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Bee health: review of the latest research findings

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News of 13/12/2021

Studying the causes of bee mortality, identifying the pathogens affecting bees, taking better account of the effect of pesticides on their health… Every two years, the Agency organises a one-day meeting on the research, expert appraisal and surveillance work relating to bees. This is an opportunity to review the various research projects carried out by the Agency on this theme.

ANSES, and in particular its Sophia Antipolis Laboratory, is recognised at national, European and international level for its expertise in bee health. Its research aims to better understand, detect and remedy all the factors threatening bee health.

PoshBee, a European project on honeybees and wild bees

The Agency is a participant in the European PoshBee project, in which it is coordinating the work package on bee exposure to chemicals and various pathogens. One of the studies under way is on the identification of bee pathogens. "Identification of pathogens is a familiar activity for the Sophia Antipolis Laboratory," explains Marie-Pierre Chauzat, coordinator of this work package. "What is new here is that we are developing a technology that can identify and quantify eleven different pathogens – viruses, bacteria or parasites – more specifically, more quickly, and even simultaneously. This saves time and resources." Another unique feature is that the study does not only focus on the honeybee – the most commonly studied bee – but also on the bumblebee and the mason bee, a solitary wild species of bee. "We want to implement more representative tests for all pollinators and find out whether the pathogens and parasites that affect honey-producing bees are also present in wild species."

Bee-sized instruments for measuring pesticide exposure

Another aspect of the PoshBee project covers exposure to pesticides. Two studies are exploring this theme. The first aims to design passive samplers to directly measure pesticides in the hive. "We have joined forces with a team from the Ocean and Continental Environments and Paleoenvironments (EPOC) joint research unit, which includes researchers from CNRS and the University of Bordeaux. This team had already designed samplers to measure pesticides in outdoor ambient air," says Marie-Pierre Chauzat. The first challenge was to make the samplers small enough to fit into the hives. The second challenge was to get the bees to accept these instruments, as they have an annoying tendency to coat any intruder with propolis, which makes the samplers unusable. Two models have been tested by beekeepers and the results are being analysed. 
In order to approximate as closely as possible the actual exposure of bees to pesticides, the scientists also developed a method for analysing the chemicals contained in the nectar collected by the bees. "We know how to analyse honey, but this is a product that has been processed by the bee," explains Marie-Pierre Chauzat. "In addition, not all pesticides are stored in the same way: some are hydrophobic and do not mix with honey (which contains a lot of water)." Similarly, the level of bee exposure cannot be deduced simply from the amount of pesticide applied nearby: if the treated crops – such as oilseed rape – are attractive, then the bees will be more exposed. Analysing the nectar brought back to the hive by the bees is therefore a more accurate way of determining their level of exposure. The team developed a method for making the bees regurgitate nectar, as they would do on returning to the colony, and then conducting reliable analyses on samples of just a few microlitres.

Validated methods for detecting diseases

As the reference laboratory for bee health, the Sophia Antipolis Laboratory is also responsible for developing and validating methods for identifying bee pathogens. It recently published a study in the Journal of Economic Entomology on a new method for identifying the Tropilaelaps mite. There are four species in this genus, two of which parasitise the honeybee (Apis mellifera). "It is an exotic parasite not yet found in Europe, but which could potentially arrive in France, just like the varroa mite a few decades ago," explains Marie-Pierre Rivière, head of the Bee Diseases Unit. Monitoring its presence in Europe is therefore essential, to be able to take steps quickly to prevent its spread. The method developed by the laboratory can identify the species in just one day. The laboratory has also developed a method, based on genome sequencing, to track the spread of an outbreak of American foulbrood, a bacterial disease that is fatal to bees.

In addition, the laboratory is responsible for ensuring the correct use of methods and the reliability of results of the official laboratories tasked with conducting the analyses. It therefore organises regular inter-laboratory trials at national and international level. One of them, on a method for diagnosing nosemosis, a parasitic disease of bees, was published in the Journal of Microbiological Methods. This trial not only enabled results to be harmonised between the national reference laboratories in the European Union, but also confirmed the high reliability of the diagnostic test, which is one recommended by the World Organisation for Animal Health (OIE).