Comparison of volatile compounds emitted by drone and worker brood of Apis mellifera infested by Varroa destructor mites

CORZO, MARÍA LUJÁN; MUNIENTE, MACARENA; RUSSO, ROMINA; ALBERTO GALINDO CARDONA; MONMANY GARZIA, A. CAROLINA; PALACIO, MARÍA ALEJANDRA; SCANNAPIECO, ALEJANDRA C.; LIENDO, M. C.

Congreso; Apimondia 48th International Apicultural Congress; 2023

Hygienic behavior (HB) is a social health mechanism displayed by honey bee workers of Apis mellifera by which dead or diseased brood is removed from the colony. Such behavior is known to be induced by olfactory cues and has been described as associated with hygiene of brood cells parasitized by the mite Varroa destructor. Even though the mite has preference for drone brood cells, the efficiency of hygienic behavior toward this type of brood is significantly lower compared to worker brood. A possible explanation for this difference is that the compounds associated with infested drone brood are different from those emitted by infested worker brood, and hence, adult worker bees do not respond as efficiently. The aim of this research was to explore volatile compounds associated with dead or mite infested brood of drones and workers bees, to detect similarities or differences in chemical profiles. To this end, 20 pupae of each treatment were placed in glass aeration chambers. Volatiles were collected for 24 h on filters containing adsorbent material, eluted with dichloromethane, and analysed by gas chromatography. The treatments were: dead worker brood, mite infested worker brood, dead drone brood, mite infested drone brood and healthy drone and worker brood (controls). The chemical profiles obtained differed between the treatments. Specifically, the mite-infested and dead brood share some compounds, while others were exclusive of infested brood. This pattern was similar between worker and drone pupae. When the compounds emitted by castes are compared, we found no similarities. In addition, a variation in the abundance of β-ocimene – a compound associated with HB- was found for brood of both castes, being higher for mite infested and dead pupae compared to control pupae. These results would indicate that there are specific/exclusive compounds of infested brood that differ between worker and drone brood. Further studies are needed to evaluate the role of β-ocimene and the other identified compounds in triggering the HB