Can bees survive with marroa mite?
The varroa mite is thought to be the chief cause of global bee deaths. Most beekeepers combat the pest with formic and oxalic acid, but thanks to funds from FondsGoetheanum, beekeeper Martin Dettli thinks there may be another way: co-existence between bees and varroa. The bee research project is still ongoing.
A few years back, Martin Dettli met two beekeepers who for many years had dispensed with acid treatment of varroa mite and yet had healthy colonies that were surviving despite varroa. How is such co-existence possible in the hive? To answer this question, Dettli ran a research project from 2014 to 2017.
The bees learn to live with mites
The results were surprising: both beekeepers referred to above have fewer winter losses than most of those who treat their colonies for mite. In colonies of one of the two beekeepers, investigators from the Liebefeld Centre for Bee Research demonstrated that the bees had developed a varroa-sensitive hygiene procedure, whereby the bees cleaned out brood cells containing mite, along with damaged grubs.
Bee journal reports on varroa tolerance
Dettli’s project had an impact on Swiss beekeepers as exciting as its actual findings. Without hesitation, the Swiss bee journal published two articles on varroa tolerance,1 a radical departure given that, in the past, beekeepers who did not treat the pest were thought to be beyond the pale and a risk to other keepers. How tolerance develops, and how it is passed on between colonies, is something we are only beginning to understand. In several studies it has also been found that existing tolerance is lost when hives are moved to a different site. At the conference of the working group for natural beekeeping in 2017, Ralph Büchler, director of the bee research institute in Kirchhain (DE), suggested that tolerance behaviour can be passed on between bees by imitation. This would mean that young bees learn it from their older sisters. Rudolf Steiner, in his day, already stated that this non-genetic form of behaviour replication underlies the evolution of all living creatures. 2
Follow-up project to provide confirmation
Dr Eva Frey and the author are now working on a follow-up project.
The trial design is simple. The investigators create two colony groups: group A has varroa-tolerant queens and bees, while group B contains tolerant queens and non-tolerant bees. The study aims to discover any differences between the trial and control group colonies regarding survival, mite numbers, bee viruses and reproductive success of the mites.
Research can lead to rethinking
If this proves to be the case, the project will lead to a big rethink amongst beekeepers, both about the important of heredity (genetics) for varroa tolerance and the way such tolerance is passed on within colonies.
The investigators are fortunate in that one of the participating beekeepers in this follow-up has made queens and bees available, allowing them to continue their study in the Swiss Emmental and at the Mellifera association trial apiary in the Swabian Mountains (DE), in this way also studying the possible effects of location and local adaptation.
Dr Johannes Wirz, biologist, Natural Science Section
1) Dettli, M. (2018): Varroatolerante Bienenvölker (1. Teil). Schweizerische Bienen-Zeitung 01/2018, S. 14–17; 1) Dettli, M. (2018): Varroatolerante Bienenvölker (2. Teil). Schweizerische Bienen-Zeitung 02/2018, S. 15–17;
2) Steiner, R. (1899): Haeckel and His Opponents, in GA 30. Published in German in Methodische Grundlagen der Anthroposophie, Dornach 1961.