Myrmecochory, a type of ant-mediated seed dispersal, is a diffuse, widespread mutualism in which both partners are purported to benefit from the services or rewards of the other. However, ant benefits in this interaction are conflicted and understudied, especially in the context of microbial third parties. Here, we investigate the effect of a myrmecochore plant-produced antimicrobial chemical (sanguinarine) on the growth of a common entomopathogenic fungus (Beauveria bassiana). We then explore whether sanguinarine, through its effect on entomopathogen growth, might influence ant survival and foraging behavior. At high concentrations, sanguinarine increased the growth of B. bassiana, but fungal growth was not affected at concentrations of sanguinarine near natural levels produced in seeds. When ant colonies were exposed to B. bassiana, survival was not affected by a sanguinarine-supplemented diet. Furthermore, ant foraging patterns (preference for or avoidance of food items with sanguinarine) did not change when ants were exposed to the entomopathogen. Though sanguinarine promotes the growth of an entomopathogen at higher concentrations, which might pose an additional risk for ants in myrmecochory, we assert that social immune behavioral defenses (such as grooming or redispersal of seeds after elaiosome consumption) help ants mitigate this risk. By incorporating a microbial third party into this ant-plant interaction, we seek to more fully understand the risks and benefits provided to both partners in this mutualism. We encourage the investigation of third-party influences in reciprocal pairwise interactions to assist in the understanding of the evolution and persistence of mutualisms.

中文翻译：

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myrmecochore 产生的化学物质对昆虫病原真菌生长和种子传播蚂蚁存活率和觅食模式的影响

Myrmecochory 是一种蚂蚁介导的种子传播，是一种扩散、广泛的互惠互利，据称双方都可以从对方的服务或奖励中受益。然而，蚂蚁在这种相互作用中的好处是相互矛盾和研究不足的，特别是在微生物第三方的背景下。在这里，我们研究了 myrmecochore 植物产生的抗菌化学品（血根碱）对常见昆虫病原真菌（白僵菌）生长的影响。然后，我们探索血根碱是否通过其对昆虫病原体生长的影响，可能会影响蚂蚁的生存和觅食行为。在高浓度下，血根碱会促进 B. bassiana 的生长，但在接近种子中产生的天然水平的血根碱浓度下，真菌生长不会受到影响。当蚁群暴露于 B. bassiana 时，存活率不受补充血根碱的饮食的影响。此外，当蚂蚁暴露于昆虫病原体时，蚂蚁的觅食模式（偏好或避免含有血根碱的食物）并没有改变。尽管血根碱在较高浓度下会促进昆虫病原体的生长，这可能会给 myrmecochory 中的蚂蚁带来额外的风险，但我们断言，社会免疫行为防御（例如在食用弹性体后梳理或重新传播种子）有助于蚂蚁减轻这种风险。通过将微生物第三方纳入这种蚂蚁与植物的相互作用，我们力求更全面地了解这种互惠互利为双方提供的风险和利益。