Tobacco Plants Chemically Summon Insects to Defend Themselves Against Caterpillar Attack

tobacco leaves photo

photo: minnemom via flickr

I admit there's no direct connection between this next one and sustainability, but from a science perspective it's just too interesting to pass by: New research shows that tobacco plants have evolved a "chemical SOS" signal that attracts insect predators when caterpillars are eating their leaves. Like TreeHugger said back in 2007, Plants, they're smarter than you think...According to new work by scientists at the Swammerdam Institute of Life Sciences and the Max Planck Institute of Chemical Ecology, published in the journal Science, the chemical signal sent by the tobacco plants caused Geocoris insects to be attracted to the plant whenever attacked by tobacco hornworm caterpillars (pictured below).

tobacco hornworm photo
The scientists discovered that the saliva of the caterpillars caused a chemical change in the "green leaf volatiles" produced by the plant.

BBC News describes the experiment performed:

They glued caterpillar eggs onto two groups of tobacco plants, using cotton swabs to coat the eggs on one group of plants with the plant's own GLVs. The eggs on the other plants were treated with GLV mixed with caterpillar spit.

Those plants perfumed with the plant chemical alone had only 8% of the eggs attacked by Geocoris, while those with both the plant chemical and the caterpillar-plant mixture had 25% eaten.

Tobacco hornworm caterpillar photo: Rudi Riet via flickr
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