Effects of essential oils on mortality and population density of the whitefly ( Bemisia tabaci Genn.) and the two-spotted spider mite ( Tetranychus urticae Koch) in the greenhouse

Essential oils (EOs) and their components have toxic effects on insects and mites. In the present study, we evaluated the effects of the EOs of mexican oregano, grapefruit, albahaca and sour orange at 0.2% (v/v) on the mortality and population density of Bemisia tabaci and Tetranychus urticae in a greenhouse. All EOs caused significant mortality (70–90%) of eggs and nymphs of B. tabaci, with the highest by the mexican oregano EO. This EO also produced the highest mortality (50–55%) of adults and nymphs of T. urticae. All EOs caused a significant decrease in the population density of T. urticae, but no effect was observed on the population of B. tabaci. Gas chromatography-mass spectrometry analysis showed that the major constituent in mexican oregano EO was carvacrol, in grapefruit and sour orange EOs was d-limonene, and in albahaca EO was eucalyptol.