An assessment of mosquito production and nonchemical control measures in structural stormwater best management practices in southern California

A 3-year study was conducted to assess mosquito production in structural stormwater Best Management Practices (BMPs) installed by the California Department of Transportation in San Diego and Los Angeles Counties. Thirty-seven BMPs were monitored weekly for presence and relative abundance of immature mosquitoes and for conditions conducive to mosquito production. Species identified were Aedes squamiger, Anopheles franciscanus, An. hermsi, Culex quinquefasciatus, Cx. stigmatosoma, Cx. tarsalis, Culiseta incidens, and Cs. inornata. Structures designed with accessible, permanent sources of standing water in sumps, vaults, or basins were observed to support immatures all year. In BMPs intended to drain rapidly and completely, observed larval habitats resulted from design features, component failure, construction flaws, and non-stormwater runoff flows. Specific nonchemical mitigation measures to minimize or eliminate mosquito production were developed, implemented, and evaluated. This study provides a 1st assessment of mosquito production, species composition, and nonchemical control measures in structural stormwater BMPs in southern California.     

Detection of chicken antibodies to mosquito salivary gland antigens by enzyme immunoassay

Sentinel chickens are used to detect western equine encephalomyelitis, St. Louis encephalitis, and West Nile virus activity. Flocks that receive high mosquito exposure will be most effective for surveillance purposes. However, mosquito population indices at the flock sites may only provide an indirect measure of potential exposure. Therefore, we developed an indirect enzyme immunoassay to detect chicken antibodies to salivary gland antigens (SGAs) from Culex tarsalis, the primary arbovirus vector in California. Chickens fed upon by Cx. tarsalis developed an antibody response that was proportional to the amount of exposure. Cross-reactivity between sera from Cx. tarsalis-exposed chickens and SGAs from Culex pipiens quinquefasciatus, Culex pipiens pipiens, Ochlerotatus melanimon, and Ochlerotatus sierrensis was likely due to shared SGAs among these species. This serologic assay for mosquito exposure could be used to evaluate the sensitivity of sentinel flocks for detecting arboviral activity.     

Vector competence of California mosquitoes for West Nile virus

To identify the mosquito species competent for West Nile virus (WNV) transmission, we evaluated 10 California species that are known vectors of other arboviruses or major pests: Culex tarsalis, Cx. pipiens pipiens, Cx. p. quinquefasciatus, Cx. stigmatosoma, Cx. erythrothorax, Ochlerotatus dorsalis, Oc. melanimon, Oc. sierrensis, Aedes vexans, and Culiseta inornata. All 10 became infected and were able to transmit WNV at some level. Ochlerotatus, Culiseta, and Aedes were low to moderately efficient vectors. They feed primarily on mammals and could play a secondary role in transmission. Oc. sierrensis, a major pest species, and Cx. p. quinquefasciatus from southern California were the least efficient laboratory vectors. Cx. tarsalis, Cx. stigmatosoma, Cx. erythrothorax, and other populations of Cx. pipiens complex were the most efficient laboratory vectors. Culex species are likely to play the primary role in the enzootic maintenance and transmission of WNV in California.     

Entomologic studies after a St. Louis encephalitis epidemic in Grand Junction, Colorado

In 1986, after a St. Louis encephalitis epidemic in Grand Junction, Colorado, in 1985, vector mosquitoes in the city were surveyed to correlate their bionomics and infection rates with the occurrence of human disease. No human cases were reported, but mosquito surveillance disclosed St. Louis encephalitis virus in Culex tarsalis and Culex pipiens pipiens. Mosquitoes were collected with gravid traps designed to attract Cx. p. pipiens and with Centers for Disease Control light traps. Culex p. pipiens was the predominant vector mosquito collected and was captured chiefly in gravid traps. The Culex tarsalis population emerged and expanded approximately one month earlier than did the Cx. p. pipiens population. Consequently, Cx. p. pipiens was the predominant vector species after August. Infection rates throughout the surveillance period (June to September) were severalfold higher in Cx. tarsalis than in Cx. p. pipiens; however, in late summer, diminished numbers of Cx. tarsalis and a persistent population of Cx. p. pipiens resulted in relatively larger numbers of infected Cx. p. pipiens. Thus, the participation of Cx. p. pipiens as a St. Louis encephalitis vector would have been underestimated in previous studies employing light traps alone. These studies provide further evidence that Cx. p. pipiens-associated urban St. Louis encephalitis and rural Cx. tarsalis-associated St. Louis encephalitis cycles may coexist in the West.     

广东省清远市快速城市化过程中蚊虫群落动态变化规律

目的 研究城市化过程中病媒蚊虫群落特征和演替动态变化,了解主要传播媒介蚊虫种群动态及与城市化的关系.方法 采用人诱法,连续4年在清远市调查蚊虫种群密度.结果 此次调查清远市蚊虫有致倦库蚊、骚扰阿蚊、白纹伊蚊、中华按蚊和三带喙库蚊5种;致倦库蚊为优势蚊种,占群落种群数量的92.27％;其次为骚扰按蚊,占3.98％;白纹伊蚊和三带喙库蚊数量较少,各占1.62％;中华按蚊仅占0.51％.在研究期间,比较2006年与2008、2009年数据,结果表明群落构成发生显著变化,其中致倦库蚊在种群中所占比例逐渐减少,白纹伊蚊所占比例逐渐增加,中华按蚊在种群中逐渐消失,三带喙库蚊在群落中数量波动较大.不同蚊种在夜间呈现不同活动节律,致倦库蚊和三带喙库蚊19:00-22:00其密度逐渐增加,高峰主要在21:00之后;白纹伊蚊在夜晚各个时间段都有活动,活动高峰主要在20:00之前;骚扰阿蚊呈现与白纹伊蚊相似的活动规律.结论 清远市在城市化过程中,登革热媒介白纹伊蚊逐渐增加,而流行性乙型脑炎(乙脑)媒介三带喙库蚊则在不同年份中波动较大;传疟媒介中华按蚊逐渐减少,甚至消失.因此在城市化过程中,需要加强登革热和乙脑媒介的监测和防控.     

Surveillance of St. Louis encephalitis virus vectors in Grand Junction, Colorado, in 1987

Grand Junction, Colorado, was the site of a St. Louis encephalitis (SLE) outbreak in 1985. Epidemiologic and ecologic investigations in 1985 and 1986 suggested that Culex tarsalis may not have been the exclusive vector in the outbreak and that Cx. pipiens may have contributed to transmission as an accessory vector. A limited field study in 1987 generally confirmed observations from 1986 that Cx. pipiens was more abundant than Cx. tarsalis in late summer when SLE virus transmission normally occurs. In both years, infection rates in Cx. tarsalis were higher than in Cx. pipiens, but in 1987 the only SLE virus isolate from Cx. pipiens was obtained early in the season. Truck trap collections showed that Cx. pipiens was the principal vector species collected, comprising 86% of the total. Light trap collections underestimated the population of Cx. pipiens; gravid trap collections gave a closer approximation of the relative proportions of Cx. pipiens and Cx. tarsalis in the vector mosquito population after midsummer.     

多杀菌素Natular G30对海南省不同生境致倦库蚊的控制效果比较研究

目的 比较不同剂量多杀菌素Natular G30在生活污水与小型净水中对致倦库蚊海口种群的控制效果,为其在蚊虫控制中的应用提供依据.方法 用海南省海口市生活污水与小型净水中的致倦库蚊幼虫和水,在外环境以减退率为指标,分别测定Natular G30 10、20、40和80 mg/m2对蚊虫的控制效果.试验中,两次测量试验水体的水质pH值、温度、总固体含量、盐度、溶解氧含量.结果 生活污水的pH值、溶解氧含量分别为（9.62±0.43）、（12.79±3.01）mg/L,小型净水分别为（8.91±0.39）、（7.77±3.46）mg/L,二者差异有统计学意义（P＜0.05）.在生活污水中,多杀菌素有效浓度为10和20 mg/m2时,蚊虫控制持效时间为12d,40和80 mg/m2处理的则＞30 d;而在小型净水中,所有4个浓度均有超过30 d的持效期.两种水体所有剂量在第1天对1、2龄期幼虫的减退率即接近100％,3、4龄期幼虫在第3～7天出现100％减退,而蛹在第1天的减退率基本为负值.结论 多杀菌素Natular G30对致倦库蚊幼虫的控制效果具有高效、持久的特点;且对1、2龄幼虫的毒性高于对3、4龄幼虫的毒性,对蛹无明显的毒杀作用.因其在小型净水中的效果优于生活污水,使用时应根据水质调整剂量.     

淡色库蚊和致倦库蚊对杀虫剂抗药性的调查研究

目的 了解我国不同地区淡色库蚊和致倦库蚊对常用拟除虫菊酯类杀虫剂的抗性水平,为合理有效地使用化学杀虫剂提供依据.方法 采用滤纸接触筒法测定成蚊对10 000 mg/L溴氰菊酯和10 000 mg/L氯菊酯的1h击倒率和24 h死亡率.结果 北京市、河北和海南省淡色库蚊及致倦库蚊在溴氰菊酯和氯菊酯区分剂量下的24 h死亡率均＜80％,均为抗性种群.7株淡色库蚊对10 000 mg/L氯菊酯的24 h死亡率均＜50％;13株蚊虫对10 000 mg/L溴氰菊酯的抗性高低不一,24 h死亡率1％～66％不等.结论 北京市、河北及海南省淡色库蚊和致倦库蚊对拟除虫菊酯类杀虫剂均产生了高抗性,蚊虫抗药性的产生与杀虫剂的使用密切相关,在创建文明卫生城市工作中要科学合理用药,开展抗药性监测,采取适当措施延缓蚊虫抗药性的产生和发展.     

致倦库蚊感染堆集噬虫霉的症状及其病原形态观察

目的描述致倦库蚊感染堆集噬虫霉的症状及其形态特征,为控制蚊虫提供科学依据。方法醋酸地衣红染色法观察堆集噬虫霉的形态,分别显微测量分生孢子、细胞核和分生孢子梗直径,并摄影。结果感染堆集噬虫霉的致倦库蚊成虫漂浮于水面上,虫体向腹面弯曲,多呈＂C＂字形,双翅向侧后张开,约成90°,蚊尸腹部膨大,从节间膜长出子实层,在各节形成明显的白环。堆集噬虫霉的分生孢子梗不分支,初生分生孢子梨形至圆形,单囊壁,多核,易被醋酸地衣红染色。休眠孢子、假囊体和假根未见。结论堆集噬虫霉感染致倦库蚊未见文献报道,该菌对致倦库蚊具有控制潜力。     

Mosquito production in stormwater treatment devices in the Lake Tahoe Basin, California

In response to increasing evidence of mosquito production in structural stormwater Best Management Practices (BMPs), a collaborative project was developed to document the occurrence, species composition, and seasonal abundance of mosquitoes from selected urban and highway BMPs in the Lake Tahoe Basin, California. Structural and environmental factors associated with mosquito production in highway BMPs were identified and analyzed. Ten species of mosquitoes were collected from 47 BMPs, including Culex tarsalis, Culiseta incidens, Cs. inornata, and 7 species of Aedes. In and around South Lake Tahoe, immatures were most abundant in urban BMPs during the warmer summer and fall months, whereas natural water sources in the surrounding area harbored mosquitoes more often during the colder months of early spring. In BMPs installed along Lake Tahoe's perimeter highways, mosquitoes were observed in 11% of site visits conducted during a single season. Larval presence in highway BMPs was positively associated with water temperature and negatively associated with precipitation, sand, and unspecified organic matter. The significance of mosquito production in BMPs of the Tahoe Basin and the potential for increased transmission of mosquito-borne disease are discussed.     

Oviposition responses of gravid Culex quinquefasciatus and Culex tarsalis to bulrush (Schoenoplectus acutus) infusions

Laboratory bioassays demonstrated that fermented infusions of dried bulrushes (Schoenoplectus acutus) strongly attracted and stimulated oviposition by gravid female Culex quinquefasciatus and Culex tarsalis. The responses of the 2 species varied with the concentration and method of preparation of the infusions, with responses generally increasing with increasing concentration. No major differences were found in the responses of either species to infusions prepared with bulrushes alone, or with bulrushes plus lactalbumin hydrolysate and brewer's yeast. Infusions remained more attractive than distilled water controls to both species for up to 8 wk. Field tests corroborated the results from the laboratory bioassays. Culex quinquefasciatus, Cx. tarsalis, and Cx. stigmatosoma egg rafts were collected from water pan traps baited with bulrush infusions. A few Culiseta incidens eggs also were collected. In multiple-choice tests using gravid female or egg traps, Cx. quinquefasciatus preferred the most concentrated bulrush infusions, whereas Cx. tarsalis preferred intermediate concentrations. Female Cx. stigmatosoma and Culiseta incidens also were attracted. Overall, these results may provide new leads towards developing synthetic chemical baits to attract bloodfed mosquitoes.     

The acetylcholinesterase gene Ace: a diagnostic marker for the Pipiens and Quinquefasciatus forms of the Culex pipiens complex

The taxonomy of the Culex pipiens complex remains a controversial issue in mosquito systematics. Based on morphologic characters, 2 allopatric taxa are recognized, namely Cx. pipiens (including the form "molestus") in temperate areas and Cx. quinquefasciatus in tropical areas. Here we report on variability at the nucleotide level of an acetylcholinesterase gene in several strains and natural populations of this species complex. Few polymorphisms were found in coding regions within a subspecies but many polymorphisms were observed between subspecies in noncoding regions. We describe a method based on a restriction enzyme polymorphism in polymerase chain reaction-amplified DNA, in which the presence or absence of one restriction site discriminates Cx. pipiens, Cx. quinquefasciatus, and their hybrids. This technique reliably discriminates mosquitoes from more than 30 worldwide strains or populations. Polymerase chain reaction amplification of specific alleles may also be a useful tool for characterizing specific alleles of each sibling taxon.     

2006-2009年武汉市成蚊密度监测研究

目的调查武汉市2006-2009年成蚊种群构成和季节消长情况,为蚊虫及流行性乙型脑炎的防治工作提供科学依据。方法诱蚊灯法。结果 4年捕获蚊虫1科4属6种,共151 116只,城区致倦库蚊为优势种,占城区蚊虫总数的99.9%,农村三带喙库蚊为优势种,占农村蚊虫总数的62.3%。每年季节消长情况相似,密度高峰一般在6～8月;1～3月和11～12月成蚊密度很低,4年平均密度指数呈递减趋势。结论致倦库蚊为城区优势种,三带喙库蚊为农村优势种,种群构成和季节消长无明显变化,全市4～10月可开展蚊虫防治工作。     

广东国境口岸五种蚊种核糖体基因第2内转录间隔区分子鉴定方法研究

[目的]建立国境口岸不同蚊种的核糖体基因第2内转录间隔区（rDNA-ITS2）分子鉴定方法及其系统进化关系。[方法]针对蚊虫的rDNA核酸序列保守性，设计扩增rDNA-ITS2编码区的PCR引物，对广州机场、江门和湛江等国境口岸采集的致倦库蚊、三带喙库蚊、白纹伊蚊、中华按蚊、骚扰阿蚊等成蚊和实验室喂养的蚊幼虫进行PCR扩增和序列测定，并与GenBank中已知蚊虫的rDNA-ITS2进行同源性比较和系统进化分析。[结果]不同蚊虫的rDNA-ITS2扩增片断长度不同，M2引物对致倦库蚊、三带喙库蚊、白纹伊蚊、骚扰阿蚊和中华按蚊的扩增片断分别为447bp-520bp、432bp-438bp、527bp-586bp、439bp-448bp和644bp。序列分析和系统进化关系显示，尖音库蚊组和三带喙库蚊聚类为库蚊属，再与白纹伊蚊和骚扰阿蚊聚类为库蚊亚科，库蚊亚科再与中华按蚊进行聚类，分子进化与蚊虫形态学鉴定的亲缘关系保持一致。[结论]建立的rDNA-ITS2分子鉴别技术可成功地应用于国境口岸范围内成蚊和幼蚊的亚科、属和种的区分和确定系统发育关系。这可以弥补蚊虫形态特征信息量的不足等传统分类系统的缺点，对国境口岸范围外来的或新发现的蚊种的鉴别提供了分子水平的技术依据。     

广东省蚊虫感染沃尔巴克氏体初步调查研究

目的 了解广东省蚊虫种群中沃尔巴克氏体（Wolbachia）的分布及其基因型别.方法 利用Wolbachia的wsp基因序列建立PCR检测方法,对蚊科中库蚊属、伊蚊属、阿蚊属和按蚊属部分蚊虫种类进行检测,同时利用Mega 5.2软件对所获基因序列进行系统分析.结果 分别从致倦库蚊、骚扰阿蚊、白纹伊蚊及未分型蚊种中检测到12条目的基因序列,其中11条成功进行测序,这些序列分别属于A和B2个超级基因组,分布在5个不同的基因族中.结论 广东省白纹伊蚊、骚扰阿蚊和致倦库蚊中均存在A大组（含2个小组）和B大组（含3个小组）基因型的Wolbachia感染,埃及伊蚊和中华按蚊未检测出Wolbachia.     

The abundance and seasonal distribution of Culex mosquitoes in Iowa during 1995-97

The abundance and seasonal distribution of Culex mosquitoes were monitored by measuring oviposition activity during the summers of 1995, 1996, and 1997. Five species of culicine mosquitoes laid egg rafts in ovitraps. Egg rafts of 4 Culex species-Cx. restuans (54.98%), Cx. pipiens (25.41%), Cx. salinarius (12.18%), and Cx. tarsalis (0.14%)-constituted more than 92% of the total egg rafts collected. Culiseta inornata (0.1%) was the only other species to lay viable egg rafts in the ovitraps. A small percentage (7.19%) of egg rafts did not hatch; thus identification was not possible. Compared with New Jersey light trap data in a nearby area, the abundance of Cx. tarsalis and Cs. inornata was markedly underestimated with ovitraps. These data may also reflect differences in the specific location of the 2 trap sites rather than attractiveness of ovitraps for Cx. tarsalis and Cs. inornata. In general, Cx. restuans oviposition activity began in late May, and it was the dominant Culex species through June. After July 1, the number of egg rafts laid by Cx. restuans decreased continually until the end of the summer. Culex pipiens and Cx. salinarius oviposition began in early June and increased gradually during the summer. Over the course of a summer, there were about twice as many Cx. pipiens as there were Cx. salinarius. A crossover in the number of Cx. pipiens and Cx. restuans egg rafts occurred in late July or early August, depending on the year. By late August each year, Cx. pipiens was the most abundant species. At this time, Cx. restuans and Cx. salinarius populations were similar, but each was about half of the Cx. pipiens population. Differences in the abundance of all 3 species could not be explained by changes in ambient temperature (both minimum and maximum) or relative humidity, either within or among years.     

我国淡色库蚊/致倦库蚊对常用化学杀虫剂的抗药性

淡色库蚊/致倦库蚊是我国分布最广、危害最大的蚊种之一,也是家用杀虫剂的主要控制靶标.为了解其对常用化学杀虫剂的抗药性,应用WHO方法,各地在不同时期开展了抗药性监测、调查或研究工作,积累了大量数据.经对发表文献及监测资料的收集、整理、统计和分析,综述了我国淡色库蚊/致倦库蚊对常用化学杀虫剂的抗药性分布和特征,并对影响抗药性产生的原因进行了分析,为我国对该蚊预防控制策略的制定,抗药性监测工作的开展和不同区域抗药性治理策略的制定提供依据.     

致倦库蚊及大劣按蚊对拟除虫菊酯类杀虫剂的抗药性测定

目的掌握海南省致倦库蚊和大劣按蚊对拟除虫菊酯类杀虫剂的抗药性发生及发展趋势。方法采用幼虫浸渍法，测定其对拟除虫菊酯类杀虫剂的抗性倍数。结果五指山市、澄迈县和海口市的致倦库蚊对溴氰菊酯抗性倍数分别为7．50、6．67、8．00倍，对氟氯氰菊酯的抗性倍数分别为5．31、6．00、6．23倍；琼中县大劣按蚊对溴氰菊酯和氟氯氰菊酯的抗性倍数分别为1．12和1．31倍。结论海南省致倦库蚊对这2种拟除虫菊酯类杀虫剂均产生了低抗药性；而大劣按蚊尚未产生。     

Polymerase chain reaction assay identifies North American members of the Culex pipiens complex based on nucleotide sequence differences in the acetylcholinesterase gene Ace.2

Nucleotide sequence differences in the acetylcholinesterase gene Ace.2 were used to develop an assay to distinguish among North American mosquitoes of the Culex pipiens complex. Taxon-specific polymerase chain reaction primers based on sequence differences within intron 2 of Ace.2 distinguish among the sibling species Cx. pipiens Linneaus and Cx. quinquefasciatus Say and their F1 hybrids. This assay may be used to confirm the species composition of mosquito pools, identify individual specimens collected in arbovirus surveillance programs and other mosquito studies, and define zones of hybridization.     

Temperature-induced morphological change in Culex pipiens

The effect of temperature on Culex pipiens pipiens, Cx. p. quinquefasciatus, and reciprocal hybrids of the two was investigated by monitoring the DV/D ratios of these stocks maintained at 15.6 degrees C and 23.9 degrees C over 10 generations. Little variation occurred in mean values of the parental subspecies at either temperature. At 23.9 degrees C, the mean ratios for both hybrid lines rose from an intermediate value to a level well above the accepted minimum for Cx. p. quinquefasciatus (0.4), and the proportion of individuals identifiable as that subspecies increased 16-fold. At 15.6 degrees C, hybrid mean DV/D ratios decreased to or below the pipiens maximum value (0.2), and the proportion of pipiens individuals increased 4 to 5 times. The need to monitor closely the status of Cx. pipiens hybrid colonies is evident.