The impact of honey bee colony quality on crop yield and farmers' profit in apples and pears

Despite global interest in the role of pollinators for food production, their impact on farmers' profit, which determines farmers' livelihood and land-use decisions, is unclear. Although average values of pollinator benefits are generally assumed, there is potential for large spatial variation among crop species and varieties or among pollinator management strategies, even within the same region and year. We studied how quality of honey bee colonies used for pollination services, which included artificial feeding during winter and pathogen control, affect flower visitation, fruit production, and farmers' profit in the main apple and pear producing region of Argentina (Patagonia). For apple, high-quality colonies exhibited flower-visitation rates 130% greater than conventional colonies. Indeed, high-quality colonies increased fruit set by 15% (increasing production quantity), seed set and fruit sugar content, and subsequently farmefs profits by 70%. For pear, colony quality only affected fruit weight of the Abate Fetel variety, but not that of the Packham's Triumph variety. Fruits were 20% heavier in farms deploying high quality colonies but did not contribute to increase farmers' profits to the extent that it did for apple. In contrast to studies conducted elsewhere, we did not observe any wild pollinators visiting apple or pear flowers, highlighting the fragility of this conventionally intensified crop production system. We found that such orchard systems can suffer large pollinator deficits affecting farmers' profit Given that A. mellifera was the only flower visitor, we could estimate the impact of improving colony management on farmer's profit without the influence of other pollinators. Our study also shows that variations within pome crops, ie. apples and varieties of pears, in pollinator benefits can be very large, and that the assumption of global average values to guide local recommendations can be misleading.