Earth and Sky科普英语：Plants vs. Insects 植物和昆虫
New research is shedding light on one of the longest running battles of all time -- the war between plants and insects. Plants may seem helpless, but they have complex chemical defenses. Plants vs. insects -- today on Earth and Sky.
JB: This is Earth and Sky. Plants use chemicals to repel enemies -- some chemicals are toxic, others just taste bad. But plants also defend themselves in more subtle ways.
DB: A plant that produces salicylic acid -- a chemical in aspirin -- uses the substance to treat its own wounds -- much as humans take aspirin to stop pain. Penn State entomologist Jack Schultz has found that the plant might also use salicylic acid to wreak havoc on its enemies.
Jack Schultz: Sure, for a long time people have been taking aspirin as a medicine, but grasshoppers are getting a huge dose of this stuff when they eat plants. What does that mean to all of the signaling processes in a grasshopper that aspirin would interfere with?
JB: Schultz believes plants engage in a sort of "signal jamming" -- interfering with an insect's biochemistry, rendering it less likely to inflict damage. But insects can fight dirty too ...
Jack Schultz: It's sort of espionage. The insect sends the plant a signal that says, "Okay, this is a microbe, not an insect, turn on your disease resistance," and essentially turning on the plant's resistance to disease, it also turns down the plant's resistance to insects and makes the plant more susceptible to the insect.
DB: For more -- come to today's show at earthsky.org. Our thanks to the National Science Foundation, where discoveries begin. We're Block and Byrd for Earth and Sky.
