Effect of mite density on acquisition and transmission of citrus leprosis virus by <i>Brevipalpus yothersi</i> and <i>B. californicus</i>

Citrus leprosis is a non-systemic disease caused by citrus leprosis virus (CiLV), which is classified as cytoplasmic (CiLV-C) or nuclear (CiLV-N) based on its replication site within host cells. Mite species in the genus <i>Brevipalpus</i> vector this virus. In Mexico, <i>B. californicus</i> and <i>B. yothersi</i> have been recorded in citrus orchards, with the latter species being most abundant and widely distributed. Despite extensive research, knowledge gaps remain regarding interactions between <i>Brevipalpus</i> and CiLV-C, the predominant virus type. We investigated the vector competence of both species, with a detailed analysis of density-dependent acquisition and transmission for <i>B. yothersi</i>. Virus acquisition was assessed using three densities (5, 10, or 15 adult females) for <i>B. yothersi</i> and a single desity (15 mites) for <i>B. californicus</i>. Virus detection and quantification were performed using a TaqMan probes targeting the viral movement protein gene. Transmission assays were conducted on <i>Phaseolus vulgaris</i> plants using viruliferous <i>B. yothersi</i> at all densities. <i>B. californicus</i> did not acquire the virus and was therefore excluded from transmission experiments. In contrast, <i>B. yothersi</i> successfully acquired the virus at all densities. While the proportion of viruliferous mites did not differ significantly among density treatments, viral load per mite was significantly higher at the lowest density. Virus transmission ocurred at all densities, with no significant differences in viral titres in inoculated plants. There results provide insights into density-related mite-virus interactions affecting CiLV-C transmission.