Testing the Potential for Cut Flower Pollen to Improve Bumble Bee Health

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Commodities

• Additional Plants: ornamentals
• Animals: bees

Practices

• Crop Production: pollinator habitat, pollinator health

Farmers, landscapers, conservation land managers, government and the public are all invested in providing floral resources to promote pollinator abundance, diversity and health. Pollen and nectar from certain flowers can reduce pollinator infection by detrimental pathogens, but this has been examined for only a few plant species and almost entirely in laboratory settings. The Adler lab recently discovered that sunflower pollen dramatically and consistently reduced a common detrimental gut pathogen of bumble bees in the lab, and that farms with more sunflower had bumble bees with reduced infections. If pollen from other flowers in the sunflower family (Asteraceae) similarly reduces infections in bumble bees, promoting the planting of Asteraceae cut flowers could be an avenue for farmers, landscapers, horticultural growers and land managers to improve bee health while providing a source of income. We will test this hypothesis using a two-pronged approach. We will work with growers at three ‘cut flower’ farms (at least 3/4 acre of cut flowers from our target species) and compare with 3 ‘control’ farms (1/10 acre cut flowers or less). We will deploy honey bee hives with pollen traps at the cut flower farms to collect pollen that we will sort, identify to species using DNA barcoding, and then test in the laboratory to determine effects of each cut flower species on pathogen infection. By testing the pollen of many species in the Asteraceae we will greatly expand our understanding of which pollen has medicinal benefits, may clarify underlying mechanisms, and will be able to make recommendations to stakeholders about species that promote bumble bee health. In addition, we will sample bumble bees twice from each cut flower and control farm (all will have honey bee hives to avoid confounding effects) and assess pathogen infections to determine whether cut flower plantings on farms reduce bee pathogens, as we found for sunflower. Stakeholders have shown overwhelming enthusiasm for this research, with over 97% of 2378 survey respondents saying that if we found specific flowers that reduce bee disease, they were ‘highly’ or ‘very highly’ likely to recommend or use these flowers in their farm/industry/garden. We have consulted with farmers on study design, cut flower selection and potential obstacles during proposal preparation, and will engage with farmers who host the cut flower and control sites. We will solicit input on study design and results via our advisory committee, and disseminate results widely via websites, listservs, fact sheets, our Research Buzz newletter, Vegetable Notes, Hort Notes, and presentations at stakeholder meetings. Taken together, this research will provide insights into how specific flowers may mediate pollinator health, and provide novel opportunities for low-input, non-chemical management practices that stakeholders can use to manage pollinator health and maintain sustainable agroecosystems.

Our goal is to evaluate whether pollen from cut flowers in the sunflower family (Asteraceae) can reduce disease in bumble bees, based on our discovery of this effect in sunflower pollen. We will collect a diversity of pollen from farms growing Asteraceae cut flowers to test its effects on bee pathogens in lab trials, and will collect bumble bees at ‘cut flower’ and ‘control’ farms to assess impacts of cut flowers on wild bees. Our work is novel for innovating sustainable, low-input approaches to manage pollinator health by growing specific crops whose pollen could reduce pollinator pathogens while providing income.