Biodiversity and population dynamics of mites associated with apple trees at Dakahlia and Giza governorates, Egypt

A two-year study (2024 and 2025) was conducted to assess the biodiversity and population dynamics of mites and insects on apple trees at Dakahlia and Giza governorates, Egypt. The survey recorded 20 species belonging to 10 families and five arthropod orders, with mites representing the dominant group (18 species). Eriophyid mites were the most abundant in both regions, particularly Aculus schlechtendalii (Nalepa) and Calepitrimerus baileyi Keifer, whereas Epitrimerus pyri (Nalepa) was highly prevalent at Giza governorate but only moderately present at Dakahlia governorates. Tenuipalpid mite, Cenopalpus pulcher (Canestrini & Fanzago) was abundant at Giza governorate but very rare at Dakahlia governorate, while tetranychid mites (Tetranychus urticae Koch and Panonychus ulmi (Koch)) were widely distributed, with P. ulmi more dominant at Dakahlia governorate. Predatory mites, especially Amblyseius swirskii Athias-Henriot, was abundant in both regions, whereas predatory insects varied between locations. Seasonal monitoring revealed clear and repeatable patterns. All phytophagous mites increased from late spring, peaked in summer (June-August), and declined in autumn. Population peaks consistently coincided with high temperatures (28–37°C) and high relative humidity (69–74%). Natural enemies showed delayed peaks, reflecting strong numerical responses to prey abundance. Statistical analyses demonstrated that plant age and maximum temperature were the primary determinants of mite population dynamics in both governorates, explaining up to 98% of observed variation. Relative humidity and minimum temperature had weaker or inconsistent effects. Predator-prey correlations were strong at Dakahlia governorate for both years, whereas Giza governorate exhibited variable responses, with insect predators showing particularly strong associations in 2025.