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United States Department of Agriculture

Agricultural Research Service

Research Project: RISK ASSESSMENT STUDIES OF CLASSICAL BIOLOGICAL CONTROL OF BRAZILIAN PEPPER

Location: Invasive Plant Research Laboratory

2011 Annual Report


1a.Objectives (from AD-416)
To reduce the invasibility and dominance of Brazilian pepper in agricultural and natural areas of the U.S. through the use of biologically based IPM.


1b.Approach (from AD-416)
Conduct foreign explorations to identify and prioritize potential agents for biological control. Testing will be conducted to determine suitability for safe biological control introductions. Suitability will be determined through feeding/oviposition/developmental trials on related plant species available in South America. Priority will be given to species that show a high level of specificity for the target weed and pose minimal risk to desirable plant species.


3.Progress Report

This research is related to inhouse objective 4: Conduct risk analysis to determine environmental safety of new and existing potential biological control agents for weeds such as melaleuca, Brazilian pepper, lygodium, downy rose myrtle, Chinese tallow, waterlettuce and skunk vine.

The health and functioning of the greater Everglades ecosystem is being compromised by the proliferation of invasive exotic species. Brazilian peppertree (Schinus terebinthifolius Anacardiaceae), hereafter BP, is acknowledged to be one of the most harmful invasive plant species negatively affecting biodiversity and proper functioning of the system. The plant presently covers over 280,000 ha in southern Florida alone. Several studies have been completed and several other long-term studies are ongoing over this time period (1 October 2009 – 15 July 2011). The results from our common garden study performed the previous year to gauge whether hybrid BP haplotypes are fitter than either parental type showed that indeed, hybrid BP haplotype seeds and seedlings outperformed the other types. These results were further strengthened by both chloroplast haplotype and microsatellite genotyping which confirmed that the original sampling protocol accurately captured the distribution of haplotypes sampled for the common garden experiment. The manuscript was published in the International Journal of Plant Sciences. The results from our seed bank dynamics study to investigate seed longevity under several field microsite treatments agreed with previous studies that there is a transient seed bank lasting about seven months. However, there were significant differences among the microsite treatments that have important management ramifications. It appears that BP management that physically removes large trees, or creates bare ground areas adjacent to fruiting trees, may have the inadvertent effect of burying seeds in the soil which results in greater seed germination. The manuscript is being readied for submission to the Journal of the Torrey Botanical Society. Our team has completed the second season of a multi-year BP biomass harvesting study to predict reproduction (i.e the number of fruit) from plant allometric measures. We have harvested an additional 87 trees from our 6 long-term BP demographic study sites. We have completed setting up all our long-term demographic study plots at our 6 field sites across Florida. The complete first year census of all 1050 tagged individuals at the 6 field sites has been finished. Multi-year data from the tagged BP individuals within these plots will be used to perform a population viability analysis (PVA). The PVA will calculate the population growth rate, that is, whether the studied populations are declining, static, or growing, along with several other key population characteristics.


Last Modified: 4/21/2014
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