Department of Environmental Conservation – Seminar Series
Fridays 12:20 -1:10
Holdsworth Hall Room 202

Tom Dudley, University of California, Santa Barbara, Riparian Research Laboratory

Seminar,”Complex interactions in establishing a new herbivore-host plant association with a wildley distributed invasive plant: Biological control of Tamarix in the western U.S.

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Seminar description: Several species and hybrids of non-native tamarisk, or saltcedar (Tamarix spp.) have established throughout western riparian systems, in part as a consequence of human modification of hydrologic regimes but also in relatively pristine watersheds. The introduction of the tamarisk leaf beetle, Diorhabda spp., for the biological control of invasive populations and to promote recovery of native cottonwood-willow vegetation and associated wildlife has led to both spectacular successes and many failures, with anticipated beneficial effects, some potential non-target impacts, and extraordinary regulatory complications. Establishment failures involved mis-matching of herbivore and hosts, mis-matching of developmental timing and plant phonologies, and predation, leading to alternative strategies in such locations. Where Diorhabda establishment was successful, evolutionary change has been documented allowing expansion of those populations into regions they could not originally inhabit, including areas with endangered species concerns. Hence, biological control implementation has required an equally complex approach to habitat restoration in the context of tamarisk suppression by biocontrol.