Varroa Volatiles Offer Chemical Cues to Honey Bees for Initial Parasitic Recognition.

Olfaction mediated by the antennae is a vital sensory modality for arthropods and could be applied as a tool in pest control. The ectoparasitic mite poses a significant threat to the health of the honey bee worldwide and has garnered global attention. To better understand the chemical ecology of this host-parasite relationship, we collected and characterized the volatile organic compounds (VOCs) from and used electroantennography (EAG) to record the responses of honey bee ( and ) antennae to the different VOCs. Fifteen VOCs were detected from using gas chromatography-mass spectrometry (GC-MS), which mainly contained ethyl palmitate, followed by isoamyl alcohol, nonanal, and ethyl oleate. The EAGs for ethyl palmitate were higher at the lowest stimulus loading (5 μg/μL in liquid paraffin) in compared to , suggesting that may have acute sensitivity to low concentrations of some VOCs from . After exposure to ethyl palmitate for 1 h, the relative expression levels of and in significantly increased, as well as the level of in , while showed no significant changes. The results indicate that the EAG response was influenced by the VOC composition and concentration. tended to be more responsive than to the VOCs of . Our findings offer a deeper understanding of how bees recognize , potentially using ethyl palmitate as a chemical cue.