Plants talk to the insects that eat them. Beth Tyler 05.03.01 Animals are not the only organisms capable of communication. In fact, when a plant-eating insect (herbivores) lays its eggs on a plant, the plant releases chemical compounds into the air (volatiles) that insects and insect-eaters can sense. The plants don't want the eggs on them, and the volatile chemicals help defend the plant by keeping other plant-eaters away. These same chemicals also attract insect-eaters (often insects themselves) who will eat the plant-eaters.     Two scientists in Utah hypothesized that tobacco plants release volatile chemicals to protect themselves from insect eggs. To test this hypothesis, they conducted two experiments. First, they glued insect eggs to the leaves of tobacco plants. Next, they sprayed the volatile chemicals on the leaves of other tobacco plants (Nicotiana sp.). Then the scientists watched to see if insects avoided laying their eggs on the plants that had either the eggs or the chemicals on them. They found that they did! They also observed that more insects were eaten around the plants that had the glued-on eggs or the volatile chemicals.     In these experiments, the scientists discovered that plants do release these chemicals to protect themselves from insects' eggs. The plants use the chemicals to give two messages: they tell the insects to stay away, and they tell the insect-eaters to come feast on their nearby food.  Sabelis, M.W., A. Janssen, and M.R. Kant. 2001. The enemy of my enemy is my ally. Science, 291(5511): 2104-2107. ©2001 The Aurora Collection, Inc. All Rights Reserved. Site Development by: Interactive Multimedia. Inc.