A recent study published in the Sensors journal has developed a new monitoring system that uses factors other than temperature and humidity in honeybee hives as an indicator for colony health. The study "A Monitoring System for Carbon Dioxide in Honeybee Hives: An Indicator of Colony Health" aimed to better understand the impact of carbon dioxide on the health and survival of honeybee colonies.

The current generation of NDIR carbon dioxide sensors has been demonstrated to be well-suited to the task of monitoring in honeybee colonies. B-GOOD researchers from the Nottingham Trent University have shown preliminary data suggesting that CO2 can give information about the number of foraging bees in the hive and hence the colony strength and has shown how this decreases in a dying colony.

The Sensirion SCD41 tool (Figure 1) was used for application in honeybee hives as it provides a wider and more accurate CO2 measurement range, in addition to humidity and temperature data. The honeybee colonies with gas sensor systems were sited at both the Nottingham Trent University Clifton campus in the UK and the nearby B-GOOD apiary at Holme Pierrepont Hall. 

Figure 1. (a) Hive showing brood box with queen excluder, two ‘supers’, and the modified crown board. (b) Modified crown board with two sets of measurement electronics and one SCD41 sensor mounted over a hole in the centre. (c) Queen excluder with SCD41 sensor and protective mesh cage.

A conclusion drawn from the analysis of the process is that commercial hive monitoring scales would be an effective tool in the process. The researchers suggest it would be straightforward for manufacturers of hive scales to incorporate NDIR sensors into their hardware. One simple technique that was developed during the study is the modified crown board for holding electronics which has proven to be outstanding for keeping the electronics dry and functioning. As the CO2 sensor gives good data from this location, it may be something else that hive monitoring equipment manufacturers may wish to consider implementing for themselves.

The next stage of this research will be to look at CO2 in hives during the wintertime when the brood boxes may not be opened. As little data are currently available on wintering colonies, CO2 may give an important indication of when a colony may require extra feeding to survive.