Pheromone and morphometric features of honey bee (Apis mellifera) queens imported to Canada from around the globe

Canada imports approximately 300,000 honey bee queens annually to support the beekeeping industry, in addition to producing queens domestically during the short rearing season. Over 80% of imported queens come from the U.S., with additional contributions (~5% each) from Italy, Australia, and Chile. We conducted morphometric analysis and pheromone profiling of domestic and imported queens representing all four dominant exporting countries, including "vaccinated" (transgenerational immune-primed, or TGIP) and non-TGIP queens from the U.S., to compare their physical and pheromonal qualities. Imported queens differed morphometrically from domestic queens, and this difference was driven by smaller ovary size (a plastic metric exhibiting transient changes due to temporary confinement). Queen retinue pheromone (QRP) profiles also differed in domestic and imported queens, and PERMANOVA analysis showed that transit duration and ovary size were the top two explanatory factors. TGIP queens tended to have lower pheromone abundances than non-TGIP queens; a pattern that does not appear to be driven by pre-existing morphological differences. This study did not assess whether morphometric and pheromone differences affect acceptance rates or performance, nor whether immune priming offers benefits if pheromone discrepancies are enduring. By the measured laboratory metrics, domestic (Canadian) queens are comparable or better on several dimensions and investment in local production appears justified.