PDF(Pubmed)
Abstract：
BACKGROUND: Biological invasions pose risks to the normal functioning of ecosystems by altering the structure and composition of several communities. Molluscs stand out as an extensively studied group given their long history of introduction by either natural or anthropogenic dispersal events. An alien population of the lymnaeid species Orientogalba viridis was first sighted in 2009 in southern Spain. In its native range (Australasian), this species is one of the main intermediate hosts of Fasciola hepatica, a major worldwide trematode parasite largely affecting humans, domestic animals and wildlife.
METHODS: We collected field populations of O. viridis from its native (Malaysia) and invaded (Spain) ranges. We performed detailed morphoanatomical drawings of the species and screened for natural infection of parasites. Individuals were molecularly characterized using ITS2 for comparison with existing sequences in a fine phylogeography study. We founded experimental populations at two different conditions (tropical, 26 °C and temperate, 21 °C) to study the life-history traits of exposed and non-exposed individuals to different F. hepatica isolates.
RESULTS: We found a 9% natural prevalence of trematode infection (98% similarity with a sequence of Hypoderaeum conoideum [Echinostomatidae]) in the Spanish field population. The haplotypes of O. viridis found in our study from Spain clustered with Australian haplotypes. Experimental infection with F. hepatica was successful in both experimental conditions but higher in tropical (87% prevalence) than in temperate (73%). Overall lifespan, however, was higher in temperate conditions (mean 32.5 ± 7.4 weeks versus 23.3 ± 6.5) and survivorship remained above 70% during the first 20 weeks. In parasite-exposed populations, life expectancy dropped from an overall 37.75 weeks to 11.35 weeks but still doubled the time for initial cercariae shedding. Cercariae shedding started at day 23 post-exposure and peaked between days 53 and 67 with an average of 106 metacercariae per snail.
CONCLUSIONS: Whether O. viridis will succeed in Europe is unknown, but the odds are for a scenario in which a major snail host of F. hepatica occupy all available habitats of potential transmission foci, ravelling the epidemiology of fasciolosis. This research provides a comprehensive understanding of O. viridis biology, interactions with parasites and potential implications for disease transmission dynamics, offering valuable insights for further research and surveillance.
METHODS: We collected field populations of O. viridis from its native (Malaysia) and invaded (Spain) ranges. We performed detailed morphoanatomical drawings of the species and screened for natural infection of parasites. Individuals were molecularly characterized using ITS2 for comparison with existing sequences in a fine phylogeography study. We founded experimental populations at two different conditions (tropical, 26 °C and temperate, 21 °C) to study the life-history traits of exposed and non-exposed individuals to different F. hepatica isolates.
RESULTS: We found a 9% natural prevalence of trematode infection (98% similarity with a sequence of Hypoderaeum conoideum [Echinostomatidae]) in the Spanish field population. The haplotypes of O. viridis found in our study from Spain clustered with Australian haplotypes. Experimental infection with F. hepatica was successful in both experimental conditions but higher in tropical (87% prevalence) than in temperate (73%). Overall lifespan, however, was higher in temperate conditions (mean 32.5 ± 7.4 weeks versus 23.3 ± 6.5) and survivorship remained above 70% during the first 20 weeks. In parasite-exposed populations, life expectancy dropped from an overall 37.75 weeks to 11.35 weeks but still doubled the time for initial cercariae shedding. Cercariae shedding started at day 23 post-exposure and peaked between days 53 and 67 with an average of 106 metacercariae per snail.
CONCLUSIONS: Whether O. viridis will succeed in Europe is unknown, but the odds are for a scenario in which a major snail host of F. hepatica occupy all available habitats of potential transmission foci, ravelling the epidemiology of fasciolosis. This research provides a comprehensive understanding of O. viridis biology, interactions with parasites and potential implications for disease transmission dynamics, offering valuable insights for further research and surveillance.
摘要：
背景：生物入侵通过改变几个群落的结构和组成，对生态系统的正常功能构成风险。由于软体动物通过自然或人为扩散事件引入的悠久历史，因此它们是一个经过广泛研究的小组。2009年，在西班牙南部首次发现了lymnaeid物种Orientogalbaviridis的外来种群。在其本地范围（澳大利亚），该物种是肝片吸虫的主要中间宿主之一，一种主要影响人类的全球吸虫寄生虫，家畜和野生动物。
方法：我们从其本地（马来西亚）和入侵（西班牙）地区收集了O.viridis的田间种群。我们对该物种进行了详细的形态解剖图，并筛选了寄生虫的自然感染。在精细的系统地理学研究中，使用ITS2对个体进行分子表征，以与现有序列进行比较。我们在两种不同的条件下建立了实验种群(热带，26°C和温带，21°C），以研究暴露和未暴露个体对不同肝肠球菌分离株的生活史特征。
结果：我们发现在西班牙野外种群中，吸虫感染的自然患病率为9％（与螺旋藻[Echinostomatidae]序列具有98％的相似性）。在我们来自西班牙的研究中发现的O.viridis的单倍型与澳大利亚单倍型聚集在一起。在两种实验条件下，肝菌的实验性感染均成功，但在热带地区（患病率87％）高于温带地区（73％）。整体寿命,然而,在温带条件下较高（平均32.5±7.4周与23.3±6.5周），并且在前20周内生存率保持在70％以上。在接触寄生虫的人群中，预期寿命从总体的37.75周下降至11.35周,但仍是最初尾蚴脱落时间的两倍.cer虫脱落始于暴露后的第23天，并在第53天和第67天之间达到峰值，每个蜗牛平均有106个尾c。
结论：O.viridis是否会在欧洲取得成功还不得而知，但是很有可能出现这样一种情况，即Hepatca的主要蜗牛宿主占据了所有潜在传播病灶的可用栖息地，盘旋法西斯的流行病学。这项研究提供了对O.viridis生物学的全面了解，与寄生虫的相互作用以及对疾病传播动力学的潜在影响，为进一步的研究和监测提供有价值的见解。
方法：我们从其本地（马来西亚）和入侵（西班牙）地区收集了O.viridis的田间种群。我们对该物种进行了详细的形态解剖图，并筛选了寄生虫的自然感染。在精细的系统地理学研究中，使用ITS2对个体进行分子表征，以与现有序列进行比较。我们在两种不同的条件下建立了实验种群(热带，26°C和温带，21°C），以研究暴露和未暴露个体对不同肝肠球菌分离株的生活史特征。
结果：我们发现在西班牙野外种群中，吸虫感染的自然患病率为9％（与螺旋藻[Echinostomatidae]序列具有98％的相似性）。在我们来自西班牙的研究中发现的O.viridis的单倍型与澳大利亚单倍型聚集在一起。在两种实验条件下，肝菌的实验性感染均成功，但在热带地区（患病率87％）高于温带地区（73％）。整体寿命,然而,在温带条件下较高（平均32.5±7.4周与23.3±6.5周），并且在前20周内生存率保持在70％以上。在接触寄生虫的人群中，预期寿命从总体的37.75周下降至11.35周,但仍是最初尾蚴脱落时间的两倍.cer虫脱落始于暴露后的第23天，并在第53天和第67天之间达到峰值，每个蜗牛平均有106个尾c。
结论：O.viridis是否会在欧洲取得成功还不得而知，但是很有可能出现这样一种情况，即Hepatca的主要蜗牛宿主占据了所有潜在传播病灶的可用栖息地，盘旋法西斯的流行病学。这项研究提供了对O.viridis生物学的全面了解，与寄生虫的相互作用以及对疾病传播动力学的潜在影响，为进一步的研究和监测提供有价值的见解。
