Optimal Combination of Bt Toxins and Gene Silencing RNAs for Management of Citrus Root Weevil
Posted August 2025
Researchers: Bryony C. Bonning, Nabil Killiny, Lukasz Stelinski, Manjul Dutt
Contact: Bryony C. Bonning, UF/IFAS Gainesville bbonning@ufl.edu
Summary:
The citrus root weevil, Diaprepes abbreviatus, also known as the Diaprepes root weevil (DRW), poses a serious threat to the citrus industry. The recent relaxation in chemical insecticide application for management of Asian citrus psyllid, has resulted in a rebound of weevil populations in groves weakened by huanglongbing (HLB), costing Florida citrus growers up to $500/acre for combined DRW and associated Phytophthora control. As current management strategies are proving inadequate, we plan to address the urgent need for new management strategies. Bacillus thuringiensis (Bt)-derived proteins, along with gene silencing RNAs have been successfully deployed for management of a range of pest insects, most notably against another beetle pest, the corn rootworm. For this project, we aim to screen Bt proteins and gene silencing RNAs for activity against DRW, and to test existing transgenic citrus rootstocks that express Bt proteins for resistance to DRW. Both Bt proteins and gene silencing RNAs have a strong track record as safe and effective insecticides. Elucidation of the best combinations for use against DRW will provide growers with an environmentally friendly option for DRW management.
Take Home Message:
- Diaprepes root weevil larvae are susceptible to the impacts of both Bt proteins and gene silencing RNAs.
- Of 16 Bt proteins and 13 gene silencing RNAs tested, several were toxic to DRW in preliminary bioassays.
- This two-pronged approach will provide for an environmentally benign strategy for DRW management.
