In the past, plants and insects have lived in a delicate dance of pollination. According to the study, insects are eating plants more now than in the past.
Lauren Azevedo-Schmidt is a paleoecologist at the University of Maine.
In order to look at plant-insect interactions over time, Azevedo-Schmidt and colleagues compared the leaves of modern-era plants from three forests to fossils from 67 million years ago.
They found a sharp increase in insect-inflected damage, with insects piercing, sucking, hole-punching, and skeletonizing plant leaves.
"Despite insect declines, insect damage to plants is higher in the modern era compared with other time periods represented in the fossil record," Azevedo-Schmidt and colleagues wrote.
Plants have evolved to quietly dominate life on Earth, with land plants now accounting for 80% of global biomass Small insects are more abundant than large ones. Despite being sensitive to temperature, both have been able to adapt to environmental change.
They can't endure everything. Some research suggests that insect numbers are decreasing in some parts of the world. Plants are growing earlier and shortening the pollen season due to climate change. There are sickening rates of human-caused habitat and extinction.
The leaves carbon-dated from 1955 to present had more insect damage than any of the fossils dating back millions of years.
Two forests in the northeastern United States and a third in Costa Rica were collected from leaves.
Fossil data stretching from 68.6 million years ago to 2 million years ago was compiled from published datasets.
Azevedo-Schmidt and colleagues suggest that the rapid warming trends of the modern era may be to blame for the higher herbivory frequencies.
Researchers warn that the increased insect herbivory could have unknown consequences.
The researchers took steps to account for how leaves are preserved, as the fossil record only captures a small portion of life. They compared insect damage on buried leaves to that of leaf litter and fossils.
The researchers say that a long-term perspective is needed to understand the ancient organisms and their longstanding ecological associations.
It's clear that something has changed in the seven decades since 1955, the briefest of windows compared to the geological eras that unfolded before humans started shaping the biosphere.
Past research from the US has found a correlation between rising temperatures and insect damage on herbarium specimen from the early 2000's.
It's possible that insect populations are increasing in the forests studied, which are located within the grounds of research stations surrounded by roads, housing developments and farming.
Azevedo-Schmidt and colleagues theorize that the creation of insect biodiversity hot spots may have been caused by urbanization.
A fast-warming climate is influencing insect life-cycles and feeding habits, as well as pushing their range of habitats poleward, which could be driving increased insect herbivry.
Plants may have to start fighting each other to attract pollinators as agriculture is decimating insects. Human fingerprints are all over the issue.
They conclude that the strength of human influence on plant-insect interactions is not controlled by climate change alone.
The study was published in a peer reviewed journal.
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