Evaluation of the Susceptibility of Clearwing Moth, Synanthedon caucasica, to Bark Spray and Trunk Injection of Insecticides on Plane Trees in Isfahan.

The clearwing moth, Synanthedon caucasica (Gorbunov), is known as an important wood-boring pest of plane trees in Isfahan landscape. It has been reported that more than 50% of the plane trees in the various urban areas of Isfahan have been infested by this species. This research was conducted to evaluate the efficacy of some insecticides on S. caucasica by two application methods namely bark spray and trunk injection of infested plane trees, in two urban areas of Isfahan, in a completely randomized design. Tested insecticides in bark spray were imidacloprid (Confidor® EC 35%), chlorpyrifos (Dorsban® EC 40%) and deltamethrin (Decis ® EC 25%), and in trunk injection the treatments were imidacloprid (Confidor® EC 35%), oxydemeton methyl (Metasystox® EC 25%) and azadirachtin (EC 1%). For both application methods, evaluation was based on the number of active larval holes and pupal exuviae (in summer) or number of live larvae under bark (in October). The results show that bark spray by chlorpyrifos, imidacloprid and deltamethrin significantly reduced S. caucasica larval populations by 92%, 81%, 81% and 81%, respectively. The highest reduction in the larval population by trunk injection of insecticides compared to the water control in October was obtained in azadirachtin treatment (95%), followed by oxydemeton methyl (89%) and imidacloprid (81%). The results of this study show that the effect of insecticide application on the larval population of S. caucasica increased with increasing duration of treatment. Based on the results, application of either bark spray or trunk injection in appropriate period could have suitable effects in the integrated management of S. caucasica.