Squash Pollinator Search

Project Overview

Project description

Squash, pumpkin, and gourd crops (genus: Cucurbita) were among the first crops domesticated in the Americas. These plants are pollinator-dependent because they have separate male and female flowers that require insects to move pollen from anthers to stigmas to produce high-quality fruits. The large yellow Cucurbita flowers support a diverse community of bee pollinators including honey bees, bumble bees, carpenter bees, and the highly specialized squash bees. Before the domestication and widespread cultivation of Cucurbita crops, squash plants were not found in the northern latitudes of North America, neither were squash bees. However, now both bees and plants are widespread and these plant-pollinator systems have been poorly characterized in most of these areas.

In this project, we will utilize the experience, knowledge, and dedication of community scientists (entomologists, botanists, ecologists, gardeners) to plant and grow wild and domesticated pumpkins, squashes and gourds (genus Cucurbita) to compare the attractiveness of their flowers to bee pollinators. Participants will receive seeds of three species of Cucurbita: C. pepo (cultivated), C. maxima (cultivated), and C. foetidissima (wild) and plant these seeds in raised beds in their own gardens over the summer. During the flowering period of the plants, participants will collect data for 10 minutes weekly on male and female flowers and collect bee species visiting them. Collected bees will then be returned to the López-Uribe Lab at Penn State University in University Park, PA for pinning and identification. All the data collected for this project will be made publicly available through SCAN and GBIF.

Project goals

Gain a better understanding of the variation in the pollination community of pumpkins, squashes and gourds across North America
Identify differences in bee preferences for domesticated and wild Cucurbita species
Document the distribution of squash bee specialists (Eucera (Peponapis) and Xenoglossa) across North America
Engage project participants in scientific research through data collection, and the importance of bee pollination for food production

Resources for participants

Instructional video for collection methods

Protocols

Planting protocol

Collecting protocol

Printable data collection sheets

2023 project results

2023 was the first year and pilot study for the project. We collected data from Pennsylvania only.

Summary of bee collections
Total bees collected: 98 bees, 4 species

Eastern bumble bee (Bombus impatiens) – 51 bees
Squash bee (Xenoglossa pruinosa) – 31 bees
Honey bee (Apis mellifera) – 14 bees
Green sweat bee (Augochlora pura) – 2 bees

By plant:

‘Black Beauty’ zucchini (Cucurbita pepo) – 57 bees
‘Lumina’ pumpkin (Cucurbita maxima) – 41 bees

By location:

Allegheny County – 13 bees
Susquehanna County – 21 bees
Warren County – 64 bees

2024 project results

Summary of bee collections
Total bees collected: 204 bees, 7 genera

1. Eastern bumble bee (Bombus impatiens) – 44 bees
2. Hoary squash bee (Xenoglossa pruinosa) – 61 bees
3. Honey bee (Apis mellifera) – 39 bees
4. Green sweat bee (Augochlora pura) – 2 bees
5. Green sweat bee (Agapostemon angelicus/texanus) – 6 bees
6. Striped sweat bee (Agapostemon spp.) – 23 bees
7. Half-black bumble bee (Bombus vagans) – 12 bees
8. Sweat bee (Lasioglossum spp.) – 7 bees
9. Two-spotted longhorn bee (Melissodes bimaculatus) – 1 bee
10. Nimble squash bee (Xenoglossa strenua) – 2 bees
11. Black-faced squash bee (Xenoglossa cf. limitaris) – 4 bees
12. Dark squash bee (Xenoglossa cf. atrata) – 1 bee