Future Sensors

There are some sensors I’d like to have, but they are not on the market, at least not yet, or if they are on the market, they are not designed for beehives. These sensors would monitor the level of my liquid feed, detect when my supers were full, measure the quality of my honey, detect the presence and levels of Varroa, listen in on my bees pheromone communications, detect nectar scents and other hive odors, monitor the level of carbon dioxide, and sense the hive’s ventilation processes.

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In the past, bees stored enough feed, in the form of pollen and honey, for their own year-round use and usually stored a surplus for the beekeeper to harvest. However modern agricultural and apicultural practices often require that bees be fed. While being fed, bees will consume some feed and store some. The rate the feeder is being emptied provides only partial information. Correlating feed data with hive weight data and brood volume data may be helpful.

Electronic feed monitoring devices
At this time we are unaware of any electronic feed monitoring devices. The simplest such device would report when the feeder is empty. A more sophisticated device would report the rate feed is being taken from the feeder.

Manual feed monitoring
Manual recording of feed consumption data is the current option. Beekeepers may note the date the feeder is filled, the amount of feed, and the date the feeder is found empty. If a container with graduated marks to indicate the quantity consumed is used, a more detailed record of consumption can be recorded. If bees are not taking feed as expected, it may indicate a problem: the feed may have gone bad, a nectar flow may have started, the number of bees may have decreased, etc.

If it is cold, it may be too cold for the bees to break cluster and reach the needed feed. Verifying that over-wintering colonies can occasionally warm up naturally and the bees can break cluster to reach stores of honey, syrup, or sugar patties is vital to colony survival. Measuring hive weight changes and feed consumption rates is one way to determine whether colonies have been configured so as to enable successful overwintering.

The main ingredients of honey are glucose and fructose. For diabetics, who must monitor the level of glucose in their blood, continuous glucose monitors have been developed. It seems plausible that these monitors could be adapted to detect the presence of honey in the parts of the hive designated to store honey. A honey detector would help disambiguate data from the weight sensor, as both bees and honey contribute to the weight of the hive.

Honey is ripe when bees cap it. The sugars have been transformed and sufficient water has been removed to prevent spoilage. Ripe honey detectors, located at the ends of a frame, near the bottom bar, could signal a frame’s readiness to be harvested. And a honey monitor in the winter stores could warn when the stores had been consumed.

It seems plausible that an in-hive or in-frame Ripe Honey Detector could be developed, though to date, none has appeared. These could be based on the continuous glucose monitors used by people with diabetes. There are numerous commercial continuous glucose monitors including:

Today, the annual cost of continuous glucose monitor for a human is thousands of dollars, but as we know, the costs of technology come down quickly, and a honey sensor, while it must be made of food-grade materials, need not meet the rigorous standards required for human medical technology.

In the laboratory, a number of methods are used in the routine quality control of honey. See, for example:

A simple portable testing device could help prevent beekeepers from accidentally mixing ‘honey’ made from sugar syrup or high-fructose corn syrup, with real honey made from nectar.

Odors in the hive include bees’ pheromones, foraged nectars, disease odors, and environmental scents. Each of these can tell us something useful about the state of our colonies.

Bees communicate among themselves using pheromones. The ability to monitor the bees’ pheromone communication system would enable beekeepers to understand colony activity at a never-before-achieved level. Imagine knowing the quality of the queen, the hunger of the brood, or the presence of an alarming visitor to the hive. The chemical environment of the hive is complex, perhaps too complex for there to be a pheromone sensor system in the near future. Nevertheless, the bees themselves manage to sense specific pheromones, and proof-of-concept efforts such as Bovinose, which monitors bovine pheromones, and other “artificial nose” research, indicate that the task is achievable.

Besides pheromones, the detection of nectar scents would inform the beekeeper of nectar sources. When honey from specific floral sources results in premium prices, this information would be useful for telling beekeepers the start and end of the nectar flow, and like other sensors, could be especially useful when one’s colonies are in remote locations.

Many bee diseases have specific odors, the scent of American Foulbrood, for example is well-known, and Maryland’s Apiary Inspector even has trained a dog to detect it. The yeast associated with Small Hive Beetles also has a specific scent an artificial nose could detect. Varroa mites, unfortunately, are capable of mimicking the scent of a honey bee’s cuticular hydrocarbons, right down to the level of the individual colony, so they would evade an e-nose detection system (Varroa destructor changes its cuticular hydrocarbons to mimic new hosts) as they now evade bees.

Finally, environmental scents, such as the exhaust from the 2-cycle engine of a mosquito fogger, or the diesel exhaust from an unexpected vehicle in the apiary, or the spoor of a bear, etc., would all be useful information.

A good example of the state of the art in e-nose research from 2016 is this article: Application and Uses of Electronic Noses for Clinical Diagnosis on Urine Samples: A Review.

And a similar case: Laser Smells Diseases via Breath Analysis.

An example of currently available sensors, the Cyranose 320 is an indication that interpreting the odors within a beehive is possible. From the manufacturer:

The Cyranose® 320 is a fully-integrated handheld chemical vapor sensing instrument designed specifically to detect and identify complex chemical mixtures that constitute aromas, odors, fragrances, formulations, spills and leaks.

Finally, an excellent article summarizing several years of research on volatile and semi-volatile organic compounds in beehive atmospheres is Volatile and semi-volatile organic compounds in beehive atmospheres; it is Chapter 2 in in the book: Honey Bees: Estimating the Environmental Impact of Chemicals.

Currently (early 2019) no commercial vendor is offering a VOC sensor, but the DIY folks at HiveTool have made one available for use with their system:

The HiveTool homepage.

Their VOC sensor.

Honey bees can sense the level of carbon dioxide (CO2) in the hive, but not the level of oxygen, Seeley reported in a 1974 paper titled “Atmospheric Carbon Dioxide Regulation in Honey-Bee (Apis Mellifera) Colonies”. When not clustering, if the CO2 level rises above 1%, bees will fan to reduce it. A high level of CO2 in the hive during brood rearing or nectar processing might indicate insufficient ventilation.

In contrast, in the winter cluster, bees apparently induce hypoxia in the cluster to reduce its metabolic rate, and the induced metabolic rate correlates inversely with CO2 levels (see “Hypoxia-Controlled Winter Metabolism in Honeybees (Apis mellifera)”). Consequently, a CO2 sensor placed in the cluster might be informative regarding winter cluster conditions.

Currently, no vendor is providing carbon dioxide sensors for beehives.

Beehive ventilation is a very important, but almost totally unexplored, dimension of colony behavior and monitoring interest. For each of the three major colony activities (brood rearing, nectar processing, and winter clustering) there is an optimal hive environment (temperature and humidity). Bees attempt to create and maintain these environments in spite of external conditions and within the limitations of hive insulation and hive apertures.

The amount of energy bees expend (i.e., honey that bees consume) in overcoming sub-optimal in-hive conditions for each of these major activity has never been determined. It has been calculated, however that approximately half the nectar brought into the hive could be consumed in processing the remaining nectar into honey. See: Thermal Efficiency Extends Distance and Variety

One has to wonder how much more energy bees expend in overcoming suboptimal hive designs. It appears that a beehive designed for the optimal performance each of major activity would minimize the effort required for fanning to ventilate the hive, and would minimize the energy required to heat or to cool the hive, thereby reducing bees’ effort and stress, and increasing their health and productivity. The air pressure sensors used on toy quadcopter drones to sense changes in altitude could possibly be used in beehives to monitor air motion.

It is hard for bees to detect Varroa mites. Varroa mites evade detection by adapting their scent to that of the colony, by having a shape that fits closely to a bee’s body, and by having a surface that mimics a bee’s. It is also hard for bees to dislodge mites from their bodies, when found. And mites reproduce inside capped brood cells, where they are out of sight.

Some bees are capable of detecting mites in capped brood cells. These Varroa sensitive hygienic (VSH) bees apparently detect these mites by smell.

Varroa mites and bees are different colors, but as it is dark inside a beehive that is of no use to bees. It may, however, be useful in developing a mite detection device.

A prototype Varroa detector based on interpreting images of bees entering a hive is discussed here.