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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Research Project #437366

Research Project: Biological Control of Schinus terebinthifolia (Brazilian pepper tree) in South Florida With Special Reference to Miami-Dade County

Location: Invasive Plant Research Laboratory

Project Number: 6032-22000-013-62-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Sep 1, 2020
End Date: Aug 31, 2025

Objective:
Overall objectives of this research is to mass produce Brazilian pepper tree biocontrol agents (thrips and psyllid), disperse them in Brazilian pepper infestations within Miami Dade County, Florida, monitor agents establishment and impact on target weed and plant species diversity in research sites. Specific objectives are as follows: 1. Mass produce Brazilian pepper plants for rearing biocontrol agents. 2. Mass produce biocontrol agents by inoculating in plants maintained in cages, screenhouses, common gardens and open field nurseries. 3. Establish research field sites, document major plant species in the sites, make single or multiple releases (as needed) within research sites and other areas in order to establish self sustained populations of biocontrol agents. 4. Monitor biocontrol agent population dynamics (density/branch/tree), overall health (defoliation level, branch/tree mortality, fruit/seed production) of the target plant and changes in populations densities of target and other plant species dynamics within study sites over the proposed 5-year study period.

Approach:
1) Plant Production: Fully mature (red) Brazilian pepper tree (BP) fruits will be collected outer skins will be removed, clean seeds will be sown in plastic containers filled with commercial growth media, placed on glass/screenhouse benches, irrigated as needed, allowed to grow ca. 10 cm height, and transferred to 1- or 3-gallon pots filled with commercial growth media containing basal dose of fertilizer. The plants will be protected from unwanted native pests by using using mild safer soap/neem oil or other insecticides as needed to maintain pest-free Brazilian pepper plants for thrips and psyllid production. We will develop field nurseries by trimming field grown plants and inoculate new growth with biocontrol agents and will use them as additional sources for agents and epicenters for self-dispersal into adjacent areas. 2) Biocontrol Agent Production: Initial efforts will focus on identifying the most effective laboratory rearing setup to improve on our current standard practice. Thrips and psyllid will be reared by using the pest-free 1- or 3-gallon potted plants placed in specially-designed, vented acrylic cylinders (current thrips standard), ventilated acrylic boxes, mesh sleeves, and/or cages made up of nylon screens fitted over a frame (current psyllid standard). Initially, agents will be reared separately here in the enclosure that works best for each species. These plants will be inoculated with adult stages of biocontrol agents (thrips or psyllid), placed either in our laboratory or on benches in partially shaded screenhouses, irrigated and fertilized as needed. Agents will be monitored for oviposition, occlusion (hatching), and life stage development. Dispersal methods including appropriate life stages will also be developed to enhance dispersal efficacy. 3) Site Selection and Biocontrol Agent Dispersal. Following consultation with participating biologist(s) charged with BP management in Miami-Dade County, sites for biocontrol agent releases will be selected in Miami-Dade County natural and recreational areas. Dispersal protocols will include- a) Counting adult thrips and psyllid transferring them to plastic vials followed by release in on suitable BP plants and b) Biocontrol agent-infested plants will be enclosed in mesh sleeves, transported to the field sites, and placed adjacent to BP plants. The number of individual agents will be estimated using the method developed in Task 2. 4) Biocontrol Establishment and Impact Monitoring: Release sites will be inventoried for pre-release BP biometric data such as basal diameter of the main trunk and major stems (at point of origin) within 1-m above the ground, ground cover (% of total ground area), vertical height of the tallest live stem and the narrowest and broadest diameter of the crown in two dimensions. These and other biometric data lites in objective 4 will be gathered at a 6-mo interval, once in the early spring and once during the fall season.