Flumethrin
Behandlungsmittel
Flumethrin is a synthetic pyrethroid, i.e.
Flumethrin is a synthetic pyrethroid, i.e. an active substance structurally derived from the natural pyrethrins of chrysanthemums. It acts neurotoxically: at the mite's nerve membrane it keeps sodium channels open for a long time, which first causes overexcitation, then coordination disorders and paralysis, and, given sufficiently long exposure, the death of the mite.
Flumethrin is introduced into the colony via impregnated strips, which are either hung in the comb spaces or fitted as perforated strips at the hive entrance. The bees pick up the active substance while walking over the strips or passing through the entrance lock, and distribute it through the colony. Flumethrin is considered highly effective against the mites sitting freely on the bees and low in toxicity for bees and brood.
Flumethrin does not act into the capped brood. As with amitraz and thymol, an effect on brood mites arises only indirectly, over a long application period during which the mites freed by hatching bees are killed. For strips hung in the comb spaces, this is set at four to six weeks, for the entrance variant at least nine weeks until the end of flight activity. With entrance strips, it should be considered that they require flight activity; extended spells of bad weather reduce their effectiveness.
Two limitations are decisive for practice. Flumethrin is fat-soluble and leaves persistent residues in beeswax. And resistance of the Varroa mite to pyrethroids is also known from Germany, with a mutation at the target receptor in the sodium channel as the most common mechanism. Field studies found a resistance mutation carrier among the surviving mites in about half of the treated colonies. The active substance should therefore not be used in consecutive years.
Flumethrin-based products are approved as veterinary medicinal products in Germany and subject to pharmacy sale. With proper use outside the nectar flow, the withdrawal period for honey is zero days. A flumethrin treatment alone is generally not sufficient; a final mite treatment during the broodless period remains necessary. When handling the strips, gloves should be worn in addition to the usual protective clothing; used strips are hazardous waste.