Agricultural habitats are frequently disturbed, and disturbances could have major effects on species in upper trophic levels such as hymenopteran parasitoids that are important for biological control. A strategy for conservation biological control is to provide a diversified agricultural landscape which increases the availability of resources such as sugar required by parasitoid biological control agents. Here, we ask whether parasitoids occurring in agriculture benefit from sugar resources more or less than parasitoids occurring in natural habitats surrounding agricultural fields. We collected parasitoids from agricultural alfalfa fields, field margins, and natural prairies, and in the lab we randomly divided them into two treatments: half were given a constant supply of a sugar source to test their residual lifespan, and half were given neither sugar nor water to test their hardiness. Collected individuals were monitored daily and their day of death recorded. Parasitoids receiving a sugar source lived substantially longer than those without. Parasitoids collected in prairies lived longer than those from alfalfa fields in both the residual lifespan and hardiness treatments, with parasitoids from field margins being intermediate between them. Furthermore, the benefits of a sugar source to increase longevity was lower for parasitoids collected in agriculture than in natural habitats. This suggests that, even though parasitoid biological control agents benefit from sugar resources, their short lifespans make the benefit of sugar resources small compared to parasitoids that occur in natural habitats and have longer lifespans, and are adapted to consistent sugar sources.

中文翻译：

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膜翅目寄生蜂在自然与农业生境中的寿命及其对生物防治的影响


农业生境经常受到干扰，干扰可能对上层营养级的物种产生重大影响，例如对生物控制很重要的膜翅目寄生蜂。保护性生物防治策略是提供多样化的农业景观，从而增加寄生生物防治剂所需的糖等资源的可用性。在这里，我们询问农业中出现的寄生蜂从糖资源中获益是否比农田周围自然栖息地中的寄生蜂更多或更少。我们从农业苜蓿田、田边和天然草原收集寄生蜂，在实验室中我们将它们随机分为两种处理：一半给予持续供应的糖源以测试其剩余寿命，另一半既不给予糖也不给予它们。水来测试它们的坚韧性。每天对收集的个体进行监测并记录他们的死亡日期。接受糖源的寄生蜂比没有糖源的寄生蜂寿命要长得多。在剩余寿命和耐寒性处理方面，草原采集的寄生蜂比苜蓿田采集的寄生蜂寿命更长，田边采集的寄生蜂介于两者之间。此外，对于在农业中收集的寄生蜂来说，糖源对延长寿命的益处低于在自然栖息地中收集的寄生蜂。这表明，尽管寄生蜂生物防治剂受益于糖资源，但与自然栖息地中存在的、寿命较长且适应一致糖源的寄生蜂相比，其较短的寿命使得糖资源的益处较小。