A FLOWER'S delicate fragrance is not just a come-hither call to insect pollinators. Some scent molecules act as deterrents to drive away blossom-munching predators.
Ian Baldwin of the Max Planck Institute for Chemical Ecology in Jena, Germany, and colleagues genetically modified petunia plants to silence genes responsible for producing specific scent molecules. They then tested how these altered plants fared in the presence of flower-eating beetles and crickets.
When the production of the scent molecules benzyl benzoate or isoeugenol was blocked, the insects ate several times more of the flowers than they did when they were presented with petunias that hadn't been genetically altered.
To confirm whether it was indeed the scent putting off the insects, the researchers placed vials of isoeugenol or benzyl benzoate next to the genetically modified petunias. Sure enough, the presence of the chemical was enough to deter the insects (Ecology Letters, doi.org/jv7).
The study is the first to demonstrate that scent chemicals are used by flowers to discourage and attract insects. The complex scents of other flower species probably also include repellent as well as attractive chemical signals, says team member Thomas Colquhoun of the University of Florida in Gainsville.
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Sweet scent doubles as repellent for flower eaters
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Sweet scent doubles as repellent for flower eaters
