Global warming to increase insect attacks on plants
February 11, 2008

Global warming will increase attacks on plant leaves by insects, reports a study published in Proceedings of the National Academy of Sciences.

Analyzing more than 5,000 fossilized leaves dating from the Paleocene-Eocene Thermal Maximum (PETM), a period of intense global warming some 55 million years ago, Ellen Currano and colleagues found that insect damage increased with rising temperature.

The researchers attribute increased predation to a warming-induced decrease in nutrients insects derived from feeding on plant leaves.

"With more carbon dioxide available to plants, photosynthesis is easier and plants can make the same amount of food for themselves without having to put so much protein in their leaves," said Currano, a researcher at Pennsylvania State University and the Smithsonian Institution.

Roughly one third of a legume leaf consumed by insects from the PETM. Credit: Ellen E. Currano.

"Consequently, when carbon dioxide increases, leaves have less protein and insects need to eat more to acquire the nutrients they need," explained a news release from Penn State. "While increased carbon dioxide is good for the plants in that they can increase growth, plants also suffer from increased feeding by insects."

"Insects need to eat more to achieve their dietary requirements," stated PNAS.

The researchers also found a link between rising temperature and the number of insect species feeding on plants.

"Our study convincingly shows that there is a link between temperature and insect feeding on leaves," said Currano. "When temperature increases, the diversity of insect feeding damage on plant species also increases."

Implications for the future

The authors say their work has implications for current warming trends driven by rising anthropogenic greenhouse gas emmisions

"The dramatic rise in diversity and frequency of herbivore attack on all abundant plant species during the PETM suggests that anthropogenic influence on atmosphere and climate will eventually have similar consequences," they conclude.

Ellen D. Currano at al (2008). Sharply increased insect herbivory during the Paleocene-Eocene Thermal Maximum. PNAS for the week of February 11, 2008.

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CITATION: (February 11, 2008).

Global warming to increase insect attacks on plants.