Greening the City

Biodiversity, the city’s ally

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Bees as environmental sentinels in France

Of course, one of the chief services provided by bees is pollination. However, certain species can also be used as indicators of plant diversity in towns, and of contamination of the urban environment by certain pollutants. This can be done by studying colonies and carrying out analyses of collected pollen, honey, nectar, beeswax and dead bees. But doing this requires the development of an effective and fast-reacting system. This was one of the aims of a study recently carried out by the Evolution, génome et spéciation Laboratory (LEGS (1)). Gérard Arnold’s team has managed to develop a strict protocol which could well serve as a benchmark for this kind of work. This consists in equipping hives with electronic sensors that continuously count the number of bees flying in and out, as well as with an automatic balance that weighs the hive several times a day. The data is stored in a laptop and can be sent daily by SMS. “As soon as an anomaly is detected, we can rapidly go to the site to check the state of the colony, and take samples for sanitary and toxicological analysis,” Arnold explains. “We need to be able to react quickly, especially when it comes to analyzing pesticides, which can break down in a short time.” The LEGS team tested the system successfully for three years on nine domestic apiaries in the Paris area with bees of the species Apis mellifera: three in an urban area, Saint-Denis (Seine-Saint-Denis), three in Rambouillet (Yvelines) and three in Saint-Cyr-sous-Dourdan (Essonne). “Unlike the other two sites, we didn’t record any loss of colonies in Saint-Denis,” Arnold says. “In addition, the urban bees had no specific problems, and produced more honey than the bees located in the rural areas of Rambouillet and Saint-Cyr-sous-Dourdan.” This is the first time that a scientific study has backed up the many observations that show that the activity of bee colonies is excellent in an urban environment. However, Arnold is also a member of the steering committee for an ongoing large-scale study in the Pays de la Loire region*. The main goal of the study is to use Apis mellifera as an environmental sentinel for pollution by lead, pesticides and polycyclic aromatic hydrocarbons. “In all, 144 samples have been taken from 16 apiaries throughout the region, four of which are in an urban environment in the heart of Nantes,” explains Monique L’Hostis, the researcher who is leading the project. “Analyses are currently being carried out on honey, pollen, beeswax and bees’ bodies.” Specific multiresidue analytical methods for around 80 different pesticides are being used, which were developed by CNRS’s central analytical department at Solaize (2) (Rhône). All the results will be correlated with those from field surveys (spraying with pesticides, discharge of pollutants, vegetation cover, etc). Conclusions are expected at the end of 2010.

*Study led by the Plateforme Environnementale Vétérinaire at ONIRIS in Nantes. ONIRIS is a higher education and research establishment belonging to the French Ministry of Food, Agriculture and Fisheries.
1. CNRS Laboratory - Gif-sur-Yvette, Essonne, France
2. A CNRS department