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Title: Insect / pathogenic fungi synergism for the biological control of Lepidium draba, an invasive weed in the U.S.

item TANNIERES, MELANIE - European Biological Control Laboratory (EBCL)
item BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL)
item Smith, Lincoln

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/4/2015
Publication Date: 6/24/2015
Citation: Tannieres, M., Bon, M., Smith, L. 2015. Insect / pathogenic fungi synergism for the biological control of Lepidium draba, an invasive weed in the U.S. Meeting Proceedings. Pathobiome: pathogens in microbiotas in hosts symposium, 24th-26th june 2015, Paris, France. Poster.

Interpretive Summary:

Technical Abstract: Lepidium draba sp. draba, also named hoary cress, is a deep-rooted perennial plant in the family Brassicaceae. It is an invasive rangeland weed in the U.S. and Canada that originates from Eurasia. The collar gall weevil, Ceutorhynchus assimilis (Coleoptera: Curculionidae), has been identified as a possible biological control agent. Larvae develop inside galls in the root collar region and exit when they complete development, creating holes that may facilitate infection by soilborne plant pathogens. In the native range galls have been shown to be infected by the pathogenic fungus Rhizoctonia sp. We are conducting field experiments to determine if there is a synergistic interaction between the weevil and Rhizoctonia regarding impact on the target weed. Treatments included control plant, plant + weevil, plant + Rhizoctonia, and plant + weevil + Rhizoctonia. Preliminary results show that introduction of both Rhizoctonia and the weevil caused higher impact on mortality of L. draba than either the weevil or the fungus alone. This indicates that a soil fungus can significantly increase the impact of this weevil which should be considered when trying to use it as a biological control agent. To get a better understanding of processes and interactions that occur between biocontrol agents, a targeted invasive weed and microbial communities, the soil microbial diversity among the different conditions will be compared. This should help to prevent negative feedback of biocontrol strategies.