Dynamics of a host-parasitoid interaction clarified by modelling and DNA sequencing

It has been hypothesized that the 2-year oscillations in abundance of
Xestia moths are mediated by interactions with 1-year Ophion parasitoid
wasps. We tested this hypothesis by modelling a 35-year time series of
Xestia and Ophion from northern Finland. Additionally, we used DNA
barcoding to ascertain the species diversity of Ophion and targeted
amplicon sequencing of their gut contents to confirm their larval hosts.
Modelling of the time-series data strongly supported the hypothesized
host–parasitoid dynamics and that periodic occurrence of Xestia moths is
mediated by Ophion. DNA barcodes revealed that Ophion included five
species rather than just one while targeted amplicon sequencing verified
that Ophion does parasitize Xestia. At least one Ophion species employs
1-year Syngrapha interrogationis as an alternate host, but it did not
detectably affect Xestia–Ophion dynamics. We also demonstrate the
previously unrecognized complexity of this system due to cryptic
parasitoid diversity.

已有假说认为，Xestia蛾类数量的2年周期性波动是由其与1年生命周期的Ophion寄生蜂之间的相互作用介导的。我们通过对芬兰北部35年的Xestia与Ophion时间序列数据进行建模，对该假说展开验证。此外，我们利用DNA条形码（DNA barcoding）技术确定Ophion的物种多样性，并通过对其肠道内容物进行靶向扩增子测序（targeted amplicon sequencing）来确认其幼虫宿主。时间序列数据建模结果强烈支持假设的宿主-寄生蜂动态关系，以及Xestia蛾类的周期性出现是由Ophion介导的这一结论。DNA条形码结果显示，Ophion包含5个物种而非单一物种；同时，靶向扩增子测序验证了Ophion确实寄生Xestia。至少有一种Ophion物种以1年生命周期的Syngrapha interrogationis作为替代宿主，但这并未对Xestia-Ophion动态产生可检测的影响。我们还揭示了该系统因隐性寄生蜂多样性而此前未被认识到的复杂性。