The role of eriophyoids in fungal pathogen epidemiology, mere association or true interaction?

A considerable number of plant feeding mites representing different families such as Acaridae, Siteroptidae, Tydeidae, and Tarsonemidae interact with plant pathogenic fungi. While species within the Eriophyoidea appear to be the most common phytophagous mites vectoring virus diseases, little is known of their role in fungal pathogen epidemiology. In the present article, we present two studies on eriophyoid-fungal relationships. The first focusing on the association between Aceria mangiferae and the fungal pathogen Fusarium mangiferae in mango is presented as a case study. The second, as the research is still in a preliminary phase, reports on quantitative and descriptive associations between the cereal rust mite Abacarus hystrix and rusts caused by Puccinia spp. Mango bud tissue colonized with F. mangiferae, and wheat and quackgrass leaves colonized with Puccinia spp., supported significantly higher populations of eriophyoid mites. Both mite species were observed bearing the spores of the respective pathogens on their body integument. Aceria mangiferae vectored the pathogen's spores into the bud, the sole port of entry for the fungal pathogen and the frequency and severity of fungal infection increased in the presence of A. mangiferae. While it appears that eriophyoids are playing a role in fungal epidemiology, clearly further research is needed to enhance our understanding of direct and indirect (plant mediated) interactions between plant pathogens and eriophyoid mites in different plant-pathogen systems.