Università degli studi di Firenze, Dipartimento di Biologia, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Firenze, Italy.
Sci Rep. 2019 Feb 28;9(1):3171. doi: 10.1038/s41598-019-38963-3.
Honeybee colonies are under the threat of many stressors, biotic and abiotic factors that strongly affect their survival. Recently, great attention has been directed at chemical pesticides, including their effects at sub-lethal doses on bee behaviour and colony success; whereas the potential side effects of natural biocides largely used in agriculture, such as entomopathogenic fungi, have received only marginal attention. Here, we report the impact of the fungus Beauveria bassiana on honeybee nestmate recognition ability, a crucial feature at the basis of colony integrity. We performed both behavioural assays by recording bee guards' response towards foragers (nestmate or non-nestmate) either exposed to B. bassiana or unexposed presented at the hive entrance, and GC-MS analyses of the cuticular hydrocarbons (CHCs) of fungus-exposed versus unexposed bees. Our results demonstrated that exposed bees have altered cuticular hydrocarbons and are more easily accepted into foreign colonies than controls. Since CHCs are the main recognition cues in social insects, changes in their composition appear to affect nestmate recognition ability at the colony level. The acceptance of chemically unrecognizable fungus-exposed foragers could therefore favour forager drift and disease spread across colonies.
蜜蜂种群受到许多胁迫因素的威胁，包括生物和非生物因素，这些因素强烈影响着它们的生存。最近，人们对化学农药的关注度越来越高，包括其在亚致死剂量下对蜜蜂行为和蜂群成功的影响；而在农业中广泛使用的天然杀虫剂的潜在副作用，如昆虫病原真菌，却只受到了有限的关注。在这里，我们报告了真菌球孢白僵菌对蜜蜂巢内识别能力的影响，这是蜂群完整性的基础上的一个关键特征。我们通过记录守卫蜜蜂对在蜂巢入口处出现的暴露于或未暴露于 B. bassiana 的觅食者（巢内或巢外）的反应，进行了行为分析，同时对暴露于和未暴露于真菌的蜜蜂的表皮碳氢化合物（CHCs）进行了 GC-MS 分析。我们的结果表明，暴露于真菌的蜜蜂的表皮碳氢化合物发生了变化，比对照更容易被接受进入其他蜂巢。由于 CHCs 是社会性昆虫的主要识别线索，其组成的变化似乎会影响巢内识别能力。因此，对化学上无法识别的真菌暴露觅食者的接受可能会促进觅食者的漂移和疾病在蜂群之间的传播。
