The use of essential oils as an alternative for the control of Tetranychus urticae (Acari: Tetranychidae)

Abstract

Considering that the use of essential oils is a promising technique and a valuable alternative in the control of unwanted organisms, this study aimed to chemically characterize the essential oil of Acanthospermum australe (Loefl.) O. Kunze (Asteraceae) through gas chromatography, as well as to evaluate the repellent and acaricidal effect of the essential oils from A. australe and Baccharis psiadioides (Less.) Joch.Müll (Asteraceae) against Tetranychus urticae Koch (Tetranychidae). For the repellency test, concentrations of 0.25, 0.5 and 1% were used for both oils, and concentrations of 10 μL/L(air) and 20 μL/L(air) to evaluate acaricidal effects. Eight compounds were identified in the essential oil of A. australe, with thymyl isobutyrate (63.4%) being the major compound, followed by thymol (13.4%) and thymyl 2-methylbutyrate (4.96%). The results demonstrated higher repellency to the essential oil of A. australe at a concentration of 0.5%, followed by B. psiadioides at a concentration of 1%. The mortality rate of TSSM exceeds 90% when exposed to both tested concentrations of the essential oil of A. australe proving effective in both cases.