Effects of some insecticides on the biological parameters of Tetranychus urticae Koch (Acari: Tetranychidae)

Tetranychus urticae Koch. (Acari: Tetranychidae) is one of the most important major pests that damage both agricultural production areas and many other commercially grown plants across the world. Agricultural producers generally prefer pesticides to control pests. However, the pesticides are sometimes used without consideration for their effects on non-target organisms. In addition, in some cases, the dose adjustment for the pesticides prior to application is incorrectly applied. In this case, the associated overdose or low dose may lead to changes in the biological parameters of the target and the non-target organisms. In this study, we investigated the effect of imidacloprid, thiacloprid, deltamethrin and cypermethrin on reproduction parameters and lifespan of T. urticae using their field recommended dose (FRD) and half of the field recommended dose (FRD/2). Insecticides and pure water (control) were applied to the larvae of the T. urticae found on the leaves on the wet cotton of the Petri dish by spray towers. Compared to the control, the developmental times for the larvae on test unit treated with deltamethrin and cypermethrin at FRD and FRD/2 were considerably longer. The developmental period of larvae treated with thiacloprid at the FRD, however, was significantly shorter than the control (P < 0.05). The duration of adults preoviposition from thiacloprid administered at the FRD/2 was significantly increased compared to the control (P < 0.05). The lifespan (4.89 days) and the duration of oviposition period (5.05 days) of adults obtained from larvae treated with imidacloprid at FRD was significantly shorter compared to the control (P < 0.05). Thus, thiacloprid at the FRD/2 significantly increased the preoviposition time (1.10 days) compared to the control (0.50 days) (P < 0.05). Deltamethrin at the FRD and FRD/2 significantly increased the preoviposition duration compared to control (P < 0.05).

Automated summary

The Tetranychus urticae Koch is a significant pest that causes damage to agricultural production and commercially grown plants worldwide. The study reveals that the improper use of pesticides can result in changes in the biological parameters of both target and non-target organisms.