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

Abstract

Background: Typhlodromus setubali Dosse (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 ulmi Koch (Acari: Tetranychidae). Results: The efficacy of the predator was significantly influenced by the initial P. ulmi density. Furthermore, the release rate of 50 individuals/tree did not provide effective control of P. ulmi. When it was released at 100 and 200 individuals per tree, T. setubali maintained the P. ulmi population below the economic threshold of 5 motile stages per leaf. Conclusions: When the initial P. ulmi density is above the economic threshold, the lower release rate of T. setubali must 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.