Biological control and field evaluation of the predatory mite, Typhlodromus setubali Dosse (Acari: Phytoseiidae) in apple orchards

Abstract Background Typhlodromus setubaliDosse (Acari: Phytoseiidae) is an indigenous predatory mite in Morocco. This study aimed to evaluate its efficacy, through 3 release rates on 2 apple varieties, namely Skarlet and Golden delicious, with different initial densities of the European red spider mite,Panonychus ulmiKoch (Acari: Tetranychidae). Results The efficacy of the predator was significantly influenced by the initialP. ulmidensity. Furthermore, the release rate of 50 individuals/tree did not provide effective control ofP. ulmi.When it was released at 100 and 200 individuals per tree,T. setubalimaintained theP. ulmipopulation below the economic threshold of 5 motile stages per leaf. Conclusions When the initialP. ulmidensity is above the economic threshold, the lower release rate ofT. setubalimust be applied with high frequency or conciliated with a selective miticide treatment at a suitable dose for a successful biological control program. Further field-based studies are needed for perfect conclusions.