Insights in the evolutionary relationships between invasive weed and its potential biocontrol agent
Project Leader: Marie-Claude BON
The ultimate focus of our research at EBCL is to seek for natural enemies which offer the greatest prospect for biological control of weeds, insect pests or plant pathogens in controlled environments prior their transfer and subsequent release in USA. Emphasis in our research is placed on the comparison of the population genetic structures of both the targeted weed and its herbivore. This inform us about the population ecology of both partners, but also the factors influencing the evolutionary interaction.
Heart-podded hoary cress, Lepidium draba L. ssp. draba sp. [=Cardaria draba (L.) Desv.] (Brassicaceae), native to Eurasia, is one of the most invasive noxious weeds in North American rangelands and croplands. As part of a management plan for its control, one of its natural enemies, the collar gall weevil Ceutorhynchus assimilis (Coleoptera: Curculionidae) has been targeted and its genetic structure in the mitochondrial genome explored.
Results clearly gave evidence of different genetic entities
within this recognized species, one being restricted to the host L. draba.
This genetic structuration
is in favor of an ongoing differentiation based on host-plant specialization which was confirmed through host specificity testing. Moreover, the weevil genetic difference seems to be supported by a comparable differentiation of the host in Europe. This study should provide conceptual bases for the development of future biological control programs. The combination of both the genetic characterization of the insect and the target, alongside with the host specificity testing in the biological control evaluation should be of general interest in limiting the risk of introduction side effects and reducing both time and cost of biological control program.
Corinne Hurard and Rouhollah Sobhian (USDA-ARS-EBCL)
Jean-François Martin (CBGP, ENSAM, France)
John Gaskin (USDA-ARS-NPARL, Montana, USA)
Boris Fumanal (INRA-UMR BGA, Dijon, France)
Jean Pierre Lumaret (University of Montpellier, France)
Enzo Colonnelli (University of Roma, Italy)
This work was supported by Mc Neel of BLM, CRIS n°4012-22000-016-03R
More details on the biological control program, ecology and systematic of this weed are to be found at the following website http://www.sidney.ars-usda.gov/hoarycress/ (broken link).
This website is hosted and operated by: USDA-ARS Northern Plains Agricultural Research Laboratory (broken link) - Sidney, MT
in collaboration with: University of Idaho (broken link) - Moscow, ID.
Lepidium draba patch in native area (click to enlarge)