Bees normally return to the hives at night. So it's unlikely that they would be able to pollinate your gourds.

There are a number of plants that attract bees among them are clover, beebalm, hairy vetch, hyssop. Most other vegetables are also attractive. You'll have to plant in quantity as honeybees prefer to work on type of plant at a time. Bumbebees however will work whatever plants are adjacent to them in any order.