Preventive Use of Tylosin in the Colonies Endangered by the Foulbrood and Residues of Tylosin in Honey and Syrup Stored by Honeybees

Veterinarni Medicina 37, 1992, 119-125

In the preceding laboratory experiments the high effectiveness of the antibiotic tylosin was tested with respect to the foulbrood disease pathogen Bacillus larvae, along with its nontoxicity to honey-bees. The present contribution indicates the results of preventive administration of tylosin to honeybee colonies endangered by the foulbrood and the results of this antibiotic residue determination in honey and syrup stored by honeybees after the therapeutic use of this medicament. Tests included the application of tylosin in the form of bee colony spraying by a medicated sugar syrup solution in which two concentrations were applied, 0.4 and 2.7 g tylosin were administered in the form of the preparation Tylan Elanco 200 injection a.u.v. with the content 200 mg active substance in 1 ml solution. In view of the target of the experiments, evidence of residues, the spray was intentionally applied to honeybee colonies at the feeding of sugar stores for winter or to colonies with already stored reserves. The total dose of the medicament was applied to colonies either in one application or in several partial in time divided sprays. Honeybee colonies tolerated the autumn treatment well and developed normally in the spring period. From all experimental bee colonies the remaining sugar stores were extracted in the spring and residues of tylosin were determined. For a comparison, control honey samples and extracted syrup stores with the inmixed tylosin concentration were prepared. The tylosin concentrations were equal to doses of 4, 27 and 63 ml Tylan per 10 kg feed. Tylosin residues were determined on agar diffusion plates containing a growth of Bacillus subtilis ATCC 6633. The determination method of tylosin in honey and sugar stores proved to be suitable, the sensitivity of the method made 5 mg in 1 kg feed. The concentration of the found residues in the control samples did not sink even after one-year storing of the above mentioned feeds at a room temperature (Tab. I). The occurrence of tylosin residues in the extracted sugar stores from the experimental bee colonies proved to be dependent on the administration of the medicament. Some residues were found at the colony where Tylan was applied simultaneously with the application of sugar stores (Tab. II). The residues in the colony treated in this way represented 8% of the originally applied autumn medical dose. With respect to the above-mentioned results and because of the well-known capability of the macrolid antibiotics to form the rapidly beginning chromosomal resistance of bacteria, it is necessary to apply the preventive chemotherapy of the foulbrood based on the antibiotic tylosin after careful consideration

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