Formic Acid
Lexikon
Formic acid is an organic acid and one of the approved active ingredients against varroosis.
Formic acid is an organic acid and one of the approved active ingredients against varroosis. Its particular feature is what makes it so important for beekeeping: it is the only commonly used active ingredient that also reaches mites sitting under the cell capping in capped brood. All other organic acids only reach the mites sitting on the outside of the bees, and therefore require a broodless colony. This is precisely why formic acid is the usual active ingredient for summer treatment, that is, for the period when the colony still has brood.
The timing does not follow the calendar but the management style and the measured infestation level. The bee institutes schedule the first treatment immediately after the year's last honey harvest, so that the winter bees are reared as free of mites as possible. Depending on the infestation and the method used, a further application follows after feeding. A treatment before the last extraction is taboo, because it can alter the taste of the honey and the honey can then be rejected as defective.
Formic acid works through evaporation, and that is why the weather decides success. If too little acid evaporates, the mites survive. If too much evaporates, brood and queen are at risk of damage. Depending on the method of application, the institutes name different temperature windows, roughly in the range of about ten to thirty degrees. Long-term evaporators are considered less dependent on the weather and less error-prone than short shock treatments.
The most common mistake is not remeasuring after the treatment. Every treatment has an aftereffect period during which mite drop remains elevated. Only after that does the natural mite drop show whether the treatment worked. As a target figure, the institutes name fewer than about half a mite per day. Only approved veterinary medicinal products may be used, and strictly according to the package insert. Formic acid is strongly corrosive: acid-resistant gloves, safety goggles, respiratory protection, and water on hand belong to every application.
Quellen (4)
- Arbeitsgemeinschaft der Institute für Bienenforschung: Varroa unter Kontrolle (Broschüre, PDF)
- LAVES Institut für Bienenkunde Celle: Leitfaden zur Varroa-Bekämpfung (PDF)
- LWG Veitshöchheim, Fachzentrum Bienen: Varroa-Sommerbehandlung (PDF)
- BienenSchweiz: Übersicht Methoden Sommerbehandlung (Merkblatt 1.2, PDF)