Investigating the potential for plant-mediated interactions between two biological control agents for Brazilian peppertree

Abstract

ABSTRACT Invasive species cause damage to ecosystems by altering and dominating native habitats. Classical biological control can be a safe and effective way to control invasive species, especially in areas where chemical and mechanical control are not recommended, because of potential damage to non-target species, difficulty to access sites, and the costs associated with the treatment of large areas. Schinus terebinthifolia, Brazilian peppertree (BP) was introduced into Florida as an ornamental plant in the 1890s and is considered an aggressive invasive species in Florida. Pseudophilothrips ichini was the first biological control agent of BP released in Florida in 2019 and three Calophya spp., are under study as potential biological control agents. Feeding by Calophya can either elicit a hypersensitive response (HR) from BP that kills immatures at the feeding point or susceptibility with complete development and adult emergence. Pseudophilothrips ichini feeding does not elicit such response. To determine if previously elicited HR to the feeding of Calophya lutea affected P. ichini or its impact on, we measured the change in plant growth and the number of adults after one generation of P. ichini on susceptible and hypersensitive BP. After one generation of thrips feeding, plant height was the only factor that differed between plants that were hypersensitive and susceptible to Calophya lutea exposure, with hypersensitive plants being significantly shorter than susceptible plants. Our results suggest that even when HR is elicited by prior feeding of Calophya lutea, it will not affect P. ichini feeding and reproduction and should enhance control of BP.