Impacts of Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae) on Brazilian peppertree recovering from fire or herbicide damage

Fire, primarily used for other land management objectives, can cause incidental damage to Brazilian peppertree. This invasive plant is adept at recovering from both fire damage and herbicide application, making frequent retreatments necessary. We investigated whether Pseudophilothrips ichini, a biological control agent for Brazilian peppertree, can reduce the plant’s ability to recover following damage from fire or herbicide. Saplings in a garden plot were randomly assigned one of three damage treatments: foliage singed with a propane torch (n=13), foliar spray with 0.75% Glyphosate (n=13), or no disturbance (control, n=14). Plant attribute data were collected in early March 2023 before damage treatments and 3 weeks after damage treatments when defoliation was maximized but before regrowth began. Plants had recovered with new flushing foliage by the end of April when plant attribute data were collected a third time. Adult thrips were then released onto plants. Plant attribute data were collected 40 d after thrips release, which allowed enough time for one generation of thrips feeding damage to accumulate. Plants that had recovered from fire damage had a significantly greater increase in dead stem tips after thrips release compared to undamaged or herbicide-damaged plants. Plants recovering from herbicide damage tended to have minimal changes in dead stem tips after thrips release. In a field setting, there may be potential for thrips to disperse from undamaged refugia and target regrowth in stands of Brazilian peppertree recovering from fire. This will aid in understanding how to incorporate the agents into integrated land management strategies.