Biological control of Oligonychus afrasiaticus (Acari: Tetranychidae) by thepredaceous mite, Phytoseiulus persimilis Athias-Henriot (Acaria: Phytoseiidae) in datepalm farms at El- Dakhla region, New Valley Governorate, Egypt

Date palm plantations are seriously threatened by infestations of the date dust mite (DDM), Oligonychus afrasiaticus (McGregor), a major pest of unripe date fruits which results decrease in crop output and financial losses.Therefore, the aim of this research is to evaluate the biological control of DDM by releasing three rates (1000, 2000 and 3000 individuals) of the predatory mite, Phytoseiulus persimilis on date fruits in two date palm cultivars (Siwi and Sakkoti) planted in El-Dakhla Oasis, New Valley Governorate, Egypt during 2023 and 2024 years.The effect of DDM infestation on some physical and chemical characteristics of infested dates was also studied compared to uninfested dates, and a comparison was made between these characteristics in the two tested cultivars.The obtained results showed that the reduction percentages in O. afrasiaticus population were increased with the increase in the predator release rate in both tested cultivars along the two years.Besides, the reduction % in dust mite population was significantly higher in Siwi cultivar than in Sakkoti cultivar.The results also clearly that the highest mean of reduction % in O. afrasiaticus population on date fruits across the two years and tested date cultivars were found in the Siwi cultivar, at the fourth month, with release rate of 3000 individuals of P. persimilis, as well as the mean reduction % of the second year 2024.Results showed that DDM infestation led to a significant decrease in the tested physical and chemical characteristics, which led to a significant decrease in the quantity and quality of the date crop.Therefore, it can be recommended, based on these results, to increase the number of predatory mites or add one of the other biological control elements, such as essential oils or other predators, when controlling dust mites in severely infested varieties, to obtain date fruits free of dust mites and pesticide residues, and acceptable for marketing and export.