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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.

Aethina tumida (Coleoptera: Nitidulidae - Small Hive Beetle - SHB), is a parasite of honey bee colonies that causes the notifiable disease called aethinosis. In 2014, SHB was detected in Southern Italy, where it is still present (Calabria region). As part of surveillance activities, official diagnosis of the disease is performed by veterinary services via visual inspection of single hives in the apiaries. New outbreaks can be eradicated and the spread of SHBs limited by early detection of new introductions. We report an alternative protocol for the diagnosis of SHB through swabs and hive debris analysis by PCR. This was tested in three apiaries through the evaluation of different SHB infestation levels with a hive inspection method. This approach for sampling, followed by biomolecular methods, was fast and useful in unfavorable conditions (bad weather, aggressiveness, robbing), could be integrated in the official diagnosis procedures and may act as pre-clinic indicator.