Comparing Species of Bees for Controlled Pollination of Helianthus petiolaris in Field Cages

Honey bees, Apis mellifera, have been used for several years to pollinate caged plant species maintained at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS), Ames, Iowa. Because maintaining large numbers of honey bees is expensive and time consuming, we began looking in 1995 for other pollinator species that can be easily managed and less expensive to maintain than A. mellifera. One species we tested was the hornfaced bee, Osmia cornifrons, a solitary bee imported from Japan in the late 1970s. We also tested a mixture of native bumblebees, Bombus bimaculatus and B. impatiens, which are native to the U.S. Midwest. These bee species were compared in field cages to determine which would produce the greatest number of seeds/plant on the wild annual sunflower, Helianthus petiolaris. After 2 years testing, honey bees consistently produced more seeds/plant than did the other bees tested