Environmental Control of Ovarian Development in Mosquitoes of the Culex pipiens Complex

Gonotrophic dissociation, a condition in which the ovaries remain undeveloped in female mosquitoes that have taken a full blood meal, occurs in Culex pipiens L., when incubated at low temperature (10 degrees to 15 degrees C) with short photoperiod and held at low temperature after feeding. Gonotrophic dissociation occurred sporadically in Culex quinquefasciatus Say after conditioning by low temperature, irrespective of photoperiod. Two major considerations are posed: first, the importance of gonotrophic dissociation to hibernation potential; and, second, the potential of a hibernating female mosquito to serve as a virus reservoir.     

Amplification of an esterase gene is responsible for insecticide resistance in a California Culex mosquito

An esterase gene from the mosquito Culex quinquefasciatus that is responsible for resistance to a variety of organophosphorus (OP) insecticides was cloned in lambda gt11 phage. This gene was used to investigate the genetic mechanism of the high production of the esterase B1 it encodes in OP-resistant Culex quinquefasciatus Say (Tem-R strain) from California. Adults of the Tem-R strain were found to possess at least 250 times more copies of the gene than adults of a susceptible strain (S-Lab). The finding that selection by pesticides may result in the amplification of genes encoding detoxifying enzymes in whole, normally developed, reproducing insects emphasizes the biological importance of this mechanism and opens new areas of investigation in pesticide resistance management.     

Culex (Melanoconion) aikenii: natural vector in Panama of endemic Venezuelan encephalitis

Experiments performed in an endemic area of Venezuelan equine encephalitis in the Panama Canal Zone demonstrated transmission of Venezuelan equine encephalitis virus from naturally infected Culex aikenii mosquitoes to laboratory hamsters. Results of experiments indicate that Culex aikenii is an efficient natural vector and the principal species of mosquito transmitting Venezuelan equine encephalitis in this endemic zone.     

Suppression and elimination of an island population of Culex pipiens quinquefasciatus with sterile males

The release of 8,400 to 18,000 males per day of Culex pipiens quinquefasciatus Say which had been exposed to a sterilizing agent (thiotepa), suppressed and eliminated an indigenous population of this mosquito on an island off the coast of Florida in a 10-week period. Sterile males were effective in seeking out and mating with females on the island.     

Isolation of St. Louis encephalitis virus from overwintering Culex pipiens mosquitoes

Two strains of St. Louis encephalitis virus were isolated from overwintering mosquitoes collected in Maryland and Pennsylvania during January and February 1977. There isolations from Culex pipiens constitute evidence that a mosquito-borne flavivirus can persist in a vector mosquito in temperate climates during the winter season.     

A G1 glycoprotein epitope of La Crosse virus: a determinant of infection of Aedes triseriatus

Arthropod-borne viruses (arboviruses) have specific vector-vertebrate host cycles in nature. The molecular basis of restriction of virus replication to a very limited number of vector species is unknown, but the present study suggests that viral attachment proteins are important determinants of vector-virus interactions. The principal vector of La Crosse (LAC) virus is the mosquito Aedes triseriatus, and LAC virus efficiently infects the mosquito when ingested. However, a variant (V22) of LAC virus, which was selected by growing the virus in the presence of a monoclonal antibody, was markedly restricted in its ability to infect Ae. triseriatus when it was ingested. Only 15% of the mosquitoes that ingested V22 became infected and 5% of these developed disseminated infections. In contrast, 89% of the mosquitoes that ingested LAC became infected and 74% developed disseminated infections. When V22 was passed three times in mosquitoes by feeding, a revertant virus, V22M3, was obtained that infected 85% of Ae. triseriatus ingesting this virus. In addition, V22M3 regained the antigenic phenotype and fusion capability of the parent LAC virus. These results suggest that the specificity of LAC virus-vector interactions is markedly influenced by the efficiency of the fusion function of the G1 envelope glycoprotein operating at the midgut level in the arthropod vector.     

几种菊科植物提取物对蚊幼虫的光活化活性初试

对８种菊科植物２０种提取物的光活化和非光活化活性筛选，证实万寿菊根甲醇浸根物，全株乙醇浸提物和花石油醚萃取物对白纹伊蚊和致倦库蚊４龄幼虫有非常明显的光活化毒杀作用，值得指出的是根甲醇索氏提取物在有或无近紫外光照条件下对两种蚊幼都非常高效，０．１ｇ／Ｌ的致死率均为１００％。     

2011～2014年华东四地区口岸蚊类监测报告

[目的]掌握华东四地区口岸蚊类种群构成、分布、密度、季节消长和携带病原体情况,为蚊类的口岸防治提供基础数据.[方法]采用CO2诱蚊器、集卵器法、捞勺法、目测法对华东四地区口岸蚊类进行调查,对捕获蚊类进行分类鉴定和病原体检测.[结果]2011～2014年本底共捕获蚊类102 583只,隶属于1科6属18种,以致倦库蚊/淡色库蚊为优势种.5～10月均可捕获蚊类,以6月为高峰者最多.集卵器法阳性率为9.41％,孳生地阳性率为7.23％.入境截获蚊类数量较少,以淡色库蚊为主.登革热、疟疾等病原体检测均为阴性.[结论]华东四地区口岸以致倦库蚊/淡色库蚊为优势种,6月为高峰,口岸存在蚊类孳生环境,应在今后的防控工作中作为重点对象.     

Genome sequence of Aedes aegypti, a major arbovirus vector

We present a draft sequence of the genome of Aedes aegypti, the primary vector for yellow fever and dengue fever, which at approximately 1376 million base pairs is about 5 times the size of the genome of the malaria vector Anopheles gambiae. Nearly 50% of the Ae. aegypti genome consists of transposable elements. These contribute to a factor of approximately 4 to 6 increase in average gene length and in sizes of intergenic regions relative to An. gambiae and Drosophila melanogaster. Nonetheless, chromosomal synteny is generally maintained among all three insects, although conservation of orthologous gene order is higher (by a factor of approximately 2) between the mosquito species than between either of them and the fruit fly. An increase in genes encoding odorant binding, cytochrome P450, and cuticle domains relative to An. gambiae suggests that members of these protein families underpin some of the biological differences between the two mosquito species.     

褐尾库蚊幼虫捕食行为的初步研究

褐尾库蚊(Culexfuscanus Wiedemann)幼虫捕食行为的研究结果表明:单个饲养的褐尾库蚊4龄幼虫的日捕食量随白纹伊蚊密度的提高而增大,随自身密度的提高而减小;褐尾库蚊4龄幼虫喜食白纹伊蚊4龄幼虫,对蛹的捕食量远远低于幼虫.猎物的大小、密度和活动能力影响了褐尾库蚊幼虫对猎物的选择性.     

Genetic selection of a Plasmodium-refractory strain of the malaria vector Anopheles gambiae

The anopheline mosquito is the target in most malaria control programs, primarily through the use of residual insecticides. A mosquito was studied that is refractory to most species of malaria through a genetically controlled mechanism. A strain of Anopheles gambiae, which was selected for complete refractoriness to the simian malaria parasite Plasmodium cynomolgi, also has varying degrees of refractoriness to most other malaria species examined, including the human parasites P. falciparum, P. ovale, and P. vivax for which this mosquito is the principal African vector. Furthermore, the refractoriness extends to other subhuman primate malarias, to rodent malaria, and to avian malaria. Refractoriness is manifested by encapsulation of the malaria ookinete after it completes its passage through the mosquito midgut, approximately 16 to 24 hours after ingestion of an infective blood meal. Fully encapsulated ookinetes show no abnormalities in parasite organelles, suggesting that refractoriness is due to an enhanced ability of the host to recognize the living parasite rather than to a passive encapsulation of a dead or dying parasite. Production of fully refractory and fully susceptible mosquito strains was achieved through a short series of selective breeding steps. This result indicates a relatively simple genetic basis for refractoriness. In addition to the value these strains may serve in general studies of insect immune mechanisms, this finding encourages consideration of genetic manipulation of natural vector populations as a malaria control strategy.     

Culex nigripalpus: seasonal shift in the bird-mammal feeding ratio in a mosquito vector of human encephalitis

Blood-engorged Culex nigripalpus (Theob.) collected throughout the year in two Florida localities were serologically tested to determine the host range of this mosquito in nature. A proportional increase in feeding on mammals occurred in early summer, reached a maximum between July and October, and was followed by a shift back to avian hosts which dominated the feeding pattern during winter and spring. This finding strengthens the hypothesis that a biphasic pattern of feeding is a basic characteristic of an enzootic vector that, in epidemic years, also serves as the primary vector of avian arbovirus to man.     

新型阿卡斑病毒SYBR Green I荧光定量RT-PCR建立及广西边境地区蚊携带新型阿卡斑病毒调查

【目的】建立检测新型阿卡斑病毒（AKAV）的SYBR Green I荧光定量RT-PCR,并结合序列测定开展广西边境地区蚊携带新型AKAV调查,了解其流行趋势及遗传进化特征,为建立重要蚊媒病毒病预警机制提供技术支持。【方法】分别针对新型AKAV的S基因和M基因主要变异位点设计引物,建立SYBR Green I荧光定量RT-PCR并通过Ct值、标准曲线斜率、相关系数、扩增效率及扩增准确性等指标确定最佳反应体系及扩增程序;以优化的SYBR Green I荧光定量RT-PCR检测2019年6—10月在广西边境地区采集的139份蚊样品,获得的新型AKAV经测序后采用ClustalW构建遗传进化树。【结果】 SYBR Green I荧光定量RT-PCR最佳反应体系: SYBR Premix Ex Taq II 10.0 μL,上、下游引物（4 μmol/L）各1.0 μL,标准品或反转录产物2.0 μL,双蒸水补齐至20.0 μL。扩增程序: 95℃预变性30 s; 95℃ 30 s,64℃（S基因）/66℃（M基因）30 s,72℃ 30 s,进行40个循环。SYBR Green I荧光定量RT-PCR检测新型AKAVS基因和M基因的极限为1.0×101 copies/μL和1.0×102 copies/μL,对应的扩增效率分别为98.61%和105.81%,但不能扩增蓝舌病病毒、鹿流行性出血热病毒、竹鼠圆环病毒和布鲁氏杆菌;检测S基因和M基因的批内重复试验、批间重复试验变异系数（CV）均低于5.00%。采用建立的SYBR Green I荧光定量RT-PCR成功从广西边境地区防城港市、东兴市、宁明县、大新县及北海市的阿蚊和库蚊中检出新型AKAV,且均属于基因Ia型,尤其与广东和湖南蠓虫、中华按蚊、致倦库蚊分离毒株具有较高的相似性。【结论】针对新型AKAV S基因和M基因建立的SYBR Green I荧光定量RT-PCR具有特异性强、灵敏度高、重复性好的特点,更适用于检测病毒拷贝数低的样品。此外,从广西边境地区蚊样品中检出的AKAV毒株均为新型AKAV,属于基因Ia型,与广东和湖南蠓虫、中华按蚊、致倦库蚊分离毒株具有较高的相似性,推测新型AKAV已在广西周边省份流行。     

伊蚊3HKT基因RNAi载体构建及口服对伊蚊的致死作用

构建伊蚊3HKT基因的RNAi表达载体pMaa7IR/3HKTIR,转化莱茵衣藻,将得到的转基因藻株喂饲伊蚊幼虫.结果表明,3HKT RNAi转基因藻株对伊蚊有一定的致死作用.伊蚊是登革热、寨卡病毒病、黄热病、基孔肯雅病的媒介昆虫;微藻是蚊子幼虫天然食物,在自然界广泛存在,并且小球藻、衣藻等可大规模生产、生产成本低廉,...     

Anopheles balabacensis balabacensis identified as vector of simian malaria in Malaysia

The mosquito Anopheles balabacensis balabacensis has been identified as a natural vector of at least two species of simian malaria in the monsoon forests of the northern Malay States. This mosquito is also a serious vector of human malaria from Viet Nam to northern Malaya. This is the first report of a mosquito which transmits both human and simian malaria in nature.     

Isolation and characterization of larvicidal principle of garlic

The larvicidal principles of garlic, Allium sativum L.,have been isolated and identified as diallyl disulfide and diallyl trisulfide. Both natural and synthetic samples of these larvicides are fatal at 5 parts per million to Culex pipiens quinquefasciatus Say.     

Juvenile hormone induction of biting behavior in culex mosquitoes

Juvenile hormone deprivation caused by surgical removal of corpora allata shortly after adult emergence blocked the initiation of biting behavior in Culex. pipiens and Culex quinquefasciatus. Reimplantation of corpora allata or injection of a synthetic juvenile hormone (JH-I) corrected the juvenile hormone deficiency and restored biting behavior. Ovariectomy experiments demonstrated that this behavioral effect of juvenile hormone was independent of ovarian involvement.     

一株对蚊子幼虫高效的Bt新菌株的特性研究

苏云金芽胞杆菌WFS-97菌株是从土壤中筛选出的对蚊子幼虫具有特异杀虫活性的新菌株,本研究通过对该菌株的形态特征、培养特性及杀虫基因型的研究,了解其作为杀蚊制剂的开发应用潜力.在光学显微镜下,观察该菌株产生球形伴胞晶体,SDS-PAGE检测显示主要表达27 kDa主要蛋白条带,此外,还有131、79、43和31 kDa...     

Dieldrin susceptibility: partial restoration in Anopheles selected with a carbamate

Selection of dieldrin-resistant Anopheles albimanus Wied. and normal Culex pipiens quinquefasciatus Say with m-isopropylphenyl methylcarbamate for 21 and 30 generations, respectively, resulted only in vigor tolerance to this and other aryl methylcarbamates. However, it caused substantial restoration of dieldrin- and DDT-susceptibility in Anopheles by increasing the frequency of homozygous susceptible phenotypes from 10 to 83 percent.