For immediate release: February 10, 2023, 2 PM Eastern Time (US)

Contacts:

Scott Hoffman Black, Executive Director, The Xerces Society for invertebrate Conservation, 503-449-3792, [email protected]

Matthew Forister, McMinn Professor of Biology, University of Nevada, Reno, 775-784-6770, [email protected]

SACRAMENTO, Calif.; February 10, 2023---A study published today in the journal PLOS ONE finds that planting the margins of agricultural fields with pollinator-friendly plants and minimizing pesticide use in the Central Valley of California could help pollinators survive in this highly altered landscape.

Pollinators are vital for agricultural production and for maintaining intact ecosystems. More than 85% of flowering plants require an animal, mostly insects, to move pollen, and 1 in 3 mouthfuls of food we consume come from an insect pollinator. Unfortunately, pollinators are rapidly declining.  The United Nations Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services assessment found that greater than 40% of invertebrate pollinator species may be facing extinction, particularly bees and butterflies.

Pollinators need high-quality, connected habitats to move across landscapes in search of new habitats and as a refuge from a changing climate.  Improving habitat connectivity enables pollinators to move among populations, increasing genetic diversity and helping to prevent populations from becoming too small. 

The Central Valley was once dominated by native grasslands, wetlands, and river and floodplain habitat but most of this habitat has been lost.  Many farm properties in California contain little or no natural habitat, and where patches of pollinator habitat remain, they tend to be isolated. Pesticides – including highly toxic, systemic, long-lived insecticides – are also pervasive on many farms and in cities and towns. 

To determine the best way to provide habitat connectivity for pollinators in the Central Valley, scientists from the University of Nevada at Reno and the Xerces Society for Invertebrate Conservation developed a tool for modeling landscape connectivity for insects – with pollinators in particular in mind – that uses land use information, lethality of pesticides, and expert opinion on insect movement.

“Using a modeling approach, we found that agricultural margins have the potential to greatly enhance habitat connectivity for pollinating insects,” said Tom Dilts, a spatial analyst and research scientist at the University of Nevada Reno.  “Our study is unique because it considers pesticide application rates to estimate limitations to movement for pollinating insects.”

Agricultural areas have often suffered the most severe declines in pollinator abundance, yet these areas need pollinators and other beneficial insects to ensure agricultural productivity. The Central Valley produces 25% of the country’s food and 40% of its fruits and nuts. The value of pollination services from wild pollinators to California agriculture is between $937 million and $2.4 billion per year.

The connectivity modeling suggested higher resistance to insect movement in the inner region of intensive cropping in the Central Valley, particularly in the southern areas of the San Joaquin Valley with greater acreage of crops with high pesticide inputs, such as citrus. In addition to restoring habitat in agricultural margins, reducing pesticide loads in these areas has the potential to increase connectivity for pollinators: the models indicated that the number of least-cost paths across the Central Valley for pollinators increased more than ten percent as pesticide use decreased.

“Restoring habitat connectivity to provide for pollinating insects is critical for preventing biodiversity collapse, providing natural pollination services, and preventing extinction,” said Scott Black, Executive Director of the Xerces Society for Invertebrate Conservation. “This modeling shows that if we maximize field edge plantings with diverse native plants and minimize pesticide use, we can both improve pollinator survival and protect our future crops and food supply.” 

Beyond allowing pollinators to move across the landscape, restored and enhanced field borders can also provide substantial areas of habitat. The study found that over 1 million acres of habitat could be added to the Central Valley by restoring drainage ditches, field edges and uncultivated borders.

Farmers who plant hedgerows at their field edges will see more benefits than just returning pollinators. This habitat can also attract insects that are beneficial for pest control, provide habitat for birds and other wildlife, and minimize soil erosion. Additionally, USDA offers cost share conservation programs that allow for a quicker return on investment for a hedgerow or other type of habitat planting.

“Many studies have shown that restoring hedgerows and other habitat along agricultural margins can be valuable for many beneficial insects – from pollinators to predators of crop pests,” said Matt Forister, Trevor J. McMinn Endowed Professor in Biology, at the University of Nevada Reno. “This study suggests that these areas might also be used to enhance the movement of pollinators across the landscape to find new habitats, which we expect to become of increasing importance with accelerating impacts of climate change.”

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The Xerces Society for Invertebrate Conservation is a science-based, international nonprofit organization that protects the natural world through the conservation of invertebrates and their habitats. By utilizing applied research, engaging in advocacy, providing educational resources, addressing policy implications and building community, we endeavor to make meaningful long-term conservation a reality. Xerces works to raise awareness about the plight of invertebrates and to gain protection for the most vulnerable species before they decline to a level at which recovery is impossible. Learn more at xerces.org.

The University of Nevada, Reno, is a public research university that is committed to the promise of a future powered by knowledge. As a Nevada land-grant university founded in 1874, the University serves 21,000 students. The University is a comprehensive, doctoral university, classified as an R1 institution with very high research activity by the Carnegie Classification of Institutions of Higher Education. Additionally, it has attained the prestigious “Carnegie Engaged” classification, reflecting its student and institutional impact on civic engagement and service, fostered by extensive community and statewide collaborations. Through a commitment to world-improving research, student success and outreach benefiting the communities and businesses of Nevada, the University has impact across the state and around the world. For more visit unr.edu.

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Description: Native plants installed on a farm border in California's San Joaquin Valley provide habitat for pollinators.

Image credit: Cameron Newell, Xerces Society

File name: Poe Ranch hedgerow_Grimmway_CA_Cameron Newell_XercesSociety