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 agonistic 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 spaces between the combs. The bees walk over the strips and distribute the active substance throughout the colony.
Amitraz reaches only the mites sitting freely on the bees; it does not penetrate capped brood cells. An effect on the mites in the brood arises only indirectly through the long application period of six to ten weeks, during which the mites released with the emerging bees are continuously killed. The active substance is therefore not suitable for a rapid emergency treatment, as its effect builds up slowly.
The recommended time for treatment is late summer or autumn after the last honey harvest, when only little brood is present compared with the annual peak. However, the bees must still be active enough to walk over the strips, otherwise the active substance is not distributed. The usual dosage 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 with repeated use in successive years. It is currently the only active substance available for honeybees for which a maximum residue limit 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. Where resistance is known, the active substance must not be used, and in affected areas it should no longer be used at all.
Preparations containing amitraz are prescription-only in Germany and can only be obtained through a veterinarian. The bee institutes recommend synthetic varroacides only as an emergency option; they are excluded for certified organic operations. The withdrawal period for honey is zero days when used as directed outside the nectar flow. Common mistakes are leaving the strips in beyond the authorized period, using the same active substance for years, and reusing brood combs as honey combs. Protective gloves must be worn when handling the strips, as amitraz can cause neurological reactions, skin sensitivity and eye irritation in humans. Leftovers and used strips must be disposed of as hazardous waste.
Sources (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