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Marga...     

西藏黑斑原鮡消化道寄生蠕虫的群落结构和感染情况

为了解西藏特有鱼类黑斑原鮡(Glyptosternum maculatum)消化道寄生蠕虫的群落结构和感染情况, 于2019年5—8月对383尾黑斑原鮡进行了调查。在黑斑原鮡消化道中共发现7种寄生蠕虫, 分别为深槽绦虫未定种(Bothriocephalus sp.)、原头绦虫未定种(Proteocephalus sp.)、异肉吸虫未定种(Allocreadium sp.)、新棘吻虫未定种(Neoechinorhynchus sp.)、裸鲤棘头虫(Echinorhynchus gymnocyprii)、Contracaecum eudyptulae和杆咽线虫未定种(Rhabdochona sp.), 并对各个物种的形态特征进行了描述。将黑斑原鮡按整个群体、不同性别和不同全长群体进行划分, 分别对其消化道寄生蠕虫的群落多样性和优势虫种进行分析, 并对各寄生蠕虫物种的感染情况进行统计。结果表明: 在黑斑原鮡群体中, 消化道寄生蠕虫群落的Shannon-Wiener指数为1.53, Berger-Parker指数为0.37, 优势物种为C. eudyptulae, 其感染数量、感染率、感染强度和平均丰度均为最高; 在黑斑原鮡不同性别群体中, Shannon-Wiener指数为0.26—1.57, Berger-Parker指数为0.34—0.93, 优势物种为C. eudyptulae, 雄性群体中新棘吻虫未定种也为优势虫种, 两者的感染率和平均丰度均较高; 在黑斑原鮡不同全长群体中, Shannon-Wiener指数为0.22—1.59, Berger-Parker指数为0.34—0.94, 优势物种为C. eudyptulae或新棘吻虫未定种, 感染率和平均丰度基本以二者为最高。研究进一步明确了西藏鱼类寄生虫的种类组成和寄生特点, 为研究体内寄生蠕虫的环境适应性及与宿主的协同进化提供基础资料。     

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。     

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。     

西藏拉萨河鱼类内寄生蠕虫的种类组成及其群落特征

2004年7月对西藏拉萨河鱼类的体内寄生蠕虫进行了调查,共采集到7种鱼类,其中6种隶属于裂腹鱼亚科,1种隶属于鳅科。在这些鱼类中,共发现了2种棘头虫和1种棘头虫未定种、3种线虫、3种绦虫及异肉吸虫属(Allocreadium)的种类。它们分别是青海新棘吻虫(Neoechinorhynchus qinghaiensis)、裸鲤棘头虫(Echinorhynchus gymnocyprii)和新棘吻虫未定种(Neoechinorhynchus sp.),希蚋杆咽线虫(Rhabdochona hellichi)、对盲囊线虫(Contracaecum sp.)和胃瘤线虫(Eustrongylides sp.),东方短结绦虫(Breviscolex orientalis)、舌状绦虫(Ligula sp.)和裂头绦虫(Diphyllobothrium sp.),以及寄生裂腹鱼的异肉吸虫(Allocreadium spp.)。对青海新棘吻虫、杆咽线虫、东方短结绦虫、异肉吸虫和新棘吻虫未定种在鱼类中发育成熟的寄生虫进行了形态描述。从不同的裂腹鱼中获得的异肉吸虫属的种类未能鉴定到种;其他没有鉴定到种的寄生虫主要是利用鱼类作为中间寄主的种类,其种类鉴定则有赖于成虫的获得。迄今为止,青海新棘吻虫和裂腹鱼异肉吸虫(A.schizothoracis)仅在裂腹鱼类中被发现,可能表明裂腹鱼具有特异性的棘头虫和异肉吸虫。在所检查的7种鱼类中,除异齿裂腹鱼(Schizothorax oconnori)没有发现蠕虫外,其他6种鱼都发现了4~6种蠕虫,显示较高的物种丰富度;5种裂腹鱼蠕虫群落的Shannon-Wiener指数较高(0·6131~1·5434),而细尾高原鳅(Triplophysa stenura)的较低(0·2911);5种裂腹鱼寄生虫群落之间的相似性相对较高,为(0·1732±0·2303)~(0·3751±0·2758),而裂腹鱼与细尾高原鳅的相似性则较低,为(0·0288±0·0877)~(0·0916±0·1618)。在这些寄生蠕虫中,以鱼类为中间宿主的寄生虫种类有4种,他们都以鸟类为终末寄主,因而也在一定程度上反映了该地区的动物区系组成。     

鲻鱼(Mugil cephalus)寄生蠕虫群落生态研究

从1017尾鲻鱼（Mugil cephalus）肠道内获得寄生蠕虫9种,均为常见种类,即复殖吸虫（Digeneans）8种,棘头虫（Aacnthodephala）1种,总感染率为24.0％,平均感染强度8.73,种群平均密度2.10,其中惠东拟囊腔吸虫（Saccocoe-lioides huidongensis）的感染率、感染强度和平均密度最大。鲻鱼寄生蠕虫群落多样性指数为20193,群落均匀度指标为0.6370。鲻鱼感染寄生蠕虫种数在1－3种之间,优势种1种,为惠东拟腔吸虫;次优势种3种,分别为鲻长尾吸虫（E－longinus mugilus）、单睾椭囊吸虫（Elliptobursa singlorchis）和圆颚针鱼新棘吻虫（Neoechinorhynchus tylosuri）;非优势种5种,分别为楔形单脏吸虫（Haplosplanchnus cuneatus）、长形单脏吸虫（Haplosplanchnus elongatus）、双睾原单脏吸虫（Pro-haplosplanchus diorchis）、粤东纵睾吸虫（Tandemorchis yuedongensis）和浦里单脏吸虫（Haplosplanchnus purii）。略多于 寄生蠕虫复合群落和组分群落在一年四季中均由9种蠕虫组成,其感染率、平均感染强度和平均密度变化各有所不同,即从夏季开始,鲻鱼寄生蠕虫总感染率和各组分群落的平均密度则逐渐增高,冬季碹以一个高峰,随后逐渐下降;鲻鱼寄生蠕虫复合群落的平均密度从冬季开始逐渐下降,至秋季为最低;而圆颚针鱼析棘吻虫的感染率的四季变化与8种吸虫的变化趋势差异较大,即从春末开始增大,夏季达到最大值,随后维持在一个较高水平上,至春初则有所下降。9种寄生蠕虫的种间协调关系经卡方值测定,呈无明显协调关系。各种寄生蠕虫的种群分布均为聚集分布。     

丹江口水库三种鲤科鱼类寄生木村小棘吻虫的季节动态

作者于2004年2月至2005年2月调查了丹江口水库木村小棘吻虫Micracanthornhynchina motomurai(Harada,1935)感染三种小型经济鲤科鱼类--马口鱼(Opsariichthys uncirostris)、宽鳍(鱼鼠)(Zacco platypus)和油(粲鱼)(Hemiculter bleekeri bleekeri)的季节动态情况.在感染率和感染丰度方面,寄生于马口鱼和油(鱼鼠)的木村小棘吻虫呈现出显著的季节变化:秋冬季节感染率和感染丰度都比较高,而春夏季节比较低;与此不同的是,寄生于宽鳍(鱼鼠)中的木村小棘吻虫则全年都维持着较稳定的感染水平;木村小棘吻虫种群在三种宿主体内的总体感染丰度差异显著,但都呈聚集分布,三者的方均比与感染率和感染丰度之间无显著相关关系.     

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。     

洄游型、淡水型和陆封型刀鲚的寄生蠕虫群落结构

由于对淡水环境的适应和江湖阻隔,部分洄游型刀鲚(Coilia nasus)分化成淡水型和陆封型,为寻找区分洄游型、淡水型和陆封型这3种生态型刀鲚的寄生虫标志,并分析其寄生蠕虫群落结构特征,本文调查了3种生态型刀鲚鳃部、胃、肠和幽门盲囊中寄生蠕虫的种类和感染情况。共发现10种寄生虫,包括鳃上3种单殖吸虫:林氏异钩铗虫(Heteromazocraes lingmueni)、细长嗜鳀虫(Helciferus tenuis)和长江中华钩铗虫(Sinomazocraes changjiangensis);胃部1种复殖吸虫:鲚套茎吸虫(Elytrophallus coiliae);肠道3种线虫:简单异尖线虫(Anisakis simplex)、对盲囊线虫(Contracaecum sp.)和胃瘤线虫(Eustrongylides sp.),以及肠和幽门盲囊的3种棘头虫:陈氏刺棘虫(Acanthosentis cheni)、鲇异吻钩棘头虫(Arhythmacanthus parasiluri)、长江傲刺棘头虫(Brentisentis yangtzensis)。林氏异钩铗虫和陈氏刺棘虫在3种生态型的刀鲚中都有较高的感染率和平均丰度;海水性寄生虫细长嗜鳀虫、鲚套茎吸虫和对盲囊线虫只感染洄游型刀鲚,可作为区分洄游型刀鲚的寄生虫标志;淡水性寄生虫长江中华钩铗虫、鲇异吻钩棘头虫和长江傲刺棘头虫只在淡水型刀鲚中发现,可作为淡水型刀鲚的寄生虫标志。洄游型刀鲚的物种丰富度和Brillouin多样性最高,分别在1.25和0.19以上,淡水型刀鲚的较低,分别为0.79~1.12和0.10~0.12,陆封型刀鲚的最低,分别在0.66和0.02以下,这主要是由于淡水型和陆封型刀鲚中海水性寄生虫大部分丢失,以及淡水性寄生虫感染率和平均丰度都较低造成的。盐度降低和中间宿主缺乏是导致淡水型和陆封型刀鲚中海水性寄生虫丢失的主要原因;而淡水性寄生虫较低的感染水平可能是由于其对新宿主的适应时间较短;地理隔离可能是陆封型刀鲚中寄生虫群落多样性最低的另一重要原因。     

长江中游鱼类寄生棘头虫区系的研究

经过3年10次调查,剖检湖北省宜都、黄冈两处江段所产72种鱼类,共计766尾。收集棘头虫10种,其中包括2新种和1新组合,即蛇鮈新棘吻虫(新种)Neoechinorhynchus saurogobi sp.nov.,长江丽棘虫(新种)Brentisentis yangtzensis sp.nov.(Illiosontidae),鲤丽棘虫(新组合)B.cyprini comb.nov.。对长江中游鱼类寄生棘头虫区系的特点进行了分析和探讨。     

Diversity of intestinal helminth communities of carp from six lakes in the flood plain of the Yangtze River, China

The infra- and component communities of intestinal helminths of carp Cyprinus carpio were investigated in six lakes in the flood plain of the lower and middle reaches of the Yangtze River, China. Eight species of helminth parasites were recorded. The intestinal helminth communities were species rich in Niushan and Tonghu lakes where the digenean Asymphylodora japonica was the dominant species, whereas in Qinggang and Yanglan lakes a species-poor helminth community had only one species, Khawia sinensis . The degree of similarity within localities was highest in Qinggang and Yanglan lakes, and was high between communities where K. sinensis was the dominant species. The rich composition of these helminth communities may be because China is the heartland for carp while the poor helminth composition of those in Qinggang and Yanglan lakes may reflect the poor fauna there. It is suggested that species compositions of intestinal helminth communities of carp may be diversified in lakes in the flood plain of the Yangtze River.     

长江中下游三个湖泊中鳜消化道寄生蠕虫群落的组成与多样性

鱼类在食物网中的营养位置对其消化道寄生蠕虫的群落结构有重要作用。本研究调查了梁子湖、洞庭湖、鄱阳湖中鳜(Siniperca chuatsi)消化道寄生蠕虫群落的组成和多样性。在3个湖泊中共发现11种寄生蠕虫, 优势种均为范尼道佛吸虫(Dollfustrema vaneyi), 频率分布中感染有12种寄生虫的样本占65%, 单个样本中最大物种数为6。3个湖泊中平均物种丰富度为1.532.13, Brillouin多样性指数为0.120.33, 其中鄱阳湖中的多样性最高。梁子湖和洞庭湖之间的Jaccard相似度和百分比相似指数最高。通过比较食物网中不同营养位置鱼类的消化道寄生蠕虫群落结构, 发现鳜的消化道寄生虫群落的物种丰富度与多样性水平都高于植食性和杂食性鱼类。研究还讨论了宿主食物组成对消化道寄生蠕虫群落结构的影响。       

Helminth communities of green frogs Rana clamitans Latreille, from southwestern Michigan.

A total of 239 green frogs Rana clamitans, collected between June 3 and August 27, 1998 from 6 locations in southwestern Michigan, was examined for helminths. Of the 26 helminth taxa found, the larval cestode Mesocestoides sp. had the highest mean intensity, followed by the larval trematode Fibricola sp. Of the helminths that mature in frogs, Haematoloechus varioplexus had the highest prevalence and Gorgodera amplicava had the highest mean intensity. Frogs from 118th Pond had the highest species richness (20), mean helminth species richness (5.2), and mean helminth abundance (153.7). Frogs from Constantine East had the highest mean helminth species diversity (0.8778) and evenness (0.6033), followed by frogs from 118th Pond. In all comparisons of mean helminth community species richness, abundance, diversity, and evenness, adult frogs had significantly higher or higher values than did juveniles at each location. Jaccard's coefficients of similarity for the helminth communities for location pairs ranged from 0.545 to 0.823. Nine and 2 core helminth taxa occurred at the local and regional levels, respectively. The differences in several helminth community measures in green frogs among locations stress the importance of local ecological conditions on helminth community structure.     

Helminth infracommunities of a population of the Gran Canaria giant lizard Gallotia stehlini

A survey of gastro-intestinal helminth communities of Gallotia stehlini (Sauria: Lacertidae) from Gran Canaria island (Canary Archipelago, Spain), was conducted to determine the prevalence, abundance and species diversity of intestinal parasites in these lizards. Pharyngodonid nematodes were the most common intestinal helminths, three species being Gallotia specialists. Helminth infracommunities of G. stehlini were rich and appear to be closer to the interactive end of the continuum isolationist-interactive helminth communities, according to the high values of helminth diversity. It is the first case of a saurian reptile showing this kind of diverse helminth infracommunity, produced by a large size, a wide-ranging plant diet and exposure to helminths with direct life-cycles.     

Richness and diversity of helminth communities in the Japanese grenadier anchovy, Coilia nasus, during its anadromous migration in the Yangtze River, China

To determine the relationship between the species richness, diversity of helminth communities, and migration distance during upward migration from coast to freshwater, helminth communities in the anadromous fish Coilia nasus were investigated along the coast of the East China Sea, the Yangtze Estuary, and 3 localities on the Yangtze River. Six helminth species were found in 224 C. nasus . Changes in salinity usually reduced the survival time of parasites, and thus the number of helminth species and their abundance. Except for the 2 dominant helminths, the acanthocephalan Acanthosentis cheni and the nematode Contracaecum sp., mean abundance of other 4 species of helminths was rather low (<1.0) during the upward migration in the Yangtze River. Mean abundance of the 2 dominant helminths peaked in the Yangtze Estuary and showed no obvious decrease among the 3 localities on the Yangtze River. Mean species richness, Brillouin's index, and Shannon index were also highest in the estuary (1.93 ± 0.88, 0.28 ± 0.25, and 0.37 ± 0.34, respectively) and did not exhibit marked decline at the 3 localities on the Yangtze River. A significant negative correlation was not seen between the similarity and the geographical distance (R = -0.5104, P = 0.1317). The strong salinity tolerance of intestinal helminths, relatively brief stay in the Yangtze River, and large amount of feeding on small fish and shrimp when commencing spawning migration perhaps were responsible for the results.     

Helminth communities of three sympatric species of shorebirds (Charadrii) from four summer seasons at Bristol Bay, Alaska

Helminth communities in sympatric black turnstones (Arenaria melanocephala), ruddy turnstones (Arenaria interpres), and dunlin (Calidris alpina) were examined over 4 summers in Bristol Bay, Alaska. The compound community, made up of component communities of all 3 species of hosts for 4 summer seasons (n=164), consisted of 43 helminth species, with cestodes, especially Anomotaenia clavigera, accounting for 47% of the helminth species and 95% of the abundance. The black turnstone had significantly higher species richness and abundance than either the ruddy turnstone or dunlin. The congeneric black and ruddy turnstone component communities were the most similar, and the dunlin's was the least similar. New helminth species continued to be acquired in all 3 host species during years 2 to 4. There was no significant difference for abundance among sample years for each of the 3 species of host. The 3 component communities all included a predictable suite of helminths with 1 dominant species and 4 to 5 associates, a large number of less-predictable species, and a greater prevalence and abundance of cestode species. Consistencies over time included high diversity, low evenness, low species richness (<5), and continued recruitment of small numbers of helminth species with low prevalence and abundance. There was minimal circulation of helminth species between the dunlin and the 2 turnstone species, indicating a considerable degree of specialization, particularly among species of cestodes.     

Helminth communities of the lesser sandeel Ammodytes tobianus L. off the west coast of Ireland

The helminth parasites present in 412 lesser sandeels (Ammodytes tobianus) taken from June 1996 to May 1997 from the Aran Islands on the west coast of Ireland were examined. Ten helminth parasite species were recorded, and more than 92% of the sandeels were infected with at least 1 helminth species. Seven of the species were digeneans, including Brachyphallus crenatus, Hemiurus communis, Derogenes varicus, Lecithaster gibbosus, Opechona bacillaris, Cryptocotyle lingua, and Galactosomum lacteum; 2 nematodes, including Hysterothylacium sp. and Contracaecum sp.; and 1 cestode, Scolex pleuronectis. Three of the 7 digenean species were either larvae or immature. Only 2 species, the digeneans G. lacteum and H. communis, had prevalences greater than 50%. The dominant species was G. lacteum, accounting for 67% of all parasites present. The relationship between spawned groups, host length, and season versus the abundance, prevalence, species richness, and the total number of parasites in the infracommunities was investigated. No difference was found between the parasite communities of the 2 spawning races of the host population. Mean abundance and prevalence of the different parasite species showed seasonal variation. Numbers of parasite species and numbers of parasites increased with fish length. The role of A. tobianus as an intermediate host for helminths was assessed; it was determined that most were infectious to birds or mammals, with the majority of the parasite species being autogenic (infectious to fish). The mean number of parasites per fish was nearly a quarter of the value recorded for A. tobianus in the North Sea, where a much higher intensity of infection was recorded.     

Helminth parasites of the tropical gar, Atractosteus tropicus Gill, from Tabasco, Mexico

A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (< 17%) and abundance (< 1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 +/- 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 +/- 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar.     

Cyclic and non-cyclic dynamics in populations of the helminth parasites of wood mice, Apodemus sylvaticus

Two populations of Apodemus sylvaticus, one in deciduous woodland and another in coniferous forest in Co. Down, Northern Ireland, were trapped at monthly intervals over 33 months. The dynamics, reproduction and age structure of the mouse populations differed between years with over a 40 fold range of population size. Nine species of helminths were recovered from the alimentary tract and associated organs of the mice. The prevalence and mean worm burden of the cestodes, Catenotaenia lobata, Hymenolepis hibernia and Taenia taeniaeformis varied erratically. The trematodes, Corrigia vitta and to a lesser degree Brachylaima recurva, had seasonal changes in abundance. The nematodes Capillaria murissylvatici and Nematospiroides dubius had strongly seasonal cycles of abundance associated with the onset of host reproduction. Trichuris muris was the rarest helminth. Despite protracted periods of absence this species maintained a seasonal increase in mean worm burden in late winter. The nematode, Syphacia stroma, had a weakly seasonal pattern of dynamics. The bases of these cyclical and non-cyclical dynamics of the helminths of A. sylvaticus are discussed.     

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna, Murcia, Spain

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna was characterized after a complete analysis of its helminth community component and infracommunity structure relative to host age, sex and year of capture. The helminth community comprised 13 species: one trematode, four cestodes and eight nematodes. The cestode Pseudocatenotaenia matovi and the nematode Syphacia frederici were the most prevalent and abundant helminth species, respectively. Sixty four percent of mice analysed presented helminths with a direct cycle and 42% presented helminths with an indirect cycle. The helminth community presents a low diversity with infracommunities usually made up of only one or two helminth species. Host age and year of capture seem to play a major role in determining species richness and helminth diversity, but not in determining the abundance of helminths. Host sex does not seem to affect the infection rate nor the diversity. Further studies on more samples of wood mice and other small mammal species in this regional park are needed to explore any possible interactions between helminth communities in the host populations.