Effects of Ocimum basilicum and Ruta chalepensis hydrosols on Aphis gossypii and Tetranychus urticae

Hydrosols are by‐products derived during the extraction of essential oils and are produced in a high amount and at very low cost. Their effects on crop pests have been little studied, although recent studies have shown their insecticidal properties. In this work, the effects of hydrosols derived from Ocimum basilicum (sweet basil) and Ruta chalepensis (rue) were investigated on the serious crop pests Aphis gossypii and Tetranychus urticae. The main compounds of basil hydrosol were linalool (66.5%), eugenol (18.9%) and eucalyptol (7.1%), while rue's were 2‐nonanone and 2‐undecanone at 77.0% and 8.9%, respectively. The mortality and fecundity of A. gossypii and T. urticae were recorded for 7 days after application of hydrosols. Apterous adult aphids and female mites were sprayed on cucumber leaves in special structures. Both hydrosols caused significant mortality rates, which fluctuated between 46.0% and 64.0%. The negative control (deionized water) caused no mortality, while for the positive controls (synthetic pesticides) was 100%. The fecundity of A. gossypii and T. urticae was significantly reduced after the application of the hydrosols (17.1 nymphs of A. gossypii and 22.8 eggs for T. urticae had been produced per female after treated with the hydrosol of R. chalepensis and O. basilicum, in comparison with 41.6 and 49.5 in the negative controls, respectively). In conclusion, the hydrosols from both plants presented an important effect on the mortality and fecundity of both pests.