Holland Manja P
School of Forestry and Environmental Studies, Yale University, 370 Prospect Street, New Haven, Connecticut 06511, USA.
J Parasitol. 2010 Oct;96(5):851-5. doi: 10.1645/GE-2351.1. Epub 2010 May 14.
Echinostomes are receiving increased attention because of their emerging parasite status in landscapes associated with human development and their ability to infect and kill many North American larval amphibians. While laboratory experiments have shown that echinostomes can cause extensive mortality in their amphibian hosts, their effect on tadpoles in the field is less clear. I conducted a controlled-infection field-enclosure experiment in 4 ponds to compare the effects of echinostomes on green frog (Rana clamitans) and gray tree frog (Hyla versicolor) tadpoles in the field. I measured tadpole growth, development, mortality, and infection intensity. Echinostome infection resulted in high mortality in green frog tadpoles and less mortality in gray tree frogs. However, metacercariae encystment rates were higher in gray tree frog tadpoles than in green frog tadpoles. The effect of echinostomes on mortality varies across amphibian species, with the result that some species may experience more extensive echinostome-induced mortality than others. Mortality as a result of echinostome infection in green frog tadpoles was similar to mortality observed in predation experiments.
由于棘口吸虫在与人类发展相关的环境中成为新兴寄生虫，且具有感染并杀死许多北美两栖类幼体的能力，它们正受到越来越多的关注。虽然实验室实验表明棘口吸虫可在其两栖类宿主中导致大量死亡，但其对野外蝌蚪的影响尚不清楚。我在4个池塘中进行了一项受控感染的野外围隔实验，以比较棘口吸虫对野外绿蛙（绿蛙）和灰树蛙（变色雨蛙）蝌蚪的影响。我测量了蝌蚪的生长、发育、死亡率和感染强度。棘口吸虫感染导致绿蛙蝌蚪的高死亡率和灰树蛙较低的死亡率。然而，囊蚴包囊率在灰树蛙蝌蚪中高于绿蛙蝌蚪。棘口吸虫对死亡率的影响因两栖类物种而异，结果是一些物种可能比其他物种经历更广泛的由棘口吸虫引起的死亡。绿蛙蝌蚪因棘口吸虫感染导致的死亡率与在捕食实验中观察到的死亡率相似。
