Improving the success rate of colony development for bumblebees (Bombus spp.) has been thte 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 has been attributed to predation by mice and the 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. This would directly aid growers by increasing the supply of pollinators.
In 2008, we selected the best designs for colony boxes as gleaned from numerous published articles and related literature. To our dismay, only a single one of 140 boxes were successfully colonized by bumblebees. During this time, other work evaluating populations of regional pollinators indicated that Bombus impatiens was the dominant species of bumblebee in the area. This species is almost exclusively a ground dweller explaining our low success rate for colony establishment. Therefore, a new design that also included a ground entrance, plus space for multiple tubes for other seasonal native bees was created.
While many native bees other than bumblebees have used the new design, like many researchers before us, we have yet to create a design that attracts newly emerged spring Bombus queens. It seems that the best hope to increase populations of bumblebees is through habitat creation and renovation versus building field nest boxes. Substantial habitat studies have been implemented in 2010 and 2011 at the Penn State Southeast Research and Extension Center in order to evaluate the impact of managed habitats on pollinator visitation.
This project was started both with the collapse of managed honeybees due to Colony Collapse Disorder (CCD) and the observation(s) that honeybees were not the primary pollinator of strawberries and cucurbits. It is well known that bumblebees will pollinate many plants that honeybees cannot and will do so under weather conditions that keep honeybees in their colony boxes. Increasing the number of successful bumblebee colonies thus pollinating bees through better colony boxes appeared to be a solution to both problems.
-Develop farm-ready, economical, durable, nesting boxes for bumblebees and other native bees.
-Determine the best locations and protocols for placing nestingboxes (ie: sun, shade, direction of entrance, location of entrance….)
-Create presentations, demonstrations, publications and plans to encourage the adoption of this technology should it prove workable.
Over 90 nest boxes using a new design modified from Part 1 of this project were placed on 3 farms. All of the boxes were designed with a plexiglass window that allowed for the inspection of the nesting chamber without disturbing any potential bees within. Since the primary bumblebee in our area is B. impatiens, we installed a tube that was placed at ground level to provide what was hoped was a more inviting entrance. Also the outer shell of the new design was constructed out of a plastic wood made from recycled horticultural plastic to improve durability as many of the original pine boxes deteriorated quickly.
In Part 1 of this project, we identified a number of brood chambers for other solitary bees that had been created either inside or attached to the 3 original designs. A stack of predrilled wooden boards was attached to the top of the new designs as an attempt to make the boxes do double duty and provide easier nesting for Mason bees and other like pollinators.
These colony boxes were inspected three times during the growing season (summer, late summer, and early fall). Below are uploaded photos/images of all types of boxes with graphic instructions on building one model.
- Image of 2009 bee boxes prior to installation
- Several colors were tried based on reported bee preferences
- Instructions for building a bee box based on first season plans
- Box installation on “U” post to prevent ants and mice from entering
- View inside original sunlge room box showing cotton nest materials
- Image of ‘new’ bee box showing predrilled solitary bee egg tubes
We redesigned the nest boxes used in Part 1 of this program (2008) and added both an underground entrance and a stack of predrilled wooden boards to encourage native bees other than solely Bombus spp. This was to create an all-purpose nest unit to increase potential adoption by growers.
Upon inspection of the nest boxes in the summer, late summer and early fall, no bumblebees had used any of the nest boxes. One of the problems of the new ground entrance was that it tended to fill with debris when there were no occupants to keep it open (active colonies of ground nesting bees must regularly reopen and maintain their entrance). Many of the predrilled boards had been used by other native bees for egg laying. After several years, 4 designs and several hundred nest boxes, it is clear that something is missing is our attempts to attract bumblebees to these nest boxes. The big question: What attracts a newly emerged bumblebee queen to specific 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. Without some new line of reasoning or information, there does not appear any reason to pursue another nest box design. These are numerous plans available online for solitary bee tubes that are both less expensive and easier to construct than our stacked design. It seems as if habitat creation and improvement are better avenues in promoting and encouraging native bee population enhancement.
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 bumblebee queens to utilize the colony boxes and thus increase their survival. This increase in bumblebee colonies would directly improve crop pollination as foraging bumblebees generally stay within several hundred yards of their respective colonies.
After many designs and many hundreds of hours of labor, there seems no immediate answer or solution as to how to build or encourage newly emerged spring bumblebee queens to use man-made nest boxes. A related project on habitat creation using a collection of annual and perennial flowers that bloom continually over the entire growing season appears to be the better solution at this juncture. Like other researchers before us, man-made bumblebee next boxes have simply not worked out to any reasonable extent.
Education & Outreach Activities and Participation Summary
Presentations on this project were made at several grower meetings including the 2010 Mid-Atlantic Fruit and Vegetable Conference. That power point is attached
As none of the bumblebee nest / colony boxes worked, there is no economic impact.