Survey Synthesis of Toulouse iGEM Team

In order to have a better idea of the extent of beehives’ infestation by varroas, we have created a survey together with the METU HS Ankara iGEM team that was spread through Turkey and France.

We wish to underline the fact that in France there are few professional beekeepers, most of them are amateurs and own only a few hives. Thus there is no unity between these beekeepers, nor any syndicate. Hence the beekeepersthat answered our survey were already interested in our project and aware of the problem caused by Varroa. We take this opportunity of thanking them for their participation and their help: Matthieu Bourgeois,  Michel Rives, François Sénéchal, Daniel Goubert, Lauras, Sébastien Bernard, Henri Martin, Marie Nadau, Michel Muller, Charlotte Bompard, Bruno Frémont, Gérard Corvée, Jean Rouquet.

As said previously, all beekeepers having answered the survey know about varroa and other ailments of the bees, such as American/European foulbrood,  varroosis (caused by varroa), mycosis, chronical paralysis, nosema, sacced or chalk brood, deformed wings virus, colony collapse syndrome, acariosis or other dangers like the Asian hornet (a predator), pesticides or mold.

Impacts of Varroa’s presence:

Varroa itself acts both as a parasite feeding itself of the bee’s hemolymph, which weakens it, but also as a vector of pathogens like viruses that spread in an already weakened colony.  A beehive’s infestation by varroa is visible through:

• the presence of bees with deformed or atrophied wings,

• the decrease of honey yield,

• the weakening of the colony,

• in the most serious cases, the death of the queen and total loss of the colony.

Beekeepers observed an exponential growth of varroa population in the colonies during summer. Infestation stays at a bearable level during the summer, and it increases tremendously at the end of it, leading to the death of the colonies during fall or winter. Needless to say, this infestation has a financial impact, be it because of a decreased honey yield when it is sold, or because of the necessity of buying treatments or even new swarms. ¾ of beekeepers say they are affected financially by this mite.

Measures against varroa and their efficiency:

Beekeepers use different kinds of methods in the fight against varroa: physical methods such as a wire-mesh floor or the destruction of male broods preferentially infested by varroas,  chemical methods with products like apivar, amitraz, formic and oxalic acids, or essential oils, and finally the genetic selection of resistant bee strains.

These diverse methods are more or less efficient. The most efficient of treatments are the chemical ones, but this efficiency is never 100%.

These products have in common a few disadvantages: the varroa might habituate itself to it and become resistant, secondary effects can affect humans and bees, and finally it is usually not possible to use the treatments during honey making season when it is destined to be sold.

Impact of treatment use on honey yield:

Some beekeepers believe they don’t have enough perspective to estimate this impact. Furthermore, since most of them are amateurs honey production is not their first object. They are more concerned about the welfare of bees as pollinators.

This being said, we can state that honey quality is not affected by most products since they are used after the harvest and have enough time to disappear from the hive before the following year’s harvest. On the other hand, production is affected in the sense that an insufficiently treated beehive will have a population too small to effectively make honey. The size of the colony is linked to the harvest. If the queen lays a lot of eggs but varroas are numerous and weaken the new bees, the colony will weaken and will not be able to gather a lot of pollen to make honey. Furthermore, it is interesting to note that most beekeepers told us they would be interested in a treatment against varroa that is efficient, ecological and respectful of the bees.