Projekte 2019

Serial Killer – The varroa destructor

The worldwide dying of honeybees, wild bees and insects in general is a complex and enigmaticcphenomena. Pesticides, diseases and the general species shrinking in our modern agriculturalclandscape - all these factors play a certain role - even though it is yet not clear how they influence each other reciprocally. But beekeepers and scientists agree on the assumption that the worst threat for honey bees is a parasite living in bee colonies, called varroa-destructor.

In March 1784, 24 Ukrainian bee colonies of the western honeybee apis mellifera reached their new home. Colonel Arshenewskij, commander of an Irkutsk regiment, shortly stationed in Kasachstan had ordered them from his sister in Kiew. Wether he did so because of strategic considerations or as a hobby is unknown. In the following year all his bee colonies had died. But he did not give up. Again he ordered bee-colonies, this time from Bashkiria at the Ural. The second settlement succeeded and beekeeping became a prosperous business in the region. Slow but steady the descendants of the western European honeybee spreaded out to the east. From Tomsk (1803) to Krasnojarsk (1823), into the Baikal region (1851), to Chabarowsk (1887) and finally to the pacific coast in the area around Wladiwostok, close to the Korean border– right in the middle of the settlement area of the eastern honeybee apis cerana.

Above all "contact" between bee colonies means robbery. In late summer and autumn, when the food offer for bees is getting less, strong colonies set out to plunder the stocks of the weaker colonies. Often weak colonies are infested by parasites and so the plundering bees do not only bring home the honey but also the parasites of the weak colonies. For one of these parasites – the varroa mite – this is an ideal spreading mechanism. For the eastern honeybees apis cerana the varroa-mite is not really a problem because they had millions of years to „learn“ to defend themselves against the mite on an evolutionary basis. The mites, each not bigger than 1,5 millimeters, sting the bees and suck their blood – more accurate the haemolymphe. – and damage their brood. Apis cerana recognizes the varroa mite and makes it harmless by cleaning it out an biting off its legs. On the other hand the western honeybee did not have the same evolutionary „learning effect“. Instead the western bees meet the mite in the context of a cultural evolution through trade routes and economic aspects. So, Apis mellifera has no defending mechanism against the mite at all, which regularly leeds to the collapse of the colonies within one to two years. Trough this unrestrained proliferation the varroa mite is currently the biggest danger for the western honeybee.

For a long time the danger that goes out from the varroa mite was unnoticed by humans. So, parallel to a flourishing beekeeping in southwest Asia a roaring trading with bee colonies developed. And another new business at that time developed quite well too: the Trans-Siberian-Railway - an ideal vehicle to transport bee colonies over long distances - and with the bees the mites. According to this today the spread of the varroa mite can be verified precisely along the new transport system. In Europe the varroa mite appears for the first time end of the 70’s of the last century. Detected for the first time is the mite in 1965 in Bulgaria. In the 70’s the mite reaches West Europe, in the 80’s it arrived in North America. Only Australia is still free from the varroa mite, perhaps due to their strict quarantine regulations.

Currently, apis mellifera with its worldwide spread only has a chance to survive if it is supplied with a regular and and costly medical treatment through beekeepers. The wildly living western honeybees have disappeared and nearly every single honeybee we can see is only living on the basis of human efforts.

The sudden spread of the varroa mite is a consequence of our social development. Livestock farming, engineering, world trade. We won’t stop with this development and it can’t be undone. But the varroa mite shows: we don’t develop alone. With every step and every progress we are carrying things with us which we know and pay attention to, and others which we don’t know, estimate low or simply overlook.