Data from: Cuticular hydrocarbon cues of immune-challenged workers elicit immune activation in honeybee 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.

近期已有研究证据表明，健康蜜蜂可通过表皮碳氢化合物（cuticular hydrocarbons, CHCs）谱的差异识别患病巢伴，并对其发起攻击行为。本研究旨在探明：患病巢伴释放的这类“免疫信号”是否仅能被工蜂感知并触发卫生行为、将其逐出蜂群，还是蜂王同样能够识别此类信号并做出相应应答。本研究让健康蜂王通过直接身体接触，分别接触三组巢伴：(1) 健康个体、(2) 林格液（Ringer）注射个体、(3) 脂多糖（lipopolysaccharide, LPS）注射个体。采用气相色谱-质谱联用仪（GC-MS）对上述三组巢伴的表皮碳氢化合物谱进行定量差异分析。通过实时定量PCR（qPCR），检测接触后的蜂王体内四种编码抗菌肽（antimicrobial peptides, AMPs，属于蜂王免疫应答组分）的基因的转录水平。实验结果显示，当蜂王与林格液注射组、脂多糖注射组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出现显著上调。本研究首次证实，对表皮碳氢化合物的识别可触发昆虫的免疫应答。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递给蜂王，同样引发了相似的免疫应答。通过距离实验，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，并为社会免疫的全新潜在机制提供了新的研究视角。