Temporal changes in the composition and abundance of floral visitors during floral anthesis influence the rate of deposition and germination of pollen in stigmas, as well as the rate of removal of pollen from anthers. In the tropics, the squash (Cucurbita pepo) is visited by a great diversity of bees, but little is known regarding the dynamics of its pollinators and pollination during its floral anthesis in tropical environments. We studied the foraging cycle of different species of bees in squash crops in Costa Rica and the relationship of this cycle with nectar production, pollen loads in anthers and bees, and number of pollen grains and pollen tubes in stigmas and styles. It was determined that despite the short duration of the floral anthesis of this crop, there are changes in the composition of visitors during anthesis from bees with twilight flight capacity that visit male flowers in the opening to primarily social bees at later hours. Loss of pollen from anthers and deposition of pollen on stigmas occurs rapidly in early hours. Pollen transport by bees may be facilitated by pollen accumulation at the bottom of the corolla of male flowers. After 6 a.m., little change occurs in crop pollination levels. The dominance of stingless bees in the flowers after 6:30 a.m. appears to displace other bees from these flowers, despite the permanence of nectar flow. The Cucurbita species may be an important crop for maintaining bee diversity and enhancing the pollination of other crops in agricultural ecosystems.

花期期间花粉的组成和丰度的时间变化影响花粉在柱头中的沉积和萌发率，以及花粉从花药中的去除率。在热带地区，南瓜 ( Cucurbita pepo) 被种类繁多的蜜蜂访问，但在热带环境中其花期期间其传粉媒介和授粉的动态知之甚少。我们研究了哥斯达黎加南瓜作物中不同种类蜜蜂的觅食周期，以及该周期与花蜜生产、花药和蜜蜂的花粉负荷以及柱头和花柱中的花粉粒和花粉管数量的关系。已经确定，尽管这种作物的花期持续时间很短，但在开花期间游客的组成发生了变化，从具有暮光飞行能力的蜜蜂到在开放时间访问雄花，到稍后时间主要是群居的蜜蜂。花药的花粉损失和花粉在柱头上的沉积在早期迅速发生。雄花花冠底部的花粉积累可以促进蜜蜂的花粉运输。早上 6 点之后，作物授粉水平几乎没有变化。早上 6 点 30 分之后，无刺蜜蜂在花朵中的主导地位似乎取代了这些花朵中的其他蜜蜂，尽管花蜜流动是永久性的。这葫芦科植物可能是维持蜜蜂多样性和加强农业生态系统中其他作物授粉的重要作物。