Eriophyid Mites Vector the Kitavirus Blueberry Necrotic Ring Blotch Virus: Insights into the Viral Transmission and Its Infection on Blueberries Plants

Blunerviruses, family Kitaviridae, infect and cause diseases of important crop plants including tomato, tea, and blueberry. Despite the economic importance of blunerviruses, their epidemiology and the mechanism underlying plant-to-plant transmission are largely unknown. In 2006 the blunervirus blueberry necrotic ring blotch virus (BNRBV, Blunervirus vaccinii) was detected in Florida, USA, causing disease on blueberry plants and tentatively linked to an eriophyid mite vector. To gain insights into plant-virus interaction and plant-to-plant transmission of BNRBV, in this study, we investigated sap transmission and the potential vector of blueberry-infesting eriophyid and Brevipalpus mites collected in Florida during 2022 and 2023. While kitaviruses are vectored by several species of Brevipalpus mites, our experiments revealed a distinct vector for BNRBV. Both mite types acquired the virus, but only viruliferous eriophyids of the species Calacarus corymbosi, described for the first time in this work, transmitted the virus. Assays for BNRBV mechanical transmission were unsuccessful. This study marks the first demonstration of a characterized pathogen vectored by a mite in the genus Calacarus within kitavirus. Upon transmission by the eriophyid mite, BNRBV caused characteristic local necrotic ring blotch symptoms in blueberry leaves, and the virus was detected in symptomatic tissues and also in roots, but only at 6 months after inoculation, suggesting restricted or inefficient long-distance movement of the virus within the plant. This paper introduces a model for investigating the transmission of blunerviruses, a rapidly growing group of plant viruses.