Bee-collected pollen and nectar contain multiple phytochemicals that can have anti-pathogenic effects when ingested. For example, the plant alkaloid, nicotine, can reduce infections by the trypanosome gut parasite (Crithidia bombi) in bumblebees. Parasitized bumblebees may be drawn to nicotine and thereby self-medicate their infection. We tested the hypothesis that nicotine can reduce infections of a common microsporidian pathogen, Nosema ceranae, in the honey bee gut. We found, however, that that a field realistic exposure dose of 1 ppm nicotine was not preferentially consumed by Apis mellifera foragers fed live Nosema spores (5 × 104 spores per bee; N = 160). One-day-old bees infected with Nosema (1 × 104 spores per bee; N = 160) showed no repression of nosemosis over a chronically applied exposure gradient of 0, 10−2, 10−1, 100, 101, 102, 103 or 104 ppm nicotine. Since imbibed nicotine may not effectively reach the spores in the bee gut, we conducted an in vitro experiment, in which Nosema spores were exposed up to 104 ppm nicotine in vials, rinsed of nicotine, and then fed to 1 day old bees (2 × 104 spores per bee; N = 216). However, the in vitro nicotine-treated spores remained infectious. Nicotine did impair bee mortality at high concentrations. Dietary nicotine is evidently not a treatment for nosemosis, but future studies should continue to examine the role of phytochemicals and bee health.

中文翻译：

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尼古丁不会减少蜜蜂的 Nosema ceranae 感染

蜜蜂采集的花粉和花蜜含有多种植物化学物质，摄入后可产生抗病原作用。例如，植物生物碱尼古丁可以减少大黄蜂锥虫肠道寄生虫（Crithidia bombi）的感染。被寄生的大黄蜂可能会被尼古丁吸引，从而自我治疗感染。我们测试了尼古丁可以减少蜜蜂肠道中常见微孢子虫病原体 Nosema ceranae 感染的假设。然而，我们发现，喂食活的 Nosema 孢子（每只蜜蜂 5 × 104 个孢子；N = 160）的蜜蜂采食者并不优先消耗 1 ppm 的现场实际暴露剂量的尼古丁。感染 Nosema 的 1 日龄蜜蜂（每只蜜蜂 1 × 104 个孢子；N = 160）在长期施加的 0、10-2、10-1、100、101、102、103 或 104 ppm 尼古丁。由于吸入的尼古丁可能无法有效地到达蜜蜂肠道中的孢子，我们进行了一项体外实验，其中 Nosema 孢子在小瓶中暴露于高达 104 ppm 的尼古丁，冲洗掉尼古丁，然后喂给 1 天大的蜜蜂 (2 ×每只蜜蜂 104 个孢子；N = 216）。然而，体外尼古丁处理的孢子仍然具有传染性。尼古丁在高浓度下确实会降低蜜蜂的死亡率。膳食尼古丁显然不能治疗鼻息肉，但未来的研究应该继续检查植物化学物质和蜜蜂健康的作用。然而，体外尼古丁处理的孢子仍然具有传染性。尼古丁在高浓度下确实会降低蜜蜂的死亡率。膳食尼古丁显然不能治疗鼻息肉，但未来的研究应该继续检查植物化学物质和蜜蜂健康的作用。然而，体外尼古丁处理的孢子仍然具有传染性。尼古丁在高浓度下确实会降低蜜蜂的死亡率。膳食尼古丁显然不能治疗鼻息肉，但未来的研究应该继续检查植物化学物质和蜜蜂健康的作用。