Using Pollinator Environmental DNA to Assess the Ecological Resilience of America’s Grasslands

Overview

Scientists from six USGS science centers are collaborating with USDA, university, and Tribal partners, and Department of the Interior land managers, to assess the status of pollinator communities and the distribution of species of conservation concern using environmental DNA. These methods will be used to improve assessments of habitat quality and pollinator responses to restoration, including across the imperiled grasslands of the Midwest and shrublands of the western United States.

bumble bee perched on a bright orange flower, grassy field in the background — An endangered rusty patched bumble bee visiting a butterfly milkweed flower at the Minnesota Landscape Arboretum.

Why Pollinators?

Pollinators contribute substantially to the economy and food stability of the United States by pollinating fruit, nut, and vegetable crops. Nearly 85% of all flowering plants benefit from the pollination services they provide. There have been significant losses of pollinator species over the past few decades due to threats such as habitat loss, pesticides, and pathogens, threatening the foundation of terrestrial food webs worldwide. As a result, there is a growing need to keep tabs on these vulnerable and valuable animals.

Why Environmental DNA?

Researchers traditionally studied pollinator biodiversity by trapping or netting and identifying species using morphological characteristics visible under a microscope. Not only is this method lethal to the animal, but it requires specialized identification skills and considerable amounts of time. Environmental DNA sampling is an alternative, non-lethal method that has the potential to reduce the cost and difficulty of pollinator surveys relative to traditional methods. When a pollinator, such as a bee or butterfly, visits a flower during foraging, it leaves behind trace amounts of DNA from its skin, hair, saliva, or feces. Scientists collect this eDNA and use it to identify which pollinator species are present.

three people standing in a grassy field looking at tape measures on the ground — USGS technicians preparing to sample a grassland for bees and flowers in the North Dakota plains.

Progress, Goals, and Impact

With funding from the Bipartisan Infrastructure Law, and as part of a larger effort aimed at assessing ecological resilience of restored grasslands, the grassland pollinator team launched the project in 2022. During the first year, our team collected and processed nearly 2,000 flower samples from grasslands in national parks, wildlife refuges, Bureau of Land Management lands, and other public lands in eight states. We are establishing standards, protocols, and molecular resources for using pollinator eDNA to solve real-world natural resource problems. Department of the Interior partners are interested in applying our methods to:

Improve native seed selection strategies through a better understanding of plant-pollinator interactions
Quantify the success of grassland restoration investments by documenting pollinator communities

Improve predictions for how pollinator communities may respond to climate change in America’s grasslands
Document the distribution of rare or at-risk pollinators to inform management agencies assessing listed species or making pre-listing decisions

Pollinator Species We Study

The species below are important members of grassland communities and are in decline across the United States. Our team is using eDNA to learn more about their distribution, what can be done to protect them, and how they are linked to ecological resilience of America's grasslands.

a bumble bee perched on a bright yellow flower, background is blue sky — The rusty patched bumble bee is the first pollinator species to be listed as Endangered under the Endangered Species Act in the continental United States. It was once distributed across the eastern U.S. and upper Midwest. Although the exact cause of the bumble bee’s decline is unknown, research points to an introduced pathogen and pesticide exposure.

Western bumble bee — The western bumble bee was once one of the most common bumble bees across the western U.S. and Canada. Research indicates that it has declined substantially across its range. The U.S. Fish and Wildlife Service is considering it for listing under the Endangered Species Act.

a black and yellow bumble bee sitting on a bright yellow flower — Franklin’s bumble bee is endemic to northern California and southern Oregon but has not been detected since 2006. The species was listed as Endangered in 2021.

a gold flying insect sitting on a bright orange lily flower — The Dakota skipper is a small butterfly that once lived throughout the grasslands of the north-central U.S. and south-central Canada. Extensive historical loss of native prairie habitats combined with climate change, drought, wildfire, and invasive species has led to its decline. It is now listed as Threatened under the Endangered Species Act.

Science

Click the links below to learn more about pollinator research at the USGS.

Multimedia

Publications

Use the links below to access the grassland pollinator eDNA team's publications.

News

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