Research reveals unprecedented levels of insects

image: Lauren Azevedo-Schmidt searches for fossilized plants in Wyoming’s Hanna Basin in a deposit about 60 million years old. She and other researchers compared fossil leaves with modern samples and found higher rates of insect damage today.
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Credit: Lauren Azevedo-Schmidt

Insects are now causing unprecedented levels of damage to plants, even as insect numbers are declining, according to new research from scientists at the University of Wyoming.

The first study of its kind compares herbivorous insect damage to modern-era plants with that of fossilized leaves dating as far back as the Late Cretaceous period, nearly 67 million years ago. The results appear in the prestigious journal Proceedings of the National Academy of Sciences.

“Our work bridges the gap between those who use fossils to study plant-insect interactions over time and those who study these interactions in a modern context with fresh leaves,” says lead researcher, UW Ph.D. Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. “The difference in insect damage between the modern era and the fossil record is striking.”

Azevedo-Schmidt conducted the research with Professor Ellen Currano of UW’s Department of Botany and Department of Geology and Geophysics, and Assistant Professor Emily Meineke of the University of California-Davis.

The study looked at insect-damaged fossilized leaves from the Late Cretaceous to the Pleistocene era, just over 2 million years ago, and compared them to leaves collected by Azevedo-Schmidt from three modern forests. . The detailed research looked at different types of insect damage, finding marked increases in all recent damage compared to the fossil record.

“Our results demonstrate that modern-era plants are experiencing unprecedented levels of insect damage, despite widespread insect decline,” the scientists wrote, suggesting the disparity may be explained by activity. human.

More research is needed to determine the precise causes of increased insect damage to plants, but scientists say global warming, urbanization and the introduction of invasive species have likely had a major impact.

“We hypothesize that humans have influenced the frequency and diversity of (insect) damage in modern forests, with the greatest human impact occurring after the Industrial Revolution,” the researchers wrote. “Consistent with this hypothesis, herbarium specimens from the early 2000s were 23% more susceptible to insect damage than specimens collected in the early 1900s, a trend that has been linked to global warming.”

But climate change doesn’t fully explain the increase in insect damage, they say.

“This research suggests that the strength of human influence on plant-insect interactions is not controlled solely by climate change, but rather by how humans interact with the terrestrial landscape,” the researchers concluded.

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