Insecticides found to be primary driver of butterfly decline

The recently published study appeared in the journal PLOS ONE and features contributions from the Department of Agricultural Food and Resource Economics and W.K. Kellogg Biological Station.

EAST LANSING, Mich. — Insecticide use is the single largest factor contributing to a decline in total butterfly abundance and species diversity in the Midwest, according to a newly released study published by the journal PLOS ONE. The author team was led by researchers from the College of Agriculture and Natural Resources (CANR) and the College of Natural Science (NatSci) at Michigan State University (MSU).

This study builds upon research performed by Braeden Van Deynze with Scott Swinton, a University Distinguished Professor in the Department of Agricultural, Food and Resource Economics (AFRE). Van Deynze earned his Ph.D. from MSU in 2019 and is currently a Natural Resource Economist for the Washington State Department of Fish & Wildlife. In addition to Van Deynze and Swinton, co-authors for this paper include ecologist Nick Haddad from the MSU W.K. Kellogg Biological Station and the Department of Integrative Biology, economist David A. Hennessy (Iowa State University) and entomologist Leslie Ries (Georgetown University).

“What drives butterfly decline is a hard nut to crack, due to rapid changes in chemical and genetic technologies alongside changes in climate and butterfly habitat,” says Swinton. “Our team was able to link 17 years of farm-level data on crops and inputs with detailed county-level data on butterfly abundance by species. This research is the first to evaluate the long-term effects on butterflies of herbicides, sprayed insecticides, and systemic insecticides, while controlling for climate and land use change.”

While habitat loss, climate change and pesticides have all been implicated as potential causes for the declining insect abundances being observed globally, this work was the first comprehensive long-term study to evaluate their relative effects. Using 17 years of land use, climate, multiple classes of pesticides and butterfly survey data across 81 counties in five states, they found that shifts in insecticide use towards neonicotinoid-treated seeds are associated with an 8 percent decline in butterfly species diversity across the American Midwest.

These findings include the decline of the migratory monarch butterfly, which has been a prominent concern. Specifically, it is noted that insecticides rather than herbicides are the strongest pesticide factor associated with monarch declines.

This research is particularly impactful as butterflies play an essential role in pollination and serve as key markers of environmental health. Understanding the primary factors contributing to their decline will help researchers working to protect these species, benefiting our environment and the sustainability of food systems.

“As the best-known insect group,” said Haddad, “butterflies are key indicators of broader insect decline, and the implications of our findings for conservation will extend to the entire insect world.”

The paper notes the complexity of these many contributing factors and how difficult they can be to separate and measure in field. The study calls for more publicly available, reliable, comprehensive and consistently reported pesticide use data, particularly for neonicotinoid seed treatments, to fully understand the drivers of butterfly decline.

The full paper can be found here.

About Department of Agricultural, Food, and Resource Economics (AFRE):

AFRE addresses societal policy questions and solves practical problems for producers, consumers, and the environment. Our undergraduate and graduate programs prepare the next generation of economists and managers to meet the needs of the food, agricultural, and natural resource system in Michigan and around the world. One of the leading departments in the United States, AFRE counts over 50 faculty, 60 graduate students and 400 undergraduate students. You can learn more about AFRE here.

About W.K. Kellogg Biological Station (KBS):

The W.K. Kellogg Biological Station (KBS) is Michigan State University’s largest off-campus education complex and one of North America’s premier inland field stations. Located between Kalamazoo and Battle Creek, Michigan (about 65 miles from MSU’s main campus in East Lansing), the 3,873 acres/1,566 ha station includes W.K. Kellogg Bird Sanctuary, W.K. Kellogg Farm, KBS Academic and Research Facilities, W.K. Kellogg Conference Center and Manor House, and Lux Arbor Reserve. The nearby W.K. Kellogg Experimental Forest is closely affiliated with KBS.

KBS is a premier site for field experimental research in aquatic and terrestrial ecology that takes advantage of the diverse managed and unmanaged ecosystems. The varied habitats of KBS include forests, fields, streams, wetlands, lakes, and agricultural lands. You can learn more KBS here.

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