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RESEARCH PRODUCT

Evolutionary biology as a tool towards a more customized biological control strategy of weeds: Lepidium draba as a case study

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Lepidium draba (Brassicaceae), native to Eurasia, is one of the most invasive noxious weeds in North American rangelands and croplands. As part of the 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 COI gene explored. Results clearly gave evidence of different genetic entities within this recognized species, one being restricted to the host L. draba and distributed in Southern France, Northern Spain and Italy. Furthermore, these results were supported by host plant spectrum studies in laboratory that showed specific and generalist populations. Underlying partial reproductive isolation which were also tested, probably explains the genetic differences that we observed between theses morphocryptic entities. Likewise, a study was jointly undertaken to trace the origin of the L. draba American populations and to evaluate the phylogeography of the species in its native range. Results tend to show some similarities in the evolutionary pattern of both the weed and the weevil. These multiple approaches will provide a valuable interest in biological control strategy and in the risk assessment.