Plant Communication –  According to new German research, plants send out airborne GLV compounds when distressed. “They found that when these plants are attacked by tobacco hornworm caterpillars,Manduca sexta, the caterpillars’ saliva causes a chemical change in the GLV compounds the plants had produced. These modified compounds then attract predatory “true bugs,”Geocoris, which prey on hornworm eggs and young larvae. Although more research will be needed to figure out exactly how the molecules in the caterpillar saliva cause this change in the GLVs, it’s clear that the caterpillars themselves cause the change in the GLV signal, the researchers say. It may thus be possible someday to induce the same sort of change via genetic engineering, which might protect plants against pests without encouraging the resistance that pests develop in response to pesticides.”

However, some people believe it is much more likely the predators have evolved to detected the GLV compounds to hunt prey. 

Whether the plant evolved to attract predators of its attacker or the predators evolved to associate the GLV compounds with dinnertime, evolution is incredible.