中国尖音库蚊复合组支序系统学的研究

本文应用支序系统学原理和方法,采用形态和生态性状,对尖音库蚊复合组的４个成员进行了支序系统学研究,提出在尖音库蚊复合组中,尖音库蚊是原始的类群,骚扰库蚊为较进化的类群,而致倦库蚊和淡色库蚊是最为进化的类群。     

中国尖音库蚊复合组生物分类学的研究(英文)

本文对我国尖音库蚊复合组(Culex pipiens complex)进行了研究,其中包括从新疆采集尖音库蚊。建立实验室株,进行杂交、不同地理株形态学数值分析、杂种F_1代形态学的数值分析,表皮碳氢化合物、体内脂肪酸和单糖气相色谱分析以及卵蛋白质的电泳分析等。在我国首次发现了骚扰库蚊。根据研究结果,我国异域分布的尖音库蚊复合组实际上包含着同一个种的4个亚种,即指名亚种(Culex pipiens pipiens),淡色库蚊亚种(Culex pipiens pallens)、致倦库蚊亚种(Culex pipiens quinquenfasciatus)和骚扰库蚊亚种(Culex pipiens molestus)。致倦库蚊不应作为独立的蚊种,淡色库坟也不应作为所谓“中间型”。在亲缘关系上根据形态学特征聚类分析等结果表明,尖音库蚊与致倦库蚊的距离较远。     

尖音库蚊复合组杂交子一代4龄幼虫形态性状的研究

对我国尖音库蚊复合组（Culex pipiens complex）中的尖音库蚊Cx. Pipiens pipiens、淡色库蚊Cx. Pipiens pallens和致倦库蚊Cx. Pipiens quinquefasciatus之间杂交的F₁代幼虫形态进行了方差和典型变量分析,结果发现杂交组F₁代4龄幼虫在呼吸管指数、1-S第1对毛和第2对毛的分枝数3个性状上与亲本有明显的差异,而且介于两亲本之间。     

中国尖音库蚊复合组生物分类学的研究：雄蚊阳茎DV／D的数值分析

本文报道了我国23个不同地区的尖音库蚊复合组(Culex pipiens complex)雄蚊阳茎DV/D的数值分析结果。经过多元相关与回归分析发现,雄蚊阳茎DV/D的比值与纬度、经度之间存在着负相关的关系,并建立了DV/D与纬度的单元回归方程,以及DV/D与纬度、经度之间的多元回归方程。根据DV/D=0.5为区分淡色库蚊和致倦库蚊的一般标准,从回归方程中求得北纬30°左右为我国淡色库蚊和致倦库蚊地理分布的理论分界线。     

应用气相色谱法鉴别淡色库蚊与致倦库蚊

从70年代以来,应用气相色谱法分析医学昆虫表皮烃类碳的波形,能有效地鉴别复组的亲缘种类(sibling species),包括蚊、蚋、釆釆蝇等重要传病媒介,已成为昆虫的化学分类法(Carlson, 1984; Phillips & Milligan, 1986)。本文试用气相色谱法鉴别尖音库蚊(Culex pipiens Complex)的淡色库蚊(Culex pipiens pallens)北京株、致倦库蚊(Culex quinquefasciatus)的武汉株和广州株。     

不同地理株尖音库蚊复组雄蚊尾器的光学镜和扫描电镜观察

本研究对烟台、济南、徐州、镇江、杭州、福州及厦门等不同纬度地区尖音库蚊复组的雄蚊尾器在光学镜下进行了观察。结果表明:在杭州以南地区,致倦库蚊为本复组的唯一成员,属南方组;而徐州及镇江地区的本复组成员中,尚包括淡色库蚊及中间型,与武汉地区的类似,统属中介组。济南以北地区的本复组蚊虫,仅有淡色库蚊,属于北方组。 通过光学显微镜和扫描电镜观察,进一步揭示了本复组雄蚊尾器的形态随纬度发生递交的现象;阳茎侧板中叶的形态特征是我国古北界与东洋界交错过渡地带本复组蚊虫的可靠鉴别依据。在过渡地带,所谓纯的淡色库蚊或致倦库蚊是很难得到的,这一假想在蚊虫抗性试验中具有实际意义。在扫描电镜下,还发现了在光学显微镜下未见过的一些特征,它们在分类学上的地位及其生理意义有待进一步探讨。但是,尾器的感觉毛数量多、分布广,可能在完成交配行为中具有重要意义。     

我国尖音库蚊复合组蚊虫的杂交及其与Wolbachia感染的关系

为了了解我国尖音库蚊复合组蚊虫间杂交卵的不孵化现象和明确该现象与共生微生物Wolbachia感染的关系,对该复合组实验室种群4个亚种进行了笼内杂交和抗生素处理后的杂交。试验表明: 在复合组蚊虫中骚扰库蚊Culex pipiens molestus与淡色库蚊Cx. Pipiens pallens、致倦库蚊Cx. Ipiens quinquefasciatus与尖音库蚊Cx. Pipiens pipiens之间存在有单向胞质不融合现象,骚扰库蚊的雄虫与尖音库蚊、致倦库蚊和淡色库蚊的雌虫杂交卵的孵化率分别为0.06%、0.46%和0.19%;该胞质不融合现象可以通过抗生素处理而消除,处理后骚扰库蚊雄虫与其余3个亚种雌虫F₃杂交卵的孵化率均有提高,分别为89.49%（t=3.90×10^-28＜t_0.01=2.704）、23.39%（t=9.15×10^-7＜t_0.01=2.660_）和22.27%（t=5.08×10^-4＜t_0.01=2.750）,并可因抗生素处理而产生新的不融合类型。     

有机磷抗性致倦库蚊种群中酯酶基因扩增的定量分析

致倦库蚊Culex qinquefasciatus是丝虫病的主要传染媒介。通过生物测定、单个蚊虫酯酶α2和β2基因拷贝数分析和酯酶β基因序列比较, 分析了抗性水平、抗性相关基因在种群中的分布及其基因拷贝数等的抗性分子特征。应用快速PCR仪（realtime quantitatIve PCRs）直接检测库蚊中酯酶基因和mRNA拷贝数。结果显示：上海致倦库蚊对对硫磷的抗性LC₅₀为8.12, 酯酶活性升高是上海致倦库蚊种群对有机磷杀虫药剂产生抗性的主要机理。编码致倦库蚊酯酶β的氨基酸序列同编码尖音库蚊酯酶B1的氨基酸序列相比同源性为98%;同致倦库蚊酯酶B2氨基酸序列相比同源性为100%,同环蹶库蚊酯酶B3氨基酸序列相比同源性为90%, 上海致倦库蚊中酯酶α和β基因均扩增。有机磷抗性的上海和PellRR蚊虫种群中单个蚊虫酯酶α2 和β2定量基因拷贝数均不同,其同一蚊虫个体的酯酶α2 比酯酶β2基因的拷贝数高,但没有明显的规律性,酯酶结构基因的扩增是上海致倦库蚊种群对有机磷杀虫药剂抗性的主要机理,估计在野外种群的杂合个体中存在多种调控机制。     

几种蚊虫线粒体DNA-16SrRNA序列及其相互关系的研究

测定我国尖音库蚊复合组4亚种（尖音库蚊、淡色库蚊、致倦库蚊和骚扰库蚊）、三带喙库蚊、白纹伊蚊和中华按蚊的线粒体DNA 16S rRNA基因（mtDNA-16S rRNA)序列,发现我国尖音库蚊复合组4亚种mtDNA-16S rRNA序列基本一致,长度为555bp(554bp),GC含量为25．41％。该序列与其他3种蚊虫在种间存在差异,与三带喙库蚊的种间差异为0．54％;与白纹伊蚊的种间差异为5．77％;与中华按蚊的种间差异为9．62％。分子系统关系分析表明该序列与传统分类系统的同属或同亚科种类近似性相一致。     

致倦库蚊饲养驯化的初步体会

致倦库蚊是丝虫病、流行性乙型脑炎、东方马脑炎等多种疾病的传播媒介,对人类健康和工农业生产的发展危害甚大。为测试蚊虫对各种杀虫剂的敏感性等生物和化学测定,需人工饲养和驯化大量的致倦库蚊,得到实验室品系。我们自1999年以来开展了实验室饲养驯化致倦库蚊的工作,已连续数年饲养致倦库蚊达60多代。各个世代蚊虫生长发育良好,种群情况稳定。现将初步体会简报如下。     

BIOSYSTEMATICS OF CULEX PIPIENS COMPLEX IN CHINA

Abstract The present paper is the results of the biosystematic studies of Culex pipiens complex in China, including hybridization, mathematical analyses of morphological characters and GC analyses of culticular hydrocarbons. On the bases of the results of these studies, in addition to their allopatric distribution, it can be concluded that Cx. pipiens complex in China consists of four subspecies, including Cx. p ipiens molestus recently discovered in Beijing. Cx. pipiens quinquefasciatus can not be considered as a spearate species and Cx. pipiens pallens is not an intermediate form as claimed by some western workers.     

Hybridization and population structure of the Culex pipiens complex in the islands of Macaronesia

The Culex pipiens complex includes two widespread mosquito vector species, Cx. pipiens and Cx. quinquefasciatus. The distribution of these species varies in latitude, with the former being present in temperate regions and the latter in tropical and subtropical regions. However, their distribution range overlaps in certain areas and interspecific hybridization has been documented. Genetic introgression between these species may have epidemiological repercussions for West Nile virus (WNV) transmission. Bayesian clustering analysis based on multilocus genotypes of 12 microsatellites was used to determine levels of hybridization between these two species in Macaronesian islands, the only contact zone described in West Africa. The distribution of the two species reflects both the islands' biogeography and historical aspects of human colonization. Madeira Island displayed a homogenous population of Cx. pipiens, whereas Cape Verde showed a more intriguing scenario with extensive hybridization. In the islands of Brava and Santiago, only Cx. quinquefasciatus was found, while in Fogo and Maio high hybrid rates (～40%) between the two species were detected. Within the admixed populations, second-generation hybrids (～50%) were identified suggesting a lack of isolation mechanisms. The observed levels of hybridization may locally potentiate the transmission to humans of zoonotic arboviruses such as WNV.     

Evolutionary history of a mosquito endosymbiont revealed through mitochondrial hitchhiking

Due to cytoplasmic inheritance, spread of maternally inherited Wolbachia symbionts can result in reduction of mitochondrial variation in populations. We examined sequence diversity of the mitochondrial NADH dehydrogenase subunit 4 (ND4) gene in Wolbachia-infected (South Africa (SA), California and Thailand) and uninfected (SA) Culex pipiens complex populations. In total, we identified 12 haplotypes (A-L). In infected populations, 99% of individuals had haplotype K. In the uninfected SA population, 11 haplotypes were present, including K. Nuclear allozyme diversity was similar between infected and uninfected SA populations. Analysis of nuclear DNA sequences suggested that haplotype K presence in uninfected SA Cx. pipiens was probably due to a shared ancestral polymorphism rather than hybrid introgression. These data indicate that Wolbachia spread has resulted in drastic reduction of mitochondrial variability in widely separated Cx. pipiens complex populations. In contrast, the uninfected SA population is probably a cryptic species where Wolbachia introgression has been prevented by reproductive isolation, maintaining ancestral levels of mitochondrial diversity. Molecular clock analyses suggest that the Wolbachia sweep occurred within the last 47000 years. The effect of Wolbachia on mitochondrial dynamics can provide insight on the potential for Wolbachia to spread transgenes into mosquito populations to control vector-borne diseases.     

Sympatric occurrence of Culex pipiens (Diptera,Culicidae) biotypes pipiens,molestus and their hybrids in Portugal,Western Europe: feeding patterns and habitat determinants

Culex (Culex) pipiens (Diptera: Culicidae) has two recognized biotypes, pipiens and molestus, which differ in physiology and behaviour; this difference may influence vectorial capacity for West Nile virus (WNV). Our goal was first to determine the presence of Cx. pipiens populations in 31 locations in Portugal and to subsequently analyse their host‐feeding preferences and habitat determinants. Molecular identification of Cx. pipiens forms and their hybrids was performed in 97 females; bloodmeal sources were identified in 59 engorged specimens. Overall, 61.9% of specimens were identified as Cx. pipiens f. pipiens, 20.6% as Cx. pipiens f. molestus, and 17.5% as hybrid forms. Culex pipiens f. pipiens fed preferentially on birds, and Cx. pipiens f. molestus on humans. Hybrid forms fed mostly on birds, but human bloodmeals were common. With reference to habitat, Cx. pipiens f. pipiens and hybrid forms were positively correlated with peri‐urban habitats. Our results confirm the sympatric presence of different Cx. pipiens biotypes in 14 of the 31 locations studied. Peri‐urban areas were a common habitat of all biotypes and may represent zones of hybridization. The feeding preferences and sympatric distribution of the Cx. pipiens biotypes observed in Portugal favour the epizootic circulation of WNV and the occurrence of disease outbreaks of WNV.     

Detection and widespread distribution of sodium channel alleles characteristic of insecticide resistance in Culex pipiens complex mosquitoes in China

Culex pipiens complex mosquitoes are widely distributed throughout China and are known to be important disease vectors. Two pyrethroid resistance associated mutations have been identified in Cx. pipiens complex (Diptera: Culicidae), but there is little information on the diversity and distribution of kdr alleles in pyrethroid resistance in Cx. pipiens complex mosquitoes in China. In the present study, we report on a modified three tube allele-specific (AS)-PCR method for detecting the 1014F and 1014S alleles. The new technique was applied to identify the distribution of the two alleles in natural Cx. pipiens complex populations in China. The results confirmed that the new method is both sensitive and specific. The 1014F allele was found in all 14 of the field populations tested (frequency ranged from 6.8 to 76.2%) and the 1014S allele was found in almost two-thirds (frequency from 2.4 to 28.6%), indicating that the genotypes known to be associated with pyrethroid resistance are widespread in China. The resistance-associated alleles were more common in southern Chinese sampling sites than in northern sites. The coexistence of the two resistant mutations in individual mosquitoes was also observed in five of the field populations. Two alternative mutations within the L1014 codon were identified in Culex pipiens molestus Forskal, 1775, including a non-synonymous mutation resulting in a 1014C substitution.     

Experimental interspecific hybridization in fleas of the genus Nosopsyllus (Siphonaptera: Ceratophyllidae)]

Experimental interspecific hybridization between males and females of Nosopsyllus fasciatus and N. mokrzeckyi was carried out. Most abundant progeny was obtained after hybridization between N. fasciatus females and N. mokrzeckyi males. Hybrid descendants inherited, in general, the characters of the maternal species and in less number the paternal characters and those of both parents. The fecundity of hybrid progeny of N. fasciatus females and N. mokrzeckyi males in two generations was studied. A conclusion is made concerning close affinity of the species and their relative evolutionary youth.