Science Articles

PhD student reveals insects that communicate using plants  

News from The Netherlands Institute of Ecology. A PhD student shows that insects that live above and below ground in the same location use chemical signalling to communicate their presence to each other and to the parasitic wasp. 

Many PhD research projects are excellent but don’t receive widespread coverage or much recognition. One recent completed project that did came from the Netherlands, where Dutch ecology graduate Roxina Soler showed that insects above ground communicate with others under ground using plants as a type of telephone.

A chemical telephone, but a remote communication system nevertheless.

Insects that normally live in the stems and leaves of plants above ground inject the plant with chemicals that travel through the phloem system of the plant and reach the roots. This faint chemical signal is picked up by insects or insect larvae that normally feed and live at the roots and other parts of the plant that are underground. They then avoid this plant and move on to the next preferring a ‘virgin’ plant that doesn’t already have an insect infestation.

Similarly, the root dwellers inject the plant with chemicals that find their way to the plants and stems, having the same effect above ground.

This may appear that insects are being very fussy, but there is a sound ecological reason for this behaviour. A single plant is considerably stressed by an insect infestation, so overloading it is likely to kill it, making it a useless host. By limiting the level of infestation, the insects protect the plant, making sure that it stays healthy enough to provide them with the food and shelter they need. Living on a stressed plant means smaller insects, fewer offspring and a lowered chance of survival. By keeping top dwellers on one plant and root dwellers on another, both colonies of insects fare better.

In ecology terms, its something called spatial separation.

But, the system can be hacked into, like all telecommunications. And the hacker in this case is the parasitic wasps that lay their eggs inside the insect larvae of insects that live above ground. They use the chemical signals as a beacon to find a plant full of great hosts for their own offspring.

The research was carried out at the Netherlands Institute for Ecology (NIOO-KNAW) by Roxina Soler, Jeffrey Harvey, Martijn Bezemer, Wim van der Putten and Louise Vet. The PhD project, in which this study was carried out, was funded by the Free Competition of NWO Earth and Life Sciences.