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Bee health: new data uncovered by the PoshBee project
The aim of the European PoshBee project was to better understand the factors driving the decline in pollinating insects, particularly the impact of plant protection products. At a scientific meeting that it convened on 7 December 2023, ANSES reviewed the project’s contributions to assessing current and future threats suffered by pollinating insects.
The PoshBee project brought together more than 40 partners from 14 European countries, including ANSES, to determine the nature and extent of the threats faced by three pollinating bee species considered as sentinels: the honey bee, a social species forming large colonies, the buff-tailed bumblebee, a social species forming smaller colonies and the red mason bee, a solitary bee. PoshBee ran from 2018 to 2023 and was funded by the European Horizon 2020 programme. ANSES coordinated the component on measuring exposure to chemicals, pathogens and nutritional issues.
Improving data usability with exposure indices
The sheer amount of data being considered can make it difficult to determine the factors affecting the health of bees and other pollinators: “Using high-throughput pathogen detection and quantification analysis, a great deal of data can be collected,” says Marie-Pierre Chauzat, a project manager in bee surveillance at the ANSES Laboratory of Animal Health and leader of a multipartner working group within PoshBee. “But we don’t necessarily have the statistical tools to make sense of these data.” PoshBee project scientists have thus developed indices to help produce a summary of insect exposure to pathogens. “It’s a kind of toolbox that describes three different indices that can be used according to the type of data considered and research goals,” says Éric Dubois, a project leader in virology within the Bee Diseases Unit at the ANSES Sophia Antipolis Laboratory.
Establishing correlations between the pathogens found and environmental factors
These indices have been useful in PoshBee to study the factors influencing the pathogens found in pollinating bees. The study was carried out on 128 sites across 8 countries. Sites with similar profiles were grouped based on the index calculations, which showed the abundance and types of pathogens found. “We wanted to find out whether there was any correlation between pathogen distribution and factors such as crop type, pesticide use, pathogen interactions and the biogeographical area,” says Aurélie Babin, a project manager within the Bee Diseases Unit at the Sophia Antipolis Laboratory. This research has not yet been published, and the findings cannot be discussed in detail. “But we can already say that the most virulent pathogens are not the most useful for assessing the effects of environmental changes,” explains Éric Dubois. “In fact, the opposite is true: the pathogens that are most commonly found but usually latent are actually the best indicators: when bees are exposed to new stress factors such as plant protection products, they will develop clinical forms of diseases caused by pathogens that they used to tolerate without developing symptoms.”
Identifying future threats to pollinators
In another PoshBee study that it was involved in, ANSES conducted an overview of risks for honeybees, bumblebees and mason bees and opportunities for addressing these risks in Europe in the next five to ten years. “This study brought together 20 experts from several European countries. It could serve as a basis for new research programmes or for developing protection actions at the national, European and even global level,” says Marie-Pierre Chauzat.
One of the main threats identified is the rise in new predators and pathogens. For example, the Asian giant hornet (Vespa mandarinia), which originated in Asia and has recently been detected in the United States, could arrive in Europe. At the same time, other exotic species that attack native pollinators and are already established in some European countries, such as the Asian hornet (Vespa velutina) and the small hive beetle (Aethina tumida), are expected to increase their geographical ranges. Pollinators are also negatively affected by extreme weather events, such as heat waves, heavy rainfall and severe frost.
Uncertainties remain on the effects of specific events on bee health
Other developments could either threaten or improve pollinator health. For example, the development of pesticides made using nanotechnologies could lead to fewer chemicals being used, but their health effects on pollinators are still poorly understood.
The geopolitical context may also lead to changes in farming practices, which could affect bees. For example, the European Union has authorised the growing of crops on set-aside land to compensate for the reduced trade in agro-food products following the conflict in Ukraine. Fallow land is usually a source of food for pollinators. However, flowering crops, such as sunflower or clover, may partly offset the loss of fallow land.
Innovation to help bees survive
Lastly, several future developments may support pollinators or mitigate the threats that they are facing. Technological advances to monitor bee health more accurately and remotely can be useful, for example. Bees could also benefit from promoting further research on the toxicity of co-formulants contained in plant protection products, and from selecting honey bees resistant to the parasitic mite Varroa.
Other studies under the PoshBee project due to be published in the coming months are expected to improve knowledge on the factors affecting the health of honey and wild bees.