Plants are damaged by insects


Plants are experiencing “unprecedented levels” of insect damage, despite a widespread decline in insects, according to a study by the University of Wyoming in the United States, which points to human activity as a possible explanation.

The researchers publish their findings in the journal PNAS, in an article in which they compare the damage of modern plants to that of fossil leaves from the Late Cretaceous, nearly 67 million years ago. Specifically, the authors compared 64 fossil leaf assemblages spanning the Late Cretaceous to the Pleistocene epoch, around 2 million years ago, with modern leaves collected from three locations in the United States and Costa Rica dating from 1955 to the present day.

Plant damage

According to observations, in the latter all types of damage were increased compared to those in the fossil record, notes a note from the university: “the difference in insect damage between the modern era and the fossil record is striking”, summarizes the principal researcher Lauren Azevedo-Schmidt. The total fraction of insect-damaged leaves in modern specimens was about twice the average for all fossil assemblages.

“Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite the widespread decline of insects.”conclude the scientists, suggesting that this disparity can be explained by human activity.

Although further research is needed to determine the precise causes of this increase in damage, the authors point out that global warming (influencing insect feeding and the timing of life cycle processes), urbanization and introduction of invasive species “probably had a major impact”.

Thus, climate change does not fully explain the increase in insect damage: “The strength of human influence on plant-insect interactions is not controlled by climate change alone, but rather by how humans interact with the landscape”.

“Our hypothesis is that humans influenced the frequency and diversity of insect damage in modern forests and that the greatest human impact occurred after the Industrial Revolution”support the authors.

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