Impact of agricultural landscape on honey reserves in bee colonies

Abstract

Intensive farming systems are now scarce floral environments leaving honey bees with low food availability at some periods. This scarcity could be related to the current recorded honeybee and wild pollinator decline. An assessment of the nectar provision of occurring species is needed in order to identify key species for honeybees. Such knowledge would allow environmental measures protecting pollinators to put their focus on these species that could be developed as crops or companion plants in different systems. The aim of this study is to assess the seasonal contribution of mass flowering crops (rapeseed and sunflower) vs other floral resources, as well as the role of different landscape elements on the hives performance. This study is based upon a survey from an extensive data set collected in the United Kingdom. Using existent datasets, we model the seasonal nectar availability and connect it to the performance of the hives. From April to August, the mass of available nectar follows a bimodal pattern, marked by a two-month dearth period between the two oilseed crops mass flowering occurring in May for rapeseed and July for Sunflower. The pattern of honey reserves in the hive did not match up with the rapeseed peak blooming period, it is likely that honeybees are focused on brood production and therefore target pollen to feed the brood rather than nectar. Bees collected nectar mainly from oilseed crops however during the dearth period weeds represent the main floral resources for nectar. Our study highlights a food supply depletion period for nectar between the two oilseed crops blooming and a key role of weeds: only resource of the dearth period. Our results therefore highlight the importance of flower availability in agricultural landscapes which is supported by the agri-environmental schemes intended to promote honeybees and beekeeping sustainability.