From roots to canopy, many trees can indeed tell if they are being eaten – and by whom, says Alex Morss.
They have evolved extraordinary abilities to discern chewing by beetles and caterpillars, piercing and sucking by bugs, acoustic vibrations from grasshoppers, deer saliva, microbes left by various animals, even the stress signals released by nearby trees being browsed by giraffes.
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Many trees respond by making more unpalatable chemicals or growing tougher leaves. Oaks, for example, produce more tannins and phenol compounds after heavy grazing by caterpillars. Pines, elms, acacias and many others release alarm gases that attract predators, such as parasitic wasps, to attack their enemies.
Lodgepole pines share information about mountain pine beetle infestations with neighbouring pines, and those trees react by boosting their own chemical defences. Climate stress may weaken such resilience, though.
Research shows that Aleppo pines are up to 75 per cent less able to respond to a pine weevil attack during drought.
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Main image: Getty
