Varroa Mite (Varroa destructor)
Lexikon
The varroa mite is the most significant parasite of the honey bee.
The varroa mite is the most significant parasite of the honey bee. It originally came from the Eastern honey bee and was introduced into Germany in the 1970s. It was not adapted to our honey bee, which is why untreated colonies generally die out. The adult female mite is brown, oval and flattened, and easily visible to the naked eye, for example when it sits between the abdominal segments of a bee or lies as a brown dot in the hive debris.
Decisive for understanding it is the reproductive cycle. The mother mite slips into a brood cell shortly before capping and reproduces there, protected under the cell cap. More daughter mites can develop in the longer-capped drone brood than in worker brood, which is why drone brood is infested considerably more heavily. The mites feed on the body substance of larvae, pupae and adult bees. Varroosis is thus neither a pure brood disease nor a disease of the adult bee, but a parasitic infestation that affects both sides.
The damage occurs twice over. Even a single mite in the cell weakens the emerging bee; several mites lead to malformations or death. In addition, the mite transmits viruses, above all the Deformed Wing Virus. It becomes critical in late summer: when brood volume and bee numbers decline, the infestation level rises sharply, and it is precisely then that the winter bees are being reared. Added to this is reinvasion, that is, the introduction of mites from collapsing colonies in the surrounding area through drifting and robbing.
In practice, several components lead to the goal: regular infestation monitoring via debris diagnosis or bee samples, biotechnical measures such as cutting out drone brood, forming nucleus colonies or brood removal, and, coordinated with these, treatment with authorized veterinary medicinal products. Every treatment then needs a follow-up check of its success. Legally, in Germany: varroosis is not among the notifiable bee diseases subject to compulsory reporting like American foulbrood, the small hive beetle and Tropilaelaps mites, but it is subject to the notification requirement. At the same time, the Bee Disease Ordinance obliges the owner to treat all colonies at an infested site against varroosis every year.