Evaluation of the Varietal Impact of Two Citrus Species on Fluctuations of Tetranychus urticae (Acari: Tetranychidae) and Beneficial Phytoseiid Mites

The activity of Tetranychus urticae Koch, 1836, and its predators (Euseius stipulatus Athias-Henriot, 1960, Typhlodromus sp., and Phytoseiulus persimilis Athias-Henriot, 1957) on two citrus varieties (Nules (Mandarin) and Valencia late (Orange)) was studied in citrus orchards in Machraa Belksiri at the Gharb region of Morocco in the years 2020-2021. In this trial, during the first year of monitoring, we detected that on the Valencia late variety (Citrus sinensis), the occupancy of leaves by T. urticae was important, with 3200 mobile forms (50%). The predator Typhlodromus sp. presented 1385 (22%), followed by E. stipilatus with 1186 mobile forms (18%), while P. persimilis presented the lowest number with 621 forms (10%). Conversely, on the Nules variety (Citrus Clementina), we found (52%) 2475 forms for the pest T. urticae. E. stipulatis was the most abandoning predator, with 1344 (28%), followed by Typhlodromus sp., with 944 (22%); however, the predator P. persimilis was absent. From our results, it can be concluded that synergistic control by these predators can reduce the rate of T. urticae and constitutes a sustainable alternative method in the absence of chemical control. Regarding the effect of the variety of the different mites studied, the varieties Nules and Valencia late showed no impact on the rates of E. 1tipulates and T. urticae, with relatively similar averages, while on the predator Typhlodromus sp. and P. persimilis, the varietal impact was important.