The role of weeds in supporting bee populations in agroecosystems

Abstract

Recent concerns about the global decline in pollinators, as a result of agricultural intensification, have called for more knowledge about the drivers of bee abundance and diversity in agro-ecosystems. Weeds in field margins provide food and refuge for pollinators, and play a significant role in supporting biodiversity and ecosystem services. This study investigates the role of margin weed flora in supporting bee populations in Mediterranean cereal agro-ecosystems, with a landscape perspective. The experiment was carried out from 2014-2016, at 27 cereal field margins in Catalonia, Spain. Margins represented a gradient in surrounding landscape, from mainly agricultural to mainly forest. Sampling took place during the peak period of bee activity and comprised: plant inventory, bee trapping and observations of pollinator foraging activity. Bees collected in traps were identified to genus level. From 2014-2015, 161 plant species were identified from 44 different families. In bee traps, 3066 wild bees were collected and identified, representing 26 genera and 7 families. The most abundant family was Halictidae, comprising 75% of bees captured. A total of 1720 pollinators, from 5 orders of insect, were observed foraging on flora within margin transects. Analysis will model multivariate relationships between margin characteristics, surrounding landscape and bee populations. Functional relationships between the morpho-physiological features of bees (e.g., body characteristics, behaviours, etc.) and associated floral traits present in the margin (e.g., size, shape, colour, nectar/pollen qualities, etc.) will be analyzed. Hopefully this research will help with the development of forward-thinking policies and management strategies for efficient and environmentally sustainable farming.