A 3D Printed Pollen Trap for Bumble Bee (Bombus) Hive Entrances

Summary

We present a non-lethal and automated mechanism to collect pollen from bumble bee (Bombus) workers returning to a hive. Instructions for producing, preparing, installing and using the devices are included. By using 3D-printed objects, modification to the design was timely, efficient and allowed for quick turnaround for testing.

Abstract

To verify the plant sources from which bumble bees forage for pollen, individuals must be collected to remove their corbicular pollen loads for analysis. This has traditionally been done by netting foragers at nest entrances or on flowers, chilling the bees on ice, and then removing the pollen loads from the corbiculae with forceps or a brush. This method is time and labor intensive, may alter normal foraging behavior, and can result in stinging incidents for the worker performing the task. Pollen traps, such as those used on honey bee hives, collect pollen by dislodging corbicular pollen loads from the legs of workers as they pass through screens at the nest entrance. Traps can remove a large quantity of pollen from returning forager bees with minimal labor, yet to date no such trap is available for use with bumble bee colonies. Workers within a bumble bee colony can vary in size making size selection of entrances difficult to adapt this mechanism to commercially reared bumble bee hives. Using 3D printing design programs, we created a pollen trap that successfully removes the corbicular pollen loads from the legs of returning bumble bee foragers. This method significantly reduces the amount of time required by researchers to collect pollen from bumble bee foragers returning to the colony. We present the design, results of pollen removal efficiency tests, and suggest areas of modifications for investigators to adapt traps to a variety of bumble bee species or nest box designs.

Introduction

Bumble bees (Bombus spp.) are large robust insects that are found across the temperate, alpine, and arctic regions of the world¹. They are important to plant communities and provide important pollination service for the agricultural crops that they visit². Recent declines in the abundance and distribution of several species has brought their importance as pollinators to the forefront of public awareness³. Researchers have identified several stressors that are likely contributing to population declines including a lack of diverse and abundant floral resources ....

Protocol

1. Print pollen trap structures

1. Download the appropriate STL file for the nest box that bumble bees are nesting in (e.g., Biobest or Koppert style hives, https://www.ars.usda.gov/pacific-west-area/logan-ut/pollinating-insect-biology-management-systematics-research/docs/pollen-traps/). The files are available to the public, free for download and modification by the end user.
2. Open the STL file in the printer program. Follow printer manufacturer directions to build the four trap components.
   NOTE: Allow approximately 3 h for the trap body to print, 2 h for catch basin to print and 30 min each for the filter and trap closure insert to print. Tr....

Results

Eight different pollen filter designs were tested to determine their efficacy and efficiency at removing corbicular pollen loads from returning bumble bee workers. All designs were successful at removing at least of one corbicular pollen load from a returning forager. However, some were found to slow workers from leaving or entering the hive or failed to remove pollen loads (Table 1). Pollen traps with various filters were tested sequentially on 4 laboratory reared colonies of B. huntii Greene f.......

Discussion

Collection of pollen from bumble bee colony entrances can allow for a variety of ecological and agricultural studies. Identifying the floral sources from which bumble bees collect pollen provides valuable information and insight into the diversity of plants that contribute to a colony’s overall diet¹⁹. Identifying the pollen source has implications for both agricultural production and studies of ecosystem services in wild lands^12,20........

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
MakerBot Replicator+	MakerBot	Model PABH65
MakerBot Tough Material	PLA Filament		various colors
Nest Box	Biobest		Not sold publicly without bee purchase