Varroa destructor mite electrophysiological responses to honey bee (Apis mellifera) colony volatiles.

Detection and interpretation of chemical cues is essential for Varroa destructor Anderson and Trueman, an important parasite of honey bees (Apis mellifera L.), to complete its life cycle. We collected volatiles from honey bee brood at various developmental stages and screened for V. destructor electrophysiological responses to these with gas chromatography-linked electrotarsal detection. Volatile collections contained several methyl-alkanes that evoked electrophysiological responses from V. destructor. Moreover, odors in honey bee colonies that regulate honey bee colony structure and function were also detected by V. destructor. Collections from mid- to late-stage larvae had detectable levels of low-volatility odors identified as components of the honey bee brood pheromone and branched alkanes likely originating from brood cuticle. Among these, several mid- to heavy-molecular weight compounds elicited high proportional electrophysiological responses by V. destructor relative to their abundance but could not be identified using chemical standards of previously documented honey bee brood odors. We suggest further investigation of these unknown volatiles and future behavioral assays to determine attractiveness/repellency (valence) of those identified through chemical standards.