INNOVATIVE dsRNA-BASED STRATEGIES FOR THE CONTROL OF DERMANYSSUS GALLINAE AND MITIGATION OF LAYING HENS VIRAL DISEASES

Dermanyssus gallinae, commonly known as the poultry red mite, is an important hematophagous ectoparasite of laying hens and acts as vector of various viral pathogens in poultry farms worldwide, including avipox virus, Marek’s disease virus, fowl adenovirus, chicken infectious anemia virus and influenza virus, leading to detrimental effects on productivity and animal welfare (1, 2). Current acaricide-based control strategies are becoming unsustainable due to the mite’s ability to develop resistance, highlighting the need for novel approaches to parasite control, such as RNA interference (RNAi)-mediated gene silencing (3). This study aimed to investigate the stability of dsRNAs targeting D. gallinae acetyl-CoA-carboxylase (DgACC) and vitellogenin 1 (DgVg 1) genes, as well as the effects of their silencing on mite survival and fecundity, the two main components of fitness. Plasmids containing DgACC and DgVg sequences, were purchased from Eurofins Genomics, amplified in Escherichia coli DH5α cells and subsequently extracted. PCR using primers containing T7 promoter sequences was carried out to amplify the sequences of interest. PCR products were purified and subjected to in vitro transcription using T7 RNA polymerase. DNase treatment was then performed, followed by dsRNA purification using the MEGAclear™ Transcription Clean-Up Kit (ThermoFisher Scientific). The dsRNAs were administered to engorged adult female mites by soaking at 4 °C for 14 h. After treatment, a pool of live mites was collected for RNA extraction and analyzed by qRT-PCR to assess RNAi efficiency. The remaining live mites were transferred into transparent gelatin capsules, and their survival and reproductive capacity were daily monitored under a stereomicroscope for 8 days. Preliminary results showed efficient dsRNA production and gene silencing that significantly impacts mite fitness, supporting the potential of this novel strategy to control D. gallinae and the spread of viral pathogens in poultry systems. References 1) Xu K, Zhang X, Wang Z, Liu J, Yin S, Wang Y, et al. Potential role of Dermanyssus gallinae as a vector of chicken infectious Anemia Virus. Poultry Science. 2025 Aug;104(8):105365. doi:10.1016/j.psj.2025.105365. 2) Schiavone A, Pugliese N, Otranto D, Samarelli R, Circella E, De Virgilio C, et al. Dermanyssus gallinae: the long journey of the poultry red mite to become a vector. Parasites Vectors. 2022 Jan 20;15(1):29. doi:10.1186/s13071-021-05142-1. 3) Chen W, Bartley K, Nunn F, Bowman AS, Sternberg JM, Burgess STG, et al. RNAi gene knockdown in the poultry red mite, Dermanyssus gallinae (De Geer 1778), a tool for functional genomics. Parasites Vectors. 2021 Dec;14(1):57. doi:10.1186/ s13071-020-04562-9.