Ventilation of greenhouses increases honey bee foraging activity on melon,Cucumis melo

Melons are grown in Israel in 'walk-through' tunnel greenhouses. We compare d honey bee (Apis mellifera) foraging activity and melon nectar characteris tics in well-ventilated and in closed greenhouses. Foraging activity in the open greenhouses was two- to five-fold greater than that in the closed gre enhouses. This higher activity could be explained by higher flower attracti vity due to a higher nectar sugar concentration both in hermaphroditic flow ers and male flowers. The higher sugar concentration in the open, ventilate d greenhouses was probably as a result of the relatively lower humidity the re. The greater foraging activity in the open greenhouses also may have bee n due to lower air temperatures and better accessibility for the bees. It s eems that greenhouse ventilation can improve honey bee pollination activity in melon and probably other greenhouse crops as well.