Pfenning Alaina C, Sparkes Timothy C
Department of Biological Sciences, DePaul University, 2325 North Clifton Avenue, Chicago, IL, 60614, USA.
School of Biological Sciences, University of Nebraska-Lincoln, 424 Manter Hall, 1104 T St, Lincoln, NE, 68588, USA.
Parasitol Res. 2019 Apr;118(4):1225-1229. doi: 10.1007/s00436-019-06251-8. Epub 2019 Feb 14.
Acanthocephalans have multi-host life cycles that include arthropods as intermediate hosts and vertebrates as definitive hosts. Eggs are dispersed into the habitat from definitive hosts and in some species eggs possess fibrils, which have been proposed to facilitate transmission to intermediate hosts. We examined the potential role of fibrils in transmission of the acanthocephalan Acanthocephalus dirus to its intermediate host Caecidotea intermedius, a stream-dwelling isopod. We identify three properties of fibrils that could favor transmission. First, there was a slow rate of fibril release, which was dependent on the actions of stream microorganisms. Second, eggs with fibrils were more likely to adhere to the substrate than those without fibrils. Third, in feeding trials, isopods exposed to eggs with fibrils had a higher infection prevalence than isopods exposed to eggs without fibrils. These properties could favor transmission by increasing the likelihood that eggs sink to the sediment occupied by their target hosts before adhering to items on the substrate (e.g., leaves) and by increasing recruitment after the eggs have been consumed.
棘头虫具有多宿主生命周期，其中节肢动物作为中间宿主，脊椎动物作为终末宿主。卵从终末宿主散布到栖息地，在某些物种中，卵具有纤维，有人认为这些纤维有助于传播到中间宿主。我们研究了纤维在棘头虫Acanthocephalus dirus传播到其中间宿主Caecidotea intermedius（一种生活在溪流中的等足类动物）中的潜在作用。我们确定了纤维可能有利于传播的三个特性。首先，纤维释放速度缓慢，这取决于溪流微生物的作用。其次，有纤维的卵比没有纤维的卵更有可能附着在基质上。第三，在喂食试验中，接触有纤维卵的等足类比接触无纤维卵的等足类感染率更高。这些特性可能通过增加卵在附着到基质上的物品（如树叶）之前沉入其目标宿主占据的沉积物中的可能性，以及通过增加卵被消耗后的招募率来促进传播。
