Flower-rich organic crops improve the health of bumblebee colonies

A recent study published in the journal Insect Conservation and Diversity found that non-crop flowering fields are helpful in attracting bumblebees to cropland, but organically managed crops rich in flower resources, like winter cereals, are most beneficial for bumblebee health. Pollinators have been in decline across the globe for several decades. Loss of habitat and floral resources, along with increased use of pesticide sprays, are largely attributed to the decline. This study measured the foraging activity and health indicators of bumblebee colonies like worker bee weight and body size, and number of queen brood cells in colonies placed next to four types of farms: 1) Conventionally managed winter wheat fields, 2) Conventionally managed flowering fields not used for food production, 3) Organically managed mono-crop of winter spelt, and 4) Organically managed flowering mixed-crop.

Bumblebee colonies next to organic winter spelt fields had larger body sizes and more foraging activity than the other field types. Phacelia tanacetifolia is a flowering plant that bees find very attractive.  This plant was only found in the cultivated flowering fields and accounted for about 50% of the pollen that was collected and identified, indicating that these flowering fields can draw in bees to the cropping region. However, the healthiest bees foraged on the organically managed cereal crops, suggesting that while increasing floral resources at a landscape level is important for attracting and supporting wild bee colonies, organic management is important for supporting the health of those bees once they’re there. This study shows the importance of taking a dual approach to promote pollinator communities by conserving and promoting flower diversity in farmland at local and regional scales, while also using organic crop management to preserve bee health. 


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