Acaricidal and repellent effects of <em>Aloe vera</em> L. leaf extracts against <em>Tetranychus urticae</em> Koch (Acari: (Tetranychidae)

Abstract

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a cosmopolitan pest that causes considerable damage to vegetables, fruit and flower plants. The acaricidal, ovicidal and repellent activity of four different extracts of Aloe vera L. (Asphodelaceae) leaves were evaluated against T. urticae under laboratory conditions. Four different solvents of A. vera leaf extracts were tested against T. urticae at concentrations of 0.25, 0.50, 1.0 and 2.0%. The results indicated that all extracts had lethal and repellent effects on T. urticae. The acetone extract showed the highest mortality (95.0%) of adult females followed by ethanol (83.0%) at 2.0% concentration. The LC50 values of acetone, ethanol, methanol and petroleum ether extract for adult females were 0.446, 0.667, 0.953 and 1.279, respectively and for eggs were 0.950, 1.406, 2.115 and 3.312, respectively. The ethanol extract was found to be more effective as a repellent against adult females of T. urticae followed by acetone, methanol and petroleum ether causing a reduction in egg production per female by 96.0, 94.0, 85.0 and 83.0%, respectively. In the residual test, the acetone extract showed the highest mortality (49%) after 1 hour of treatment followed by ethanol (43.0%), methanol (29.0%) and petroleum ether (25.0%). The percent of mortality decreased after 48 and 72 hours after treatments. The results show that A. vera has a high potential to become a botanical acaricide for controlling T. urticae.