Exploring Bumblebee Nesting Boxes for Low-Cost Crop Pollination, Species Diversity

FAYETTEVILLE, Arkansas – As more small farmers turn to native pollinators as a source of crop pollination, they are seeking to enhance species diversity and increase populations, while keeping their maintenance costs low.

One graduate student at the University of Arkansas is focusing on the bumblebee and whether artificial nesting boxes can be developed as an economical means to increase populations and tie specific bumble bee species to crop bloom times. The work is supported by a two-year $9,000 Southern Sustainable Agriculture Research & Education (SARE) Graduate Student Grant.

“Honeybees have been our primary crop pollinators for a long time, but recent declines are impacting managed pollination services. Farmers may be able to obtain free or low-cost pollination services by managing populations of native pollinators,” said Amber Tripodi, a PhD student in entomology. “Bumblebee nest boxes are an economical solution and an ideal appropriate technology, but can they be relied upon to increase bumblebee populations? That’s what my study aims to find out.”

Tripodi hopes to develop a set of recommendations for using artificial nesting boxes to increase bumblebee populations by identifying the best designs.

“If there is an increase in populations, I can provide farmers with the design to construct the boxes, as well as provide recommendations for placement and quantities,” said Tripodi.

In addition, Tripodi plans to record the species that use the nest boxes to pair the right bumblebee with the right crop.

“Arkansas’ seven bumble bee species exhibit different seasonal patterns. By relating bumblebee and crop phenology, I hope to be able to tell farmers which bumblebees are available to pollinate their specific crops in the area,” she said.

Tripodi chose the bumblebee for her study because of its indiscriminatory nature in crop pollination, making the native pollinator particularly suitable for small-scale farms with crop diversity.

“Unlike many short-lived, solitary bees, bumblebees, since they are social, can keep pace as farmers rotate their crops throughout the season. They also have the ability to efficiently pollinate plants like tomatoes, eggplant, peppers and blueberries which honey bees and most solitary bees cannot,” said Tripodi. “The issue is lack of suitable natural nesting sites which may be a limiting factor in bumblebee abundance. That’s where the artificial nesting sites come into play.”

In her first year of the project, Tripodi will use 100 wooden boxes about the size of a shoebox to test two types of entrances (a simple hole and a buried hose) and two types of bedding material (cotton insulation and poly-rayon craft stuffing) to determine the best design.

“Bumblebees are cavity nesters. Queens look for sites that have a small opening that can be easily defended and insulating materials, such as softened straw or hair on the inside,” said Tripodi. “My designs are simply to see which ones they prefer the most. “

In the second year of the project, Tripodi will trial 240 nest boxes of the most successful design on a single farm to determine if there are population increases and to identify bumblebee species that use the nests.

“The local farmer I’m collaborating with grows 20 acres of fruits and vegetables for local markets, incorporating row, greenhouse and high tunnel production,” said Tripodi. “Fruit set in his high tunnel tomatoes has been historically low, and lack of pollination is suspected as the cause.”

Tripodi hopes to develop educational materials based on the results of her study, including a brochure with the nest box design, instructions for use and maintenance, recommendations for enhancing bumblebee populations for small farms, and a user-friendly guide to Arkansas’ bumblebee species, their seasonal abundances with respect to crop bloom times and information on crops that they are known to pollinate.

For more information on the project, “Evaluation of the Utility of Adding Artificial Bumblebee Nesting Sites to Increase Pollination Services in a Small Farm Environment,” visit the national SARE projects database and search by project number GS11-106.

--30--

Published by the Southern Region of the Sustainable Agriculture Research and Education (SARE) program. Funded by the USDA National Institute of Food and Agriculture (NIFA), Southern SARE operates under cooperative agreements with the University of Georgia, Fort Valley State University, and the Kerr Center for Sustainable Agriculture to offer competitive grants to advance sustainable agriculture in America's Southern region.