The results of the expert appraisal highlight a large number of infectious and parasitic agents affecting bee colonies, numerous xenobiotic residues (insecticides, fungicides and acaricides) present in bee matrices, as well as a great diversity of stressors to which bees may be exposed, concurrently or successively. The expert appraisal underlines the multifactorial nature of the causes of bee colony mortality and highlights the role of co-exposure to pesticides and infectious agents in the determinism of their collapse.
In this context, the Agency recommends taking action on all of these factors, in particular through the adoption and respect of good beekeeping practices, but also the overall reduction in the exposure of bees to pesticides. The Agency also emphasizes the importance of eventually having a harmonized and structured observation network at national level, making it possible to produce reports of the state of health of the colonies, in particular by creating reference apiaries. Finally, the Agency recommends – within the framework of discussions to be initiated at European level – the development and then the integration of additional tests to measure the effect of co-exposure to fungicides and acaricides in the procedure for assessing the toxicity of insecticides.
There are many pollinating species in the world contributing to the survival and evolution of more than 80% of plant species. Among these pollinators are some 20,000 species of bees, of which about 850 are present in France, in particular the honey bee Apis mellifera.
For many years, a phenomenon of weakening and mortality of bee colonies has been observed in many countries and is partly responsible for the drop in honey production. These phenomena of weakening, collapse and mortality of bee colonies, observed in most countries where agriculture is intensive (Europe, Americas), have been the subject, in recent years, of a large number of studies aimed at understanding the mechanism(s) involved in these disorders.
Better understand concomitant or successive exposures to stressors
In this context, the Agency issued an internal request in 2012 on the question of the co-exposure of bees to stress factors and the interactions between these factors.
In the opinions and report that it publishes today, the Agency proposes a definition of the “normal” state of health of a colony, as well as health indicators that can be used by the beekeeper, the bee health technician, the veterinarian or researcher. This definition is an essential prerequisite for assessing the state of health of a colony.
Bees are exposed to many stress factors likely to interact with each other: infectious, chemical, physical, food, beekeeping practices, weather conditions, etc. A large number of infectious and parasitic agents can affect bee colonies and many xenobiotics (mainly insecticides, fungicides and acaricides) are found in bee matrices.
Apiaries are co-exposed to multiple combinations of factors. The presence of infectious agents within colonies, and the exposure of bees to pesticides of various origins and mechanisms of action, in all likelihood lead to the transition from a “normal” state of health to the expression of pathologies. which can lead to their collapse, through a drop in immunity or a reduction in the detoxification mechanisms of bees.
The Agency’s recommendations
Even if in some cases bee deaths are the result of the action of a single factor, the Agency’s work underlines the often multifactorial nature of the causes of colony deaths and particularly insists on the importance of co-exposure of bees to pesticides and infectious agents.
These phenomena are all the more marked when bees are exposed to multiple molecules. Some interactions have already been demonstrated in the scientific literature and the Agency recommends continuing research to study other potential interactions.
In general, ANSES notes that despite the acuteness of the phenomena of the weakening of bee colonies and their now long-standing nature, the deployment of multiple studies, carried out by various operators in recent years , does not provide a consolidated diagnosis of the state of health of the colonies at the national level, nor of their co-exposure to infectious and chemical hazards.
In this context, and if it is not possible to act in the short term on stress factors such as the climate, ANSES stresses the need to intervene on all the factors identified as contributing to the weakening settlements.
For this, in order not to add other stress factors, zootechnical or nutritional in particular, it recalls the importance of maintaining biodiversity as well as respecting good beekeeping practices to keep bees and colonies in good health. It also recommends reducing the use of inputs in agricultural practices in order to reduce the overall exposure of bees to plant protection products.
Within the framework of discussions to be initiated at European level, the Agency recommends that tests be incorporated into the procedure for assessing the toxicity of plant protection products (insecticides in particular), before their marketing effect of chronic chemical co-exposure to other molecules:
- an anti-Varroa acaricidal molecule;
- a fungicidal molecule known to inhibit the detoxification mechanisms of bees;
- an insecticide having the same mode of action as the product to be tested and known to be present in beekeeping matrices, if the plant protection product to be tested is an insecticide.
The effective implementation of this proposal is subject to an adaptation of the Community regulations, after finalizing the necessary tests and procedures.
Finally, the Agency recommends the use of quantitative methods in the qualification of the status of the hive vis-à-vis infectious agents, as well as the creation of reference apiaries, brought together in a network, to constitute the most complete network possible. of the French territory, making it possible to define regional references for the various actors.
This recommendation should ultimately make it possible to have harmonized reference systems and a structured observation network making it possible, under the responsibility of national coordination, to produce assessments of the state of health of the colonies, of their co-exposure to infectious and chemical agents and their evolution.