Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 8, 2002
Publication Date: November 8, 2002
Citation: Pettis, J.S., Kochansky, J.P., Feldlaufer, M.F. 2002. Larval honey bee mortality following topical application of antibiotics and dusts. Journal of Economic Entomology. 97(2):171-176. Interpretive Summary: A bacterial disease of honey bees, American Foulbrood, is commonly controlled by the application of antibiotics in a powdered sugar carrier to bee colonies. Anecdotal reports by beekeepers indicate that the antibiotic, oxytetracycline, can be toxic when applied in powdered sugar to bees in their larval stage. It is not known if the purported toxicity is due to the antibiotic or the sugar carrier. We tested three antibiotics, the powdered sugar carrier, and several other dusts for larval toxicity. Oxytetracycline was shown to be toxic to larval bees, while two new candidate antibiotics being tested for use in bee colonies, were both non-toxic. The common antibiotic carrier, powered confectioners sugar, was shown to be non-toxic. However, wheat flour, talc, and a commercially available protein supplement were all toxic when applied to bee larvae. This information will be used by scientists and state apiary inspectors to design new delivery methods for the treatment of bee diseases.
Technical Abstract: Beekeepers apply various dusts to honey bee colonies to dislodge parasitic mites and control bacterial brood diseases. The bacterial disease American Foulbrood is commonly controlled by the application of antibiotics in a powdered sugar carrier. Anecdotal reports by beekeepers indicate that the antibiotic oxytetracycline can be toxic when applied in powdered sugar to cells containing immature bee brood. It was not known if the purported toxicity is due to the antibiotic or the sugar carrier. Additionally, the toxicity of various dusts used for parasitic mite control is poorly known. In the current studies we tested for larval toxicity using oxytetracycline and two other antibiotics (tylosin and lincomycin, candidate compounds for use in honey bee colonies) in a powdered sugar carrier. Additionally, we tested several dusts that have been proposed for mite control for toxicity to immature bee brood. Oxytetracycline was toxic at the concentrations used in the bee colonies (200mg in 20g sugar) and at half this concentration. In contrast, tylosin and lincomycin were both non-toxic at the 200mg dose. The addition of dusts, other than powdered sugar, resulted in mortality levels equal to that seen with oxytetracycline. Wheat flour, talc, and a commercially available protein supplement were all toxic when applied to immature brood. The common antibiotic carrier, powered confectioners sugar, was shown to be non-toxic. Two new candidate antibiotics for use in honey bee colonies were shown to be less toxic to immature brood than the currently labeled antibiotic, oxytetracycline.