COS 78-4 - Titrating local and spatial impacts of a biocontrol agent

Wednesday, August 10, 2011: 2:30 PM
10B, Austin Convention Center
Katherine M. Marchetto, Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, Katriona Shea, Department of Biology, The Pennsylvania State University, University Park, PA, Dave Kelly, Biological Sciences, University of Canterbury, Christchurch, New Zealand, Ronny Groenteman, Landcare Research, Lincoln, New Zealand, Zeynep Sezen, Department of Entomology, University of Minnesota, St. Paul, MN and Eelke Jongejans, Radboud University Nijmegen, Nijmegen, Netherlands

Biological control focuses on the use of natural enemies to reduce the local abundance or density of the pest. However, this paradigm makes no mention of the control of spatial invasion, mediated by enemy effects on pest dispersal and spread rates.  We used a combination of empirical data on seed production, seed release, and seed terminal velocity and population spread rate modeling to quantify the effects of herbivory by the biocontrol agent weevil, Rhinocyllus conicus, on seed dispersal and population spread rates of the invasive thistle, Carduus nutans.


We show that, in addition to reducing C. nutans seed production, R. conicus also inhibits both the release and dispersal of seeds by wind.  We further show that this combination of effects gives rise to different relative impacts on spatial and local control in populations in the USA and New Zealand.  Screenings of potential biocontrol agents should examine the effects of agents on host dispersal and spread, as well as on host abundance, and practitioners should also refine their objectives to specify whether control of pest population abundance or spread rates is most desired.

Copyright © . All rights reserved.
Banner photo by Flickr user greg westfall.