Fryer S E, Oswald R C, Probert A J, Runham N W
School of Animal Biology, University College of North Wales, Bangor, Gwynedd, United Kingdom.
J Parasitol. 1990 Aug;76(4):557-63.
Three species of bulinid snails were monitored to determine the effect of infection with 2 sympatric strains of Schistosoma haematobium on longevity, growth, and reproductive output, from the onset of cercarial production until death. Bulinus senegalensis was least affected by infection, with total fecundity reduced by less than 34%. Infected Bulinus truncatus showed an acceleration in growth accompanied by a 63% reduction in fecundity, although the majority of snails continued to oviposit at a low level. The longest-lived snails in this study, Bulinus globosus, showed decreased growth and survival when infected. In addition a significant proportion of infected individuals of this species failed to oviposit, and those that retained some reproductive capacity produced fewer embryos than controls. Total fecundity of B. globosus was reduced almost 90% by infection with S. haematobium, yet long-term monitoring of individuals showed that reproductive activity recovered when parasite productivity was low. Results from this and similar studies indicate that the time of infection by a trematode in relation to reproductive maturity of the molluscan host is important in determining the subsequent effects on host growth and fecundity.
对三种双脐螺进行了监测，以确定感染两种同域分布的埃及血吸虫菌株对其寿命、生长和繁殖产出的影响，监测时间从尾蚴产生开始直至死亡。塞内加尔双脐螺受感染的影响最小，总繁殖力降低不到34%。受感染的截形双脐螺生长加速，繁殖力降低63%，不过大多数蜗牛仍能少量产卵。本研究中寿命最长的球形双脐螺在受感染时生长和存活率下降。此外，该物种有很大比例的受感染个体无法产卵，而那些仍保留一定繁殖能力的个体产生的胚胎比对照组少。感染埃及血吸虫后，球形双脐螺的总繁殖力降低了近90%，但对个体的长期监测表明，当寄生虫繁殖力较低时，繁殖活动会恢复。这项研究及类似研究的结果表明，吸虫感染时间与软体动物宿主生殖成熟度的关系对于确定随后对宿主生长和繁殖力的影响很重要。
