Zelmer D A, Esch G W
Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27109, USA.
J Parasitol. 1998 Aug;84(4):778-82.
Interactions between metacercariae of Halipegus occidualis and ostracod second intermediate hosts (Cypridopsis sp.) were examined over 5 wk using female ostracods exposed to 4 cercariocysts each and maintained in isolation. Control ostracods were subjected to the same manipulations but were not exposed to cercariae. Growth of metacercariae over 4 wk was not constrained by either infection intensity or ostracod size. The number of eggs produced by ostracods was significantly reduced by the presence of metacercariae in an intensity-dependent manner. This reduction in reproductive output, combined with a significantly higher survivorship of exposed ostracods, suggests infection by H. occidualis may result in ostracod castration. These effects are considered to be the result of persistent ancestral traits rather than adaptation.
使用单独饲养的雌性介形虫，使其每只接触4个尾蚴囊，在5周内研究了偶见哈氏吸虫（Halipegus occidualis）囊蚴与介形虫第二中间宿主（Cypridopsis sp.）之间的相互作用。对照介形虫接受相同操作，但未接触尾蚴。4周内囊蚴的生长不受感染强度或介形虫大小的限制。介形虫产生的卵数量因囊蚴的存在而显著减少，且呈强度依赖性。生殖产出的这种减少，加上暴露介形虫的存活率显著更高，表明偶见哈氏吸虫感染可能导致介形虫去势。这些影响被认为是持久的祖先特征而非适应性的结果。
