ARS | Publication request: Antagonism or synergism between two natural enemies of an invasive Brassicaceae

Submitted to: Ecology International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 21, 2011
Publication Date: February 6, 2012
Citation: Bon, M., Caesar, A.J. 2012. Antagonism or synergism between two natural enemies of an invasive Brassicaceae? Ecology International Congress Proceedings. 7th 'Réunion du Réseau Ecologie des Interactions Durables' February 6-8 2012, Rennes, France. p.46.

Technical Abstract: Natural enemies are known to affect host plant 'tness through competitive interactions among themselves. Some plant species acquire multiple feeding guilds of natural enemies and they may experience various degrees of top-down regulation of their populations. Interactions among higher trophic levels of the natural enemies are common in nature as they exploit the same plant tissues. Therefore, intra-guild interactions may in'uence ef'cacy of biological control agents under 'eld conditions. These interactions can be direct, for instance, insects may vector plant pathogens or indirect, where alteration of plant tissues by one may affect the survival and performance of the other organism. These interactions between microorganisms, fungi in particular, and insects may range from antagonistic to synergistic. However, these interactions as an area of classical biological control research have not been fully considered when selecting new agents. The root galling weevil, Ceutorhynchus assimilis and the non-sporulating root rotting fungus, Rhizoctonia sp. are two natural enemies of the perennial and Eurasian weed, Lepidium draba sp draba (Brassicaceae). This weed is highly invasive and noxious in the central and western U.S. and so far, biocontrol agents are lacking. The objective of the present study is to test the hypothesis that the combined effect of the weevil and the pathogen would suppress performance of the weed as compared to the simple effects of an insect galling or a pathogen-infection alone. The framework of this study carried out in France is presented here.