It’s pumpkin season, so the title of Bee of the Month for this month could only ever go to the Peponapis or Pumpkin Bees of Central and North America. Peponapis in ancient Greek translates as ‘Pumpkin Bee’ and these guys are real pumpkin pollinator specialists.
The Peponapis or Pumpkin Bee
There are 13 species of the Peponapis bee native to North America. They are cucurbit specialists, feeding on a variety of wild gourds, squash and cucumber as well as farmed cultivars including pumpkin and butternut squash. Both male and female bees feed exclusively on cucurbit pollen and nectar.
These bees are slightly larger than a Honey bee, covered in a dense pile of hair and are fast-flying even in very cool conditions which means they can visit many more flowers than a Honey Bee can during the same period of time. They also spend more time on each individual flower than most other bees and their movements inside the flower result in increased transfer of pollen grains compared to other bees.
Peponapis bees emerge very early in the morning often before the sunrise and are busy pollinating pumpkin in the near-darkness, well before any other bees are active. The female bees excavate nest burrows in the soil around or very close to their host plants. The burrows may be a foot or more deep and contain numerous chambers where pollen is cached, and an egg laid.
The male bees roost communally inside the male flowers and emerge at dawn from their sleep covered in pollen which they then transport to the female flowers as they search for nectar. It’s thought that the male bees are more efficient at pollinating pumpkin crops than the females because of this habit.
The most widespread and important of the Peponapis Bees is Peponais pruinosa which can form large nesting aggregations on pumpkin farms meaning that farmers have no need to import honey bee hives to pollinate the crop. Recent genetic studies have shown that Peponapis pruinosa originated in Latin America and Western North America and as humans began to cultivate wild cucurbits and spread them northwards and eastwards across North America the bee expanded its range alongside the crop plants to become the most widely-distributed and abundant of the squash bees. Today it’s a bee of significant economic importance for its contributions in pollinating pumpkins and represents the earliest evidence of a bee expanding its range in response to human agriculture.
This YouTube video tells the story of how squash bees colonised North America.