Parasites and a host's sense of smell: reduced chemosensory performance of fathead minnows (Pimephales promelas) infected with a monogenean parasite

1. Parasites residing within the central nervous system of their hosts have the potential to reduce various components of host performance, but such effects are rarely evaluated. 2. We assessed the olfactory acuity of fathead minnows (Pimephales promelas) infected experimentally with the monogenean Dactylogyrus olfactorius, the adults of which live within the host's olfactory chambers. 3. Olfactory acuity was compared between infected and uninfected hosts by assessing electro-olfactography (EOG) neural responses to chemical stimuli that indicate the presence of food (L-alanine) or the presence of conspecifics (taurocholic acid). We also compared differences in gross morphology of the olfactory epithelium in infected and uninfected minnows. 4. Differences in EOG responses between infected and uninfected minnows to both cue types were non-significant at 30 d post-exposure. By days 60 and 90, coincident with a two times increase in parasite intensity in the olfactory chambers, the...1. 寄生于宿主中枢神经系统内的寄生虫，可对宿主的多项生理性能指标产生抑制作用，但此类效应的相关评估却极为匮乏。 2. 我们对经实验感染单殖吸虫（monogenean）嗅器指环虫（Dactylogyrus olfactorius）的黑头呆鱼（Pimephales promelas，fathead minnow）开展了嗅觉灵敏度评估，该吸虫的成虫阶段寄生于宿主的嗅囊腔内。 3. 我们通过检测宿主对两类化学刺激物的电嗅觉描记法（electro-olfactography, EOG）记录的神经反应，对比感染与未感染宿主的嗅觉灵敏度：其中一类刺激物为指示食物存在的L-丙氨酸（L-alanine），另一类为指示同种宿主个体存在的牛磺胆酸（taurocholic acid）。此外，我们还对比了感染与未感染黑头呆鱼的嗅上皮大体形态差异。 4. 感染与未感染黑头呆鱼对两类刺激物的EOG反应差异在暴露后30天时均无统计学显著性。至暴露后60天与90天时，宿主嗅囊内的寄生虫感染强度较此前提升一倍，此时……