Author
Dale Halbritter
dale.halbritter@usda.gov
United States Department of Agriculture
Fort Lauderdale, FL
Coauthors
Carey Minteer, University of Florida, Fort Pierce, FL, United States of America
Manoj Pandey, The Ohio State University, Columbus, OH, United States of America
Dean Brookes, Commonwealth Scientific and Industrial Research Organisation, Brisbane , Australia
Telmah Telmadarrehei, Florida Department of Agriculture and Consumer Services, Fort Pierce, FL, United States of America
Jorge Leidi, United States Department of Agriculture, Fort Lauderdale, FL, United States of America
Emily Le Falchier, University of Florida, Fort Pierce, FL, United States of America
Abstract
Despite selecting biological control agents most likely to succeed in their introduced ranges, variability in agent efficacy post-release persists. Here, we investigated this scenario with the thrips Pseudophilothrips ichini, a biological control agent targeting Brazilian peppertree, Schinus terebinthifolia, and released in Florida, USA, since 2019. The agent has successfully established at multiple field sites across the state but has failed to establish or produce sufficient damage at other sites. Based on preliminary observations from post-release surveys at 366 field sites, we identified ~ 30 habitat-specific variables for which we collected data to characterize 22 field release sites. These sites varied in agent success and had at least three post-release surveys from which we derived the following agent success metrics: proportion of surveys with thrips detected; average number of thrips observed; average canopy damage. Random Forest models were used to determine variable importance scores to identify the main drivers of agent success. Additionally, Brazilian peppertree tissue samples were collected to identify single nucleotide polymorphisms used to examine genetic clustering patterns in relation to site-specific agent success. The applied goal of this research is to provide better guidelines for researchers and stakeholders for selecting release sites where agents would be most successful. We expect this workflow can be adapted for other weed biocontrol systems.
keywords
habitat complexity
stage-specific microhabitat
RADSeq
plant quality
predation
Highlights
Within large areas of Brazilian peppertree infestation, some plants are more damaged than others
Pseudophilothrips ichini damage is greatest at sites two or more years old
A more diverse woody canopy and taller understory vegetation may be more supportive of P. ichini