Amitraz
Behandlungsmittel
Amitraz belongs to the substance group of triazapentadienes and, like many antiparasitics, originates from crop protection.
Amitraz belongs to the substance group of triazapentadienes and, like many antiparasitics, originates from crop protection. It acts as a nerve poison: through antagonistic effects at the octopamine receptors in the mite's central nervous system, it triggers overexcitation, abnormal behavior, and paralysis; the mite detaches from the host and dies. In beekeeping, the active substance is introduced via impregnated strips that are hung in the comb spaces. The bees walk over the strips and distribute the active substance through the colony.
Amitraz only reaches mites sitting freely on the bees; it does not penetrate into capped brood cells. An effect on brood mites arises only indirectly, over the long application period of six to ten weeks, during which the mites freed by hatching bees are continuously killed. It is therefore not suitable for rapid emergency treatment; the effect builds up slowly.
Late summer or autumn after the last honey harvest is recommended as the treatment time, when, compared with the annual peak, only little brood is present. The bees must, however, still be active enough to walk over the strips, otherwise the active substance is not distributed. The usual dose is 1 gram of amitraz per colony, corresponding to two strips of 500 milligrams each.
Two points are critical. First, residues: amitraz is fat-soluble and leads to residues in wax and honey, especially at higher doses and repeated application in consecutive years. It is currently the only active substance available for honey bees for which a maximum residue level has been set; it is 200 micrograms per kilogram of honey. Second, resistance: resistance of the Varroa mite to amitraz has been described, and insufficient efficacy has also been reported from Germany. If resistance is known, the active substance must not be applied, and in affected areas it should no longer be used.
Amitraz-based products are prescription-only in Germany and must be obtained through a veterinarian. The bee institutes recommend synthetic varroacides only as an emergency option; they are excluded for organically certified operations. The withdrawal period for honey is zero days for proper use outside the nectar flow. Common mistakes are leaving the strips in beyond the approved duration, using the same active substance year after year, and reusing brood combs as honey combs. When handling the strips, protective gloves should be worn, since amitraz can cause neurological reactions, skin sensitivity, and eye irritation in humans. Leftovers and used strips belong in hazardous waste.
Quellen (4)
- Emmerich, I.: Zugelassene Arzneimittel für Honigbienen in Deutschland, Berliner und Münchener Tierärztliche Wochenschrift 2018
- LLH Bieneninstitut Kirchhain: Infoblatt Varroazide
- bienen&natur: Amitraz, die chemische Behandlung
- Hernández-Rodríguez, C. S. et al.: Large-Scale Monitoring of Resistance to Coumaphos, Amitraz and Pyrethroids in Varroa destructor, Insects 12(1):27, 2021