Acaricidal, repellent, and oviposition-deterrent activities of 2,4-di-tert-butylphenol and ethyl oleate against the carmine spider mite Tetranychus cinnabarinus

Tetranychus cinnabarinus (Boisduval) is highly polyphagous and is considered one of the most important crop pests, infesting over 100 crop species grown in field and greenhouse crops worldwide. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, 2,4-di-tert-butylphenol (DTBP) and ethyl oleate (EO) were investigated for their acaricidal, repellent, and oviposition-deterrent properties against T. cinnabarinus under laboratory conditions. Both DTBP and EO exhibited significantly adulticidal, larvicidal, and ovicidal activities against T. cinnabarinus in a concentration-dependent manner after treatment, with LC50 values of 1,256.51, 625.39, and 743.64 ppm for DTBP and 1,621.57, 859.25, and 987.26 ppm for EO, respectively. The mites exhibited the highest run-off rate on bean leaf surfaces sprayed with both DTBP and EO when applied at sub-lethal doses and moved toward surfaces that had not been sprayed with these compounds, according to Pearson’s χ2 test. Furthermore, not only in a choice assay but also in a no-choice assay, a significant difference was found using an ANOVA between the numbers of eggs laid on bean leaves that were sprayed with DTBP and EO at sub-lethal doses compared to the number laid on unsprayed bean leaves. Additionally, stability assays revealed that EO was more sensitive to environmental factors than DTBP. These results demonstrate that the two compounds DTBP and EO have potential for development as new, natural acaricides for controlling carmine spider mites.