Development of monitoring system to assess honeybee colony health

In the last decades, beekeepers recorded millions of honey bee (Apis mellifera) colony losses due to climate change, and crop chemical treatments, but mostly the parasitic spreading of mites, in particular Varroa destructor. The mite lives in synchrony with the brood, parasitizing bees' brood before capped. The growing mites start feeding on the larva, weakening without killing the host. Once the affected larva becomes a bee, it leaves the brood cell, by uncapping the wax cap, allowing the parental mites and their offspring to spread out. The weakening from the mite feeding leads to evident symptoms as bees are unable to fly (deformed wing virus), helping mites to spread out and lead the colony to collapse. The presence of these viruses has been directly linked to colony losses, thus raising the need for more accurate techniques to measure and estimate the rate of infestation. The most used method for detecting a Varroa destructor infestation is manual sampling. Typically, a bunch of live bees (almost 300 bees) is put into a jar with alcohol or powdered sugar and shaken until most mites fall off. An alternative consists of sampling the brood by opening brood cells and checking for mites' presence. Lastly, a noninvasive method but still manual makes use of a bottom sticky board placed under each beehive to monitor the natural mite drop. However, all these methods have drawbacks. For these reasons, automatic monitoring inside the beehive might be a valid support tool for beekeepers to estimate the mite infestation level, limiting manual inspections and continuously monitoring the mite infestation level. In this research project, the authors are working on developing an image-based acquisition system to gather samples of healthy and sick bees inside the beehive, with the aim of providing a tool for beekeepers to support the decision-making phases to limit the spread of mites.