Introduction

Honeybees are incredibly important pollinators responsible for the abundance and diversity of our food. Unfortunately, honeybees are in trouble: the fittingly named Varroa destructor (from here on ‘Varroa’ or ‘Varroa mite’)weakens the bees and spreads diseases. iGEM Wageningen UR 2016 aims to save the bees from Varroa.

Honeybees can pollinate an enormous range of plants through active collection of pollen¹, making them important for pollination of crops. Apples, almonds and numerous other crops rely heavily on bee pollination, tying the diversity of our diet to the well-being of these insects¹. Therefore, it is of key importance to keep bees alive and healthy.

Unfortunately bees are not doing well at all. There has been a sustained loss of bee colonies in the western world for at least 10 years. In 2014-2015, US beekeepers lost over 40% of their colonies²! Such numbers are unacceptable!

Varroa destructor

What causes the loss of bee colonies? According to beekeepers we have spoken to and as has been suggested in scientific studies^3,4,5, the most important factor is the mite Varroa destructor. Varroa mites feed on haemolymph (‘bee-blood’) weakening the bees, while spreading serious diseases like the deformed wing virus. Beekeepers and bee researchers stress that the first and most important step to save the bees should be to control Varroa more effectively.

Currently in the Netherlands and other European countries, beehives are treated against Varroa with a combination of organic products consisting of thymol, formic acid and oxalic acid. These compounds can contaminate beeswax and honey⁶. More importantly, beekeepers are wary that such compounds can be harmful to bees and humans when the concentration used is too high^7,8. On the other hand, too low concentrations fail to kill Varroa and facilitate resistance⁹. The hobbyist character of beekeepers further adds to the concerns that accompany Varroa treatment. Beekeepers often care for their bees in their spare time and might not have time, resources or the experience to use existing treatments in the intended manner.

Bee T

We propose a Varroa specific treatment through the use of engineered bacteria that releases toxin in a specified and regulated manner. The released toxin is not harmful to bees or humans. To do so, the bacteria will employ a network of regulation mechanisms to produce the toxin only when mites are present and when enough bacteria are present to effectively kill the mite. Other mechanisms are intended to strictly confine the bacteria to the treated hive, preventing them from spreading and mixing with natural ecosystems.

References

1. Spivak, M., Mader, E., Vaughan, M., & Euliss Jr, N. H. (2010). The Plight of the Bees†. Environmental science & technology, 45(1), 34-38. ↩

2. Seitz, N., Traynor, K. S., Steinhauer, N., Rennich, K., Wilson, M. E., Ellis, J. D., ... & Delaplane, K. S. (2016). A national survey of managed honey bee 2014–2015 annual colony losses in the USA. Journal of Apicultural Research, 1-12. ↩

3. Van Der Zee, R., Gray, A., Pisa, L., & De Rijk, T. (2015). An observational study of honey bee colony winter losses and their association with Varroa destructor, neonicotinoids and other risk factors. PloS one, 10(7), e0131611. ↩

4. Genersch, E., Von Der Ohe, W., Kaatz, H., Schroeder, A., Otten, C., Büchler, R., ... & Meixner, M. (2010). The German bee monitoring project: a long term study to understand periodically high winter losses of honey bee colonies. Apidologie, 41(3), 332-352. ↩

5. Guzmán-Novoa, E., Eccles, L., Calvete, Y., Mcgowan, J., Kelly, P. G., & Correa-Benítez, A. (2010). Varroa destructor is the main culprit for the death and reduced populations of overwintered honey bee (Apis mellifera) colonies in Ontario, Canada. Apidologie, 41(4), 443-450. ↩

6. Serra Bonvehí, J., Ventura Coll, F., & Ruiz Martínez, J. A. (2016). Residues of essential oils in honey after treatments to control Varroa destructor. Journal of Essential Oil Research, 28(1), 22-28. ↩

7. Bonnafé, E., Alayrangues, J., Hotier, L., Massou, I., Renom, A., Souesme, G., ... & Armengaud, C. (2016). Monoterpenoid‐based preparations in beehives affect learning, memory, and gene expression in the bee brain. Environmental Toxicology and Chemistry. ↩

8. Charpentier, G., Vidau, C., Ferdy, J. B., Tabart, J., & Vetillard, A. (2014). Lethal and sub‐lethal effects of thymol on honeybee (Apis mellifera) larvae reared in vitro. Pest management science, 70(1), 140-147. ↩

9. Goodwin, M., & Van Eaton, C. (2001). Control of Varroa. A guide for New Zealand Beekeepers. New Zealand Ministry of Agriculture and Forestry (MAF). Wellington, New Zealand. ↩