RESUMEN
Two-spotted spider mite causes significant damage to various crops, often requiring synthetic acaricides for their control. However, the frequent use of these products causes several environmental problems. Thus, this work aimed to evaluate the acaricidal action, using the application by fumigation on female adults of Tetranychus urticae of essential oil from the leaves of Rosmarinus officinalis L., and its major compound, α-pinene. In addition, the essential oil was characterized by gas chromatography and mass spectrometry. α-pinene was the compound with the highest relative area in the oil (29.2%). In fumigation tests, α-pinene showed more significant toxicity than rosemary essential oil on two-spotted spider mite females with LC50 and LC90 values of 1.58 and 49.61 µL/L air, showing the impact of the chemical composition of the essential oil on the biological activity.