New state records of Aculops ailanthi (Lin, Jin, and Kuang) (Acariformes: Trombidiformes: Prostigmata: Eriophyidae), in USA; a pest or biological control agent of Ailanthus altissima (Mill.) Swingle?

We report the first detections of Aculops ailanthi Lin, Jin, and Kuang (1997) (Acariformes: Trombidiformes: Prostigmata: Eriophyidae) from Montgomery County, Virginia, and Wayne County, Michigan, USA; the fourth and fifth states to report this non-gall forming rust mite on Ailanthus altissima (Mill.) Swingle. We initially became aware of the pest in Virginia due to severe symptomology on greenhouse-cultivated Ai. altissima. In Michigan, similar observations from a field survey led to the mites' discovery. We tentatively identified the pest as an eriophyid mite of unknown species. Samples from both states were sent to USDA-ARS for identification and, using scanning electron microscopy, confirmed the species as A. ailanthi based on the morphological features. Moreover, we describe the impacts that high populations of A. ailanthi can have on Ai. altissima in greenhouse settings and potential use as a biological control agent. Field observations from Michigan are encouraging that A. ailanthi can affect Ai. altissima outside of greenhouse settings.