Chitosan-dsRNA improves tissue stability and delivery for RNAi-mediated Varroa destructor control.

Authors

Sanghyeon Kim, Rashmi Manohar Mahalle, Hoe Nan Jeong, Keon Mook Seong

Published in

Pest management science. Sep 09, 2026. Epub Sep 09, 2026.

Abstract

Varroa destructor is an ectoparasitic mite and a major threat to honey-bee colony health worldwide. RNA interference (RNAi) offers a potentially species-specific approach for mite control, but practical application is limited by double-stranded RNA (dsRNA) degradation and inefficient delivery to mites. This study evaluated coatomer protein I (COPI) complex subunits as RNAi targets and tested whether chitosan-based dsRNA formulation could improve dsRNA stability, tissue uptake, and delivery from honey-bees to mites.
Direct microinjection of dsRNAs targeting COPB, COPD, and COPE significantly reduced target-gene expression and mite survival compared with the double-stranded green fluorescent protein (dsGFP) control, with 72-h survival rates of 8.0%, 12.7%, and 5.3%, respectively, compared with 40.7% in the control group (all log-rank P < 0.0001). Chitosan-conjugated dsRNA remained detectable for longer periods than naked dsRNA in honey-bee tissue fluids, and CNP-Cy3-dsGFP was detected in the honey-bee midgut and fat body. A qualitative fluorescence observation in V. destructor was consistent with host-to-mite dsRNA transfer. Ingestion of COP-targeted chitosan-dsRNAs reduced mite survival, whereas honey-bee survival and expression of honey-bee COP orthologs were not affected. In silico analysis detected no contiguous ≥19-nt matches between Varroa COP dsRNAs and the honey-bee transcriptome or genome.
COPI subunits are promising RNAi targets in V. destructor, and chitosan formulation may improve dsRNA persistence and uptake while supporting honey-bee-mediated delivery to mites. These laboratory findings support further evaluation of chitosan-formulated dsRNA as a potentially species-selective strategy for Varroa management, while broader safety assessment and field validation remain necessary. © 2026 Society of Chemical Industry.

PMID:
42717425
Bibliographic data and abstract were imported from PubMed on 10 Sep 2026.

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