When a hen sees an eagle wandering in the sky, she will instinctively call her chicks and hide together. Scientists have discovered that there is a similar mechanism in plants.
After tomatoes are damaged by Spodoptera litura , they release a chemical called "(Z)-3- vinyl alcohol ". When neighboring tomatoes receive this substance, it is like hearing their companions shouting "Spodoptera litura is coming!" and immediately produce a substance that can antagonize the growth and development of Spodoptera litura, reducing the survival rate of Spodoptera litura. [1]
When tomatoes are harmed by Spodoptera exigua, the chemical substances released can instruct its tomato neighbors to release a substance called "beta-ocimene", which means: "Sister Alphid Braconi, Here are the Spodoptera exigua that you like to eat, come on!" Tomatoes use this method to call the natural enemies of pests to save themselves. [2]
Similarly, after European and American hybrid poplars are infested by gypsy moth , they will induce neighboring poplars to increase the content of terpene compounds in their bodies to enhance the resistance of poplars to gypsy moth larvae. [3]
So, a philosophical question arises here: What good does it do to itself if the victim plant (Party A) releases a danger signal? First, releasing chemical substances consumes energy; second, helping your neighbor (Party B) reduce harm will put you at a more disadvantaged position in the competition for nutrients, water, and sunlight. In other words, Party A’s release of danger signals will do more harm than good to itself. Therefore, some researchers believe that Party A does not intentionally release signals, but Party B actively seeks and receives signals, which is a kind of "eavesdropping" behavior. [4]
References
[1] Proceedings of National Academy of Sciences of the United States of America,2014, 111(19): 7144-7149
[2] Scientific Reports, 2017, 7(1): 15522
[3 ] Biocontrol Science and Technology, 2008, 18(9): 921-933
[4] Ecology, 2002, 83(5): 1209-1213
