Control of Tetranychus urticae by three predatory mites (Acari: Phytoseiidae) in a commercial greenhouse rose

The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest of many greenhouse crops such as bean, cucumber, rose and other products. The control of this important pest has been mainly based on the use of acaricides. Phytoseiid mites are used mostly for biological control of pest mites. In this study, control of TSSM by phytoseiid predatory mites, Phytoseiulus persimilis Athias-Henriot, Amblyseius swirskii Athias-Henriot and Neoseiulus californicus McGregor was evaluated on four rose varieties including Avalanche, Dolcevita, Samurai and Sorbet in a commercial rose greenhouse. The total number of motile stages and eggs of each studied species on a leaf were counted weekly, through a zigzag sampling pattern and using a hand lens. The sampling was carried out randomly and the leaves of a rose plant were taken from the canopy base (shoots bent over beds), the middle (area between base and top) and the top of the canopy (flowering shoots), which added up to a total of 30 leaves. The highest population density of TSSM per leaf was recorded on Samurai (17.96 ± 0.85) and the lowest population density was observed on Dolcevita (5.32 ± 0.39). Based on population fluctuation data of TSSM and its predators on four rose varieties, it was found that the predatory mite P. persimilis had the ability to reduce the high TSSM density and N. californicus also continued to operate in low TSSM density, but A. swirskii did not have a clear impact on TSSM density reduction.