Co-incubation of dsRNA reduces proportion of viable spores of Ascosphaera apis, a honey bee fungal pathogen

Abstract

There are viral, fungal, bacterial and trypanosomal pathogens that negatively impact the individual and superorganismal health of the western honey bee. One fungal pathogen, Ascosphaera apis, affects larvae and is the etiological agent of the disease chalkbrood. A previous genome analysis of A. apis revealed that its genome encodes for RNA interference genes, similar to other fungi and eukaryotes. Here, we examined whether A. apis-targeting double-stranded RNA species could disrupt the germination of A. apis. We observed that when spores were co-incubated with A. apis-targeting dsRNA, fewer spores were activated for germination, suggesting an uptake of exogenous genetic material at the very onset of germination and consequent damage to essential transcripts needed for germination. Overall, these results indicate that the causative agent of chalkbrood disease can be successfully targeted using an RNAi-based strategy.

Keywords:

• Honey bee
• pathogen
• Ascosphaera apis
• RNAi
• dsRNA
• control

Acknowledgements

J.T. was supported by an appointment to the Agricultural Research Service (ARS) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA). ORISE is managed by ORAU under DOE contract number DE-SC0014664. J.T. was also supported by the ARS Research Associate Program (Class of 2018). USDA is an equal opportunity provider and employer. The authors declare that they have no competing interests. All opinions expressed in this paper are the author’s and do not necessarily reflect the policies and views of USDA, ARS, DOE, or ORAU/ORISE. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. We thank Baris Tursun and Anne Krause for supplying the bacterial strain and plasmid; Dawn Lopez for coordinating various aspects of this work; Kerstin Klutzny for supplying S. lacrymans from the BAM reference organism collection; Louela A. Castrillo and others at the USDA-ARS for organizing and shipping the fungal strains; Thorben Sieksmeyer for helpful discussions regarding the project; and Hannes Meissner for help during experiments. J.T., D.M., R.E. and J.E. designed the project; J.T. did the experiments and analyses; J.T. wrote the manuscript with contributions from others; D.M. and J.E. funded/contributed reagents for this project; J.T., D.M., R.E. and J.E. approved the submitted manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary content is available via the ‘Supplementary’ tab on the article’s online page (http://dx.doi.org/10.1080/00218839.2020.1754090).