Mechanical distribution of Phytoseiulus persimilis on chrysanthemum

A prototype of a device for centrifugal distribution of arthropods was constructed in order to carry out the distribution of natural enemies both in open field and in greenhouses, installing three or more prototypes on a horizontal bar carried by a tractor or a wheel frame.Preliminary tests were conducted under laboratory conditions to evaluate the vitality and the damages possibly caused to the predators. No physical damage to the arthropods limiting their mobility and vitality was observed. The field test was carried out in a cultivation of chrysanthemum, using the predatory mite Phytoseiulus persimilis Athias-Henriot to control the two-spotted spider mite Tetranychus urticae Koch and the predatory bug Orius laevigatus (Fieber) to control the western flower thrips Frankliniella occidentalis (Pergande). The trial was conducted in September 2010 on 2 plots divided into 3 subplots each. On one plot natural enemies were mechanically distributed using three prototypes installed on a wheel frame and on the other one the distribution was performed manually. A central subplot was left untreated. The results show that after 7 days in most of the mechanised subplots P. persimilis was regularly recovered, therefore reducing the percentage of leaves infested with the two-spotted spider mite and its density after 14 days. In the plot treated by mechanical release the pest was controlled sooner than in the one treated by manual release, where T. urticae persisted in a considerable number of subplots two weeks after the first release.