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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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@#Abstract: Objective To understand the kdr (knockdown resistance, kdr) gene mutation of the voltage-gated sodium channel (VGSC) of Anopheles sinensis in Yunnan Province. Methods From 2018 to 2019, mosquitoes were collected in Luoping County, Suijiang County, Tengchong City, Yingjiang County, Yuanjiang County and Mengla County in Yunnan Province. The collected mosquitoes were morphologically identified as Anopheles sinensis and genomic DNA was extracted by kits. The DNA templates were sequenced after PCR amplification and the sequencing results were identify as Anopheles sinensis by homology alignment in NCBI. After the ⅡS5 and ⅡS6 fragments of the sodium channels in Anopheles sinensis were amplified and sequenced, the sequencing results were multiple aligned by DNAMAN software, and the mutations were analyzed one by one with BioEdit software to determine the kdr allele types and genotypes, and the frequencies were calculated. Results This survey amplified 287 sequences, and the sequence maps showed that 1014 loci had three alleles, including wild type TTG/L (89.20%), mutant type TTT/F (9.76%) and TCG/S (1.04%). Five genotypes: homozygous wildtype L/L (85.02%), homozygous mutant F/F (6.27%) and S/S (0.35%), heterozygous mutant L/F (6.97%) and L/S (1.39%). The wild type allele TTG/L was the main allele in six sampling sites except Suijiang County. The frequency of wild type allele in Tengchong City was the highest (100.00%). That is, no mutation was detected, while the rest of counties occurred different degrees of mutation at 1014 loci. The frequency of mutant allele in Suijiang County was the highest, reaching 55.68%. Luoping County, Mengla County and Suijiang County had two mutant types. Yingjiang County and Yuanjiang County had one heterozygous mutant L/F. Conclusion Wild type L1014 (TTG/L) is still dominant in most areas of Yunnan Province. The kdr mutation type is mainly L1014F, followed by L1014S, and the mutation frequency is lower than that in central provinces of China.
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Objective To analyze the changes of small molecular metabolites in the larvae of a deltamethrin-sensitive strain of Anopheles sinensis following exposure to deltamethrin, so as to provide the scientific basis for investigating the metabolic pathway and screening metabolic markers of deltamethrin in An. sinensis. Methods The 50% and 75% lethal concentrations (LC50 and LC75) of deltamethrin against the larvae of a deltamethrin-sensitive strain of An. sinensis were calculated in laboratory. The type and content of An. sinensis larvae metabolites were detected using high performance liquid chromatography and mass spectrometry (LC-MS/MS) following exposure to deltamethrin at LC50 and LC75 for 30 min and 24 h, and the changes of metabolites were analyzed. Results The LC50 and LC75 values of deltamethrin were 4.36 × 10-3 µg/mL and 1.12 × 10-2 µg/mL against thelarvae of a deltamethrin-sensitive strain of An. sinensis. Following exposure of the larvae of a deltamethrin-sensitive strain of An. sinensis to deltamethrin at LC50 and LC75 for 30 min, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, fatty acyl and pyrimidine nucleotides, with reduced glucose levels. Following exposure for 24 h, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, aliphatic acyl and purine nucleotides, with increased glucose level detected. Conclusion Carbohydrate, carboxylic acid and its derivatives, fatty acyls, amino acids and their derivatives may play important roles in deltamethrin metabolism in the larvae of a deltamethrin-sensitive strain of An. sinensis.
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Objective To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. Methods An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. Results In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. Conclusion An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..
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Malaria was one of the major infectious diseases in Jiangsu Province, where Anopheles sinensis and An. anthropophagus are main vectors for malaria transmission. Following the concerted efforts for decades, the goal of malaria elimination was achieved in Jiangsu Province in 2019, and the vector control strategy has played a vital role during the progress towards malaria elimination in Jiangsu Province. Hereby, we review the historical distribution and ecological features of An. sinensis and An. anthropophagus and describe vector control strategies at different stages of malaria control in Jiangsu Province. In addition, the advances in the research of vector biology and control in Jiangsu Province are discussed, including vector identification, strain colonization, susceptibility to malaria parasites and insecticide resistance.
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Objective To evaluate the effect of malaria vector control measures so as to provide the evidence for consolidating the control effectiveness of malaria and carrying out the vector surveillance in Suizhou City. Methods The distributions of Anopheles sinensis and An. anthropophagus were investigated by the combination of retrospective review and field survey. The changes of density and population of mosquito vectors were investigated and compared among various years. Results From 1985 to 1996, both An. sinensis and An. anthropophagus were found in 18 towns, and An. anthropophagus mosquitoes accounted for 52.3% of the total Anopheles mosquitoes. Only An. sinensis mosquitoes were found in other 26 towns. In 2003 and 2004, An. anthropophagus mosquitoes were found in the original 18 towns, and they accounted for 47.0% and 38.1% respectively, but in 2005, An. anthropophagus mosquitoes were not found in this city. However, the density of An. sinensis presented an upward trend. Conclusions An. anthropophagus population has gradually disappeared in Suizhou City, and currently, An. sinensis is the main Anopheles population, which might be the malaria vector in suitable conditions. Therefore, the surveillance and control of Anophe les vector should be strengthened in order to consolidate the achievements of malaria elimination.
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Objective To evaluate the effect of malaria vector control measures so as to provide the evidence for consolidating the control effectiveness of malaria and carrying out the vector surveillance in Suizhou City. Methods The distributions of Anopheles sinensis and An. anthropophagus were investigated by the combination of retrospective review and field survey. The changes of density and population of mosquito vectors were investigated and compared among various years. Results From 1985 to 1996, both An. sinensis and An. anthropophagus were found in 18 towns, and An. anthropophagus mosquitoes accounted for 52.3% of the total Anopheles mosquitoes. Only An. sinensis mosquitoes were found in other 26 towns. In 2003 and 2004, An. anthropophagus mosquitoes were found in the original 18 towns, and they accounted for 47.0% and 38.1% respectively, but in 2005, An. anthropophagus mosquitoes were not found in this city. However, the density of An. sinensis presented an upward trend. Conclusions An. anthropophagus population has gradually disappeared in Suizhou City, and currently, An. sinensis is the main Anopheles population, which might be the malaria vector in suitable conditions. Therefore, the surveillance and control of Anophe les vector should be strengthened in order to consolidate the achievements of malaria elimination.
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Objective To investigate the malaria vectors in Nanyang City. Methods Two townships were selected as malaria vector surveillance sites in Nanyang City from 2005 to 2017, including Mazhenfu Township in Tanghe County and Huaiyuan Township in Tongbai County, and the malaria vectors were investigated using the semi-overnight human baiting trapping method and mosquito trapping in nets. Results The mean density of Anopheles sinensis was 0.65 to 22.30 mosquitos/(person · hour) in the two surveillance sites in Nanyang City using the human baiting trapping method from 2005 to 2017, and the peak density was detected in June and July. An. anthropophagus was captured only in Tongbai County during the period between 2008 and 2011, with a mean density of 0.03 to 1.10 mosquitos/(person · hour). The mean density of An. sinensis was 0.08 to 0.24 mosquitos/(net · night) using the mosquito trapping in nets from 2005 to 2011, and the peak density was detected in July and August, while few An. anthropophagus captured only in Tongbai County, with a mean density of 0.01 to 0.02 mosquitos/(net · night). Conclusions There are malaria vectors in Nanyang City, including An. sinensis and An. anthropophagus, and An. sinensis is the dominant mosquito species.
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To analyze the vector surveillance results during the stage of malaria elimination, so as to provide the evidence for assessing the local transmission risk of imported malaria and carrying out the surveillance work after malaria elimination in Jiangsu Province.From 2011 to 2017, the mosquito population was monitored and human biting rates were calculated by the half overnight human baiting trapping method and overnight lamp trapping method in 7 surveillance sites from June to October. The insecticide resistance level was tested by the force contact method recommended by WHO.A total of 5 106 Anopheles mosquitoes were captured by the half over-night human baiting trapping method in the 7 sites from 2011 to 2017, and all the mosquitoes were identified as Anopheles sinensis. The annual human biting rates were 1.075, 0.786, 1.057, 0.787, 0.790, 1.797 and 1.185 mosquitoes/ (human·hour), respectively. Totally 28 186 Anopheles mosquitoes were caught by the overnight lamp trapping method, and all the mosquitoes were An. sinensis. The densities of Anopheles mosquitoes were 57.950, 50.932, 14.800, 4.405, 58.070, 72.406, and 17.145 mosquitoes/ (night·lamp), respectively. In 2012, the resistance indexes of An. sinensis to deltamethrin, DDT and malathion were at R level in Jiangsu Province.The major vector is An. sinensis and no An. anthropophagus is found in Jiangsu Province. An. sinensis has a high level of resistance to deltamethrin, DDT and malathion.
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Objective To explore the expression characteristics of cytochrome P450(CYP)candidate genes(CYP6M3, CYP6Y1,CYP6P5,CYP4H14,CYP4G17,CYP12F16)in Anopheles sinensis.Methods The samples were collected from dif-ferent developmental stages(eggs,larvae,pupae and adult mosquitoes(females and males)),and different tissues(salivary glands,malpighian tubes,midguts,ovaries,and fat bodies)of An.sinensis and the female adult mosquitoes exposed by differ-ent insecticide doses(0,1.25,3.75,6.25,12.5μg/bottle)and time points(0,5,15,30,60 minutes),then the total RNA was extracted. Quantitative reverse transcription PCR(qPCR)assay was used to analyze the relative expressions of six CYP genes in An.sinensis at different developmental stages,tissues and different insecticide exposure doses and time.Results The expressions of CYP6M3 and CYP6Y1 in the male adult mosquitoes were the highest,the expression of CYP6M3 gene in the males was 35.1 times higher than that in the females,the expression of CYP6Y1 in the males was 61.4 times higher than that in the females;the expression level of CYP4H14 in the larvae was the lowest,the expression of CYP4H14 in the females was 22.5 times higher than that in the fourth instar larvae.The expressions of candidate CYP genes in different tissues of An.sinensis were significantly different,the expression of CYP6M3 in the malpighian tubule was 38.9 times higher than that in the ovary,the ex-pression of CYP6Y1 in the fatbody was 9.1 times higher than that in the ovary,the expression of CYP4G17 was 4.6 times higher than that in the ovary,and the expression of CYP12F16 was 4.4 times higher thanthat in the ovary.The exposure to different in-secticide doses and time showed some induction effects in the expressions of candidate CYP genes,which affected the expres-sions of candidate CYP genes in An.sinensis.Conclusion The expression of candidate CYP genes varies significantly in differ-ent developmental stages and various tissues of An.sinensis,and exposure to deltamethrin at various doses and time points af-fects CYP genes expression in An.sinensis.
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Objective To investigate the density seasonal fluctuation and insecticide resistance of Anopheles sinensis in the Taibai Lake area and to provide a scientific basis for formulation of Anopheles sinensis control strategy.Methods The surveillance was carried out from June to October in 2013-2016.The adult mosquito density was monitored using human bait trapping method.WHO bioassay method was used to measure the sensibility of mosquitoes to insecticides.Results In 2013-2016,totally 2 318 Anopheles sinensis were captured,the Anopheles sinensis peaked in late July till early August,which were 67-127,317-386,77-89,107-139,respectively.Anopheles sinensis showed high resistance to dichlorodiphenyltrichloroethane,malathion,and initial resistance to propoxur and deltamethrin (mortality ratio:38.10％,41.82％,86.11％,83.02％).Conclusions The Taibai Lake area has a diverse Anopheles sinensis population,its seasonal fluctuations and insecticide resistance monitoring can provide effective guidance for malaria control.In order to prevent the development of resistance to the insecticides,integrated management measures should be adopted in the future.
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Objective To understand the population,density,seasonal fluctuation and nocturnal pattern of malaria vectors in Jiangsu Province,thus to provide evidences for malaria elimination in this province. Methods Seven counties(cities,dis?tricts)were selected as the monitoring sites for malaria vectors in Jiangsu Province from 2013 to 2015. The mosquitoes were cap?tured by human bait trapping in bed nets and mosquito?lured lamp overnight,and the seasonal fluctuation and nocturnal pattern of malaria vectors were observed. Results A total of 11 041 Anopheles sinensis mosquitoes were captured by the mosquito?lured lamps in 7 counties of Jiangsu Province from 2013 to 2015,and no An. anthropophagous was found. Among all the 7 monitoring sites,the number of An. sinensis captured in Sihong County was the most(6 742 mosquitoes),while that in Xuyu County was the least(34 mosquitoes). During this period,the density peaks of An. sinensis were the first half of July,the first half of August and the second half of July. A total of 2 421 An. sinensis were collected in 7 monitoring sites from 2013 to 2015 by human bait trapping in bed nets overnight. Among all the 7 monitoring sites,the captured number of An. sinensis in Sihong County was the most(1 085 mosquitoes),while that in Ganyu County was the least(13 mosquitoes). The nocturnal peak of An. sinensis was from 19:00 to 20:00 and 525 An. sinensis mosquitoes were captured during this period of time,which accounted for 21.68%of the total. Hereafter,the captured number of An. sinensis reduced over time. Conclusion The density of An. sinensis mosquitoes is still high in individual areas in Jiangsu Province,so the epidemic and vector monitoring still should be strengthened to prevent the local transmission of imported malaria.
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Objective To study the cyfluthrin resistance and potential mechanisms of Anopheles sinensis in Nanchang Chang-bei International Airport,Nanchang City,Jiangxi Province. Methods The resistance levels of the local An. sinensis were de-tected by WHO drug resistance bioassay. During the bioassay,the dying mosquitos were classed as sensitive mosquitos,and the survival ones were classed as resistant mosquitos. The P450 monooxygenase activity and glutathione S-transferase activity were detected and compared between the two groups. At the same time,the death time of each sensitive mosquito was recorded,and the correlations between the death time and the P450 monooxygenase activity and glutathione S-transferase activity were ana-lyzed,respectively. Results The bioassay mortality of the local An. sinensis was 59.5%. The differences of the P450 monooxy-genase activities among the resistant mosquitos,sensitive mosquitos and laboratory sensitive mosquitos had statistical signifi-cances(F=151.89,Psensitive mosquitos>laboratory sensitive mosquitos. The differences of glutathione s-transferase activities among the three groups had no statistical significance(F=0.72,P=0.49). There existed positive correlation between the mosquito death time and the P450 monooxygenase activity,and the regression equation was y=79.479+1.512x with the correlation coefficient of 0.88,while there was no correlation between the mosquito death time and the glutathione S-transferaseactivity. Conclusion The An. sinensis in Nanchang Changbei International Airport has been resistant to cyfluthrin,and the promotion of P450 monooxygenase activity maybe one of the reasons for the resistance.
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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 existence of genetic divergence of sympatric populations of Anopheles sinensis of different feeding preferences based on the rDNA-ITS2 sequence differences. Methods A large number of wild anopheles popu-lations were trapped all night by man-baited net and calf-baited net that had been set up between high-density natural villages of An. sinensis populations and vector-breeding sites,from which two groups of An. sinensis were separated by morphological iden-tification and brought back to the lab for conventional breeding. A large closed greenhouse which temperature and humidity was appropriate was selected as research settings of mark-release-recapture methods by female mosquitoes ,in the center of which above An. sinensis populations baited by man and calf and respectively correspondingly marked by red and yellow phosphors were released in together,in each side of which An. sinensis were recaptured simultaneously by man-baited net and calf-baited net. An. sinensis populations trapped by man twice were brought back to the lab and bred with man-blood,correspondingly ones trapped by calf with calf-blood. Man-preferring and calf-preferring strains were screened respectively from An. sinensis which had been baited by man and calf by the mark-release-recapture methods after parent and F1 mosquitoes,and sequencing and aligning of both rDNA-ITS2 were conducted via PCR amplification. Results The recapture ratios of wild parental mosquitoes An. sinensis of man-preferring group by man-baited net and calf-baited net were 54.07%(339/627)and 45.93%(288/627)re-spectively,and ones of calf-preferring group by man-baited net and calf-baited net were 58.01%(409/705)and 41.99%(296/705)respectively. Two groups of parental mosquitoes trended towards selecting the original blood hosts in host-seeking prefer-ence(χ2=19.42,P<0.01). The recapture ratios of F1 mosquitoes An. sinensis of man-preferring group by man-baited net and calf-baited net were 63.43%(765/1 206)and 36.57%(441/1 206),and ones of calf-preferring group by man-baited net and calf-baited net were 68.22%(1 039/1 523)and 31.78%(484/1 523). Two groups of F1 mosquitoes had more significant characteris-tics of selecting the original blood hosts in host-seeking preference(χ2=271.69,P<0.01)and showed the genetic differentia-tion phenomenon,but the results of sequencing and aligning of the rDNA-ITS2 via PCR amplification showed no difference in base sequence between the two strains and both were 469 bp. Conclusions The genetic divergence based on the rDNA-ITS2 se-quence does not happen in An. sinensis sympatric populations of different feeding preferences.
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Vivax malaria is a significant military and civilian health threat in the north of the Republic of Korea (ROK). The island of Baengnyeong-do is the westernmost point of the ROK and is located close to the southwestern coast of the Democratic People's Republic of Korea (DPRK). Mosquitoes were collected using a black light trap on Baengnyeong-do, and Anopheles spp. were assayed by PCR, to identify the species, and screened for sporozoites of Plasmodium vivax. Of a subsample of 257 mosquitoes, Anopheles lesteri was the most frequently collected (49.8%), followed by Anopheles sinensis (22.6%), Anopheles pullus (18.7%), Anopheles kleini (7.8%), and Anopheles belenrae (1.2%). The overall sporozoite rate was 3.1%, with the highest rates observed in An. kleini (15.0%), An. sinensis (5.2%), and An. lesteri (1.6%). No sporozoite positive An. pullus or An. belenrae were observed. The results extend our knowledge of the distribution and potential role in malaria transmission of An. kleini, An. lesteri, and An. sinensis, for an area previously considered to be at a low risk for contracting vivax malaria.
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Animals , Anopheles/classification , Plasmodium vivax/genetics , Polymerase Chain Reaction , Prevalence , Republic of KoreaABSTRACT
Objective To observe the residual effect of Demand CS - impregnated bednets to Anopheles sinensis.Methods The numbers of adult mosquitoes which were knocked down at every minute after treatment were observed by using the enforced contact method recommended by WHO,and the mortality of mosquitoes tested after 24 h was calculated.Results The Kt_(50) of Demand CS - impregnated bednets with impregnations concentrations of 10,15,20 mg/m~2 to Anopheles sineasis were 21.40,16.20,15.70 min,respectively,and the 24 h mortality was 100%.The Kt_(50) of Responsar SC (12.5 % Beta - cyfluthrin) impregnated bednets with a impregnation concentration of 15 mg/m~2 to Anopheles sinensis was 16.06 min,and the 24 h mortality was 100%,too.Conclusions Both the Demand CS - impregnated bednets and the Responsar SC impregnated bednets can kill Anopheles sinensis.
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To investigate the population densities of potential malaria vectors, Anopheles species were collected by light traps in malaria endemic areas, Paju and Gimpo, Gyeonggi-do of Korea. Five Anopheles Hyrcanus sibling species (An. sinensis, An. pullus, An. lesteri, An. kleini, and An. belenrae) were identified by PCR. The predominant species, An. pullus was collected during the late spring and mid-summer, while higher population consists of An. sinensis were collected from late summer to early autumn. These 2 species accounted for 92.1% of all Anopheles mosquitoes collected, while the other 3 species accounted for 7.9%. Taking into account of these population densities, late seasonal prevalence, and long-term incubation period (9-13 months) of the Korean Plasmodium vivax strain, An. sinensis s.s is thought to play an important role in the transmission of vivax malaria in the study areas.
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Animals , Humans , Anopheles/classification , Malaria, Vivax/transmission , Polymerase Chain Reaction/methods , Population Dynamics , Republic of Korea , SeasonsABSTRACT
Extensive previous studies on taxonomy, behavior/bionomics and control of Anopheles sinensis are reviewed and summarized. Recent molecular identification revealed that the population of An. sinensis complex includes An. sinensis, An. pullus, An. lesteri and at least two new species, and An. yatsushiroensis is synonmy of An. pullus. An. sinensis is the main vector specie of vivax malaria in Korea. Larvae of An. sinensis breed in wide range of habitats which are naturally-made clean water, stagnant or flowing; main habitats include rice fields, ditches, streams, irrigation cannals, marshes, ponds, ground pools, etc. Their host preferences are highly zoophilic. Human blood rate is very low (0.7-1.7%) ; nevertheless An. sinensis readily feeds on man when domestic animals are not found near by. They feed on hosts throughout the night from dusk to dawn with a peak period of 02: 00-04: 00 hours; they are slightly more exophagic (biting outdoors) ; much larger numbers come into the room when light is on. Main resting places are outdoors such as grasses, vegetable fields and rice fields. A mark-release-recapture study resulted that 37.1% was recaptured within 1 km, 29.4% at 1-3 km, 21.1% at 3-6 km, 10.3% at 6-9 km and 2.1% at 9-12 km distance. An. sinensis hibernate outdoors (mostly under part of dense grasses) during October-March. At the end of the hibernation period (March-April) they feed on cows at daytime. Until today any single measure to effectively control An. sinensis population has not been found. Indoor residual spray with a long-lasting insecticide can not reduce vector population densities, but shorten their life spans in some degree, so contributes to malaria control.
Subject(s)
Animals , Humans , Animals, Domestic/parasitology , Anopheles/parasitology , Bites and Stings , Ecosystem , Feeding Behavior , Insect Vectors , Korea , Larva/physiology , Malaria, Vivax , Mosquito Control , Plasmodium vivax , Population Density , SeasonsABSTRACT
In order to study the range of flight and feeding activity of Anopheles sinensis, the dispersal experiment was conducted in Paju city, located in the northern part of Gyeonggi-do, Republic of Korea, during the period of 7th to 28th September 1998. Unfed females An. sinensis were collected in cowshed and released after being marked with fluorescent dye at 23:00 hours on the same day. Released female mosquitoes were recaptured everyday during 21 days using light traps, which were set at 10 sites in the cowsheds located 1, 3, 6, 9 and 12 km north-northwest and north-northeast and at 3 sites located 1, 6 and 9 km toward south-west from the release point. In addition, to study the longest flight distance in one night, we set the light traps at 16 and 20 km toward north-northeast from the release site. All the collected mosquitoes were placed on filter papers and observed on UV transilluminator after treatment with one drop of 100% ethanol. Out of 12,773 females of An. sinensis released, 194 marked females mosquitoes were recaptured, giving 1.52% recapture rate. Of 194, 72 mosquitoes (37.1%) were recaptured in light traps from three places set at 1 km from the release point, 57 mosquitoes (29.4%) from two places at 1-3 km, 41 mosquitoes (21.1%) from three places at 3-6 km, 20 mosquitoes (10.3%) from three places at 6-9 km, and 4 mosquitoes (2.1%) from two places at 9-12 km. Since 170 female mosquitoes (87.6%) out of 194 marked mosquitoes were captured within 6 km from the release point, this flight radius represents the main activity area. An sinensis was found to be able to fly at least 12 km during one night.