State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2011;6(8):e23260. doi: 10.1371/journal.pone.0023260. Epub 2011 Aug 11.
Optimality models of host-parasitoid relationships have traditionally assumed that host quality increases as a function of host size at parasitism. However, trade-offs may play a crucial role in species evolution and should be found in host-parasitoid interactions where the host quality may differ between different sizes. Here, we investigated the effects of host size differences of Monochamus alternatus larva on foraging decisions, parasitism and related fitness in a gregarious ectoparasitoid, Sclerodermus harmandi. Two-choice and non-choice experiments were conducted with M. alternatus larvae to evaluate preference and performance of S. harmandi, respectively. Results from two-choice test showed that adult females prefer to attack large larvae rather than small larvae. In no-choice tests, adult females needed more time to paralyze large larvae than small larvae before laying eggs on the body surface of M. alternatus larvae and had lower survival and parasitism rate on those large larvae. Foraging decisions of S. harmandi led to the selection of the most profitable host size for parasitoid development, which showed more offspring gained on large M. alternatus larvae than on small larvae and got higher body weight on those large hosts. This study demonstrates the existence of trade-off occurring during host-parasitoids interactions according to host size related quality.
宿主-寄生蜂关系的最优模型传统上假定，在寄生时，宿主质量随着宿主大小的增加而增加。然而，权衡可能在物种进化中起着至关重要的作用，并且应该在宿主质量在不同大小之间存在差异的宿主-寄生蜂相互作用中找到。在这里，我们研究了宿主大小差异对聚集外寄生蜂 Sclerodermus harmandi 觅食决策、寄生和相关适应性的影响。利用 M. alternatus 幼虫进行了二选一和非选择实验，分别评估了 S. harmandi 的偏好和性能。二选一测试的结果表明，成年雌性更喜欢攻击大幼虫而不是小幼虫。在非选择测试中，成年雌性在将卵产在 M. alternatus 幼虫体表之前，需要更多的时间来麻痹大幼虫，而不是小幼虫，并且在那些大幼虫上的存活率和寄生率较低。S. harmandi 的觅食决策导致了最有利于寄生蜂发育的最有利宿主大小的选择，这表明在大 M. alternatus 幼虫上获得的后代比在小幼虫上获得的后代更多，并且在那些大宿主上获得的体重更高。这项研究表明，根据与宿主大小相关的质量，宿主-寄生蜂相互作用中存在权衡。
