Redberry mite, Acalitus essigi (Hassan) (Acari: Eriophyidae), an additional biological control agent for Rubus species (blackberry) (Rosaceae) in Australia

Abstract  Acalitus essigi , the eriophyoid mite that causes red berry disease in Rubus species (Rosaceae), was collected from the fruits of three species of weedy blackberry, R. anglocandicans , R. laudatus and R. ulmifolius , in south-west Australia. This is the first record for this species in Western Australia and these plants appear to be new host records for A. essigi , which causes uneven ripening of fruit. Information on the mite is reviewed in the context of determining its potential as a biological control agent for Rubus species, especially those that are not susceptible to Phragmidium violaceum (Uredinales), the rust fungus being released against species of European blackberry in Australia. Published records also show that A. essigi will attack a wide range of Rubus species including species of North American origin that currently escape biological control in Australia. It may also be useful for preventing the spread of commercial varieties of Rubus (e.g. raspberry and loganberry) that have escaped to become weedy. However, the mite may have limited dispersal ability and thus require redistribution.