By Blake Jackson
Pollination in cucurbit crops depends on a complex mix of honey bees and wild bees, with sensitivity varying by crop type, season, and location. In the Cucumis genus, which includes cucumbers and melons, research shows that effective pollination often relies heavily on honey bees, though wild bees play an important supporting role.
Studies in central Indiana documented more than 28 wild bee species visiting cucumber flowers, with similar diversity observed in Pennsylvania.
Further research in eastern Pennsylvania and parts of New Jersey found even greater diversity. On small, diversified farms, scientists recorded 44 bee species visiting watermelon flowers.
Using pollination models that combined visitation rates with pollen deposition per visit, researchers found that wild bees alone provided sufficient pollination on about 90% of farms.
Honey bees alone achieved adequate pollination on roughly 70-80% of farms. The presence of both groups increased reliability and resilience of pollination services.
The balance shifts in the Cucurbita genus, which includes squash and pumpkins. In these crops, wild bees often dominate flower visitation regardless of honey bee stocking. Studies from New York, Massachusetts, Virginia, and Pennsylvania confirm this pattern.
In large commercial pumpkin fields in Columbia and Lancaster Counties, data from nearly 5,000 bee visits showed that bumble bees accounted for 67% of visits, squash bees 25%, and honey bees only about 6%.
Among Pennsylvania’s bumble bees, Bombus impatiens is especially important. Queens emerge in early spring and require abundant, nearby floral resources to establish nests and raise their first brood. Researchers are testing fall-planted cover crops to supply early-season flowers, timed to end blooming before pumpkin pollination begins in mid-summer.
Late summer presents another critical phase, when colonies produce reproductive males and females. These future queens must build energy reserves before overwintering, prompting trials of late-season flowering seed mixes to support their survival.
Photo Credit: istock-kerem-hanci
Categories: Pennsylvania, General