Project Number: 2080-21000-019-032-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2017
End Date: May 31, 2021
Bees provide important pollination services to agriculture and natural systems, and it is imperative to understand their foraging behavior, nutritional needs, and response to beneficial habitat to support bee conservation. Many agroecosystems become food deserts for bees after crops bloom, and this is especially important for social bees with colonies that are active through the year. Bumblebees are important pollinators of a variety of crops due to their abundance and ability to buzz pollinate, and some species are commercially available as alternatives to honey bees. However, their foraging ecology is poorly understood, especially in regards to their range, nutrition, and nesting densities in agricultural systems. In this project, we will employ a unique combination of field studies and spatial modeling to understand bumble bee ecology in agricultural landscapes. Using a combination of protein and fluorescent markers, we will determine foraging range of two species (Bombus huntii and Bombus impatiens). This will be supported by determining how colony nutritional needs drive their foraging in diverse landscapes and studying their response to habitat enhancements in agricultural landscapes. An *individual-based?* foraging model will be used to explore how habitat quality affects the foraging range and nest density of these bumble bee species, and to model movement and disease transmission based on foraging range in agricultural landscapes. Results from this project will inform best management practices for implementing habitat restoration to conserve native bumble bee populations, and will improve sustainable pollination practices on farms through enhanced understanding of where habitat enhancements should be located. Specific Objectives: Objective 1. Determine foraging range of B. huntii and B. impatiens colonies Objective 2. Determine how colony forage needs drive foraging strategies on diverse landscapes. Objective 3. Determine response of bumble bee foraging to habitat enhancements in agricultural landscapes Objective 4. Model nesting density of B. huntii and B. impatiens Objective 5. Model disease transmission in bumble bees based on B. huntii and B. impatiens foraging range in agroecosystems
Objective 1. Determine foraging range of B. huntii and B. impatiens colonies. To determine the forage range of bumble bee colonies, two simultaneous experiments will occur, replicated at two locations. We will test colony forage range, by placing lab-reared colonies in an agricultural landscape in which high-quality floral provisioning strips have been planted. Colonies of bumble bees will be located at distances remote from the floral strip at several sites. While bees are foraging, we will spray the strip with non-toxic protein and dye markers and then calculate the number of returning foragers at each from each nest that were visiting the strips at the time of application. At the same time, some workers on the strips will be sample and analyzed using microsatellite markers to determine relatedness of individuals on patches. These experiments will be repeated at bi-weekly intervals to study the change in foraging dynamics over the summer. Objective 2. Determine how colony forage needs drive foraging strategies on diverse landscapes. This study will take place in two parts: (1) a greenhouse experiment where bumble bee resource intake will be monitored and (2) a field experiment in which pollen loads from bumble bees will be collected to determine the amount of pollen bees bring back from a single foraging trip. We will use these with calculations of pollen produced by plants, to determine the forage needs of a colony throughout the colony life. Objective 3. Determine response of bumble bee foraging to habitat enhancements in agricultural landscapes. We will use protein uptake on marked plots and colony density calculated using microsatellite markers to determine the effect of habitat enhancements on bumble bee populations. Objective 4. Model nesting density of B. huntii and B. impatiens. We will create a mathematical model of bumble bee colony on the landscape, using the parameters that we generate in Objectives 1-3 to understand the effects of habitat enhancement on the number of colonies that are contributing pollination service to farms. Objective 5. Model disease transmission in bumble bees based on B. huntii and B. impatiens foraging range in agroecosystems. Using the protein markers as surrogates, we will determine the flight range of bumble bees and transmission rate of markers from colony to colony. Using these parameters we will employ epidemiological modeling to determine the rate of spread of pathogens in bumble bee communities.