Effectiveness of predatory mites (Phytoseiidae) in controlling two-spotted spider mite (Tetranychus urticae Koch.) on black currants determined in field experiments

The effectiveness of four phytoseiid species (Neoseiulus fallacis, Typhlodromus pyri, Phytoseiulus persimilis, Metaseiulus occidentalis) in controlling two-spotted spider mite (Terranychus urticae) on black currants was examined in two field experiments in Central Poland. The highest effectiveness was observed when the largest number (200 specimens per 2-year-old bush) of predators were released. When N. fallacis was introduced in lower quantities (10, 20, 50 or 100 individuals per bush), the effectiveness of predator was lower and no correlation was observed between the number of introduced predators and their efficacy. Of the four species examined on 5-year-old plantation (Ojebyn and Rodknop cvs) moderately infested with the pest (3-5 two-spotted spider mites per leaf), only T. pyri suppressed significantly population of T. urticae, especially on Ojebyn cv.