Want to save butterflies? Use less pesticide, UNR study says

Chris Halsch, a doctoral candidate in the Ecology, Evolution, and Conservation Biology program...
Chris Halsch, a doctoral candidate in the Ecology, Evolution, and Conservation Biology program of the University of Nevada, Reno, surveys for butterflies in the high elevation Sierran study transect of Castle Peak. The survey, ongoing for 40 years, has found a consistent decline in butterfly population(Matt Forister/UNR)
Published: Mar. 7, 2021 at 4:25 PM PST
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RENO, Nev. (KOLO) - Butterflies have been in decline for the past 40 years and new methods of conservation and management of butterfly habitat – like less backyard pesticide use -- may be needed to stop the decline, a University of Nevada, Reno said.

UNR Biology Professor Matt Forister was the lead author of a report published in Science.

“The widespread butterfly declines highlight the importance of careful management of the lands that we do have control over, including our own backyards where we should use fewer pesticides and choose plants for landscapes that benefit local insects,” Forister said.

This report differs from others in that it includes wide areas of unpopulated land. The estimated 1.6% per year decline is consistent with reported declines for other insect groups from other parts of the world.

“The fact that declines are observed across the undeveloped spaces of the western U.S. means that we cannot assume that insects are okay out there far from direct human influence,” Forister said in a statement by UNR. “And that’s because the influence of climate change is, of course, not geographically restricted.”

Researchers made the estimate using data from 72 places, with at least 10 years of data per location and looking at more than 250 butterfly species. The study covers 42 years, from 1977 to 2018, and the average length of time series from individual sites was 21 years.

The team considered land use, annual climate and season-specific rates of climate change to find the most influential predictors for decline. The widespread declines they found advance the understanding of climate change impacts and suggest a new approach is needed for butterfly conservation in the region, focused on several species with similar habitat characteristics or who rely on same plants instead of conventional conservation and management practices focused on single species.

“Western butterfly declines are associated with increasing fall temperatures across the U.S. wildlands,” co-author Katy Prudic a biologist from the University of Arizona, said. “Conservation, management and restoration on public lands, especially along cooler riparian areas, will be critical for preventing butterfly declines and extinction.”

The study published in Science complements other, recent work on insect declines from the University of Nevada, Reno, which have included contributions to a recent special issue in the Proceedings of the National Academy of Sciences and one of the first reports of declining insect diversity from a protected forest in Costa Rica.

Participating in the study published in Science, along with Forister and Prudic, were Christopher Halsch, Department of Biology, Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno; C. C. Nice, Department of Biology, Texas State University; J. A. Fordyce, Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville; Thomas E. Dilts, Department of Natural Resources and Environmental Science, University of Nevada, Reno; J. C. Oliver, Office of Digital Innovation & Stewardship, University Libraries, University of Arizona, Tucson; J. K. Wilson, School of Natural Resources and the Environment, University of Arizona, Tucson; A M. Shapiro, Center for Population Biology, University of California, Davis; and J. Glassberg, North American Butterfly Association, and Department of BioSciences, Rice University, Houston, Texas.

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