BACKGROUND The preference-performance hypothesis predicts that oviposition preference of insects should correlate with host suitability for offspring development. Therefore, insect females have to be able to assess not only the quality of a given host but also the environmental conditions of the respective host habitat. Chemical cues are a major source of information used by insects for this purpose. Primary infestation of stored grain by stored product pests often favors the intense growth of mold. This can lead to distinct sites of extreme environmental conditions (hot-spots) with increased insect mortality. We studied the influence of mold on chemical orientation, host recognition, and fitness of Lariophagus distinguendus, a parasitoid of beetle larvae developing in stored grain. RESULTS Volatiles of wheat infested by Aspergillus sydowii and A. versicolor repelled female parasitoids in an olfactometer. Foraging L. distinguendus females are known to be strongly attracted to the odor of larval host feces from the granary weevil Sitophilus granarius, which may adhere in remarkable amounts to the surface of the grains. Feces from moldy weevil cultures elicited neutral responses but parasitoids clearly avoided moldy feces when non-moldy feces were offered simultaneously. The common fungal volatile 1-octen-3-ol was the major component of the odor of larval feces from moldy weevil cultures and repelled female parasitoids at naturally occurring doses. In bioassays investigating host recognition behavior of L. distinguendus, females spent less time on grains containing hosts from moldy weevil cultures and showed less drumming and drilling behavior than on non-moldy controls. L. distinguendus had a clearly reduced fitness on hosts from moldy weevil cultures. CONCLUSION We conclude that L. distinguendus females use 1-octen-3-ol for host habitat assessment to avoid negative fitness consequences due to secondary mold infestation of host patches. The female response to fungal volatiles is innate, suggesting that host-associated fungi played a crucial role in the evolution of host finding strategies of L. distinguendus. Research on the role of host-associated microorganisms in the chemically mediated orientation of parasitoids is still at the beginning. We expect an increasing recognition of this issue in the future.

中文翻译：

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使用真菌挥发物通过寄生体进行寄主生境评估。

背景技术偏好表现假设预测昆虫的产卵偏好应与宿主对后代发育的适宜性相关。因此，昆虫雌虫不仅必须能够评估给定寄主的质量，而且还要能够评估各自寄主生境的环境条件。化学提示是昆虫用于此目的的主要信息来源。储存的产品有害生物对储存谷物的主要侵害通常有利于霉菌的强烈生长。这可能会导致极端环境条件（热点）的不同地点，从而增加昆虫的死亡率。我们研究了霉菌对贮藏谷物中生长的甲虫幼虫的拟寄生物Lariophagus distinguendus的化学方向，寄主识别和适应性的影响。结果被Sydowii sydowii和A.侵染的小麦挥发物含量较高。嗅觉计中杂色驱除雌性寄生虫。众所周知，觅食的L. Distinguendus雌性会强烈地吸引到谷类象鼻虫Sitophilus granarius的幼虫宿主粪便的气味，而Sitophilus granarius可能会大量粘附在谷粒表面。来自发霉的象鼻文化的粪便引起中性反应，但是当同时提供非发霉的粪便时，寄生寄生物显然避免了发霉的粪便。常见的真菌挥发性1-辛烯-3-醇是发霉的象鼻虫养殖和天然雌性驱除雌性寄生虫的幼虫粪便气味的主要成分。在调查双歧李斯特菌宿主识别行为的生物分析中，与非软体动物对照相比，雌性花在含有发霉象鼻文化的宿主谷物上的时间更少，并且打鼓和钻孔行为更少。L. distinguendus对发霉象鼻文化的寄主的适应能力明显降低。结论我们得出的结论是，L。disinguendus雌性使用1-octen-3-ol进行寄主生境评估，以避免由于寄主斑块的继发性霉菌侵袭而造成的不良健康后果。女性对真菌挥发物的反应是先天的，这表明与宿主相关的真菌在L. distinguendus宿主寻找策略的进化中起着至关重要的作用。寄主相关微生物在化学介导的拟寄生物定向中的作用的研究仍处于起步阶段。我们希望将来对此问题的认识会越来越高。杰出女性使用1-octen-3-ol进行寄主生境评估，以避免因寄主斑块继发霉菌侵害而带来的不良适应性后果。女性对真菌挥发物的反应是先天的，这表明与宿主相关的真菌在L. distinguendus宿主寻找策略的进化中起着至关重要的作用。寄主相关微生物在化学介导的拟寄生物定向中的作用的研究仍处于起步阶段。我们希望将来对此问题的认识会越来越高。杰出女性使用1-octen-3-ol进行寄主生境评估，以避免因寄主斑块继发霉菌侵害而带来的不良适应性后果。女性对真菌挥发物的反应是先天的，这表明与宿主相关的真菌在L. distinguendus宿主寻找策略的进化中起着至关重要的作用。寄主相关微生物在化学介导的拟寄生物定向中的作用的研究仍处于起步阶段。我们希望将来对此问题的认识会越来越高。寄主相关微生物在化学介导的拟寄生物定向中的作用的研究仍处于起步阶段。我们希望将来对此问题的认识会越来越高。寄主相关微生物在化学介导的拟寄生物定向中的作用的研究仍处于起步阶段。我们希望将来对此问题的认识会越来越高。