1. Pesticides and parasites have each been linked to increased mortality in western honey bees (Apis mellifera). Currently, it is uncertain if one makes the other worse; several studies have tested for potential synergistic stressor effects, but results have been mixed.
2. Here, we use a hierarchical meta‐analysis of 63 experiments from 26 studies to gain a clearer view of the combined effects of parasites and pesticides on honey bee health.
3. We found that combined pesticide–parasite treatments do tend to be deadlier than uncombined treatments but are significantly less deadly than predicted additive or multiplicative effects. In other words, combined treatment effects are not synergistic, but antagonistic.
4. Much of the previous uncertainty about the combined effects of pesticides and parasites on honey bee health can be attributed to a bias in the previous research against stressor antagonism; many researchers have excluded the possibility of antagonism a priori.
5. Synthesis and applications. Meta‐analysis shows that when honey bees are stressed by a combination of pesticides and parasites, the combined stress effect is antagonistic, that is, less than the sum of its parts. A better understanding of the mechanisms underlying this antagonism could prove critical for effective management of honey bee health.

中文翻译：

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寄生虫和农药对蜜蜂的健康具有拮抗作用

1. 农药和寄生虫均与西方蜜蜂（Apis mellifera）死亡率增加有关。当前，不确定一个人是否会使另一个人变得更糟。几项研究测试了潜在的协同应激作用，但结果好坏参半。
2. 在这里，我们使用来自26个研究的63个实验的分层荟萃分析，以更清楚地了解寄生虫和农药对蜜蜂健康的综合影响。
3. 我们发现，农药-寄生虫联合治疗的确比非联合治疗更致命，但比预期的累加或倍增作用致命得多。换句话说，综合治疗效果不是协同作用，而是拮抗作用。
4. 先前关于农药和寄生虫对蜜蜂健康的综合影响的许多不确定性可归因于先前对应激物拮抗作用的研究存在偏见。许多研究人员已经排除了先验对抗的可能性。
5. 综合与应用。荟萃分析表明，当蜜蜂被农药和寄生虫联合胁迫时，联合胁迫作用是拮抗的，即小于其各部分之和。更好地理解这种拮抗作用的机制可能证明对有效管理蜜蜂健康至关重要。