Industrial hemp plants are shown in a greenhouse at Cornell AgriTech in Geneva, New York.

Feb 17, 2020
Studies Show Hemp As Pollen Source For Bees

Two recently published studies have found hemp to be a pollen source for bees, especially when other floral sources may be limited.

Colorado State University

A study conducted by researchers at Colorado State University’s Department of Soil and Crop Sciences found hemp’s prolific pollen production may provide major ecological benefits and provide sustained nutritional options for bees. The study was led by assistant professor Arathi Seshadri and graduate student Colton O’Brien.

Hemp flowering in northern Colorado, where this study was conducted, occurs between the end of July and the end of September. This time period coincides with a scarcity of pollinator-friendly crop plants in the region, making hemp flowers a potentially valuable source of pollen for foraging bees, the authors wrote in their abstract.

The researchers reported 23 different genera of bees collected in the fields of flowering hemp. Of the bees collected, 38% were European honeybee, Apis mellifera; followed by Melissodes bimaculata at 25% and Peponapis pruinosa at 16%.

“As cultivation of hemp continues to expand, we expect insect pests on hemp to also become prevalent. Our results documenting bee diversity in flowering hemp provides the impetus for the development of integrated pest management plans that protect pollinators while controlling pests,” the researchers wrote.

Cornell University

Over on the East Coast, researchers at Cornell University’s Entomology Poveda Lab looked at the interaction bees had with flowering hemp fields in the New York state landscape. The study aimed to recognize how bee communities on different hemp farms are influenced by variable regional landscapes and crop networks.

Cornell researchers used sweep-nets and collected flower-visiting bees on 10 farms around Tompkins, Ontario and Seneca Counties. They analyzed and identified bee communities on each farm within crop networks of site-specific landscapes. Bees recorded visiting hemp flowers include:

  • Bombus impatiens (Common Bumblebee)
  • Apis mellifera (Common Honeybee)
  • Lasioglossum spp.
  • Ceratina spp.
  • Helictus spp.

The researchers found honeybees, bumblebees and other native bees visit male hemp flowers for their pollen but do not visit female plants as those do not offer any nectar.

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