Researchers from the Netherlands Institute of Ecology (NIOO-KNAW) and Wageningen University (WUR) discovered  that insects can use plants as telephones to communicate with other bugs. Additionally, using those same plants insects are able to leave "voicemail" messages in the soil, via their effects on soil fungi.

According to the Netherlands Institute, insects eating plant roots change the chemical composition of the leaves, causing the plant to release danger signals into the air. This can convince aboveground insects to select another food plant in order to avoid competition and to escape from poisonous defense compounds in the plant.

Furthermore, research shows that insects leave a specific legacy that remains in the soil after they have fed on a plant. Any future plants growing on that same spot can pick up these signals from the soil and pass them on to other insects.

The messages are really specific: the new plant can tell whether the former one was suffering from leaf-eating caterpillars or from root-eating insects, informing future generations of insects of whether or not this is safe to eat and for whom.

"The new plants are actually decoding a 'voicemail' message from the past to the next generation of plant-feeding insects, and their enemies," recaps NIOO researcher and first author Olga Kostenko tells NIOO. "The insects are re-living the past, the messages strongly influencing the growth and possibly also the behavior of these bugs. Today's insect community is influenced by the messages from past seasons."

According to the report , when Kostensko and her colleagues grew two generations of ragwort plants in a greenhouse and exposed them to leaf-eating caterpillars, "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," explains Kostenko. "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."

Though researchers do not exactly know how long the messages remain in the soil, they are working on,. "the question of how widespread this phenomenon is in nature."