BACKGROUND: Haematobia spp., horn flies (HF) and buffalo flies (BF), are economically important ectoparasites of dairy and beef cattle. Control of these flies relies mainly on treating cattle with chemical insecticides. However, the development of resistance to commonly used compounds is compromising the effectiveness of these treatments and alternative methods of control are required. Wolbachia are maternally transmitted endosymbiotic bacteria of arthropods that cause various reproductive distortions and fitness effects, making them a potential candidate for use in the biological control of pests. The first step towards this is the establishment and adaptation of xenobiotic infections of Wolbachia in target host cell lines. RESULTS: Here, we report the successful establishment of a continuous HF cell line (HIE-18) from embryonic cells and its stable transinfection with Wolbachia strains wAlbB native to mosquitoes, and wMel and wMelPop native to Drosophila melanogaster. HIE-18 cells were typically round and diploid with ten chromosomes (2n = 10) or tetraploid with 20 chromosomes (4n = 20), with a doubling time of 67.2 h. Wolbachia density decreased significantly in HIE-18 cells in the first 48 h of infection, possibly due to overexpression of antimicrobial peptides through the Imd immune signalling pathway. However, density recovered after this time and HIE-18 cell lines stably infected with the three strains of Wolbachia have now each been subcultured more than 50 times as persistently infected lines. CONCLUSION: The amenability of HF cells to infection with different strains of Wolbachia and the establishment of stable sustaining infections suggest the potential for use of Wolbachia in novel approaches for the control of Haematobia spp. Further, the availability of the HIE-18 cell line will provide an important resource for the study of genetics, host–parasite interactions and chemical resistance in Haematobia populations.
Bibliographical noteFunding Information:
We thank Dr Pia Olafson (USDA/ARS, Kerrville, TX, USA) and Prof. Roger Moon (Entomology, University of Minnesota) for making H. irritans eggs available for establishment of the Haematobia cell line. We thank Prof. Scott O'Neill (Monash University, Melbourne) and the Eliminate Dengue programme for donation of the two Wolbachia strains, wMel and wMelPop, used for this study. We also thank two anonymous reviewers for their suggestions and recommendations. This project was funded by Meat and Livestock Australia.
© 2020 Society of Chemical Industry
- Haematobia spp.
- horn fly
- pest management
- veterinary ectoparasite
PubMed: MeSH publication types
- Journal Article