Organic farming positively affects honeybee colonies in a flower‐poor period in agricultural landscapes

Summary

1. Conventional farming has been implicated in global biodiversity and pollinatordeclines and organic farming is often regarded as a more ecological alternative.However, the effects of organic farming on honeybees remain elusive, despitehoneybees’ importance as pollinators of crops and wild plants.2. Using 6 years of data from a large‐scale study with fortnightly measurements ofhoneybee colony performance traits (10 apiaries per year distributed across a435 km2‐large research site in France), we related worker brood area, number ofadult bees and honey reserves to the proportions of organic farmland in the surroundingsof the hives at two spatial scales (300 m and 1,500 m).3. We found evidence that, at the local scale, organic farming increased both workerbrood production and number of adult bees in the period of flower scarcity betweenthe blooms of oilseed rape and sunflower (hereafter ‘dearth period’). Atthe landscape scale, organic farming increased honey reserves during the dearthperiod and at the beginning of the sunflower bloom.4. The results suggest that worker brood development benefitted from organic farmingmostly through a more diverse diet due to an increase in the availability of diversepollen sources in close proximity of their hives. Reduced pesticide drift mayhave additionally improved bee survival. Honey reserves were possibly mostlyaffected by increased availability of melliferous flowers in foraging distance.5. Synthesis and applications. Organic farming increases honeybee colony performancein a period of resource scarcity, likely through a continuous supply of floral resourcesincluding weeds, cover crops and semi‐natural elements. We demonstratehow worker brood area increases in the critical dearth period (between the bloomsof oilseed rape and sunflower). This has previously been linked to winter colonysurvival, suggesting that organic farmland may mitigate repercussions of intensivefarming on colony vitality. We conclude that organic farming benefits a crucial croppollinator with potential positive implications for agriculture in the wider landscape