May 3, 2026 12:07 AM
https://www.eurekalert.org/news-releases/1126057
INTRO: Spring in the forest. Many insects, particularly caterpillars, hatch just when the trees’ nutrient-rich leaves are still young and soft. This means they find a table laden with food and can start eating straight away.
If oak trees are heavily infested by caterpillars in a given year, they react to this the following spring: they delay their leaf emergence by three days. This is unfavourable for the caterpillars. After hatching, they are literally faced with empty plates, because the oak leaves are still firmly hidden in the buds.
This strategy is highly effective: the three-day delay is sufficient to drastically reduce the insects’ survival rate. And it reduces the damage caused by feeding on the tree by an impressive 55 per cent. A team of international researchers reports this in the journal Nature Ecology & Evolution.
The delaying tactic is more effective for the oak than a chemical defence, such as bitter tannins in the leaves”, says Dr Soumen Mallick, a postdoc at the University of Würzburg’s Biocentre and lead author of the study. This is because the tree would have to expend a great deal of energy to increase tannin production.
“This discovery fundamentally changes our previous understanding of the onset of spring in the forest,” says the Würzburg researcher. It shows that trees do not merely react passively to the weather in timing their leaves emerge but also respond flexibly to biological threats... (MORE - details)
INTRO: Spring in the forest. Many insects, particularly caterpillars, hatch just when the trees’ nutrient-rich leaves are still young and soft. This means they find a table laden with food and can start eating straight away.
If oak trees are heavily infested by caterpillars in a given year, they react to this the following spring: they delay their leaf emergence by three days. This is unfavourable for the caterpillars. After hatching, they are literally faced with empty plates, because the oak leaves are still firmly hidden in the buds.
This strategy is highly effective: the three-day delay is sufficient to drastically reduce the insects’ survival rate. And it reduces the damage caused by feeding on the tree by an impressive 55 per cent. A team of international researchers reports this in the journal Nature Ecology & Evolution.
The delaying tactic is more effective for the oak than a chemical defence, such as bitter tannins in the leaves”, says Dr Soumen Mallick, a postdoc at the University of Würzburg’s Biocentre and lead author of the study. This is because the tree would have to expend a great deal of energy to increase tannin production.
“This discovery fundamentally changes our previous understanding of the onset of spring in the forest,” says the Würzburg researcher. It shows that trees do not merely react passively to the weather in timing their leaves emerge but also respond flexibly to biological threats... (MORE - details)
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