Research article

Plant chemical defence: a partner control mechanism stabilising plant - seed-eating pollinator mutualisms

Sébastien Ibanez^1,3 , Christiane Gallet^2,3 , Fanny Dommanget^1,3 and Laurence Després^1,3

¹Laboratoire d'Ecologie Alpine UMR CNRS 5553 Université Joseph Fourier B.P.53, 38041 Grenoble CEDEX 9 France

²Laboratoire d'Ecologie Alpine UMR CNRS 5553 Université de Savoie F-73376, Le Bourget-du-lac, France

³Station Alpine Joseph Fourier UMS CNRS 2925 Université J. Fourier, BP 53, F-38041 Grenoble, France

author email corresponding author email

BMC Evolutionary Biology 2009, 9:261doi:10.1186/1471-2148-9-261

Published:	3 November 2009

Abstract

Background

Mutualisms are inherently conflictual as one partner always benefits from reducing the costs imposed by the other. Despite the widespread recognition that mutualisms are essentially reciprocal exploitation, there are few documented examples of traits that limit the costs of mutualism. In plant/seed-eating pollinator interactions the only mechanisms reported so far are those specific to one particular system, such as the selective abortion of over-exploited fruits.

Results

This study shows that plant chemical defence against developing larvae constitutes another partner sanction mechanism in nursery mutualisms. It documents the chemical defence used by globeflower Trollius europaeus L. (Ranunculaceae) against the seed-eating larvae of six pollinating species of the genus Chiastocheta Pokorny (Anthomyiidae). The correlative field study carried out shows that the severity of damage caused by Chiastocheta larvae to globeflower fruits is linked to the accumulation in the carpel walls of a C-glycosyl-flavone (adonivernith), which reduces the larval seed predation ability per damaged carpel. The different Chiastocheta species do not exploit the fruit in the same way and their interaction with the plant chemical defence is variable, both in terms of induction intensity and larval sensitivity to adonivernith.

Conclusion

Adonivernith accumulation and larval predation intensity appear to be both the reciprocal cause and effect. Adonivernith not only constitutes an effective chemical means of partner control, but may also play a key role in the sympatric diversification of the Chiastocheta genus.