Urban biomonitoring of trace elements and antimicrobial resistance using European honey bees

European honey bees (Apis mellifera) interact with an array of potentially contaminated media like soil, water, and air during foraging, and consequently, may be efficient sentinels for evolving contamination concerns. Trace element (As, Cu, Fe, Mn, Pb, S, V, Zn) and antimicrobial resistance (AMR) trends are examined as markers of anthropogenic activity at 18 hives across an urban gradient to assess biomonitor efficacy. The data show that diverse environmental conditions are reflected by honey bees, evidenced by correlations (p < 0.05) between Pb in bees, soil and dust, and enriched ‘anthropogenic’ elements in inner-city and industrial hives. Overall, 83% (n=120) of bees were positive to one or more of five AMR targets. Resistance to the common antibiotic, trimethoprim, was evident in 35% (51) of bees. This study presents the first quantification of Class 1 integrons in honey bees. These acquired genetic markers were present at all hives and in 52% (75) of individual bees, and correlations (p < 0.005) between integron prevalence and the proportion of waterbodies within foraging distance suggests that aquatic environments are potential vectors for AMR. This study demonstrates that an insect biomarker can efficiently evaluate the presence and abundance of potentially harmful contaminants across urban environments.