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Bee diet includes large percentage of wild plant pollen in intensively farmed croplands

Scientists from several French research institutes, including INRA, collaborated on a five-year study of bee diets in intensively farmed croplands in the Poitou-Charentes region. Rapeseed and sunflower crops mass flower two months apart, creating a gap during which resources are scarce for bees, a fact that may exacerbate population declines. During this period, bees turn to blooms found on wild species of trees, shrubs, and herbaceous plants (aka “weeds”). This finding underscores the necessity of using environmentally friendly agricultural practices to increase plant diversity in farmed areas, thereby ensuring that bees have year-round access to varied resources.

ECOBEE: a facility for studying bees in the field. Located in a major grain-growing region, ECOBEE is a unique tool that allows researchers to carry out experiments examining the interactions between colony characteristics, landscape features, and environmental constraints. © INRA, MAITRE Christophe
Updated on 11/05/2015
Published on 11/02/2015

Honey bee populations are struggling. They are currently in decline worldwide, which may threaten pollination in major agricultural areas. This trend appears to be caused by a wide array of factors, such as pesticide use, diseases, parasites, and predators. However, the loss of semi-natural habitats (e.g., hedges, pastures, woods) might also play a role, by reducing the food resources available to bees. To date, however, few studies have attempted to characterize seasonal variation in honey bee diets. For this reason, French researchers compared the relative dietary importance of two major oilseed crop species—rapeseed and sunflower—and that of other plant species over the honey bee’s active season, from April to October. They also explored the dietary effects of pollen nutritional quality and landscape composition. To this end, between 2008 and 2012, scientists set up and monitored 250 honey bee colonies at the ECOBEE field research facility. ECOBEE is located in a major grain-growing zone in the Poitou-Charentes region.

“Weeds” supply 40% of the pollen collected by bees between May and July

From the end of May, when the last rapeseed flowers disappear, to early July, when sunflowers start to bloom, bees face a dearth of pollen and nectar. Although bees obtain most of their nectar from crop species, they harvest pollen from a wide diversity of herbaceous and woody species, including the trees and shrubs that make up nearby woods and hedges. “Weed” species supply a large percentage of the pollen gathered during this period of scarcity (more than 40%) and thus play a pivotal dietary role. Researchers also examined the nutritional quality of the different types of pollen harvested, as well as the composition of the landscape. They discovered the following three major results:

  1. The period of pollen and nectar scarcity, which occurs at the end of the spring, coincides with the annual demographic peak of honey bee colonies.
  2. Bees harvest pollen from a remarkable range of species and especially from wild herbaceous plants and trees.
  3. Pollen collection patterns are influenced by pollen nutritional quality and landscape composition. For instance, at the beginning of the honey bee’s active season, which is when bees feed their larvae, forest species are targeted as their pollen is nutritionally rich in protein and minerals.

These results should encourage the use of bee-friendly agricultural practices and sustainable apicultural approaches that increase bloom availability in agricultural landscapes, such as planting more nectar- and pollen-producing species and protecting wild flora.

Reference:
Fabrice Requier, Jean-François Odoux, Thierry Tamic, Nathalie Moreau, Mickaël Henry, Axel Decourtye and Vincent Bretagnolle.
Honey bee diet in intensive farmland habitats reveals an unexpectedly high flower richness and a major role of weeds.
Ecological Applications, 25(4), 2015, pp. 881–890. DOI: 10.1890/14-1011.1

Contact(s)
Scientific contact(s):

  • Fabrice Requier (33 (0)4 32 72 26 21) Joint Research Unit for Bees and the Environment

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Researchers and beekeepers join forces to study bees

This research project brought together scientists, engineers, and technicians from INRA, CNRS, ACTA (a network of French agricultural technical institutes), and ITSAP (the French institute for bee research). It was carried out at ECOBEE, a facility for studying bees in the field. ECOBEE is part of the Plaine & Val de Sèvre study area, a long-term ecological research site in the Poitou-Charentes region. This large study area extends over 450 km²; scientists at the CNRS center in Chizé have been conducting research on its agricultural fields for the last 20 years. Studies focus on biodiversity and agroecosystems. Three research units based in the Poitou-Charentes region were involved in the bee diet study—the INRA Experimental Unit for Alternative Animal Husbandry and Health of Monogastric Species, the INRA Entomology Experimental Unit, and the CNRS/INRA AGRIPOP research team. Two research units in Avignon also participated: the Joint Research Unit for Bees and the Environment and the PRADE joint technological unit for bee protection. Financial support was provided by the Ministry of Agriculture, Food, and Forestry (CASDAR-funded POLINOV project); the regional government (Poitou-Charentes); and France AgriMer (European funds for the apiculture industry).

ecobee

Established in 2007 by the Entomology Experimental Unit (INRA of Poitou Charentes), ECOBEE is a facility where field research can be carried out on the interactions between bee colony characteristics, landscape features, and environmental constraints. ECOBEE is part of the Plaine & Val de Sèvre study area, a long-term ecological research site run by the CNRS center in Chizé. The facility, nestled in the 450-km2 LTER site, is home to 250 colonies of honey bees and is affiliated with a palynology laboratory. Different colony variables are measured and monitored, including honey reserves and production, number of adult bees, surface area covered by brood in the hive, mortality rate in front of the hive entrance, hive temperature, amount of pollen harvested, and general colony health.