Background

Pollinator declines are a concern worldwide. It is estimated that about one third of the human food supply is reliant on pollination by animals (Klein et al. 2007). In the U.S. alone, crop pollination services provided by unmanaged or “wild” insects exceed $3 billion per year (Losey & Vaughn 2006).

The viability of wild bee populations is strongly tied to the availability of floral resources in the landscape surrounding their nests and recent efforts have sought approaches to predict responses of bee populations to resource levels in the landscape around their nests. Bumble bees are a particularly important group of social insect pollinators and also a group of conservation concern. Our group is working on detailed demographic models and empirical assessment of bumble bee population dynamics to better understand how changes in forage (flowering plants) affect colony growth and reproduction. Specifically, we are assessing the relationship between flowering resources and (1) bumble bee foraging behavior and colony growth; and (2) quantifying feedbacks in colony response that may occur through sized-based foraging (i.e., differences in resource collection by worker bees of different body size. We are seeking a highly motivated engineering student(s) to collaborate on technical aspects of the design that involve monitoring individual bees within colonies.

Project Goal

We will assess the size of worker bees and weight of forage (i.e. nectar and pollen) that individual worker bees bring back to the colony. We would like to accomplish this by integrating a microbalance or strain gauge into our monitoring system, such that individuals exiting and returning to the colony are weighed upon exit and entry. All workers are individually tagged for identification. Exit weights provide an assessment of worker size. Differences between exit and entry weights for a given trip provides an estimate of resources that individuals are bringing back to the colony. The major benefit that such a device would provide is reducing the amount of human intervention involved in monitoring foragers. Ideally, the scale will be connected to a data-logger, such that weights, and their associated timestamps, are recorded automatically.

Design Challenges

• This project involves tiny masses (<0.25 g with resolution of 0.001 grams)
• The microbalance or strain gauge must operate in association with a living bee colony. The engineering student will need to work closely with other members of the team to understand how bee behavior may influence aspects of the design.
• Scale must be robust to outdoor application (i.e. must operate in outdoor temperatures)

Current Assets

Currently, we have some elements of a preliminary design. If it would be helpful to the engineer, we have a prototype strain gauge and CAD drawings that can be referenced.

Broader Interest/Impacts

This technology and experimental set-up are of broad interest to researchers working with honeybees and other bees across North America, Europe, and Australia. As such, it could be an opening to broader collaboration and interactions.

Citations

• Cox-Foster, D.L. et al. (2007) A metagenomic survey of microbes in honey bee colony collapse disorder. Science 318(5848): 283-287.
• Klein, A., Vaissiére, B.E., Cane, J.H., Steffan-Dewenter, I., Cunningham, S.A., Kremen, C., Tscharntke, T. (2007) Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society, B 274: 303-313.
• Losey, J.E., Vaughan, M. (2006) The economic value of ecological serviced provided by insects. BioScience 56(4): 311-323.