Developmental and Caste-specific Expression Patterns of ATP-Binding Cassette (ABC) Transporters in Honey Bees (Apis mellifera)0

While honey bees play a vital role in global crop production, they face increasing exposure to xenobiotic chemicals during commercial pollination. Multidrug-resistance (MDR)-type ATP-binding cassette (ABC) transporters provide the first line of defense against xenobiotic chemicals. This study investigated the gene expression profiles of 12 ABC transporters involved in chemical detoxification across three honey bee castes and 13 life stages using quantitative real-time PCR. Six ABC genes showed increased expression during worker bee development and were identified as MDR-like transporters (Ame-ABCB1, Ame-ABCB6, Ame-ABCC4a-c, Ame-ABCG1). Four transporters showed pupal-specific expression during metamorphosis. Queens exhibited significantly reduced MDR transporter expression compared to workers between 1.7-fold lower (ABCB6) and 17.5-fold lower (ABCB1). Drones showed intermediate expression levels. Queen ovaries demonstrated tissue-specific upregulation of select transporters. These findings reveal a vulnerability hierarchy (foragers > drones > queens) and suggest caste-specific trade-offs between reproduction and chemical defense in honey bee superorganisms.