Toxic, Repellent, and Oviposition-Inhibiting Effects of Almina Diatomaceous Earth on Tetranychus urticae Koch, 1836 (Acari: Tetranychidae)

Abstract

Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) is one of the most important pests of agricultural fields worldwide. This study was carried out using the leaf disc method to determine whether local diatomaceous earth (Almina) has a toxic, repellent, and oviposition-inhibiting effect on T. urticae. Adult females of T. urticae were placed on leaf discs immersed in 10%, 5%, 2.5%, and 1.25% concentrations (w/v) of diatomaceous earth. Considering the mortality rates after 24, 48, 72, and 96 hours, respectively, the highest mortality rate was determined as 33.56% at 10% concentration. At the same concentrations, the highest repellent effects were found to be 64.54%, 42.10%, 20.35%, and 19.46% after 1 hour, respectively. Although the number of eggs laid by females increased over time at all concentrations, it was statistically less than the control at 10% and 5% concentrations. In light of the data obtained from this study, further studies are planned to increase the effectiveness of Almina diatomaceous earth by mixing it with botanical extracts or entomopathogens in the control of T. urticae.