Bioactivity of essential oils for the management of tetranychus urticae Koch and selectivity on its natural enemy neoseiulus californicus (McGregor): A promising combination for agroecological systems

Abstract

The two-spotted spider mite, Tetranychus urticae, causes damage to crops grown in northeast Brazil. The adoption of biological control methods and curative methods (plant-based insecticides) is an essential practice for pest management in agroecological systems. Therefore, the aim of the present study was to investigate the chemical properties, toxicity, and ovicidal activity of essential oils (EOs) from Lippia sidoides, Croton rhamnifolioides, Croton grewioides, Citrus sinensis, Citrus limon, Citrus aurantiifolia and Piper divaricatum for the control of T. urticae and determine the selectivity of these EOs regarding the predator mite Neoseiulus californicus. The chemical analysis (gas chromatography–mass spectrometry) of the EOs enabled the identification of 98 compounds. The major constituents were carvacrol (L. sidoides), ß-caryophyllene (C. rhamnifolioides), (E)-anethole (C. grewioides), limonene (Citrus spp.), safrole and methyl eugenol (P. divaricatum). All oils exhibited satisfactory toxicity to the eggs and females of T. urticae and were even more toxic than the commercial product Azamax. The L. sidoides oil exhibited greater toxicity compared to the other oils, with LC50 values of 0.05 and 0.09 µL mL-1 for females and eggs, respectively. All oils tested were selective to N. californicus, with RS values ranging from 3.61 to 23.28 for C. aurantiifolia and C. grewioides, respectively. Therefore, the use of products based on the EOs studied in combination with the natural enemy N. californicus is a viable option in agroecological systems for the management of T. urticae.