Author: Susan Milius / Source: Science News
Here’s the story of a caterpillar that foils gruesome violence orchestrated by corn.
No, that’s not backward. Plants often look helpless to a human, but they fight with smells and other invisible chemistry. A growing body of evidence, for example, shows that plants under attack can waft out scents that attract help, such as tiny wasps that deal a lingering death to leaf-chewing caterpillars.
A dream for future farming is to boost such crop powers. Yet a tale, published May 16 in Science Advances, of how Spodoptera littoralis caterpillars can escape a trap set for them by maize plants shows how complex a task that could be.
These attackers are “greenish, brownish, ugly caterpillars,” says Ted Turlings of the University of Neuchâtel in Switzerland, who makes no secret of where his allegiance lies. The caterpillars damage maize, cotton and a variety of other crops in the Middle East, Africa and elsewhere. But maize fights back, of course. As the caterpillars crunch into a leaf, substances in their spit trigger a burst of furious plant chemistry, which causes the release of certain scents.
The first wave of odors from damaged plants, the cut-grass smell, comes just from ripped tissues spilling their innards. Then within hours, maize sends out new scents that can advertise the kind of pests attacking it.
“You can actually smell it yourself,” Turlings says. Or at least his trained nose can.These telltale plant substances help female Microplitis rufiventris wasps track down a suitable species of fresh caterpillar flesh. The females cruise for caterpillars as sites for injecting an egg. “Out…
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