Optimizing dsRNA Concentration for RNA Interference in Asian Citrus Psyllid
Posted August 2025
Researchers: Jawwad Qureshi, Esmaeil Saberi, Mosharrof Mondal, Jorge R. Paredes-Montero, Kiran Nawaz, Judith K. Brown
Contact: Jawwad Qureshi, UF/IFAS SWFREC jawwadq@ufl.edu
Summary:
The Asian citrus psyllid (ACP) is a citrus pest and insect vector of Candidatus Liberibacter asiaticus, the causal agent of huanglongbing. Double-stranded RNA (dsRNA) biopesticides that trigger RNA interference (RNAi) offer an alternative to traditional insecticides. Standardized laboratory screening of dsRNA requires establishing the minimal effective concentration(s) that result in effective RNAi “penetrance” and trigger RNAi, resulting in one or more measurable phenotypes, herein, significant gene knockdown and the potential for mortality. In this study, knockdown was evaluated for a range of dsRNA concentrations of three ACP candidate genes, clathrin heavy chain (CHC), vacuolar ATPase subunit A (vATPase-A), and sucrose non-fermenting protein 7 (Snf7). Gene knockdown was quantified for ACP teneral adults and third instar nymphs allowed a 48 h ingestion-access period (IAP) on 10, 50,100, 200, and 500 ng/μL dsRNA dissolved in 20% sucrose followed by a 5-day post-IAP on orange jasmine shoots. Significant gene knockdown in ACP third instar nymphs and adults ranged from 12–34% and 18–39%, 5 days post-IAP on dsRNA at 10–500 and 100–500 ng/μL, respectively. The threshold concentration beyond which no significant gene knockdown and adult mortality was observed post-48 h IAP and 10-day IAP, respectively, was determined as 200 ng/μL, a concentration indicative of optimal RNAi penetrance.
Take Home Message:
- Use of dsRNA biopesticides offers an alternative to traditional insecticides.
- dsRNA concentration indicative of optimal RNAi penetrance by oral delivery was 200 ng/μL.
- A working threshold can reduce the use of excessive amounts of dsRNA, cost, and potential off-target effects.
