Author
Dale Halbritter
dale.halbritter@usda.gov
United States Department of Agriculture
Fort Lauderdale
Presenting author – Brianna Foster, University of Florida
Coauthors
Brianna Foster, University of Florida
Carly Cogan, University of Florida
Miriam Gaeta-Robles, Southern Nevada Environmental Inc.
Kamarri Davis, United States Department of Agriculture
Abstract
Since 2019, a flush-damaging biological control agent, Pseudophilothrips ichini Hood (Thysanoptera: Phlaeothripidae), has been released in Florida, USA, to aid in managing highly invasive Brazilian peppertree. In addition to thrips damage, chewing damage to flushing leaves caused by native and naturalised Paectes spp. (Lepidoptera: Euteliidae) caterpillars has been noted. Our goal was to investigate the possibility of herbivore priority effects and interspecific competition impacting thrips efficacy. A laboratory study was conducted in winter 2024 with three treatments comparing thrips reproduction and plant damage with respect to herbivore priority: (1) thrips before Paectes (n=4), (2) Paectes before thrips (n=4), and (3) thrips alone (control) (n=4). We repeated treatments 2 and 3 (n=6 each) in summer 2024 and all three treatments (n=4 each) again in winter 2025. Winter 2024 results suggested thrips numbers may be negatively impacted when Paectes are present before thrips, but summer 2024 and winter 2025 results suggested little evidence for priority effects. We also estimated Paectes damage during field surveys from November 2023 through November 2025. There was a significant, albeit very weak, negative correlation between thrips damage and Paectes damage. Overall, it appears the agent will perform comparably on plants with or without Paectes. Further study is needed to investigate the potential for additive, long-term impacts to the plant when both herbivores are present.
Keywords
competition
priority effects
thrips
Highlights
Native herbivores can coexist with agents on target weeds
Pseudophilothrips ichini and Paectes spp. can damage Brazilian peppertree simultaneously
Seasonality and host plant characteristics may influence herbivore interactions