Others on the Party Line
A plant communication network may be co-opted. Plant viruses use runners as highways to rapidly spread through connected plants.
Even a single plant acts as a transmission line for herbivorous insects. An underground pest broadcasts chemical signals up through the leaves of a plant, telling insects aboveground that the plant is already occupied.
Leaf-eaters prefer plants that are not infested by subterranean insects. Avoiding competition keeps a healthier habitat by not overtaxing plants and thereby unnecessarily damaging the community at large.
Parasitic wasps lay their eggs in caterpillars that live on stems and leaves. These wasps benefit from the signals of underground insects, as it helps reveal where they might find a good host for their eggs.
