Pollinators Save Pumpkin Pie

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Jim Cane/ARS
A female Peponapis sips nectar.

When Thanksgiving rolls around, and you’re enjoying that extra slice of pumpkin pie, give thanks for bees. In particular, the male Peponapis pruinosa, or squash bee, which flits from blossom to blossom searching for a mate.

Entomologist James Cane, with the Agricultural Research Service, and his team are discovering more about America’s native bees that pollinate pumpkins, other squash – spaghetti, pattypan, butternut, Hubbard and zucchini – and gourds. Cane is based at the ARS Pollinating Insects Biology, Management and Systematics Research Unit in Logan, Utah.

Their research shows most of those native bees are members of the genus Peponapis or the genus Xenoglossa.

Cane’s research and other similar studies are providing new details on the extent to which native bees help in pollination. Such investigations are critical in light of the difficulties surrounding the nation’s premier pollinator, the European honeybee, Apis mellifera, and the puzzling phenomenon known as colony collapse disorder.

The ARS research shows, for the first time, that male Peponapis pruinosa play a surprisingly significant role in pollinating the yellow summer squash. Earlier studies indicated that less than 10 percent of the pollination was done by male bees.

Both males and female squash bees take up the bloom’s sweet nectar. The females, however, are the only ones to seek the orange pollen grains to feed offspring at the nests.

The squash bees are early risers, Cane says, beating other bees (honeybees, bumblebees and other pollinators) to the breakfast table. That’s when the squash blossoms are just beginning to open.

By midday, the squash blossoms have closed, and the wiliest of the male bees remain in the blossoms, awaiting a hungry female when the blossom reopens the
following morning.

Study results suggest that with both male and female bees pollinating squash blossoms, fewer bees would be needed overall. This bodes well for growers and beekeepers as it would free up the increasingly scarce and in-demand hives of honey-bees for work elsewhere.

The male Peponapis pruinosa doesn’t look for its mate at the nest site, as most bees do; they seek mates among the flowers of the squash plants. As they fly from blossom to blossom, the bees carry grains of pollen trapped in the tiny hairs of their bodies, thus pollinating the plants.