Wild bees under scrutiny

For 4^e For the past year in a row, the Park has been monitoring wild bees in Périgord-Limousin this spring, as part of the European program Life Wild BeesThis operation aims to gain a better understanding of these insects on which little data is available.

Thanks to an established protocol, the monitoring carried out allows for the collection of valuable data on species diversity and their distribution. It takes place in parallel in the 5 Regional Natural Parks involved in the project. In Périgord-Limousin, 15 sites were targeted, representative of the diversity of its open natural environments: meadows, heather moors, limestone hillsides, etc.

Field work…

Follow-up sessions take place once a month between mid-March and the end of October, in order to cover the entire period of pollinator activity. For each of them, specific weather conditions must be respected: sunny weather, little wind, mild temperatures above 14°C.

Monitoring is carried out using water-filled cups, placed for 48 hours at each site. The addition of a drop of dishwashing liquid, which acts as a surfactant, allows individuals to be trapped. The colors of the cups (blue, yellow, and white) correspond to the main colors of the region's flowers. Their combination therefore makes it possible to take into account the color preferences of different bee speciesThe insects captured in the cups are then placed in pots, which are carefully labeled (site, station, cup color and date) before being sent for analysis.

This protocol, developed by experts, is currently the only one capable of obtaining reliable data. This data is essential for better understanding of wild bees, although a less invasive method would be desirable.

…and laboratory

Once the field work is completed, the samples are sent to theOPIEWhere insects are identified using specialized equipmentThe results are then analyzed by the laboratory. BIOGECO of INRAE, in order to draw robust scientific conclusionsSubsequently, all data from the LIFE project are centralized, cross-referenced with the floristic characteristics of the environments monitored and integrated into national databases.

The results of the 2022 monitoring of these 15 sites have just been published and already allow us to observe clear trends. Lasioglossum morio is thus the most abundant bee species in these surveys. The species composition of the meadows of Haute-Vienne is different from that of the meadows of Dordogne. That of the limestone hillsides of Dordogne is distinguished from that of the heather moors of Haute-Vienne with similarities of species with the meadows but with more significant specificities in moors or hillsides (more species recorded by a single individual).

In total, in 2022, 146 different species of wild bees were collected and identified at the 15 monitoring sites in Périgord-Limousin.

Why such monitoring?

Wild bees are key indicators of the health of natural environments. Their diversity and presence reflect the ecological balance of the territory. This monitoring therefore makes it possible to:

• Better understand the range of species present in our territory, based on the main open natural environments
• Experiment and adapt natural environment management policies based on concrete and objective data
• Participate in the national inventory and qualification of species conservation statuses

Ultimately, the objective is that the data collected can contribute to the development of practices in favor of wild pollinators.