Quantifying the nest density of an economically important native pollinator using population genetics

Project Overview

Project Type: Graduate Student
Funds awarded in 2016: $14,758.00
Projected End Date: 02/28/2019
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Graduate Student:
Faculty Advisor:
Dr. Taylor Ricketts
University of Vermont

Annual Reports


  • Fruits: berries (blueberries), berries (brambles)
  • Animals: bees


  • Farm Business Management: risk management
  • Natural Resources/Environment: biodiversity, habitat enhancement, wildlife
  • Production Systems: holistic management

    Proposal abstract:

    Pollinating insects are critical for food security and ecosystem function, with their contribution to agriculture valued at over $200 billion annually. Yet little is known about the population sizes of unmanaged, native pollinators in agricultural landscapes. The purpose of this project is to estimate the nesting densities of an economically-important native crop pollinator, as part of a broader effort to understand their value for farmers. Combining genetic approaches, geographic information systems (GIS) and field experimentation I will 1) estimate on-farm nest densities of the common eastern bumblebee Bombus impatiens, 2) examine whether landscape pattern or management practices explain differences in nest densities between farms and 3) demonstrate how pollinator community responses translate into economic benefits via changes in crop yield. In spite of their ecological and economic importance, surveying bumblebee populations is challenging. Novel genetic techniques have begun to allow more rigorous estimates. I will, for the first time, connect these techniques with economic analyses to relate nesting densities and blueberry yields in Vermont. My findings will support long-term sustainability of specialty crop agriculture by increasing growers’ ability to better manage pollinators for improved crop yield. The proposed research provides new information and addresses, in economic terms, a specific need of farmers. Our ongoing research has demonstrated that Vermont blueberry farms are pollinator-limited, meaning that some farm’s yields could be improved if more pollinators were present. My research will connect agricultural landscapes, bumblebee populations and yield gaps in a novel and previously unreported way. I will employ a combination of genetic and GIS techniques, thereby advancing the science of measuring pollinator populations in agricultural landscapes. Understanding the relationship between nest density and farm practices and/or landscape pattern will inform management recommendations to farmers who are in need of a suite of tools to maintain diverse and healthy pollinator communities.  

    Project objectives from proposal:

    OBJECTIVES The overarching goal of this research is to provide farmers with practical recommendations to support healthy pollinator populations. Using farm observations, genetic techniques and field experimentation the proposed research will address 3 objectives:

    OBJECTIVE 1 Use population genetics to estimate bumblebee nest density in agricultural landscapes.

    For Objective 1 I will investigate the following question: Q1.1: Do perennial berry farms differ in the nest density of an important crop pollinator? If granted, I will use NE-SARE funds to: 1) collect B. impatiens workers from each farm site during the 2016 summer field season. 2) Extract and genotype DNA from specimens. 3) Use maximum- likelihood methods to assign relatedness. 4) Use this relatedness score to derive a per-farm nest density estimate.

    OBJECTIVE 2 Identify landscape pattern and farm practices that explain differences in nest density between farms.

    For Objective 2 I will explore the following questions: Q2.1: What are the effects of landscape composition and configuration on bumblebee nest density? Q2.2: How do different farm management practices influence bumblebee nest density? I will use already gathered GIS data to characterize the landscapes around sampled farms. I will use already gathered survey data to differentiate farms based on management practices. I will use this information alongside newly gathered nest density data to identify landscape patterns and farm practices that support larger bumblebee populations.

    OBJECTIVE 3 Evaluate pollination services for a perennial berry crop.

    For Objective 3 I ask the following questions: Q3.1: Do differences in nesting density, abundance and visitation translate into differences in yield? Q3.2: What is the economic value of pollination for blueberry growers in Vermont? Our ongoing research with blueberry farms has resulted in 3 years of data on pollinator abundance, visitation rate and yield deficits. This research is well developed and will therefore not use the proposed budget.

    While Obj. 1 will provide population level information about the population status of the common eastern bumblebee and Obj.2 will test how farm management and the surrounding landscape impact bee populations, Obj. 3 will link the effects of changing farm practice and the surrounding landscape to the economic value provided by this important crop pollinator. My work will directly benefit farmers by demonstrating multiple ways in which farm practices and landscapes can be managed to improve economically important pollinator populations such as the prudent use of pesticides or recommendations for incorporating flowering resources.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.