Woods, Teresa , Jonas, Jayne , Ferguson, Carolyn .
The invasive Lespedeza cuneata attracts more insect pollinators than native congeners, with variable impacts.
Invasive plant species can exert competitive effects as well as facilitative effects on insect pollination services of native species. Through high relative abundance and/or prolific floral display, invasive plants that rely on insect pollination can successfully compete with some native plant species for shared pollinators. Alternatively, invasive plants can facilitate pollination of native plants by supporting and attracting shared insect populations. Factors that influence the effects of alien plant species on pollination services to native plants include the degree of shared pollinator species, synchronous flowering phenology, similar flower morphology and color, relatedness of invasive and natives, and showiness and densities of flowers. To investigate such plant-pollinator dynamics, this study compared the invasive Lespedeza cuneata and three native congeners, all sympatric with synchronous flowering, using in situ populations over two years during peak floral displays. The invasive demonstrated significantly higher insect visitation rates per plant in both years. Positive correlations were found between floral density and visitation rate per plant in all the native species. Although there was no such correlation found in the invasive L.cuneata, floral density was at least twenty times higher than the native species and likely saturated the pollinator community. When insect visitation rates of native plant species were compared with or without the presence of the invasive, L. cuneata showed a competitive effect on two native species, but a facilitative effect on one. The native plant species that experienced a facilitative effect had the highest degree of shared insect visitors with the invasive, and is morphologically most similar to the invasive, compared to the other native Lespedeza species. Insect visitor taxonomic analyses indicated each of the Lespedeza species had common insect visitors, with one major exception: the common honeybee, Apis mellifera, a primary visitor to the invasive plant species, was never observed on the native Lespedeza species.
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1 - Kansas State University, Olathe Campus, 22201 W. Innovation Dr., Olathe, KS, 66061, USA
2 - Colorado State University, Forestry, Rangeland and Watership Stewardship, 1472 Campus Delivery, Fort Collins, CO, 80523, USA
3 - Kansas State University, Division of Biology, Ackert Hall, Manhattan, KS, 66506, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Portland Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 8:00 AM