Injuries caused by phytophagous mites on apple trees (Malus domestica: Rosaceae)

This study aimed to assess the injuries caused by phytophagous mites at different population levels on apple tree leaves (Malus domestica: Rosaceae). The response to different infestation levels of Panonychus ulmi (Koch), Tetranychus urticae Koch and Tetranychus ludeni Zacher (Tetranychidae) on apple tree leaves was assessed through A, B, and total chlorophyll indices and membrane stability loss. Leaves infested with T. urticae showed higher chlorophyll loss, while leaves infested by P. ulmi and T. ludeni had decreased chlorophyll averages in densities of 25 mites/leaf and above. The evaluation of membrane stability loss identified T. ludeni as a potential cause of injuries in apple trees. The evaluations indicated that the higher number of mites on the leaf surface, the larger the membrane stability loss. This work warning to the apple production chain for monitoring infestations and preventing a potential threat to culture.