Influence of Tamarixia radiata on Asian Citrus Psyllid in Brassinosteroids-treated Citrus
Posted August 2025
Researchers: Jawwad Qureshi, Fernando Alferez, Xuedong Chen
Contact: Jawwad Qureshi, UF/IFAS SWFREC jawwadq@ufl.edu
Summary:
Brassinosteroids (Brs) are a natural group of hormones essential for plant growth and development. Spray treatments of Brs are employed to alleviate the negative impact of huaunglongbing (HLB) on citrus trees. The positive effects of their application on HLB-affected citrus trees include a reduction in HLB infection and improved tree performance, as observed in Florida. The Asian citrus psyllid (ACP) vector of HLB is found in all environments, including Brs treated blocks, and warrants management. Natural enemies, including ACP-specific parasitoid Tamarixia radiata, have been shown to contribute to psyllid suppression in the citrus agroecosystems in Florida and elsewhere. Tamarixia radiata is mass-produced and released into the commercial and urban environments in Florida. We evaluated the performance of this parasitoid in large plots of ‘Early Pride’, ‘Tango’, and Sugar Belle® varieties treated monthly with foliar sprays of Brs and untreated plots. Parasitism rates in the open colonies of nymphs assessed by parasitoid averaged 10-50% in the plots treated with Brs and 13-42% in the untreated plots. Females of T. radiata caged with unparasitized nymphs for one week on trees treated or not with Brs provided, 13-25% and 18-25%, respectively. Tamarixia radiata females caged with ACP nymphs that experienced immediate residual exposure and residual plus contact exposure, provided parasitism of 28-42% and 13-37%, respectively, compared to 32-47% parasitism observed in the untreated control.
Take Home Message:
- Tamarixia radiata, suppressed ACP populations in Brs treated citrus.
- Tamarixia radiata releases are compatible with Brs sprays
- ACP suppression in Brs treated blocks will reduce spread and severity of HLB and improve tree health.
