Martinson Ellen O, Werren John H
Biology Department, University of Rochester, RC Box 270211, Rochester, New York 14627.
Ecol Entomol. 2018 Apr;43(2):146-153. doi: 10.1111/een.12480. Epub 2017 Oct 13.
Parasitoid wasps sting and inject venom in arthropod hosts, which alters host metabolism and development while keeping the host alive for several days, presumably to induce benefits for the parasitoid young.Here we investigate the consequences of host envenomation on development and fitness of wasp larvae in the ectoparasitoid , by comparing wasps reared on live unstung, previously stung, and cold-killed hosts. Developmental arrest and suppression of host response to larvae are major venom effects that occur in both stung and cold-killed hosts, but not unstung hosts; while cold-killed hosts lack venom effects that require a living host. Thus, cold-killed hosts mimic some of the effects of venom, but not others.Eggs placed on live unstung hosts have significantly higher mortality during development, however successfully developing wasps from these hosts have similar lifetime fecundity to wasps from cold-killed or stung hosts. Therefore, although venom is beneficial, it is not required for wasp survival.While wasps developing on cold-killed versus stung hosts have similar fitness, multiple generations of rearing on cold-killed hosts results in significant fitness reductions of wasps.We conclude that the largest benefits of venom are induction of host developmental arrest and suppression of host response to larva (e.g. immune responses), although more subtle benefits may accrue across generations, or under stressful conditions.
寄生蜂会叮咬节肢动物宿主并注入毒液，这会改变宿主的新陈代谢和发育过程，同时使宿主存活数天，大概是为了给寄生蜂幼虫带来益处。在这里，我们通过比较在活的未叮咬宿主、先前叮咬过的宿主以及冷杀死的宿主上饲养的黄蜂，来研究宿主被注入毒液对体外寄生蜂幼虫发育和适合度的影响。发育停滞和宿主对幼虫反应的抑制是毒液的主要作用，在被叮咬和冷杀死的宿主中都会出现，但在未叮咬的宿主中不会出现；而冷杀死的宿主缺乏需要活宿主的毒液作用。因此，冷杀死的宿主模拟了毒液的一些作用，但不是全部。放置在活的未叮咬宿主上的卵在发育过程中的死亡率显著更高，然而从这些宿主成功发育的黄蜂与从冷杀死或叮咬过的宿主发育而来的黄蜂具有相似的终生繁殖力。因此，虽然毒液是有益的，但黄蜂生存并不需要它。虽然在冷杀死的宿主上发育的黄蜂与在被叮咬的宿主上发育的黄蜂具有相似的适合度，但在冷杀死的宿主上多代饲养会导致黄蜂的适合度显著降低。我们得出结论，毒液的最大益处是诱导宿主发育停滞和抑制宿主对幼虫的反应（如免疫反应），尽管在几代之间或在压力条件下可能会产生更微妙的益处。
