We tested two summer protocols for oxytetracycline (OTC) administration on beehives to evaluate: toxicity for the bees, residues in honey and presence of genes encoding for OTC antibiotic resistance in bacteria isolated from the gut of adult bees. In July 2020, eighteen healthy colonies were divided into three groups. Two OTC treatment protocols - long and short, were devised, and one group was left untreated. We did not detect any toxicity on adult bees or brood but found OTC residues in the honey of the nest up to seven months after both treatments (210.3±221.2 µg/kg after long protocol; 216.2±238.4 µg/kg after short protocol), even in the untreated group (up to the mean 75.8±173.2 µg/kg). Antibiotic resistance genes were found, even in the untreated group, possibly due to the long exposure to antibiotics. More in-depth studies should be performed to verify how the long-term persistence of antibiotics impacted the beehive during the inactive season.

American foulbrood (AFB) and European foulbrood (EFB) are the two most important bacterial diseases that affect honey bee brood. The aim of this study was to evaluate the effects of an integrated treatment of AFB and EFB in naturally infected colonies in spring, using the beekeeping technique partial shook swarm combined with oxytetracycline treatment. The following parameters were assessed: strength of the colonies, consumption of antibiotic solution, queen losses, honey production and relapses. An increase in strength was observed in both (AFB and EFB) groups. Mean syrup consumption in the AFB colonies was 444.2 mL, while in the EFB colonies it was 497.3 mL. Linear correlation between the strength of the colonies and consumption (p-values < 0.0001; R² = 0.448) was observed. Three queens out of thirty (10%) were lost during the shook swarm procedure: one in the AFB group (5.3%) and two in the EFB group (18.2%). The results highlighted four clinical relapses (22.2%) of AFB, and no relapse (0%) of EFB after two years of observation. Six colonies (four in the AFB group and two in the EFB group) produced honey in the same beekeeping season that the shook swarm and antibiotic treatment were performed. Partial shook swarm is a good alternative to colony destruction, especially for EFB, and provides productive colonies during the foraging season.