When the leaves they depend on turn a deathly yellow in the fall, leaf miner moths (Phyllonorycter blancardella) perform CPR. Even as the rest of the leaf wilts, the patch surrounding a leaf miner larva stays a bright and photosynthetically active green. Now, a new study shows that these green islands spark to life thanks to bacteria living within the grubs themselves.
“It’s a beautiful example of how an organism can solve a major problem by getting into a [mutually beneficial] relationship with a microbe,” says chemical ecologist Ian Baldwin of the Max Planck Institute for Chemical Ecology in Jena, Germany. He says there are a lot of unanswered questions, such as whether Wolbachia living outside of insect bodies can still manage this breath of life. But the study shows just how much an insect’s success is the work of its inner bugs, he says. “One can safely say that most insects … are just Trojan horses.”