Data from: Cuticular hydrocarbon cues of immune-challenged workers elicit immune activation in honey bee queens

Recently, evidence has shown that variations in the cuticular hydrocarbons (CHCs) profile allow healthy honeybees to identify diseased nestmates, eliciting agonistic responses in the former. Here, we determined whether these ‘immunologic cues’ emitted by diseased nestmates were only detected by workers, who consequently took hygienic measures and excluded these individuals from the colony, or whether queens were also able to detect these cues and respond accordingly. Healthy honeybee queens were exposed to i) healthy, ii) Ringer-injected and iii) lipopolysaccharide (LPS)-injected nestmates by allowing direct body contact. Quantitative differences in the CHC profiles of these three groups were measured using GC-MS. The transcript levels of the products of four genes that encode for antimicrobial peptides (AMPs), which are part of the queen’s immune response, were measured in bees exposed to direct contact using qPCR. A significant increase in the transcript levels of these AMP genes over baseline levels in queens was observed when body contact was allowed between the queens and the Ringer- and LPS-injected nestmates. These results provide the first evidence that the detection of CHCs contributes to the initiation of an immune response in insects. In an additional experiment, CHCs were extracted from diseased workers and directly presented to queens, which also evoked a similar immune response. A potential mechanism that relied on volatile compounds could be ruled out by conducting a distance experiment. The study helps to expand our knowledge of chemical communication in insects and sheds light on a likely new mechanism of social immunity.近年来已有研究证实，表皮碳氢化合物（cuticular hydrocarbons, CHCs）谱的差异可使健康蜜蜂识别患病的巢伴，并引发健康蜂的争斗性反应。本研究旨在探究：患病巢伴释放的这类‘免疫相关信号’是否仅能被工蜂感知，进而触发卫生防控行为并将患病个体逐出蜂群；亦或是蜂王同样能够识别此类信号并做出相应响应。实验中，研究人员通过允许直接身体接触的方式，将健康蜂王分别暴露于三组巢伴：①健康个体、②经林格液注射的个体、③经脂多糖（lipopolysaccharide, LPS）注射的个体。采用气相色谱-质谱联用（GC-MS）技术，定量分析了这三组巢伴的表皮碳氢化合物谱差异。通过定量聚合酶链反应（qPCR），对直接接触过巢伴的蜂王体内四种编码抗菌肽（antimicrobial peptides, AMPs）的基因转录水平进行了检测——这四类抗菌肽属于蜂王免疫应答的组成部分。结果显示：当蜂王与经林格液注射、脂多糖注射的巢伴发生直接身体接触时，蜂王体内上述抗菌肽基因的转录水平较基线水平显著升高。本研究首次证实，对表皮碳氢化合物的感知可启动昆虫的免疫应答。在另一项补充实验中，研究人员从患病工蜂体内提取表皮碳氢化合物并直接呈现给蜂王，同样引发了相似的免疫应答。通过设置距离实验，可排除依赖挥发性化合物的潜在作用机制。本研究拓展了学界对昆虫化学通讯的认知，并为社会免疫的潜在新机制提供了重要依据。