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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

2010 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 relates to the inhouse objective: Prioritizing and evaluating suitable target species for control; conducting surveys to discover natural enemies; studying the ecology of target species and determining the impact of their suppression on ecosystems; conducting risk analysis of potential biological control organisms; and releasing, establishing, evaluating, and transferring biological control agents against target species.

Brazilian peppertree (Schinus terebinthifolius Raddi., 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 in Fiscal Year 2010. 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 is currently being revised for resubmission to the International Journal of Plant Sciences. 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.

A new thrips species has been discovered that may be a cryptic species feeding on Brazilian pepper leaves. This discovery was made while conducting routine surveys in southern Brazil. The significance of the discovery was only made clear following DNA analysis of the thrips. Morphological examination of these individuals is in progress and plans are being formulated to return to this area of Brazil for additional collections. Surveys recovered a new weevil species; research was completed and a manuscript was drafted describing the suitability of this broad nosed weevil, Plectrophoroides lutra for biological control of this weed. Approved biological controls will reduce the health and vigor of these invasive weeds, reduce their damage to natural areas and agriculture, and reduce dependence on synthetic herbicides.


Last Modified: 9/2/2014
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