Richards-Hrdlicka Kathryn L, Richardson Jonathan L, Mohabir Leon
School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA.
Dis Aquat Organ. 2013 Feb 28;102(3):169-80. doi: 10.3354/dao02552.
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is an emerging infectious fungal pathogen of amphibians and is linked to global population declines. Until now, there has only been 1 survey for the fungus in the northeastern USA, which focused primarily on northern New England. We tested for Bd in a large number of samples (916 individuals from 116 sites) collected throughout the state of Connecticut, representing 18 native amphibian species. In addition, 239 preserved wood frog Lithobates sylvaticus tadpoles from throughout the state were screened for the fungus. Bd presence was assessed in both the fresh field swabs and the preserved samples using a sensitive quantitative PCR assay. Our contemporary survey found widespread Bd prevalence throughout Connecticut, occurring in 14 species and in 28% of all sampled animals. No preserved L. sylvaticus specimens tested positive for the fungus. Two common species, bullfrogs R. catesbeiana and green frogs R. clamitans had particularly high infection rates (0.21-0.39 and 0.33-0.42, respectively), and given their wide distribution throughout the state, we suggest they may serve as sentinels for Bd occurrence in this region. Further analyses found that several other factors increase the likelihood of infection, including life stage, host sex, and host family. Within sites, ponds with ranids, especially green frogs, increased the likelihood of Bd prevalence. By studying Bd in populations not facing mass declines, the results from this study are an important contribution to our understanding of how some amphibian species and populations remain infected yet exhibit no signs of chytridiomycosis even when Bd is widely distributed.
两栖类壶菌蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）是一种新出现的两栖类传染性真菌病原体，与全球两栖类种群数量下降有关。到目前为止，美国东北部仅对该真菌进行过1次调查，主要集中在新英格兰北部。我们对从康涅狄格州各地采集的大量样本（来自116个地点的916个个体）进行了Bd检测，这些样本代表了18种本地两栖类物种。此外，还对该州各地保存的239只林蛙（Lithobates sylvaticus）蝌蚪进行了真菌筛查。使用灵敏的定量PCR检测法对新鲜的野外拭子样本和保存样本中的Bd存在情况进行了评估。我们此次的调查发现，Bd在康涅狄格州广泛流行，在14个物种以及所有采样动物的28%中都有发现。没有保存的林蛙标本检测出该真菌呈阳性。牛蛙（Rana catesbeiana）和绿蛙（Rana clamitans）这两种常见物种的感染率特别高（分别为0.21 - 0.39和0.33 - 0.42），鉴于它们在该州分布广泛，我们认为它们可能是该地区Bd出现情况的哨兵物种。进一步分析发现，其他几个因素会增加感染的可能性，包括生活阶段、宿主性别和宿主家族。在各个地点内，有蛙科动物尤其是绿蛙的池塘，Bd流行的可能性增加。通过研究未面临种群数量大幅下降的群体中的Bd，本研究结果对于我们理解一些两栖类物种和种群如何在Bd广泛分布的情况下仍被感染但却没有出现壶菌病迹象具有重要贡献。
