Preliminary impacts of Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) on the biological control of Brazilian peppertree and indirect effects on arthropod food webs

Authors: Halbritter, Dale; Rayamajhi, Min; Wheeler, Gregory; Leidi, Jorge; Owens, Jenna; SIGMON, JOSEPH - University Of Florida

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/2/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: Brazilian peppertree is a highly invasive weed in the Greater Everglades area and is costly and difficult to manage with chemical and mechanical means. Pseudophilothrips ichini is a species of thrips that specializes in feeding on Brazilian peppertree and is being used as a biological control agent to help management efforts. Our goal was to determine the damage the thrips inflict on Brazilian peppertree and whether the thrips cause changes in the abundance and variety of other arthropod species. Field sites in Big Cypress National Preserve were visited monthly starting October 2018 and ending October 2020. Thrips were first released September 2019 and releases continued every 1-3 mo thereafter. During each site visit, we recorded plant quality data, surveyed for thrips damage and thrips abundance, and collected arthropods from each plant. We have so far focused on ants and have identified 28 species. Trends suggest that ant abundance and variety have not been impacted by the addition of thrips to the food chain. Thrips populations have persisted at all three sites and thrips damage is evident on several plants at each site, with some plants more heavily damaged than others. Future directions include determining plant characteristics that make them more desirable to thrips and determining which ant species are most likely to attack thrips. The information gathered here will help us choose locations where thrips would be most successful in helping manage Brazilian peppertree.

Technical Abstract: Brazilian peppertree is an introduced woody shrub or small tree that reproduces prolifically and easily outcompetes native vegetation. It is one of the most notorious invasive weeds in the Greater Everglades area and is costly and difficult to manage with chemical and mechanical means. Pseudophilothrips ichini is a thrips that was approved for release in Florida in May 2019 as a biological control agent of Brazilian peppertree. Our goal was to determine the direct impacts of the thrips on Brazilian peppertree and indirect effects on arthropod food webs following the initial agent releases. Three sites each containing 30 marked trees along a 200 m transect were established in Big Cypress. Sites were visited monthly starting October 2018 and ending October 2020. Thrips were first released September 2019 and releases continued every 1-3 mo thereafter. During each site visit, we recorded plant quality data, surveyed for thrips damage and thrips abundance, and collected arthropods from each plant using the beat sheet method and a powered aspirator. We have thus far focused on ants and have identified 28 species. Trends suggest that ant diversity has not been impacted by the addition of thrips to the food web. Thrips populations have persisted at all three sites and thrips damage is evident on several plants at each site, with some plants more heavily damaged than others. Future directions include determining plant characteristics that make them more susceptible to thrips damage and determining which ant species are most likely to prey on thrips.