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

This method allows researchers to collect pollen from bumblebee colonies with minimal disturbance to the bees and low risk of bee stings to the researcher. Using this protocol, pollen can be collected from multiple colonies simultaneously, permitting researchers to use more colonies with less labor and expense than hand collecting pollen. This method will benefit research in pollination and bee health, pesticide science and environmental contamination and can be adapted to multiple species of bumblebees.

Begin by removing the support structures printed with the trap body and catch basin, including those of the sieve structure and the trap body. Clear any plastic strands crossing the raised edges of the pollen filter with a hand drill, then use a box cutting razor blade and sandpaper to even out any bumps or raised edges on the flat side of the filter. Gently push the plastic pollen filter through one side of the trap body.

The filter will only fit in one way as the left side of the trap has a larger opening to accommodate passage of the raised filter cones. If the side slits are too small for the pollen filter to slide through smoothly, use a razor to scrape enough plastic away from the slit in the trap body. Ensure that the filter fits securely in place with no more than a two millimeter gap between it and the trap body.

Slide the raised edges on the bottom of the trap body into the groove on top of the catch basin. The catch basin should be positioned directly underneath the sieve region of the trap body. Cut or sand the plastic to allow smooth placement and removal of the catch basin.

Placement of the catch basin will secure the pollen filter into place. Stop pollen feeding 24 to 48 hours before deploying colonies, which will cause workers to use up any stored pollen and stimulate them to leave the nest. Prepare the hive trap body for installation by placing a trap closure insert into the filter slot to prevent bees from escaping.

Working under a red light, lift the plastic nest box out of the cardboard outer box and locate the entrance at the front of the nest. For corporate style hive entrances, pull up on the entrance tab until both entrance holes are open. Then insert the two tubes of the pollen trap into the entrance holes ensuring that the sieve of the pollen trap is on the bottom.

Gently push down on the plastic entrance tab to secure the pollen trap in place. To install the pollen trap into bio best style hive entrances, use a flathead screwdriver to gently pry the plastic entrance device from the nest box. Insert the pollen trap into the nest entrance holes until it is placed firmly against the nest.

Then secure it to the nest with tape or quick dry glue where the trap contacts the nest box. Lace the nest boxes into this study area, providing cover from precipitation and anchorage for wind as these can adversely affect the quality and quantity of the collected pollen. Provide the hives with adequate sun cover to prevent overheating.

Remove the trap closure insert from the trap body to allow bees to forage freely so that they can orient themselves with the surrounding area and the location of their nest. Orientation flight time should be complete in 24 hours under normal conditions. To engage the trap, slide the pollen filter into the filter slot, ensuring that it is securely in place.

Install the catch basin by sliding it onto the trap body from the front until it's fully closed. If the catch basin is loose or falls off the trap body, use a rubber band to secure it. Observe bees entering and exiting the pollen trap at first deployment to ensure the pollen filter holes are large enough.

If workers are unable to pass through the pollen filter, remove the filter and use the hand drill to enlarge the holes. Increase the diameter sequentially as holes that are too large will not collect any pollen. Once bees are able to pass through the filter, continue observing the entrance to ensure pollen is being removed upon re-entry.

After the designated period of pollen collection, remove the catch basin from the trap body and process the pollen loads according to the experimental design. Remove the pollen filter to allow workers to forage freely, leaving the trap body attached to the hive for the duration of the experiment. Eight pollen filter designs were tested to determine their efficacy and efficiency at removing corbicular pollen loads from returning bumblebee workers.

All designs were successful at removing at least one load, but some were found to slow workers from leaving or entering the hive, or failed to remove pollen loads. The filters were tested sequentially on four laboratory reared colonies of bee green foraging on Phacelia tanacetifolia for a cumulative 138.5 hours and 229 collected corbicular pollen loads over seven days. 52 hours of video observation and 142 pollen loads were collected during the test period.

The number of corbicular pollen loads collected was divided by the number of observed pollen laden foragers that passed through a filter to calculate efficiency. Pollen filter design efficiencies ranged from two to 58.9%Corbicular loads were removed from the legs and fell as cohesive pellets of pollen into the catch basin. Circular filter openings improved pollen collection and movement of workers into the nest environment.

In addition, filter designs that had raised structures that extended away from the nest box also improved pollen removal from the hind legs of foragers. Design number eight, a circular trap entrance with raised edges was the final design. When fixing the pollen trap body to the bumblebee hive body, there is a risk of bees escaping and the researcher getting stung.

It is important to place the trap closure into the trap before attempting this. Working under red light will further reduce the risk. Following pollen collection, the researcher can compare foraging preference, pesticide exposure studies, or environmental contaminant exposure studies.

This technique has allowed us to compare bumblebee foraging to honeybee foraging behaviors, and it has been used to look at pesticide exposure of bumblebees returning to the nest with contaminated pollen.