Improving Native Bee Pollination Part 2: Alternative Nest Boxes Building on the Lessons from the Field in 2008

Improving Native Bee Pollination Part 2: Alternative Nest Boxes Building on the Lessons from the Field in 2008

Summary

Improving the success rate of colony development for bumblebees (Bombus spp.) has been the goal of this program. It is estimated that only approximately 1% of overwintering Bombus queens establish successful colonies each spring. Much of the poor success rate has been attributed to predation by mice and destruction of young colonies by ants. The hypothesis of this 2 year program was that creating ideal colony boxes that provided protection from these predators could enhance the successful establishment of new colonies.

In 2008, we used the three best designs that could be gleaned from published articles and related literature and had only one colony establish in over 140 nest boxes on 5 sites. During this time, it was observed that the dominant species of Bombus in our area (Bombus impatiens) is almost exclusively a ground dweller. Therefore, we created a new design that also included hollow tubes for other native bees. While many native bees other than bumblebees have used the current nest boxes, we have yet to create a design that attracts newly emerged bumblebee queens.

Like many researchers before us, some piece of the puzzle is missing. It seems that the best hope to increase and attract native bees lies in habitat creation and renovation, not building field nest boxes.

Objectives/Performance Targets

-Develop farm-ready, economical, durable, nesting boxes for bumblebees and other native bees.
-Determine the best locations and protocols for placing nesting boxes (ie: sun, shade, direction of entrance…)
-Create presentations, demonstrations, publications and plans to encourage the adoption of this technology should it prove workable.

Accomplishments/Milestones

We redesigned the nest boxes used in the 2008 program and added an underground entrance plus a stack of boards predrilled in various sizes to encourage other native bees (see images uploaded below). The goal was to create an all-purpose nest unit for many native bees. One of the big changes was replacing the pine from the earlier models with a recycled plastic wood-like material to improve the long-term durability. We placed over 90 of these boxes on 3 farms. All of the boxes were designed to allow us to inspect them through a plexiglass window without disturbing the nesting bees.

Upon inspection of the nest boxes in the summer, late summer and early fall, no bumblebees had used any of the nest boxes, but many of the stacked boards had been used by other native bees for egg laying. After 2 years, 4 designs, and several hundred nest boxes, it is clear, that like others before us, we are missing some important piece of understanding as to what attracts newly emerged bumblebee queens to a nest site.

During this project, a related program establishing habitat using many native flowering plants has been very successful in drawing in vast numbers of native bees including bumblebees. Even nest boxes placed within these habitats have gone unused by bumblebees. It is difficult to develop a new line of reasoning or design for the nest box project without some new information. It seems as if habitat creation and rehabilitation is the single best course of action in promoting native bees.

• 2008 model nest boxes waiting for installation
• Interior of new nest box showing stuffing and entrance tube
• Ground boxes ready to be shipped
• 2009 model next box installed on mulch
• Contrasting image of 2008 (left) and 2009 (right) model nest boxes
• Nest box installed at Dickinson College Farm
• 2009 model nest boxes prior to field installation

Impacts and Contributions/Outcomes

When this project was started, the researchers believed that with sufficient nest boxes of various designs placed on enough farms and in multiple locations, that we could solve the puzzle of how to encourage bumble queens to utilize the nests and thus, increase their survival for enhanced pollination. After so many designs and literally hundreds of hours of labor, there seems to be no immediate answer as to how to encourage them to use a man-made nest box. Based on the sister project on habitat creation using a collection of flowers that blooms over a long season, that approach seems much more sound than placing any new design or adaption for nesting boxes.

Collaborators: