blood meals (1.009 ± 0.139) (P = 0.002). The transcriptional level of ACEs continued to increase in the ovaries of female mosquitoes after blood meals during the vitellogenesis phase, peaking at 48 h after blood meals (5.500 ± 0.734), which was 5.1 times higher than that before blood meals (1.072 ± 0.178) (P = 0.002). Small RNA interference targeting ACE resulted in a 57.2% reduction in ACE expression in female mosquitoes in the siACE group (0.430 ± 0.070) relative to the siNC group (1.002 ± 0.070) (P = 0.001), and a 41.1% reduction in male mosquitoes in the siACE group (0.588 ± 0.067) relative to the siNC group (1.008 ± 0.131) (P = 0.016). Knockdown of ACE expression resulted in a 48.0% decrease in the number of eggs laid by female mosquitoes in the siACE group [(94.000 ± 27.386) eggs] relative to the siNC group [(180.800 ± 27.386)] (P < 0.001), and a 45.0% decrease in the number of eggs laid by wild female mosquitoes mated with males in the siACE group [(104.500 ± 20.965) eggs] relative to the siNC group [(190.050 ± 10.698) eggs] (P < 0.001). Conclusions Reduced ACE expression may inhibit the fecundity of male and female mosquitoes, and ACE may be as a potential target for mosquito vector population suppression.
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Objective To compare the differentially expressed proteins between cypermethrin-resistant and -sensitive Culex pipiens pallens, so as to unravel the mechanism underlying the resistance to cypermethrin in Cx. p. pallens. Methods A quantitative proteomic analysis was performed among cypermethrin-sensitive and -resistant isolates of Cx. p. pallens using isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results A total of 164 differentially expressed proteins were identified between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, including 54 up-regulated proteins and 110 down-regulated proteins. A large number of cuticular proteins, larval cuticular proteins, pupal cuticular proteins and cuticular structural constituent proteins, which are associated with cytoskeletal structure and components, were differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens. Thirteen proteins, which were involved in energy production and conversion, translation, ribosomal structure and biogenesis, lipid transport and metabolism, post-translational modification, protein turnover, chaperones, cytoskeleton and intracellular transportation, were validated to be differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, which may serve as potential markers of cypermethrin resistance. Conclusion Multiple insecticide resistance mechanisms contribute to the resistance to cypermethrin in Cx. p. pallens, including cuticular resistance and metabolic resistance, and the cuticular protein genes and cytochrome P450 enzymes may play an important role in the resistance of Cx. p. pallens to cypermethrin.
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Objective To investigate the genes involved in Wolbachia-induced cytoplasmic incompatibility among three natural populations of Culex pipiens pallens in eastern China, so as to provide insights into the development of preventive and control measures for mosquito-borne diseases based on Wolbachia. Methods The cytoplasmic incompatibility was tested among three natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province using reciprocal crosses. Wolbachia infection was detected in C. pipiens pallens using a PCR assay, and the expression of Wolbachia wsp and WD0513 genes was quantified using a fluorescent quantitative real-time PCR (qPCR) assay. Results Bidirectional compatibility was found between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (t = 0.57 and 0.15, both P values > 0.05), while bidirectional incompatibility was seen between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (t = 63.81 and 43.51, both P values < 0.01), and between the natural populations of C. pipiens pallens collected from Nanjing of Jiangsu Province and Tangkou of Shandong Province (t = 39.62 and 43.12, both P values < 0.01). Wolbachia wsp gene was amplified in all three natural populations of C. pipiens pallens, and qPCR assay detected no significant difference in the Wolbachia wsp gene expression among the three natural populations of C. pipiens pallens (F = 2.15, P > 0.05). In addition, there was no significant difference in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Nanjing of Jiangsu Province (q = 8.42, P < 0.05) or between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (q = 7.84, P < 0.05); however, there was a significant difference detected in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (q = 0.40, P > 0.05). Conclusions Different Wolbachia numbers are detected in natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province, and WD0513 gene may be involved in the Wolbachia-induced cytoplasmic incompatibility among three natural populations of C. pipiens pallens.
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Objective To explore the sensitivity of Culex pipiens pallens to common chemical insecticides in the southwestern region of Shandong Province, so as to provide a theoretical basis for the development of reasonable and effective mosquito control measures. Methods The resistance of Cx. pipiens pallens larvae to 5 chemical insecticides, such as cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate were tested by using the WHO biological test method in 2018, and the co-toxicity coefficients after compounding the above-mentioned insecticides were tested by using a drug compounding method. Results The resistance indexes of Cx. pipiens pallens to cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate in 3 cities were 144.43–557.54, 118.17–445.33, 6.44–19.00, 2.37–8.10, and 0.88–2.98, respectively, and expect the difference between the DDVP resistances of Cx. pipiens pallens in Jining City and Heze City was not statistically significant (P > 0.05), all the other differences were statistically significant (all P < 0.05). The synergistic coefficients of cypermethrin + DDVP, cypermethrin + propoxur, DDVP + acetofenate, and propoxur + acetofenate were 199.58 – 456.95, 190.56 – 292.37, 123.32 – 319.24, and 192.31 – 367.32, respectively. The lower synergism was observed by using the mixture of DDVP + propoxur (synergistic coefficient: 99.87–108.36) . Conclusions After decades of chemical control, Cx. pipiens pallens in the southwestern region of Shandong Province has produced different degrees of resistance to common chemical insecticides. Therefore, comprehensive control measures should be taken to control mosquito breeding and prevent the development of insecticide resistance.
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Objective To examine the effect of low temperature on trehalose and trehalase levels in Culex pipiens pallens. Methods The fourth instar larvae and female adult mosquitoes of Cx. pipiens pallens were exposed at 4 ℃ for 0, 1, 3, 6, 12, 18, 24 h and 0, 1, 3, 6, 12, 18, 24, 36, 48, 72 h, respectively. Then, the trehalose and trehalase contents were detected by enzyme-linked immunosorbent assay (ELISA) in mosquitoes. Results The contents of trehalose and trehalase significantly increased in the larval and female adult mosquitoes post-exposure to low temperature. The changing trend of trehalose levels was consistent in the larval and female adult mosquitoes, and the highest levels were (2.458 8 ± 0.379 2) mg/g and (2.825 7 ± 0.211 1) mg/g 3 h post-exposure to low temperature, respectively. The trehalose and trehalase levels fluctuated greatly within the first 6 h post-exposure to low temperature. Following adaptation for a period of time, the trehalose and trehalase levels remained at a relatively high level. Conclusion Low temperature may induce the production of trehalose and trehalase in Cx. pipiens pallens, and the trehalose and trehalase may play an important role in the improvement of the cold resistance.
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Objective To compare the difference of protein expression between the post-overwintering stage and the diapauses preparation stage in Culex pipiens pallens, so as to reveal the mechanisms underlying the overwintering diapause of Cx. pipienspallens. Methods A quantitative proteomic analysis was performed in Cx. pipiens pallens before and after overwintering diapause by using isobaric tags for relative and absolute quantification (iTRAQ) labeling. Results A total of 244 differentially expressed proteins were identified in Cx. pipiens pallens before and after overwintering diapause, including 126 up-regulated proteins and 118 down-regulated proteins. iTRAQ-based quantitative proteomic analysis revealed that these differentially expressed proteins were linked to function and energy production and conversion, lipid metabolism, remodeling of cytoskeleton, carbohydrate metabolism, protein transport, molecular chaperones, stress tolerance and metabolic enzymes. Conclusions This is the first study to identify the overwintering diapause-related proteins in Cx. pipiens pallens using proteomics tools, which reveals KEGG pathways and GO terms associated with the overwintering diapauses of Cx. pipiens pallens. Our findings provide additional understandings pertaining to the mechanisms underlying the overwintering diapauses of Cx. pipiens pallens.
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Objective To study the seasonal dynamics of Culex pipiens pallens and the distribution of knockdown resistance (kdr) gene related sodium channel gene polymorphism in Zichuan District, Zibo City, Shandong Province. Methods Cx. pipiens pallens mosquitoes were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018. The DNA from Cx. pipiens pallens was extracted, and the genotypes and frequencies of kdr allele mutation were detected by polymerase chain reaction. Results Totally 830 mosquitoes belonging to six species, including Cx. pipiens pallens, Armigeres subalbatus, Aedes albopictus, Ae. vexans, Anopheles sinensis, and Cx. tritaeniorhchus were collected in this study. The number of Cx. pipiens pallens accounted for 83.13% in total, with the density of 12.32 per lamp per night. The annual density monitoring curve of Cx. pipiens pallens showed a bimodal trend, and the peaks were observed in June and September respectively. In this study, five kdr alleles were detected at the 1 014 locus of kdr gene, with TTA (75.71%), TTT (10.00%), CTA (5.71%), TCA (4.29%), and TTC (4.29%). Two nonsynonymous nucleotide mutations were detected at site 1 014 of kdr gene, namely leucine (L1014) mutated to phenylalanine (L1014F) and serine (L1014S). The kdr gene mutation frequency (%) of Cx. pipiens pallens in Luochun Town and Taihe Town was 10.53% and 40.63%, respectively, and the difference was statistically significant ( χ2 = 8.559, P = 0.003). Conclusions Cx. pipiens pallens is the dominant mosquito species in Zichuan District. In addition, two novel mutations, CTA and TTC, are identified in the voltage-dependent sodium channel gene of Cx. pipiens pallens. The kdr genotype of Cx. pipiens pallens in Zichuan area was polymorphic.
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Objective To compare the difference of protein expression between the post-overwintering stage and the diapauses preparation stage in Culex pipiens pallens, so as to reveal the mechanisms underlying the overwintering diapause of Cx. pipienspallens. Methods A quantitative proteomic analysis was performed in Cx. pipiens pallens before and after overwintering diapause by using isobaric tags for relative and absolute quantification (iTRAQ) labeling. Results A total of 244 differentially expressed proteins were identified in Cx. pipiens pallens before and after overwintering diapause, including 126 up-regulated proteins and 118 down-regulated proteins. iTRAQ-based quantitative proteomic analysis revealed that these differentially expressed proteins were linked to function and energy production and conversion, lipid metabolism, remodeling of cytoskeleton, carbohydrate metabolism, protein transport, molecular chaperones, stress tolerance and metabolic enzymes. Conclusions This is the first study to identify the overwintering diapause-related proteins in Cx. pipiens pallens using proteomics tools, which reveals KEGG pathways and GO terms associated with the overwintering diapauses of Cx. pipiens pallens. Our findings provide additional understandings pertaining to the mechanisms underlying the overwintering diapauses of Cx. pipiens pallens.
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Objective To study the seasonal dynamics of Culex pipiens pallens and the distribution of knockdown resistance (kdr) gene related sodium channel gene polymorphism in Zichuan District, Zibo City, Shandong Province. Methods Cx. pipiens pallens mosquitoes were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018. The DNA from Cx. pipiens pallens was extracted, and the genotypes and frequencies of kdr allele mutation were detected by polymerase chain reaction. Results Totally 830 mosquitoes belonging to six species, including Cx. pipiens pallens, Armigeres subalbatus, Aedes albopictus, Ae. vexans, Anopheles sinensis, and Cx. tritaeniorhchus were collected in this study. The number of Cx. pipiens pallens accounted for 83.13% in total, with the density of 12.32 per lamp per night. The annual density monitoring curve of Cx. pipiens pallens showed a bimodal trend, and the peaks were observed in June and September respectively. In this study, five kdr alleles were detected at the 1 014 locus of kdr gene, with TTA (75.71%), TTT (10.00%), CTA (5.71%), TCA (4.29%), and TTC (4.29%). Two nonsynonymous nucleotide mutations were detected at site 1 014 of kdr gene, namely leucine (L1014) mutated to phenylalanine (L1014F) and serine (L1014S). The kdr gene mutation frequency (%) of Cx. pipiens pallens in Luochun Town and Taihe Town was 10.53% and 40.63%, respectively, and the difference was statistically significant ( χ2 = 8.559, P = 0.003). Conclusions Cx. pipiens pallens is the dominant mosquito species in Zichuan District. In addition, two novel mutations, CTA and TTC, are identified in the voltage-dependent sodium channel gene of Cx. pipiens pallens. The kdr genotype of Cx. pipiens pallens in Zichuan area was polymorphic.
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Objective To examine the effect of low temperature on trehalose and trehalase levels in Culex pipiens pallens. Methods The fourth instar larvae and female adult mosquitoes of Cx. pipiens pallens were exposed at 4 ℃ for 0, 1, 3, 6, 12, 18, 24 h and 0, 1, 3, 6, 12, 18, 24, 36, 48, 72 h, respectively. Then, the trehalose and trehalase contents were detected by enzyme-linked immunosorbent assay (ELISA) in mosquitoes. Results The contents of trehalose and trehalase significantly increased in the larval and female adult mosquitoes post-exposure to low temperature. The changing trend of trehalose levels was consistent in the larval and female adult mosquitoes, and the highest levels were (2.458 8 ± 0.379 2) mg/g and (2.825 7 ± 0.211 1) mg/g 3 h post-exposure to low temperature, respectively. The trehalose and trehalase levels fluctuated greatly within the first 6 h post-exposure to low temperature. Following adaptation for a period of time, the trehalose and trehalase levels remained at a relatively high level. Conclusion Low temperature may induce the production of trehalose and trehalase in Cx. pipiens pallens, and the trehalose and trehalase may play an important role in the improvement of the cold resistance.
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Objective To understand the ecological habits of Culex pipiens pallens in Shandong Province in winter. Meth-ods From December 2015 to January 2016,the overwintering conditions of Cx.pipiens pallens were investigated in Shandong Province. Results In Shandong Province,in rural districts,the overwintering places of Cx. pipiens pallens were basements, wells and caves;and in urban areas,they were air raid shelters,holes of city walls,sewers and flower cellars.Conclusion In Shandong Province,the overwintering places of Cx.pipiens pallens are mainly basements and holes,which are under high tem-perature and humidity,and away from light.Its larvae cannot overwinter.
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[ Objective ] To assess the resistance risk of Culex pipiens pallens to pyriproxyfen in Culexpipiens pallens, to predict the rate of resistance development and to provide the reference for scientific and rational application of insecticides. [ Methods ] The resistance strain was developed by group selection, and the realized heritability ( h2 ) of Culex pipiens pallens resistance to deltamethrin was estimated by Tabashnik's method. [ Results] The resistance of Culex pipiens pallens to pyriproxyfen had increased by 5.69-fold after 12 generations of indoor breeding, and the h2 of Culex pipiens pallens to pyriproxyfen was 0.02, indicating that a relatively risk of resistance development. [ Conclusion] The results indicate that Culex pipiens pallens has resistance risk to pyriproxyfen, so the application of the insecticide must be scientific and rational.
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[ Objective] To investigate the resistance of mosquito against insecticides in Songjiang, providing scientific basis for appropriate application of insecticides. [ Methods ] The dipping method and drug velum contacting method were used for determination of the resistance of culex pipiens pallens and anopheles hurcanus sinensis against insecticides. [ Results] Culex pipiens pallens were found to have high resistance to DDVP, resistance coefficient 30.07, and low resistance to cypermethrin, fenobucarb and deltamethrin, resistance coefficient 3.96, 3.25 and 2.79, while their sensitivity to beta-cypermethrin, resistance coefficient 0.28.Anopheles sinensis had R level resistance to DDT and deltamethrin, mortality rates 73.36%and 57.50%respectively. [ Conclusion] Mosquitos in Songjiang District have developed different degrees of resistance to insecticides.In order to control and delay their resistance, insecticides should be alternated and combined in application.
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Objective To investigate the distribution patterns of mosquitoes and mosquito-borne viruses in Dehong prefecture,Yunnan province,China. Methods Mosquito samples were collected using the mosquito traps from five counties of Dehong prefecture on July,2007 and 2010. Mosquitoes were cell cultured for viral isolation,and positive isolates were identified using RT-PCR and sequence analysis. Results A total of 43 634 mosquitoes comprised of 29 species representing six genera were collected. Culex tritaeriorhynchus and Anopheles sinensis comprised 78.69% and 14.77% of the total. Six strains of viruses were isolated from the mosquito pools. RT-PCR and phylogenetic analysis revealed three strains from Cx. tritaeriorhynchus,identified as genotypeⅠJapanese encephalitis virus(JEV). One strain was identified from Cx. tritaeriorhynchus,as Getah virus (GETV). Two strains isolated from Cx. tritaeriorhynchus and Anopheles vagus were identified as Culex pipiens pallens Densovirus(CppDNV). Conclusion Cx. tritaeriorhynchus had been the major species of mosquitoes and mainly transmitting vector of mosquito-borne viruses in Dehong prefecture. GenotypeⅠJEV,GETV and CppDNV were the vectors causing transmission of mosquitoe-borne diseases in this area. Data from phylogenetic analysis showed that these newly discovered isolates seemed to have had close relationship with those viruses previously circulating in Yunnan and other provinces of China.
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Objective To investigate the distribution patterns of mosquitoes and mosquito-borne viruses in Dehong prefecture,Yunnan province,China. Methods Mosquito samples were collected using the mosquito traps from five counties of Dehong prefecture on July,2007 and 2010. Mosquitoes were cell cultured for viral isolation,and positive isolates were identified using RT-PCR and sequence analysis. Results A total of 43 634 mosquitoes comprised of 29 species representing six genera were collected. Culex tritaeriorhynchus and Anopheles sinensis comprised 78.69% and 14.77% of the total. Six strains of viruses were isolated from the mosquito pools. RT-PCR and phylogenetic analysis revealed three strains from Cx. tritaeriorhynchus,identified as genotypeⅠJapanese encephalitis virus(JEV). One strain was identified from Cx. tritaeriorhynchus,as Getah virus (GETV). Two strains isolated from Cx. tritaeriorhynchus and Anopheles vagus were identified as Culex pipiens pallens Densovirus(CppDNV). Conclusion Cx. tritaeriorhynchus had been the major species of mosquitoes and mainly transmitting vector of mosquito-borne viruses in Dehong prefecture. GenotypeⅠJEV,GETV and CppDNV were the vectors causing transmission of mosquitoe-borne diseases in this area. Data from phylogenetic analysis showed that these newly discovered isolates seemed to have had close relationship with those viruses previously circulating in Yunnan and other provinces of China.
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Objective To investigate the relationship between Wolbachia and deltamethrin resistance in Culex pipiens pal?lens. Methods PCR was used to detect Wolbachia in Culex pipiens pallens and qRT?PCR was performed to determine and compare the expression of Wolbachia between deltamethrin?resistant and ?susceptible strains of Culex pipiens pallens. Re?sults Wolbachia was detected in Culex pipiens pallens in the laboratory. The expression of Wolbachia was 18.42 3.69 4.43 3.96 6.31 1.55 and 3.76 folds higher in the deltamethrin?resistant strain than in susceptible strain in the egg 1st 2nd 3rd 4th stages, and male and female adults, but there was no statistical difference in the pupae stage. The expression of Wolbachia was 2.64 folds higher in deltamethrin?resistant females than in susceptible females which were caught in Jiangxinzhou of Nan?jing. Conclusion Wolbachia is associated with deltamethrin resistance in Culex pipines pallens.
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Objective To understand the cross-resistance of Culex pipiens pallens to common pesticides,so as to provide the evidence for improving the application of chemical pesticides. Methods The IV instar larvae of DDVP-resistant,propoxur-resistant and cypermethrin-resistant strains as well as the sensitive strain of Culex pipiens pallens were collected to detect the re-sistance to DDVP,propoxur and cypermethrin based on the WHO bioassay method. Results The resistance coefficients of DDVP-resistant strain to DDVP,propoxur and cypermethrin were 14.47,8.96 and 207.27 respectively. The resistance coeffi-cients of propoxur-resistant strain to DDVP,propoxur and cypermethrin were 3.27,6.93 and 8.65 respectively. The resistance coefficients of cypermethrin-resistant strain to DDVP,propoxur and cypermethrin were 2.93,1.61 and 501.11 respectively. Con-clusion The resistance and cross-resistance could be generated during the long-term application of a single kind of chemical pesticide,and we should pay more attention to the varieties and dosages of them.
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Objective: The bioactivity of four podophyllotoxin analogues were tested against 3rd instar larvae of Culex pipiens pallens and 5 h instar larvae of Pieris rapae L.Methods:WHO bioassay and leaf-dlpping method. Results: ①Deoxypodophyllotoxin and ?-apopicropodophyllotoxin exhibited toxicity(against) Culex pipiens pallens,and their LC_(50) were 0.001 48 and 0.001 68 g/L,respectively.②All the four podophyllotoxin analogues displayed inhibitory effect on the growth and development against Culex pipiens pallens,their pupation rates were delayed comparing with control.③Deoxypodophyllotoxin,?-apopicropodophyllotoxin and Podophyllotoxin exhibited toxicity against Pieris rapae L,the LC_(50) 96 h after treatment were 0.045 4?0.078 2 and 0.159 7 g/L,respectively.④All the four podophyllotoxin analogues showed antifeedant activity against Pieris rapae L,their AFC_(50)were 0.016 1,0.018 7,0.039 4 and(0.273 9) g /L,respectively.⑤All four podophyllotoxin analogues displayed inhibitory effect on the growth and development against Pieris rapae L,but the extent of each compound were very different. Conclusion: Based on the data obtained in this investigation,it is possible that the dissimilarity in the structure of the analogues leads to their different bioactivity.
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Objective To examine the inhibitory effect of antisense nucleic acid on the in vitro translation of esterase mRNA from dipterex resistant Culex pipiens pallens . Methods 18 mer nucleic acid was synthesized and complementary to the translation initiation site of mRNA of dipterex resistant mosquitoes. The ODNs were annealed to the corresponding mRNA molecules and they were added to rabbit reticulocyte cell free system. The translation products were analyzed by SDS PAGE. After fixing, the gel was exposed to X ray film by autoradiography for analysis of protein synthesis. Results Six ?mol/L of ODNs elicited a 50% reduction in specific protein expression , and 20 ?mol/L of ODNs inhibited the expression of esterase by 80%. The SDS PAGE showed that the band of reduced amounts of 65 kDa protein for resistant mosquito was almost the same as that for sensitive sample. Conclusion Antisense oligonucleic acids to the esterase mRNA of dipterex resistant mosquito could effectively inhibit its in vitro translation.