This fossil leaf from Wyoming’s Hanna Basin, about 54 million years old, shows damage by insects. Credit: Lauren Azevedo-Schmidt
Key Points:
- Insects today are causing unprecedented levels of damage to plants.
- Compared with 67-million-year-old fossilized leaves, modern leaves have a “striking” amount of insect damage.
- A warming climate, urbanization and invasive species are likely culprits in the significant damage uptick.
A new study by University of Wyoming scientists reveals that today’s insects—compared with those 67 million years ago—are causing unprecedented levels of damage to plants, even as their numbers decline.
The first-of-its-kind study, published in PNAS, compared insect herbivore damage on leaves from three modern forests to damage on fossilized leaves from the Late Cretaceous (67 million years ago) through the Pleistocene era (2 million years ago). The research looked at different types of damage caused by insects, finding marked increases in all recent damage compared with the fossil record.
“Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material,” said lead researcher Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. “The difference in insect damage between the modern era and the fossilized record is striking.”
More research is necessary to determine the precise causes of increased insect damage to plants, but the scientists say a warming climate, urbanization and introduction of invasive species likely have had a major impact.
“We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution,” the researchers wrote in the study. “Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming.”
However, Azevedo-Schmidt says climate change doesn’t fully explain the increase in insect damage, so there is still more to learn.
Information provided by University of Wyoming.