Increasing the Harmfulness of the Eriophyoid Mite <i>Aculus schlechtendali </i>(Nalepa), a Phytoparasite of Apple Tree in the Non-Black Earth Zone of Russia
Apple rusty mite Aculus schlechtendali (Nalepa) (Eriophyidae) is an invasive parasite in the Central region of the Non-Black Earth Zone of Russia. At the beginning of the XXI century, there were only small foci of the phytoparasite, but at present it is widespread almost everywhere, periodically giving a massive outbreak of reproduction. The number of mites reaches 1000 and more mobile individuals per 1 leaf (25.5 per 1 cm2). The body is microscopic (160-175 microns), so it is very difficult to be detected. Also, with a small number of A. schlechtendali , symptoms of plant infection do not appear outwardly, which allows the active spread of the mite with planting or other plant material. To count the number of the parasite in the spring, the tops of annual growths up to 10 cm long were sampled at 10 discount sites (in order to view opening buds), and during the vegetation, 10 leaves (4-5th leaves from the top of the sprout) were taken from each discount site. Selected samples of buds and leaves were examined under an MBS-10 binocular microscope. A. schlechtendali is especially dangerous in nurseries and young fruiting plantations of apple trees; it feeds not only on leaves (from the underside) and young sprouts, but damages flowers and buds of the apple tree. Effective control of the parasite requires constant monitoring and strict quality control of the planting material.