Eriophyoid mites on Centaurea solstitialis in the Mediterranean area

摘要

Yellow star thistle (YST), Centaurea solstitialis L. (Asteraceae), is a weedy annual plant, native to the Mediterranean area that infests rangelands, pastures and grasslands in the northern United States. In the search for biological control agents, an eriophyoid mite capable of significant impact on weed density and reproduction was studied. This research was focussed on: (a) geographical distribution of Aceria solstitialis de Lillo et al. (Acari: Eriophyidae) in the YST native area; (b) dynamic study of the eriophyoid population on YST in Apulia (Italy). In the first case, symptomatic plants were collected in Bulgaria, Greece, Italy and Turkey. In the second case, four sites were selected in Apulia, and periodical samplings were undertaken on 20 plants from February to August 2004 to 2006. Four different phenological categories of samples were collected separately from each plant: new rosette leaves, mature rosette leaves, stems and flower heads. This study ascertained the presence of A. solstitialis in the sampled localities of Mediterranean area, together with other mite species. In Apulia, ten species were detected on YST, and some of them could be related to neighbouring plants. A. solstitialis was detected only from May to August, and its density was highest at stem level, but it seems to be always low and insufficient to provide a significant reduction of weed seed production in the studied area.