How could the bioactivity of emulsifiable concentrate and nano-emulsion formulations of Rheum palmatum and Juniperus virginiana essential oils affect Tetranychus urticae (Acari: Tetranychidae) and its bio-agent, Phytoseiulus persimilis (Acari: Phytoseiidae)

AbstractTwo types of formulations, emulsifiable concentrates (ECs) and nano-emulsions (NEs), were conducted to enhance the activity of the Rheum palmatum L. and Juniperus virginiana L. essential oils (EOs). The efficacy of EOs, ECs, and NEs was evaluated under laboratory and semi-field conditions against Tetranychus urticae Koch eggs and females. In addition, assessing their selectivity towards the predatory mite, Phytoseiulus persimilis Athias-Henriot. The tested ECs and NEs showed toxicity against T. urticae females higher than bulk oils, and all caused 100% un-hatchability of T. urticae eggs. With the exception of EOs and R. palmatum EC, neither the prepared ECs nor NEs showed any phytotoxicity symptoms on treated plants. The residual effects of tested materials were dissipated over time. Juniperus virginiana EO, EC and NE were compatible with P. persimilis. Tested ECs and NEs can aid in more sustainable crop management, to develop low-risk solutions to replace the use of pesticides.Keywords: Essential oilsformulationphytoseiid mitesselectivityTetranychus urticaetoxicity AcknowledgmentsWe are sincerely thanking Mr. Khaled A. Dawoud, technician, Pests and Plant Protection Department (NRC), for his valuable assistance in lab preparations.Disclosure statementThe authors declare there is no conflict of interest.Additional informationFundingThis work was funded by the National Research Centre (NRC) project No. 13050117.