Characterization of Eriophyid Mites Inhabiting American Elderberry

Identification and control of pests is important as American elderberry (Sambucus canadensis L.) production increases in the United States. Two genera of eriophyid mites, Phyllocoptes wisconsinensis (Keifer) and Epitrimerus trilobus (Nalepa) have been described taxonomically and are known to cause foliar damage on elderberry plants. However, mites have not been examined in commercial plantings in Missouri. Thus, specimens were collected from American leaflets at two locations, Mt. Vernon and Hartsburg, MO, from April 2012 to Spring 2013. Mite-induced damage varied by location. P. wisconsinensis collected from Mt. Vernon induced curling of leaflet margins with erinea (i.e., enlarged leaf trichomes). In contrast, mites from Hartsburg reduced leaflet size and induced interveinal puckering of plant tissue. Examination of these mites using environmental scanning electron microscopy revealed a previously undescribed fusiform eriophyid mite species. Key features used to identify mites included prodorsal shield anatomy, leg morphology, and genital cover flap structure. Overwintering mites remained on plants under bud scales at Hartsburg and were quantified by bud position.  As many as 26 eriophyid mites per node were found in mid-January. The greatest average numbers of mites on buds were located at nodes 4 to 6 from the distal end of last season’s growth. Terminal buds and those at nodes 12 and 13 (i.e., near the soil surface) had the fewest mites.