Vampires in the beehive: Baykomm - Bayer Communication Center

Special Story

Vampires in the beehive

For years, bee-keepers have been used to getting a nasty surprise when they inspect their hives. Weak, deformed bees incapable of flying are a not uncommon sight. The cause is obvious to any bee-keeper; the hives have been attacked yet again by varroa mites. Close inspection in fact reveals the eight-legged parasites attached very firmly between the abdominal segments of the honey bees. The mites suck hemolymph, the bee equivalent of blood. They lay their eggs directly next to the bee larvae in the honeycomb. In the natural course of events, the bee colony seals the honeycomb, leaving the next generation of parasites to develop completely undisturbed.

An aggressive mite is causing concern among bee-keepers all over the world. Bayer is the largest company involved in research into combating varroa, and offers two well-established products to tackle the problem.

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An aggressive mite is causing concern among bee-keepers all over the world. Bayer is the largest company involved in research into combating varroa, and offers two well-established products to tackle the problem.

The problem first arose in the 1970s, when mites originating in Asia started to spread across the globe. Today practically every continent is affected, with the damage varying from one year to the next. It is estimated that bee-keepers in the USA lose one quarter of their colonies every year, although in fact this level of damage was exceeded in western Europe in 2002/2003 when some 30 percent of bee colonies did not survive the winter.

The low honey yields produced under these circumstances are just one aspect of the problem. The matter is a growing concern among fruit-growers as well, since many varieties of fruit are dependent on cross-pollination. Bees play a major role here, since their natural movements transfer pollen from one tree to the stigmas of another tree.

The search for active substances capable of controlling the varroa mite is difficult and demanding. One particularly problematic aspect is that, in biological terms, bees and mites are fairly closely related, which means that they have similar metabolic processes.

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Varroa mite in detail

Suitable active ingredients need to be able to eliminate the mites without harming the bees. Bayer has over 20 years of experience in controlling the varroa mite. The company has already developed a number of effective active substances and concepts for using them. Bayer’s first product in this field was Perizin, an aqueous solution sprinkled onto the bees. However, it only acts for a short time, so it is best used when the hives no longer contain brood. If the next generation of bees has not pupated yet, it is better to use the other product sold by Bayer, strips impregnated with flumethrin which the bee-keeper hangs in the hives. The strips release the active substance over a period of several weeks, so they are also effective against mites which develop with the brood in the capped honeycomb and do not become accessible until the brood emerges. Dr. Sabine Ippendorf from the Animal Health Division of Bayer Vital in Leverkusen comments: “So the choice of product depends mainly on the time at which the bee-keeper wants to treat the hives.”

The Animal Health Division of Bayer HealthCare is also working on other ways of protecting bees. There is the danger that, if existing products are not used correctly, the mites could develop resistance to certain active ingredients. So Bayer is collaborating with various research institutes to determine, for example, the extent to which resistance can be prevented by using products in rotation. This means that the bee-keeper needs to use a different product every year, including flumethrin and Perizin in conjunction with compounds such as lactic acid, oxalic acid and formic acid.

The sad part of this success story is that it will probably never be possible to eliminate the varroa mite completely. As long as the parasite is capable of surviving in just a few hives, it will always be able to spread again. Even bee-keepers who have successfully eliminated varroa from their hives may be affected again the following year. At least it’s good to know that there are some effective products they can use to help them.