Maize versus caterpillar: a stitch in time saves nine

press release of December 4, 2006

When a maize plant falls victim to an herbivorous caterpillar, it emits odorous molecules that enable neighbouring plants to better resist an attack when their turn comes to confront the insect. That's one of the discoveries realised by a research team from the National Centre of Competence in Research (NCCR) Plant Survival, which has just been published in The Plant Journal.

When a maize plant is attacked by the herbivorous caterpillar Spodoptera littoralis, it releases odorous substances that attract natural enemies of the insect pest, such as Cotesia marginiventris. It is a tiny wasp that helps a wounded plant by laying its eggs in the herbivorous larva. This strategy is well known to researchers. However, a team from the NCCR Plant Survival has now highlighted another function for these volatile substances.

Led by Ted Turlings, professor of evolutionary entomology at the University of  Neuchâtel, the researchers have discovered that these volatiles will trigger an enhanced defensive capacity in healthy neighbouring plants. This phenomenon is called airborne priming and enables the plant to activate its anti-insect defences quicker and stronger at the moment it is attacked itself. It is a well-known fact that chemical information can be transmitted from plant to plant, but this is the first time that this airborne priming is shown to provide protection against insect herbivory.

Jurriaan Ton, the principal author of the study and now working at the Utrecht University (The Netherlands), showed that the chemical signals prime for enhanced expression of a specific sub-set of genes that play an important role in the defence of plants. He observed that the primed plants were less infested by the herbivorous caterpillar than their congeners. Thanks to this preventive treatment, the plant improves its direct mode of defence by rapidly producing toxic substances that affect the enemy's metabolism.

Furthermore, the primed defence state enables the maize plant to release aromatic volatile compounds more rapidly than unprepared plants when they are attacked. The researchers from the NCCR Plant Survival have observed that at the moment this cocktail of volatile compounds reaches a maximum level of emission, the primed plants are significantly more attractive to the beneficial wasp than non-primed plants. Thus, the airborne priming not only enhances the direct defence barrier against insects, but it also improves the plant's ability to attract natural enemies of the herbivorous insect.

This discovery is promising for new pest control strategies. Similar communication phenomenon aimed at improving plants' defence against predators has been observed in bean, sagebrush and wild tobacco plants.

Original article:



Prof. Ted Turlings
Université de Neuchâtel (Suisse)
Tel +41 32 718 3158

Dr. Jurriaan Ton 
Utrecht University
(The Netherlands)
Tel +31 30 253 6840