For each major tree-killing species of invasive bug, around half a dozen foreign insects live quietly in our forests, causing few noticeable problems. A new study may help scientists pick out the future tree killers from the crowd, and it has a surprising conclusion: It’s the characteristics of the trees that insects feed on, not the insects themselves, that matter.
That’s the “nut graf” as we say in newspapers from this Inside Science report about a study of invasive forest insects. Since it seems like every month brings news of a new invasive bug destroying some species of our evergreens or broad-leafed trees (ash, we hardly knew ye), any insight into predicting these outbreaks is welcome.
The article is really interesting, and worth a read. Here’s a clip to whet your appetite:
The analysis revealed that the best predictor of a foreign insect’s tree-killing potential is the amount of time since the tree the insect lives on diverged from its closest ancestor in its native country. But the relationship isn’t simple: Insects living on trees that diverged long ago or very recently were much less destructive than ones that were in what Mech called a “Goldilocks time frame” of 12 million to 17 million years ago for sap feeders and 1.5 million to 5 million years ago for leaf eaters.