Fighting Hive Pests

Leveraging Science Communication to Protect Honeybees


Few animals are more critical in the pollination of fruit trees and flowers than the European honeybee, Apis mellifera. Carrying masses of pollen on their hind legs and sticky hairs, these laborious little critters are essential to the natural housekeeping of our world, allowing both plant life and resident herbivores to flourish. It is therefore paramount that we support them as best as we can – particularly by reducing chemical and biotic threats to their survival.

Over the past two decades, much attention has been devoted to finding ways to prevent the ongoing decrease in bee populations. Given the contribution of pollinators to agriculture worldwide (between USD 235-577 billion per year), estimated honeybee losses have recently become especially worrying. In the last 10 to 15 years, beekeepers throughout Europe have been reporting an unusual weakening of bee numbers, with the United States recently experiencing overwinter losses of over 45%. While several factors carry the blame for this phenomenon, the increase in pathogens and parasite infections is known to be of particular importance for beekeeping populations. The ectoparasitic mite, Varroa destructor, is one of the most prominent threats in this case.

V. destructor parasitises bee brood – the eggs, larvae and pupae of honeybees – and feeds on their fat tissue to reproduce quietly. When mature female mites leave the cell, they then start parasitising adult honeybees, thereby disseminating around the hive. Varroa is known to be a vector for various deadly viruses and pathogens in bees, meaning that their parasitism can ultimately lead to a significant increase in both viral infection and colony mortality – sometimes even wiping out entire honeybee populations at a time.

With the impact of global warming causing higher rates of V. destructor infections, it is now more important than ever to take precautions when raising bee colonies as a beekeeper. This is why a group of researchers at the University of Neuchâtel, Switzerland, recently scrutinised several measures’ effectiveness in warding off parasites.

Better honeybee protection

In their study – published late last year in Research in Veterinary Science – the team cooperated with 30 beekeepers (amounting to 300 bee colonies) around the Jura, Bern and Vaud cantons in Switzerland over the span of two years, measuring how the different beekeepers’ implementation of standardised varroacidal treatments against V. destructor would affect winter colony mortality. These were adapted from the treatment regiments recommended by Apissuise, Switzerland’s national umbrella organisation for beekeeping. The treatments consisted of the application of specific amounts of formic and oxalic acid (organic compounds that are lethal to V. destructor) two or three times per year before and during Winter respectively, depending on how great the infestation became.

As an alternative to organic acids, beekeepers also have recourse to synthetic chemicals such as pyrethroids to protect hives from parasites. Unlike organic treatments, however, synthetic chemicals can stay intact for years after implementation, causing mites to develop nation-wide resistance to them over time and potentially adding carcinogens to what would otherwise be a wonderful jar of honey.

“The organic acid treatments have not resulted in mite resistance to date and do not leave persistent residues in bee wax or honey when used correctly,” said Julie Hernandez, lead author of the paper and PhD student at the University of Neuchâtel. Clearly, the use of organic acid treatments is preferable – but there is a challenge. “Unfortunately, organic treatment regimens are complex. They lead to numerous possible deviations from [national] recommendations and thus to lower effectiveness.”

Part of the complexity in varroacidal treatments lies with different personal interpretations of their importance. How bad could it be, for instance, to apply treatments only one week early to avoid hot weather? Or to apply them less often to not stress out their bees, and perhaps to conserve products? Quite bad, the researchers believed – but by how much?

To evaluate this hypothesis, trained field assistants were sent to collect data from the apiaries twice a year; once in August, before formic acid application, and then again after the treatment in October. Finally, colony mortality was measured the following year in April.

Fieldwork to analyse colony mortality rates | Credit: Julie Hernandez

Simultaneously, beekeepers were asked to record their implementation of treatments routinely. Compliance was then quantified based on how much their actions differed from Apissuise’s recommended control protocol, and whether they applied the correct number of treatments at appropriate times. The results were alarming.

“We realised that high mite infestation rates and colony mortality were associated with noncompliance,” asserted Hernandez. Subsequent statistical analysis of the results revealed the extent of this. Compared with fully compliant beekeeper apiaries, colony mortality was found to be ten times greater with slight noncompliance (featuring a correct number of applications but not always at the right times) and twenty-five times greater with significant divergence from the control recommendations – increasing even further when they were avoided altogether.

With this in mind, it is easy to see why strictly abiding by apicultural recommendations is essential for the protection of farmed honeybees. The same study further demonstrated that any adverse side-effects of organic acid use on bee brood was negligible, stating that it “did not significantly decrease winter colony survival.”

Unless they compare their colony numbers with those under different treatment plans, these observations are not immediately obvious to the average beekeeper. As such, the researchers devised a simple strategy in the second year of their study to evaluate the effect of scientific communication on colony mortality: telling the beekeepers about it.

Communicating and keeping standards

Previous efforts have demonstrated that beekeepers’ maintenance practices are the greatest factors affecting the health of honeybee colonies. Some beekeepers believe that staying ‘hands off’ and applying a minimum number of treatments is the most natural way to go. Others have more faith in synthetic products to treat for Varroa – while yet others simply don’t have the experience to know which is best.

“Identifying the causes of this noncompliance will be central to improving honeybee health,” said Hernandez.

Besides the lack of awareness, there are probably other cultural or economic factors to noncompliant beekeeping. Nevertheless, given the recent global increase in beekeeping as a hobby, it is all the more relevant that standard treatment procedures are followed. There are several methods that could be used to ensure this.

Over the two years of the experiment, the researchers at Neuchâtel gave the involved beekeepers ready access to collected information. Although many initially had their own separate interpretation of proper beekeeping procedures, telling them of the consequences of their actions – even several months after they were taken – led to a definite and statistically significant rise in compliance throughout. From 2018 to 2019, general compliance increased by 28%. Noncompliance, in turn, dropped by the same amount to almost zero.

Comparing the effects of compliant and noncompliant varroacidal treatments on honeybees | Credit: Julie Hernandez

But this is only one example of spreading awareness. “The best way to communicate the impact of deviations to beekeepers,” Hernandez argued, “is through the publication of our and similar results in specialised journals and inclusion in beekeeper courses.” Other means of communication could be using social media to share information, spreading city posters, and having more public events dedicated to bees and beekeeping.

The researchers noted that social sciences would be key in better understanding compliant beekeeping routines. This might include a greater focus on beekeeping education; anthropological studies on the other reasons behind noncompliance, particularly when they vary between nations; and investigating the economic factors that limit honeybee protection. In all cases, however, there is potential for more efficient cooperation between beekeepers and local authorities to establish systematic approaches for honeybee protection.

Of course, beekeeping recommendations do differ across the world, whether due to climatic differences or cultural inclinations towards pesticides. Nevertheless, according to Hernandez, “the treatment regimes used in Switzerland are also used in other countries, and it is likely that noncompliance also leads to superfluous colony losses there.” In addition, as V. destructor is known to plague practically every country with honeybee populations, advances in individual treatment regimes should inspire similar changes in counterpart beekeeping systems.

Interestingly, several national systems are currently making positive strides in this very aspect. Guided by international beekeeping surveys, some countries have been encouraging the spread of beekeeping information and training to the public. Switzerland is one of these places, supported by countries such as Germany, Austria, the Netherlands, Denmark and Sweden.

The future of beekeeping

One noteworthy study on the topic of honeybee health was recently planned by COLOSS (Prevention of Honey Bee Colony Losses), an international non-profit association headquartered in Switzerland. In the years 2018 to 2019, they conducted a survey involving a total of 1534 beekeepers in Austria, in which both overwinter colony losses in the region and usual hive management practices were analysed.

The survey’s results showed that organic acid treatments were the most popular Varroa control method in the area, and that small, inexperienced apiaries were more liable to overwinter losses than bigger ones. As the high popularity inevitably leads to more noncompliant beekeepers, such findings underline the necessity of making organic beekeeping education more accessible.

Corroborating the results of the team at Neuchâtel, the COLOSS network (made up of just under 2000 researchers from 108 countries around the world at the time of writing) promises to lead the way for honeybee protection in the future. The organisation could also be an essential player in advising governments to promote best beekeeping practices.

In addition to COLOSS, Neuchâtel’s researchers are hoping to collaborate with the Swiss Honeybee Health Service to “improve knowledge transfer to the beekeepers.” All of these are steps towards encouraging greater awareness of how to better control Varroa infection rates in beehives to protect the health of honeybee populations. Of course, this will only form part of their future investigations.

As Hernandez describes it: “In our current project, we will now turn to the main goal of assessing the effect of agroecological measures on the development, health and productivity of honeybee colonies, establishing a link between agriculture practices and beekeeping.” This should impart valuable feedback on how farming land and crop pesticides can influence the health of roaming honeybees – and hence the health of a diligent beekeeper’s colonies.


Andres Hernandez Maduro studies Biochemistry at Imperial College London and is the owner of Science & Pandas, a scientific blog. He is on Twitter at @SciAndPandas.

(Small note: he and Julie Hernandez are not related.)

Artwork by Chiara Lo Zito. You can learn more about Chiara and her work on her website.