Bee Decline May Be Caused by an Excess of Manganese

An excess of manganese might be the culprit of the high bee-colony losses and the worldwide bee decline of late. This is the conclusion reached by intensive studies and practical experiments among beekeepers by Netherlands-based company Science in Water. Since winter mortality also occurs in remote areas far away from agricultural activities, and in nature conservational areas with a large quantity of flora, the root of the problem must be a general environmental factor. That factor might be manganese.


It is not the manganese itself that causes the decline in bees, but the processes that make manganese available to their systems. An excess of manganese leads to increased reproduction, resulting in too many young bees that cannot be fed sufficiently by the worker bees. An excess of manganese also stimulates bees to leave the hive. That is precisely what happens in the widely observed phenomenon Colony Collapse Disorder (CCD), one of its characteristics being empty hives.


A third issue with manganese is the role it plays in disease. The main problem in beekeeping is the occurrence of the varroa mite. “We asked the question, ‘Why does the varroa mite occur?’,” says Maarten van Hoorn, leader of the research team and owner of Science in Water. “It is known that the tick, also a spider, carries the Borrelia bacterium inside it. Borrelia, the cause of Lyme disease, helps the tick during the infection process, using manganese instead of iron. The manganese is transported to the host, in the case of the bees by the bacteria inside the varroa mite, thus influencing colony behaviour. The bee decline problem is therefore a general microbial issue, brought about by an excess of manganese.”


Science in Water asked beekeepers to supply additional iron to their colonies. Soon after application they reported a higher level of activity amongst their bees. Furthermore, they noticed a decrease in mites. “Both aspects were completely unexpected, nobody could predict this,” explains Maarten van Hoorn. “We are no beekeepers, so we must trust beekeepers’ observations; they know their bees.” Iron counteracts the effects of manganese. Work is now focused on applying iron to bee colonies on a much larger scale, and on finding more beekeepers willing to put these findings to the test.

Download this press release

Version in English

Version en Francais

Version in Deutsch

Remark: Note what Dennis van Engelsdorp says in the movie Vanishing of the bees (2010) between min. 21.00 – min. 21.40

“Something is making them susceptible for everything”.