倪氏复口吸虫在稀有鮈鲫体内的移行及对其耳石微结构的影响

倪氏复口吸虫是我国淡水鱼类的一种常见的危害严重的寄生虫。利用稀有鮈鲫作为寄主,研究了倪氏复口吸虫在其体内的移行途径,并观察了复口吸虫的感染是否在寄主耳石上留下标记轮。倪氏复口吸虫尾蚴从稀有鮈鲫体表的各个部位侵入,但主要集中在头部,侵入体内的尾蚴通过肌肉和结缔组织直接进入眼球。感染倪氏复口吸虫的稀有鮈鲫耳石表面微结构发生变化,部分鱼耳石上出现明显的标记轮。     

倪氏复口吸虫和湖北复口吸虫生活史的研究Ⅰ．早期幼虫的实验生态

本文比较研究了倪氏复口吸虫(Diplostomum niedashui pan＆Wang)和湖北复口吸虫(Diplostomum hupehensis pan＆Wang)早期生活史的实验生态,包括温度、光照度对它们直接和间接的影响及某些数量的变化。     

范尼道佛吸虫的生活史研究

范尼道佛吸虫的生活史包括毛蚴、胞蚴、尾蚴、囊蚴和成虫5个阶段。它的第一中间宿主为淡水壳菜,第二中间宿主为多种小型鲤形目和鲇形目鱼类,终末宿主是鳜。文中对这种吸虫的胞蚴、尾蚴、囊蚴和成虫的形态特征以及尾蚴的行为特征进行了观察和描述。在用人工方法成功地将尾蚴感染青后,对不同发育阶段的囊蚴在鱼体内的形态变化和器官发育进行了观察。       

福建腹口吸虫种类及生活史的研究

一、前言 腹口类吸虫由于其口孔开在身体腹面中央部位而不同于所有口孔开在前端的复殖类吸虫。本类吸虫的各幼虫期,如具纤毛棒的毛蚴、分支的胞蚴以及牛首状的尾蚴等特征也和前口类吸虫的各幼虫期有显著的差别。自从1819年Rudolphi发现腹口吸虫至今世界各地报道的种类已有一百七十余种,但是,在这许多种类中,进行过生活史研究的只有十     

窄口螺侧殖吸虫的发育史及早熟现象

1.本文描述从福州闽江泥滩采集的图氏窄口螺体中发现一新种侧殖吸虫,定名为窄口螺侧殖吸虫(Asymphylodora stenothyrae sp.nov.)并与其他相近虫种作详细比较。2.窄口螺侧殖吸虫的生活史各期发育经详细观察,本文简单介绍其各发育期形态特征。3.本文对窄口螺侧殖吸虫早熟现象及其他吸虫类的提早发育现象进行讨论,并将复殖吸虫亚纲曾经发现有提早发育现象的虫种及其中间宿主列表比较。我们的结论:早熟现象在吸虫类中是相当普遍的一种现象。       

窄口螺侧殖吸虫的发育史及早熟现象

1．本文描述从福州闽江泥滩采集的图氏窄口螺体中发现一新种侧殖吸虫,定名为窄口螺侧殖吸虫(Asymphylodora stenothyrae sp.nov．)并与其他相近虫种作详细比较。2．窄口螺侧殖吸虫的生活史各期发育经详细观察,本文简单介绍其各发育期形态特征。3．本文对窄口螺侧殖吸虫早熟现象及其他吸虫类的提早发育现象进行讨论,并将复殖吸虫亚纲曾经发现有提早发育现象的虫种及其中间宿主列表比较。我们的结论：早熟现象在吸虫类中是相当普遍的一种现象。     

雅安哺乳动物的几种棘口吸虫

1989年3—9月,用分离白雅安淡水螺体内的棘口吸虫囊蚴按100—150个/只人工感染小白鼠15只,在小白鼠的胃和肠道共检到5种棘口吸虫,现报道于下:(测量单位:mm)1曲领棘缘吸虫Echinoparyphium recurvatum第二中间宿主为赤豆螺Bithynia fuchsiana和中华圆田螺Cipangopaludina cathayen。2接睾棘口吸虫Echinostoma paraulum Dietz,1909(宫川棘口吸虫E.miyagawai Ishii,1932)第二中间宿主为尖口圆扁螺Hippeuties cantori。3鼠真缘吸虫Euparyphium murinum第二中间宿主为赤豆螺和中华圆田螺。4移睾棘口吸虫E.cinetorchis第一中间宿主为赤豆螺;第…     

闽江叶形吸虫新种的生活史研究

本文报道寄生在闽江的花鲈Lateolabrax japonicus膀胱及输尿管中的闽江叶形吸虫新种Phyllo-distomum mingensis sp.nov.。本新种以其成虫的虫卵大小、睾丸卵巢形态、不具劳氏管及后蚴的焰细胞排列公式等特征不同于现有的已知种。本新种的生活史经阐明,其第一中间宿主是河蚬Corbicula fluminea,第二中间宿主是河虾Macrobrachium nipponensis与M.aspergillus。本文尚对叶形属吸虫各发育结构等问题进行讨论。     

双穴科吸虫一新种及一种新纪录

双穴科吸虫(Diplostomatidae)属于吸虫纲、复殖目、前口亚目。寄生于鸟类及哺乳类。根据卵黄腺和寄主的不同、又分为二个亚科:重翼亚科(Alariinae)及双穴亚科(Diplosto-matinae),前者卵黄腺的分布仅限于前体、寄主为哺乳类、后者卵黄腺分布于前后体或仅限     

洞庭湖外睾吸虫新种及其生活史

本文报告洞庭湖区鲶鱼肠道寄生的洞庭湖外睾吸虫Exorchis dongtinghuensis sp.nov(新种)及其全程生活史,其第一中间宿主为湖北钉螺Oncomelania hupensis;第二中间宿主为鲤鱼、鲫鱼和金鱼;终宿主为鲶鱼Parasilurus asotus。作者对各期宿主作了人工感染试验和现场自然感染调查。对其发育过程作了观察比较。     

Monoxenous and heteroxenous parasites of fish manipulate behavior of their hosts in different ways

Adaptive host manipulation hypothesis is usually supported by case studies on trophically transmitted heteroxenous endoparasites. Trematodes and cestodes are among efficient manipulators of fish, their common intermediate hosts. In this review paper, new data on modifications of host fish behavior caused by monoxenous ectoparasitic crustaceans are provided together with a review of effects caused by heteroxenous parasites. Differences in modifications of host behavior caused by heteroxenous and monoxenous parasites are discussed. Manipulation by heteroxenous parasites enhances availability of infected fish to predators--definitive hosts of the parasites. Fine-tuned synchronization of modified anti-predator behavior with a certain phase of the trematode Diplostomum spathaceum development in the eyes of fish, their second intermediate host, was shown. Modifications of behavior are habitat specific. When juvenile salmonids are in the open water, parasites impair their cooperative anti-predator behavior; in territorial bottom-dwelling salmonids, individual defense behavior such as sheltering is the main target of manipulation. It was shown that monoxenous ectoparasitic crustaceans Argulus spp. decreased motor activity, aggressiveness and increased shoal cohesiveness of infected fish. Such a behavior facilitates host and mate searching in these parasites, which often change their hosts, especially during reproduction. Reviewed experimental data suggest that heteroxenous parasites manipulate their host mainly through impaired defense behavior, e.g. impairing shoaling in fish. Alternatively, monoxenous parasites facilitate shoaling that is profitable for both parasites and hosts. Coordination of modified host behavior with the parasite life cycle, both temporal and spatial, is the most convincing criterion of the adaptive value of host manipulation.     

Diplostomum spathaceum cercariae respond to a unique profile of cues during recognition of their fish host

During its normal life cycle, Diplostomum spathaceum cercariae attach to and invade fish intermediate hosts. They are also known to attach to various other aquatic animals in response to water currents, touch and carbon dioxide. The purpose of this study was to identify the specific stimuli used by D. spathaceum cercariae to recognise the appropriate fish host. We characterised the host cues which stimulate them to remain on the host (enduring contact) and to penetrate the skin. Cercariae were exposed to animal skin tissues and fish skin surface mucus, their extracts and chemical modifications integrated into agar or offered via membrane filters. Enduring contact was stimulated by hydrophilic extracts Mr<3kDa, which were sensitive to oxidation of carbohydrates. The stimulating cues are probably small molecular carbohydrates, as monosaccharides stimulated enduring contacts, but amino acids, urea, electrolytes and peptides did not. Penetration was stimulated by hydrophilic macromolecules, Mr>30kDa, and by lipids. The hydrophilic stimuli were protease resistant and precipitable with Alcian blue and they were sensitive to alkaline cleavage, to digestion with lysozyme and neuraminidase as well as to oxidation of sialic acids. They were considered to be glycoproteins with O-glycosidically linked carbohydrate chains and bound sialic acids as signal structures. The lipophilic penetration stimuli were contained exclusively in the fatty acid fractions, and the stimulating characteristics of these fatty acids resembled the stimulating penetrations in other cercarial species. Diplostomum spathaceum cercariae respond to a unique profile of cues in their sequence of host-recognition phases. These cues differ from those used in other fish parasites studied to date and underline the diversity of fish recognition strategies.     

Reciprocal Interaction Matrix Reveals Complex Genetic and Dose-Dependent Specificity among Coinfecting Parasites

Abstract Understanding genetic specificity in factors determining the outcome of host-parasite interactions is especially important as it contributes to parasite epidemiology, virulence, and maintenance of genetic variation. Such specificity, however, is still generally poorly understood. We examined genetic specificity in interactions among coinfecting parasites. In natural populations, individual hosts are often simultaneously infected by multiple parasite species and genotypes that interact. Such interactions could maintain genetic variation in parasite populations if they are genetically specific so that the relative fitness of parasite genotypes varies across host individuals depending on (1) the presence/absence of coinfections and/or (2) the genetic composition of the coinfecting parasite community. We tested these predictions using clones of fish eye flukes Diplostomum pseudospathaceum and Diplostomum gasterostei. We found that interactions among parasites had a strong genetic basis and that this modified genetic variation in infection success of D. pseudospathaceum between single and multiple infections as well as across multiply infected host individuals depending on the genetic identity of the coinfecting D. gasterostei. The relative magnitude of these effects, however, depended on the exposure dose, suggesting that ecological factors can modify genetic interactions between parasites.     

Population biology of the helminth parasites of Phoxinus phoxinus (L.), the minnow, in a Cardiganshire lake

Specimens of Phoxinus phoxinus (L.) were collected over a period of a year from September 1967 to September 1968 from Frongoch Lake, Cardiganshire, Wales. Of a total of 650 fish examined for helminth parasites, 32 % were definitive hosts for Macrolecithus papilliger , and 16·5% for Neoechinorhynchus rutili (Müller), both parasites of the alimentary canal. All the fish examined were second intermediate host for Diplostomum phoxini (Faust) in the brain and 1·67% for Ligula intestinalis (L.) in the coelom. An increase in incidence of infestation with M. papilliger in spring and autumn and with N. rutili in summer were evident. The sex of the fish had no apparent effect on worm burden whereas size was more significant. There was a decrease in incidence of infestation with M. papilliger and an increase with N. rutili together with an increase in intensity of infestation with D. phoxini as the fish became larger. The latter species accumulated in the brain as the host increased in age.     

Ecological factors influencing the composition of the parasite fauna of the European eel, Anguilla anguilla (L.), in Ireland

The parasites of 121 eels from three contrasting sites in the Corrib catchment area, western Ireland, were investigated. Thirteen species, Ergasilus gibbus, Diplostomum gasierostei, Diplostomum spathaceum, Sphaerostoma bramae. Bothrocephalus claviceps, Proteocephalus macrocephalus, Camallanus lacustris, Cucullanus truttae, Paraquimperia tenerrima, Raphidascaris acus, Acanthocephalus clavula, Acanthocephalus lucii and Pomphorhynchus laevis , were recorded. Two species, P. macrocephalus and P. tenerrima , have not previously been reported from Ireland. Microhabitat preferences of the parasites were noted. Variations in the occurrence and intensities of the parasites observed were analyzed in relation to sampling period, host habitat and characteristics of the eel populations studied. A variety of factors were shown to be of importance, including composition of the fish communities and distributional patterns of intermediate hosts and piscivorous birds. Differences were noted in the parasit-ocoenoses of eels in still and running water sites. The occurrence and intensities of infection of several parasite species were shown to be related to age and size of host: the occurrence of B. claviceps. C. truttae, P. tenerrima and R. acus was shown to be related to either age or size of eels, which is accounted for by the fact that eels become increasingly piscivorous with age and increasing size. Little evidence of interspecific interactions was noted.     

Polymorphic microsatellite loci for the trematode Diplostomum pseudospathaceum

We present primers for five polymorphic microsatellite loci in the eye fluke Diplostomum pseudospathaceum (Trematoda), a widely distributed parasite with a complex life cycle used as a model for parasitology and fish immunology. The loci were identified using a GA/CT‐enriched genomic library by subtractive hybridization with magnetic particles. All five loci were highly polymorphic, displaying 17 to 61 alleles and heterozygosities ranging from 0.53 to 0.92. We isolated populations of parasites within the first (snail) and second (fish) intermediate host and found small but significant genetic differentiation (F_ST = 0.012) between the two life stages of the parasite.     

Invasion character and distribution of the Diplostomum huronense (La Rue, 1927) Hugnes, 1929 metacercariae in roach of Lake Ladoga

Estimation of the invasion character and distribution of the Diplostomum huronense metacercariae depending on the fish host age has been carried out in roach of Lake Ladoga. Distribution of D. huronense in the young roach (up to age 5+) is negative binomial. Aggregation of the parasite is caused not only by individual differences in the fish host resistance to the metacercariae invasion, but by a high mortality of hyperinfected fishes as well. In older individual hosts the host-parasite system is destroyed, and the parasite distribution approximates to normal. The parasite system of the diplostomids in roach is characterized by the spatial asymmetry, when most part of parasites inhabit few individual hosts, and probability of the case when a parasite get into previously infected host is higher than that of the invasion of parasite-free host. Thus, the Diplostomum huronense metacercaria is an important factor regulating the fish fry number both in direct (death of infected fry) and indirect (elimination of hyperinfected fishes by ichthyophagous birds) way.     

Host immunization shapes interspecific associations in trematode parasites

1. Individuals of free-living organisms are commonly infected by multiple parasite species. Under such circumstances, positive or negative associations between the species are possible because of direct or indirect interactions, details in parasite transmission ecology and host-mediated factors. One possible mechanism underlying these processes is host immunity, but its role in shaping these associations has rarely been tackled experimentally.
2. In this study, we tested the effect of host immunization on associations between trematode parasites infecting eyes of fish. We first analysed the associations between three species ( Diplostomum spathaceum , Diplostomum gasterostei and Tylodelphys clavata ) in wild hosts, roach ( Rutilus rutilus ) and perch ( Perca fluviatilis ). Second, using rainbow trout ( Oncorhynchus mykiss ) as a model fish species, we experimentally investigated how sequential immunization of the host (i.e. one parasite species infects and immunizes the host first) could affect the associations between two of the species.
3. The results indicated that most of the associations were positive in wild hosts, which supports between-individual variation in host susceptibility, rather than competitive exclusion between the parasite species. However, positive associations were more common in roach than in perch, possibly reflecting differences in ecological conditions of exposure between the host species. The experimental data showed that positive associations between two of the species were eroded by host immunization against one of the parasite species.
4. We conclude that sequential immunization of hosts has a marked effect on interspecific parasite associations and basically can determine if positive associations are detected or not. This implies that correlative results suggesting non-interactive community structure in general may be obscured by the sequence of previous parasite exposure and corresponding dynamics of host immunization.     

Determinants of the parasite community of clariid fishes from Lake Victoria, Tanzania

The factors that determine parasite assemblages among the clariid fishes of Lake Victoria, Tanzania were studied between August 2003 and February 2005. Six hundred and fifty-six fish belonging to seven species were necropsied and examined for parasites, from which 31 species of metazoan parasites were recorded. The community was dominated by the nematodes both in species and numbers. Most species were generalists with only two trematodes, Diplostomum mashonense and Tylodelphys species, being specialists of Clarias gariepinus. Ten species were considered core and predictable. Parasite species richness, number of individuals per host and Shannon-Wiener diversity indices were generally high. At the compound community level, a mean number of 7.8 parasites were shared among different species of fish and the maximum number of parasites species per fish at the infracommunity level was seven. Levels of similarity in parasite species richness at the component community level ranged from 29.6 to 61.5%. The study concludes that parasite communities in clariid fishes of Lake Victoria are structured by ecological factors. At the infracommunity level, host size, diet and vagility promoted a richer parasite community. At the compound level, two factors were crucial, namely the intermixing of the waters in the lake and the predominant and mobile C. gariepinus.     

Parasite-induced change in host behaviour and susceptibility to predation in an eye fluke-fish interaction

Trophically transmitted parasites may increase their transmission efficiency by altering the behaviour of infected hosts to increase their susceptibility to predation by target hosts (the next host in the life cycle). The parasite Diplostomum spathaceum (Trematoda) reduces the vision of its fish intermediate hosts: its metacercariae lodge themselves in the eyes of fish and induce cataract formation, which gives them the opportunity to affect fish behaviour. We examined whether D. spathaceum eye flukes change the preference of fish for the surface layers of the water column or their escape behaviour, which could make the fish more vulnerable to predation by bird hosts. We also studied the influence of parasites on the susceptibility of fish to artificial aerial predators that were able to catch fish from the water surface. Infected and control fish did not differ in their preference for the surface layers but infected fish showed less escape behaviour when a black plate was drawn over the water surface. They were also more easily caught by human ‘predators’ dipping a net into the tank. Thus, infected fish should be easier prey for gulls and terns, implying that the ability of D. spathaceum eye flukes to alter fish behaviour may be a parasite strategy evolved to enhance transmission.