Patch characteristics of Carduus nutans affect movement of the insect herbivore Rhinocyllus conicus.
Sezen, Zeynep*,1, Shea, Katriona 1, 1 The Pennsylvania State University, University Park
ABSTRACT- Despite the widespread use of the seed head weevil Rhinocyllus conicus for biological control of musk thistle, Carduus nutans, the weevil′s movement and dispersal abilities are not well-known on a seasonal time scale. Thistle patches are often heterogeneous and factors such as host patch area, patch isolation and patch quality may influence the movement of insect herbivores. In May 2004, we conducted a mark-release-resight study of R. conicus on C. nutans patches of varying sizes and densities in different spatial arrangements, in order to determine how thistle patch characteristics affect the movement of R. conicus within and between patches of its host plant. Weevils were individually marked and released at different distances from host patches. The recapture rates per plot were higher on larger patches, however more weevils were recaptured per plant on smaller patches. These observations also suggest that the insects are more mobile within a season than previously suspected.
Key words: herbivore movement, Rhinocyllus conicus, Carduus nutans
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