The efficacy of some chemical and botanical pesticides against Tetranychus urticae (Acari: Tetranychidae) on Platanus orientalis (Platanaceae) in urban areas

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a destructive pest causing significant damage to trees and shrubs in urban green spaces. Using pesticides is considered the most prevalent approach towards controlling this pest. In this research, the effects of pesticides abamectin, fenproxymate, Tondexir®, Sirinol®, and Palizin® on the mortality of T. urticae were investigated in the laboratory and urban green spaces. Laboratory bioassays were conducted with five concentrations of each pesticide between 0.72–3.60, 0.50–3.00, 1275–6800, 595–5950, and 325–3900 mg ai/L for abamectin, fenproxymate, Tondexir®, Sirinol®, and Palizin®, respectively in five replicates. Field experiments were conducted based on a complete randomized block design (CRBD) in the urban green space of Mashhad city on the oriental plane trees (Platanus orientalis L.) infested with T. urticae. Treatments included triplicate sprayings with commercial formulations of abamectin (250 mg/L) and fenproxymate (500 mg/L) as well as Tondexir® (2000 mg/L), Sirinol® (2000 mg/L), and Palizin® (2000 mg/L), and water (control). Abamectin and fenproxymate showed the highest toxicity for T. urticae adult females with LC50s of 1.61 and 1.16 mg ai/L, respectively. Tondexir® showed a lower toxicity for T. urticae (LC50 = 2500.53 mg ai/L) compared to Sirinol® (LC50 = 1308.58 mg ai/L) and Palizin® (LC50 = 1494.73 mg ai/L). Abamectin and fenproxymate showed the highest population reduction in T. urticae adults on plane trees after 28 days (98.68 ± 0.64 and 99.70 ± 0.56%, respectively). For egg populations also, abamectin and fenproxymate showed a better reduction compared to other insecticides. Palizin® showed the least efficiency (32.60 ± 2.40%) in controlling T. urticae adults. T. urticae eggs were reduced better with Tondexir® (35.85 ± 2.24%) compared to Sirinol® (22.54 ± 0.69%) and Palizin® (20.85 ± 1.5%). Although abamectin and fenproxymate showed better control of T. urticae adults and eggs, spraying with more efficient botanical insecticides such as Tondexir® Sirinol® are suggested in urban areas due to health concerns for the residents.