We have completed the analysis of the air quality data and honeybee samples collected from our volunteer beekeepers in 2021. We are pleased to share a summary of our results, as well as our project report. LINK TO REPORT PDF We are extremely grateful to the 44 beekeepers who volunteered their time, and to the BBKA for funding this study.
Air quality across the 44 apiary locations was variable (Figure 1). There were sites with very low levels of airborne particulate matter, and these were all in urban and suburban areas. Agricultural landscapes in rural areas had the poorest air quality, with most sites exceeding the UK Air Quality Standards Regulations.
We divided air quality into three categories (‘low’, ‘medium’ and ‘high’), according to the UK government in air quality regulations: low airborne particulate levels (0-11 μg/m3), medium airborne particulate levels (12-20 μg/m3) and high airborne particulate levels (>20 μg/m3). The majority of apiary study sites had a PM2.5 average that fell between 3 μg/m3 and 24.1 μg/m3, although one site recorded an average of 40.8 μg/m3. In total, airborne particulate levels were low at 18 sites, medium at 18 sites and high at six sites. The 2021 UK annual average concentration of PM2.5 was 7.9 μg/m3 at urban background sites, and 8.3μg/m3 at the roadside. Thirty-nine of our apiary study sites exceeded both of these annual averages.
To establish what particles were present on honeybees we developed a new method to allow us to obtain particles from individual bees without destroying organic matter (such as pollen). Due to the intensity and time taken by this process, we analysed honeybees from half of the hives using our method in the CAWR lab, and the other half of the samples were analysed by a commercial lab using previously published methods.
In total, particles from 14 materials were identified. This included car tyres, eight plastics, and four contaminants thought to originate from beekeepers’ smoker material.
We were able to quantify particles from seven contaminants in the CAWR lab. The particles and the percentage of honeybees they were found on are as follows: car tyres (97%), polyethylene terephthalate/PET (89%), cellophane (67%), nylon (11%), polypropylene (6%), polydimethylsiloxane (3%) and polyvinyl chloride/PVC (3%). A further three plastics were detected at low frequency: polythene, polyacrylamide and urea-formaldehyde/urea-methanal. Figure 2 shows examples of the particles recovered.
We also found particles from four materials that beekeepers told us they used in their smokers. The particles and the percentage of honeybees they were found on are as follows: cardboard (92%), paper (69%), timber (75%) and eggbox (11%). It seems likely that these particles were generated by smokers, although local bonfires and wood burners cannot be discounted as honeybees forage widely in the landscape and could pick up particles on their travels.
Overall, we found that forager bees carried more particles than nurse bees. This is unsurprising as the forager bees are active outside the hive. What is interesting is that those particles made their way into the hive and onto the nurse bees. We recorded most types of materials on both forager and nurse bees, suggesting that foragers bring particles back to the hive (although we cannot discount the possibility that some arrive through airflow).
The data indicates a trend towards higher numbers of particles on honeybees from hives located in areas of high airborne particulate matter. However, our results were not statistically significantly different, which could be due to low statistical power as there was high variability in the honeybees collected from areas of high PM concentration
There was also a trend towards higher number of particles on honeybees from apiaries in farmed landscapes (improved grassland, arable and horticulture), compared to honeybees from urban, suburban, and broadleaved woodland. However, we did not find a statistically significant difference as there was high variability.
We found no linear relationship between airborne particulate matter and the number of particles found on the honeybees, the weight of the honeybees, or estimated honey produced. Interestingly, estimated honey production was highest in urban areas, and lowest in farmed landscapes, and the difference was statistically significant.
It would seem sensible for beekeepers to avoid areas of intensive agriculture when placing hives, because agricultural operations produce high level of particulates and agricultural areas also have very low abundance of forage available for bees. Beekeepers in these areas expected lower honey yields in our study. These findings are backed up by existing research which underlines that agricultural habitats are a poor environment for bees. At the same time, urban areas have been shown to provide good habitat, with cleaner air and more plentiful forage.
Through our research, and in conjunction with recent studies, we feel confident in advising that air quality is an important consideration for beekeepers. This is not because there are acute toxic effects, but because it contributes to the multiple stressors that lead to sub-lethal effects on honeybee health that can lead to chronic sub-optimal health, susceptibility to disease and low productivity. Beyond placement of hives there is little we can do directly, but informing policy makers so that they have the evidence to formulate beekeeping-friendly policy instruments would be a positive step forward.
The next steps are to examine the hive products (honey, wax and pollen) that were collected alongside honeybee samples.
If you would like to read about our results in more detail, please download our project report - Mapping Particulate Presence in Apiaries in the UK.
