Pollination value of male bees: The specialist bee Peponapis pruinosa (Apidae) at summer squash (Cucurbita pepo)

Authors: Cane, James; Sampson, Blair; Miller, Stephanie

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2010
Publication Date: 4/17/2011
Citation: Cane, J.H., Sampson, B.J., Miller, S.A. 2011. Pollination value of male bees: The specialist bee Peponapis pruinosa (Apidae) at summer squash (Cucurbita pepo). Environmental Entomology. 40(3):614-620.

Interpretive Summary: Bees are essential pollinators of squashes and pumpkins. Both honeybees as well as a group of native, nonsocial ground nesting specialist bees -- the Peponapis squash bees -- are effective squash pollinators. Male Peponapis bees visit squash flowers for mates and nectar, but do they pollinate? Field experiments by ARS scientists show that the pollination needs of summer squash flowers are fully satisfied after receiving seven male Peponapis visits, achievable in the first hour after dawn at studied sites. This intensity of visitation by male Peponapis was found to be locally sustainable year after year and widespread in the US, both for farm and garden settings. Male squash bees thus contribute valuable pollination service to the Nation's $500,000,000 squash and pumpkin crops, the first such demonstration for any crop.

Technical Abstract: Males can comprise a substantial fraction of the bees that visit flowers, particularly at floral hosts of those bee species that are taxonomic floral specialists for pollen. Despite their prevalence in a number of pollination guilds, contributions of male bees to host pollination have been largely overlooked or ignored. In this study, males of the squash bee Peponapis pruinosa Say are shown to be effective pollinators of summer squash, Cucurbita pepo L. Seven sequential visits from male P. pruinosa maximizes squash fruit set and growth rate. This visitation intensity is readily achieved within their first hour of morning foraging and mate searching. Male pollination efficacy and their abundances at squash flowers were sufficient to account for most summer squash production at our study sites, and by extrapolation, to 2/3 of all 87 farms and market gardens growing squashes that were evaluated by collaborators in the Squash Pollinators of the Americas Survey.