Over eons, plants and insects have lived in a delicate dance, from pollinators that give life to flowering plants and plants that feed insect masses. But a new study suggests that insects feed on plants more now than they did in the past 66.8 million years.
“The difference in insect damage between modern times and the fossil record is astounding,” Says University of Maine paleobiologist Lauren Azevedo Schmidt who led the study.
To look at interactions between insects and plants over time, Azevedo Schmidt and colleagues compared leaves of modern-day plants taken from three forests with the fossil assemblies of leaf prints dating back to the late Cretaceous period, roughly 67 million years ago.
By determining the type and frequency of insect damage, they found a sharp increase in insectivorous herbivores recently, with insects piercing, sucking, piercing, and structuring the leaves of the plant.
“We found that although insects were in decline, insect damage to plants is high in the modern era compared to other time periods represented in the fossil record,” Azevedo Schmidt and colleagues Type.
Plants evolved to quietly dominate life on Earth, and terrestrial plants now represent a weight 80% of the world’s biomass. Small insects, despite their small size, are unparalleled in species richness. It is clear that both have found ways to adapt to environmental changes over thousands of years, despite being very sensitive to temperature.
But there are limits to what they can tolerate. Some research has suggested that insect numbers are declining, At least in some parts of the world. Climate change It also pushes plants to bloomed earlier And the grow fasterAnd the Extending the pollen season. not to mention satisfactory rates from human-induced habitat loss and biodiversity loss.
The study by Azevedo Schmidt and colleagues found that carbon-dating papers from 1955 to the present had twice the average amount of damage done by insects than any of the 64 fossil assemblies dating back tens of millions of years.
The papers were collected from two forests in the northeastern United States (a cold and wet forest, a second warm coastal forest) and a third forest in tropical Costa Rica—a biodiversity hotspot dripping with life.
Fossil data has been compiled from published data sets covering latitudes and climates, extending from 66.8 million years ago through the Ice Age to approximately two million years ago, before early humans migrated out of Africa.
‘We suggest that the relatively rapid warming trends of [modern] Age may be responsible for its high frequencies in weeds, such that rapid warming benefits insects in an arms race against their food source: plants,” Azevedo Schmidt and colleagues Type.
An increase in insect herbivores could have unknown consequences for plants and forest communities, researchers said warning.
Of course, the fossil record only captures a small fraction of life and snapshots in time, although researchers have taken steps to calculate how the leaves are preserved. They sampled modern-day leaves from sediments, to mimic fossil outgrowths, and compared the damage done by insects on those buried leaves to leaf litter damage and leaf pressure fossils.
“A long-term perspective is required to understand these ancient organisms and their long-term ecological associations, as well as determine where future collection efforts should focus,” the researchers said. Type.
What is already clear is that something has changed in the seven decades since 1955, the shortest windows compared to the geological eras that unfolded before we humans began reshaping the biosphere.
Previous research found, also from the United States, for example Significantly more insect damage on grass samples from the early 2000s compared to those collected a decade earlier, a pattern associated with higher temperatures.
This may be due to intensification of insect feeding or that insect populations are increasing locally in the forests studied – which, in the current study, were located within the grounds of research stations, surrounded by roads, residential developments, and agriculture.
“Urbanization may have created hot spots for insect biodiversity within research forests” Azevedo Schmidt and colleagues Type.
A rapidly warming climate—affecting insects’ life cycles and feeding habits, and pushing their range of habitats toward the pole—and the introduction of invasive species are other big factors that could lead to an increase in insectivores.
At the same time, agriculture Insect decimation Research suggests that plants may have to Start to fight each other to attract pollinators. The situation is dire and human fingerprints cover the problem.
“This research indicates that the strength of human influence on plant-insect interactions is not controlled by climate change alone, but by the way humans interact with terrestrial landscapes,” deduce.
The study was published in PNAS.
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