Reitzel Adam M, Sullivan James C, Brown Briana K, Chin Diana W, Cira Emily K, Edquist Sara K, Genco Brandon M, Joseph Oliver C, Kaufman Christian A, Kovitvongsa Kathryn, Muñoz Martha M, Negri Tiffany L, Taffel Jonathan R, Zuehlke Robert T, Finnerty John R
Boston University, Department of Biology, 5 Cummington St., Boston, Massachusetts 02215, USA.
J Parasitol. 2007 Dec;93(6):1392-402. doi: 10.1645/GE-1250.1.
The lined sea anemone Edwardsiella lineata has evolved a derived parasitic life history that includes a novel body plan adapted for life inside its ctenophore hosts. Reputedly its sole host is the sea walnut, Mnemiopsis leidyi, a voracious planktivore and a seasonally abundant member of many pelagic ecosystems. However, we have observed substantially higher E. lineata prevalence in a second ctenophore species, the ctenophore predator Beroë ovata. The interplay among these 3 species has important conservation consequences as M. leidyi introductions are thought to be responsible for the severe depletion of numerous commercial fisheries in the Mediterranean basin, and both E. lineata and B. ovata have been proposed as biological controls for invasive M. leidyi. Over a 3-yr period (2004-2006), we collected 8,253 ctenophores from Woods Hole, Massachusetts, including M. leidyi, B. ovata, and a third ctenophore, Pleurobrachia pileus, and we recorded E. lineata infection frequencies, parasite load, and parasite location. We also conducted laboratory experiments to determine the likely mechanisms for parasite introduction and the effect of each host on parasite development. We observed peak E. lineata infection frequencies of 0% in P. pileus, 59% in M. leidyi, and 100% in B. ovata, suggesting that B. ovata could be an important natural host for E. lineata. However, in laboratory experiments, E. lineata larvae proved far more successful at infecting M. leidyi than B. ovata, and E. lineata parasites excised from M. leidyi exhibited greater developmental competence than parasites excised from B. ovata. Although we show that E. lineata is efficiently transferred from M. leidyi to B. ovata when the latter preys upon the former, we conclude that E. lineata larvae are not well adapted for parasitizing the latter species and that the E. lineata parasite is not well adapted for feeding in B. ovata; these developmental and ecological factors underlie the host specificity of this recently evolved parasite.
带纹海葵（Edwardsiella lineata）演化出了一种特殊的寄生生活史，包括一种适应于在其栉水母宿主内生存的独特身体结构。据说它唯一的宿主是海胡桃（Mnemiopsis leidyi），一种贪婪的浮游生物捕食者，也是许多远洋生态系统中季节性丰富的成员。然而，我们观察到在另一种栉水母物种——栉水母捕食者卵形双鳍鲳（Beroë ovata）中，带纹海葵的患病率要高得多。这三个物种之间的相互作用具有重要的保护意义，因为人们认为海胡桃的引入导致了地中海盆地众多商业渔业的严重枯竭，并且带纹海葵和卵形双鳍鲳都被提议作为入侵性海胡桃的生物控制手段。在2004年至2006年的3年时间里，我们从马萨诸塞州伍兹霍尔收集了8253只栉水母，包括海胡桃、卵形双鳍鲳和第三种栉水母——瓜水母（Pleurobrachia pileus），并记录了带纹海葵的感染频率、寄生虫负荷和寄生虫位置。我们还进行了实验室实验，以确定寄生虫引入的可能机制以及每种宿主对寄生虫发育的影响。我们观察到瓜水母中带纹海葵的感染频率峰值为0%，海胡桃中为59%，卵形双鳍鲳中为100%，这表明卵形双鳍鲳可能是带纹海葵的重要天然宿主。然而，在实验室实验中，带纹海葵幼虫感染海胡桃的成功率远高于感染卵形双鳍鲳，并且从海胡桃中取出的带纹海葵寄生虫比从卵形双鳍鲳中取出的寄生虫表现出更强的发育能力。尽管我们表明当卵形双鳍鲳捕食海胡桃时，带纹海葵能有效地从海胡桃转移到卵形双鳍鲳身上，但我们得出结论，带纹海葵幼虫不太适合寄生于后一种物种，并且带纹海葵寄生虫也不太适合在卵形双鳍鲳体内获取营养；这些发育和生态因素构成了这种最近演化出的寄生虫的宿主特异性。
