鲻鱼寄生蠕虫种群和群落组成分析

从1018尾鲻鱼（Mugil cephalus L．）体内获得各类寄生蠕虫9种,共2133个虫体,其中复殖吸虫8种,棘头虫1种。寄生蠕虫总的感染率为24．4％,感染强度1－81,平均感染强度为8．8,平均密度为2．3。鲻长尾吸虫（Elonginus mugilus）和双睾原单脏吸虫（Prohaplanchnus diorchis）的感染率随着宿主体长增加而下降,而楔形单脏吸虫（Haplosplanchnus cuneatus）、长形单脏吸虫（H．elongatus）、浦里单脏吸虫（H．purii）、惠东拟囊腔吸虫（Saccocoelioides huidongensis）、粤东纵睾吸虫（Tandemorchis yuedongensis）、单睾椭宝贵虫（Elliptobursa singlorchis）和圆颚针鱼新棘吻虫（Neoechinorhynchus tylosuri）的感染率与宿主体长相关不显著（P＞0．05）。研究结果还表明,楔形单脏吸虫、长表单脏吸虫、惠东拟囊腔吸虫和浦里单脏吸虫的感染强度则随着宿主体长增加而增大,其余5种寄生蠕虫的感染强度与宿主体长相关性不显著（P＞0．05）,鲻鱼寄生蠕虫在不同月的感染率和种群数量差异,除10月与11月及8月与9月不明显外（P＞0．05）,其余月份之间的差异显著（P＜0．01）。根据感染率和种群密度变化分析,优势种为惠东拟囊腔虫;通过模糊聚类分析,将鲻鱼体内寄生蠕虫组分群落分为3个亚群,宿主体长小于70mm的寄生蠕虫亚组分群落的平均种数、优势度、感染指数、多蠕虫组分群落分为3个亚群,宿主体长小于70mm的寄生蠕虫亚组分群落的平均种数、优势度、感染指数、多样性指标、平均密度和感染强度相对较低;体长于70mm的亚组分群落下值则随体长增加而上升,而平均种数减少。     

福建省大田县山羊的寄生蠕虫种群和群落生态分析

从３０只山羊体内检得寄生蠕虫１３种,其中吸虫６种、绦蚴１种、线虫６种．总感染率为１００％,平均感染强度为６４６条．其中以鹿同盘吸虫的感染率、平均感染强度为最高．山羊感染蠕虫种类在１～８种之间．种群分布型均为聚集分布,优势种有８种．该寄生蠕虫群落中各种群感染率和密度与山羊性别和年龄无关．种间关联分析表明该寄生蠕虫群落中具亲和性的种对有７对,关联和负关联达显著水平以上的种对分别有２对和３对．     

西藏羊卓雍错高原裸鲤肠道寄生蠕虫的群落生态

为研究西藏羊卓雍错Yamdrok Lake高原裸鲤肠道寄生蠕虫的群落生态, 探索寄生虫与西藏高原环境和独特的鱼类宿主三者之间的相互关系, 以肠道寄生蠕虫为对象, 于2020年7月对180尾高原裸鲤Gymnocypris waddellii [雌性120尾, 雄性60尾, 全长22.20—49.20 cm, 平均全长(36.76±4.18) cm, 体重77.3—896.7 g, 平均体重(425.92±148.27) g]进行了剖检, 对群落结构和种间关系等群落生态进行了分析。羊卓雍错高原裸鲤肠道寄生蠕虫群落由5个物种构成, 分别为聂氏似短节绦虫Parabreviscolex niepini、对盲囊线虫Contracaecum eudyptulae、束首线虫未定种Streptocara sp.、新棘吻虫未定种Neoechinorhynchus sp.和异肉吸虫未定种Allocreadium sp.。感染率从高到低依次为新棘吻虫未定种、聂氏似短节绦虫、异肉吸虫未定种、对盲囊线虫和束首线虫未定种。平均丰度从高到低依次为聂氏似短节绦虫、新棘吻虫未定种、束首线虫未定种、异肉吸虫未定种和对盲囊线虫。群落的Margalef物种丰富度指数为0.59, Shannon-Wiener多样性指数为1.26, Pielou均匀度指数为0.83, Berger-Parker优势度指数为0.50, 优势物种为聂氏似短节绦虫。有4组物种间存在正关联, 关联性从高到代依次为: 新棘吻虫未定种与异肉吸虫未定种、对盲囊线虫与新棘吻虫未定种、对盲囊线虫与异肉吸虫未定种、对盲囊线虫与束首线虫未定种。其他寄生蠕虫物种两两不存在种间关联。从感染与否看, 被感染的宿主数量超过采样群体宿主数量的一半, 其中, 以感染1种寄生虫的宿主出现频次最高, 感染2种寄生虫的宿主出现频次也较高, 3种和4种寄生虫共同感染的宿主出现频次明显降低, 未发现5种寄生虫同时感染的宿主。与同位于西藏南部, 并曾经相连的哲古措Chugutso Lake相比, 两个湖泊尽管地理位置相近, 宿主鱼类种类相同, 寄生蠕虫物种组成一致, 但羊卓雍错高原裸鲤肠道寄生蠕虫群落具有自身特点, 即更高的平均丰度, 绝大部分寄生蠕虫种群也具有更高的感染率, 群落中的优势物种也与哲古措不同。种间关联被用来判断肠道寄生蠕虫群落中各种群两两间是否存在共存或排斥关系, 即种间亲和性。在羊卓雍错高原裸鲤肠道寄生蠕虫群落中, 新棘吻虫未定种与异肉吸虫未定种种间亲和性最高。但这种关系并不稳定, 会随着水生态环境和群落中物种组成等的变化而变化。共感染的宿主出现频次变化提示, 随着一个亚群落中物种数的增加, 种间的相互作用越大, 保持共存也越难。     

丹江口水库马口鱼肠道寄生蠕虫群落结构

从2004年8月到2005年11月在丹江口水库调查的847尾马口鱼(Opsariichthys bidens)肠道内共获得寄生蠕虫14种,其中线虫7种,复殖吸虫4种,棘头虫2种,绦虫1种。该寄生蠕虫群落以广谱性寄生虫为主。杜父鱼驼形线虫(Camallanus cotti)、鱊头槽绦虫(Bothriocephalus acheilognathi)、卡斯杆咽线虫(Rhabdochona cascadilla)和木村小棘吻虫(Micracanthorhynchina motomurai)为群落的核心种。研究结果表明,寄生蠕虫群落随着马口鱼的体长和食性的改变而发生显著的变化。群落核心种的感染强度与马口鱼体长呈显著相关关系。种间相关性分析表明群落结构呈非随机组合,种间感染强度存在显著的相关性。同时群落种间关系受到马口鱼的体长和食性以及季节变化的显著影响。马口鱼肠道寄生蠕虫群落在宿主较大个体或夏秋季节中更容易形成显著的种间相关性。     

黄颡鱼的寄生蠕虫

黄颡鱼Pseudobagrus fulvidraco(Richardson)和瓦氏黄颡鱼P.vachellii(Richardson)是我国常见的二种小鱼,栖息于河川支流和湖泊中,除西南、西北和少数地区外,均普遍存在。它们寄生有多种寄生虫,并传播寄生虫病。我们近年来在福建许多县市进行黄颡鱼复殖     

青海湖裸鲤体腔寄生蠕虫群落研究

青海湖裸鲤体腔为三种寄生蠕虫寄生,即裂头绦虫裂头蚴,舌状绦虫裂头蚴和对盲囊缄虫的三期幼虫,这几种蠕虫不同大小的青海湖裸鲤中数量差异很大,将其看作一个组分群落,并根据其发生数量进行模糊聚类和极点排序,结果将其分为二个亚组分群落,即体长小于１５０ｍｍ的青海湖裸鲤体腔蠕虫亚组分群落和体长大于１５０ｍｍ的个体的体腔蠕虫亚组分群落。这与宿主的行为和食性改变有密切关系,舌状绦虫与另两种蠕虫间有显著负协调关系。     

鲻鱼的染色体组型研究

本文采用体内注射ＰＨＡ制备肾细胞染色体标本的方法,对鲻鱼的染色体组型进行了研究,其结果２ｎ＝４８,ＮＦ＝４８,型公式为４８ｔ。     

河南济源马铁菊头蝠不同越冬期肠道寄生蠕虫群落比较

2005～2006年和2006～2007年冬季分别对济源市人工隧道马铁菊头蝠(Rhinolophusferrmequinum)越冬群消化道寄生蠕虫进行了调查并对其寄生蠕虫群落进行比较。结果显示,济源市人工隧道马铁菊头蝠越冬期消化道寄生蠕虫共有5种,2种吸虫,即济源中孔吸虫(Mesotretes jiyuanensis)和朝鲜斜睾吸虫(Plagiorchis koreanus),2种绦虫,即垦丁蝙蝠绦虫(Vampirolepis kengtingensis)和东北蝙蝠绦虫(V.toohokuensis),1种线虫,即比勒陀利亚圆钩线虫(Strongylacantha pretoriensis)。2006～2007年越冬期缺少了垦丁蝙蝠绦虫。2005～2006年越冬期总感染率为94.74%,吸虫和线虫的感染率分别为73.68%和63.18%,2006～2007年总感染率为91.30%,吸虫和线虫的感染率分别为78.26%和65.22%。两个越冬群感染平均强度和平均密度比较高的是济源中孔吸虫和比勒陀利亚圆钩线虫,优势种以济源中孔吸虫和比勒陀利亚圆钩线虫为主;所感染蝙蝠体内寄生2种蠕虫的蝙蝠个体在两个冬眠群中占蝙蝠总数的比例都比较高(约50%以上);虫体数量在30条以内的蝙蝠个体约占蝙蝠感染总数的75%以上。数量较多的朝鲜斜睾吸虫、济源中孔吸虫和比勒陀利亚圆钩线虫在越冬群马铁菊头蝠消化道内彼此间没有明显的协同或排斥作用,这3种寄生蠕虫的寄生事件应该是相互独立的。结果表明,济源市人工隧道越冬马铁菊头蝠群消化道寄生蠕虫感染率比较高,不同年度冬眠期消化道内寄生蠕虫除朝鲜斜睾吸虫的平均强度和平均密度差异显著之外,相同种类之间几乎没有差异,冬眠期蝙蝠寄生蠕虫的群落结构几乎没有变化。     

Introduced animals and their parasites: The cane toad,Bufo marinus,in Australia

Abstract The impact of introducing animals into an established ecosystem can be directly observed through predator-prey and competition interactions. The impact of animals via more obscure relationships, such as the host-parasite relationship, are generally not considered. The cane toad Bufo marinus (Linnaeus) was introduced to Australia in 1935. Despite intensive research into many aspects of the biology of the toad, there has been no systematic survey of the parasite fauna of B. marinus in Australia. It is unknown exactly what parasites the toad may have introduced to Australia and also the range of parasites that may have adapted to the toad from native fauna since its introduction. The provisional conclusion from this review is that all the helminth parasites so far recorded from B. marmus in Australia have been acquired from local hosts. The interaction of toads and nativa fauna via their parasites remains unknown.     

Stability of within-host–parasite communities in a wild mammal system

Simultaneous infection by multiple parasite species is ubiquitous in nature. Interactions among co-infecting parasites may have important consequences for disease severity, transmission and community-level responses to perturbations. However, our current view of parasite interactions in nature comes primarily from observational studies, which may be unreliable at detecting interactions. We performed a perturbation experiment in wild mice, by using an anthelminthic to suppress nematodes, and monitored the consequences for other parasite species. Overall, these parasite communities were remarkably stable to perturbation. Only one non-target parasite species responded to deworming, and this response was temporary: we found strong, but short-lived, increases in the abundance of Eimeria protozoa, which share an infection site with the dominant nematode species, suggesting local, dynamic competition. These results, providing a rare and clear experimental demonstration of interactions between helminths and co-infecting parasites in wild vertebrates, constitute an important step towards understanding the wider consequences of similar drug treatments in humans and animals.     

Patterns in the composition and richness of helminth communities in brown trout, Salmo trutta, in a group of reservoirs

Helminth community composition and richness were studied in brown trout, Salmo trutta , in 10 reservoirs of broadly similar age and characteristics situated close to each other in a well-defined region of south-west England. Communities were compared using cluster and ordination analyses, and possible correlations between helminth richness and a number of environmental variables were investigated. The hypothesis that the helminth communities should show high degrees of similarity and that large differences between reservoirs and a high degree of clustering would be unrecognizable was refuted. Levels of community similarity were low and comparable to those determined for helminths in salmonids in natural lakes. Trout in some reservoirs exhibited very distinctive helminth faunas and clustering of reservoirs was apparent. No single factor, including reservoir size and presence of piscivorous birds, had a predominant influence on community richness or composition but rather a multiplicity of local factors was believed to influence these parameters. The results indicate that local factors promoting distinctiveness have a greater influence on the composition and richness of fish helminth communities in lakes and reservoirs than do regional factors promoting similarity.     

Are eels (Anguilla anguilla L.) planktonic feeders? Evidence from parasite communities

The metazoan parasite communities of eels Anguilla anguilla were investigated in three riverine localities and one lake in Devon. Altogether 21 species of parasite, the majority of the British eel parasite fauna, were recorded. Parasite communities in the three riverine localities were more similar to each other than to that of the lake. The four parasite component communities were typical and representative of those from eels in other parts of the U.K. They were characterized by low species diversity and domination by a single species: Pseudodacytlogyrus anguillae in the rivers and Diplostomum spathaceum in the lake. Both the dominant species and the majority of parasite species, and hence individuals, in any locality infected eels directly by free swimming planktonic larval stages or indirectly by the ingestion of infected planktonic copepod intermediate hosts. Examination of other species of fish in each locality showed that only Raphidascaris acus utilized a fish species as an intermediate or paratenic host to infect eels. Increases in prevalence and intensity of infection with size of eel by helminths such as Camallanus lacustris and Paraquimperia tenerrima were observed in localities in which transmission of these parasites could not have involved another fish species. Over 63% of the specialist, specific parasites of eels throughout Europe employ planktonic transmission to their hosts, as do several species of the commoner generalists. A study of eel parasite communities thus leads to the conclusion that eels are widely and closely associated in their habits with plankton and that eels of all sizes feed regularly upon planktonic copepods: the widely accepted view of eels as being more or less exclusively benthic in habit and feeding behaviour requires re-appraisal.     

Experimental evolution of parasite life-history traits in Strongyloides ratti (Nematoda)

Evolutionary ecology predicts that parasite life-history traits, including a parasite's survivorship and fecundity within a host, will evolve in response to selection and that their evolution will be constrained by trade-offs between traits. Here, we test these predictions using a nematode parasite of rats, Strongyloides ratti, as a model. We performed a selection experiment by passage of parasite progeny from either early in an infection ('fast' lines) or late in an infection ('slow' lines). We found that parasite fecundity responded to selection but that parasite survivorship did not. We found a trade-off mediated via conspecific density-dependent constraints; namely, that fast lines exhibit higher density-independent fecundity than slow lines, but fast lines suffered greater reduction in fecundity in the presence of density-dependent constraints than slow lines. We also found that slow lines both stimulate a higher level of IgG1, which is a marker for a Th2-type immune response, and show less of a reduction in fecundity in response to IgG1 levels than for fast lines. Our results confirm the general prediction that parasite life-history traits can evolve in response to selection and indicate that such evolutionary responses may have significant implications for the epidemiology of infectious disease.     

Parallel changes in the taxonomical structure of bacterial communities exposed to a similar environmental disturbance

Bacterial communities play a central role in ecosystems, by regulating biogeochemical fluxes. Therefore, understanding how multiple functional interactions between species face environmental perturbations is a major concern in conservation biology. Because bacteria can use several strategies, including horizontal gene transfers (HGT), to cope with rapidly changing environmental conditions, potential decoupling between function and taxonomy makes the use of a given species as a general bioindicator problematic. The present work is a first step to characterize the impact of a recent polymetallic gradient over the taxonomical networks of five lacustrine bacterial communities. Given that evolutionary convergence represents one of the best illustration of natural selection, we focused on a system composed of two pairs of impacted and clean lakes in order to test whether similar perturbation exerts a comparable impact on the taxonomical networks of independent bacterial communities. First, we showed that similar environmental stress drove parallel structural changes at the taxonomic level on two independent bacterial communities. Second, we showed that a long-term exposure to contaminant gradients drove significant taxonomic structure changes within three interconnected bacterial communities. Thus, this model lake system is relevant to characterize the strategies, namely acclimation and/or adaptation, of bacterial communities facing environmental perturbations, such as metal contamination.