Evaluation of kinetic behaviour of two preparations of tylosin administered in beehives for american foulbrood control

Abstract

We compared the kinetic behaviour of tylosin administered to beehives by dusting or paper-pack placement through three treatment protocols (D, PP, CONTROL). D (dusting): tylosin, divided in four portions, was sprinkled over the ends of the hives' top bars weekly for four weeks (n=3); PP (paper-pack placement): tylosin in paper packs was administered at two-week intervals (n=3); CONTROL (control): the hives were left untreated (n=3). In every inspection, from each of the nine hives, fifty young (2-day-old) larvae were sampled for drug analysis. The concentration of tylosin in the young larvae was determined by a microbiological assay with Geobacillus stearothermophilus ATCC 12980 as test organism. The (mean±SD) maximum concentration (Cmax) for D was 136.0±194.0 and for PP – 144.0±187.4 μg/mL; the time to reach Cmax (tmax) was 1.5±0.9 h for D and 1.8 ± 1.8 h for PP. The area under the tylosin behaviour kinetics curve between 0–1392 h with D was 308.7±185.2 and with PP: 326.4±141.0 μg/h/mL, indicating no statistical difference between the treatments (P>0.05). The shorter duration of paper-pack-administered tylosin observed in the larvae implied a lower risk of antibiotic residues in the resulting honey.