Oxalic Acid Spray Method
Behandlungsmittel
In the spray method, a diluted, sugar-free oxalic acid solution is applied as a fine mist directly onto the bee-covered combs.
In the spray method, a diluted, sugar-free oxalic acid solution is applied as a fine mist directly onto the bee-covered combs. Because virtually every bee is wetted in the process, mite exposure is higher than with trickling. The bee institutes point out that spraying broodless nucleus colonies and colonies is often more successful than repeated trickling.
As with trickling, oxalic acid acts only through contact and does not reach mites in the capped brood. The method is therefore tailored to situations in which there is no capped brood anyway: newly made nucleus colonies after the brood they were given has emerged, artificial swarms and natural swarms, as well as broodless colony parts after the split-and-treat method. It is thus a summer and early summer method and complements the winter treatment, but does not replace it.
For application, the concentrate is diluted with drinking water according to the instructions for use. For spray application with Oxuvar 5.7%, a 3% working solution is prepared, of which about 2 to 4 milliliters are sprayed per fully bee-covered comb side at temperatures above 8 degrees, up to a maximum of around 80 milliliters per colony. For swarms and artificial swarms, the Bavarian State Institute gives 20 to 25 milliliters per kilogram of bees. The combs are sprayed at an angle of about 45 degrees so that as little solution as possible gets into open cells. Treatment takes place outside of flight activity, that is, early in the morning or in the evening.
The most important application error is soaking the bees. A fine spray mist should be produced that merely wets the bees, not drenches them. Equally critical is a treatment while capped brood is still present, because then a considerable proportion of the mites remain unreached. A further mistake is omitting a later residual mite treatment, because the efficacy of the summer measures alone is generally not sufficient.
Legally, spray application applies only to products that are expressly authorized for it. For Oxuvar 5.7%, the withdrawal period is zero days for correctly treated colonies, and the treatment must be carried out without honey supers in place. Spraying produces an aerosol, so in addition to acid-resistant gloves and safety goggles, an FFP2 respirator mask is also required.
Sources (3)
- Emmerich, I.: Zugelassene Arzneimittel für Honigbienen in Deutschland, Berliner und Münchener Tierärztliche Wochenschrift 2018
- LWG Veitshöchheim: Bayerisches Varroabehandlungskonzept, Medikamentöse Standardverfahren
- Varroose-Bekämpfungskonzept Baden-Württemberg, Landesanstalt für Bienenkunde Hohenheim, Stand 11/2024