We know that plants communicate with "clicks." Now it turns out that the insects that live on these plants use the soil they grow in to leave "voicemail" messages with each other in the fungi in the soil.
Insects can use plants as 'green phones' for communication with other bugs. A new study now shows that through those same plants insects are also able to leave 'voicemail' messages in the soil. Herbivorous insects store their voicemails via their effects on soil fungi.
A few years ago, scientists discovered that soil-dwelling and above-ground insects are able to communicate with each other using the plant as a telephone. Insects eating plant roots change the chemical composition of the leaves, causing the plant to release volatile signals into the air. This can convince above-ground insects to select another food plant in order to avoid competition and to escape from poisonous defense compounds in the plant. But the impact doesn't stop there.
New research shows that insects leave a specific legacy that remains in the soil after they have fed on a plant. And future plants growing on that same spot can pick up these signals from the soil and pass them on to other insects. Those messages are really specific: the new plant can tell whether the former one was suffering from leaf-eating caterpillars or from root-eating insects.
Researcher Olga Kostenko says, "The new plants are actually decoding a 'voicemail' message from the past to the next generation of plant-feeding insects, and their enemies. The insects are re-living the past." Today's insect community is influenced by the messages from past seasons.
According to Kostenko, "What we discovered is that the composition of fungi in the soil changed greatly and depended on whether the insect had been feeding on roots or leaves. These changes in fungal community, in turn, affected the growth and chemistry of the next batch of plants and therefore the insects on those plants."
Do those bugs ever press the "erase" button? "How long are these voicemail messages kept in the soil? That's what I also would like to know!" says Kostenko. "We're working on this, and on the question of how widespread this phenomenon is in nature."
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