The acaricidal activity of some essential and fixed oils against the two-spotted spider mite in relation to different temperatures

摘要

The acaricidal activity of some essential and fixed oils against the two-spotted spider mite, Tetranychus urticae Koch were evaluated at 15 degrees C, 27 degrees C and 35 degrees C under laboratory conditions. The essential oils namely, rosemary (0.125%), garlic (0.5%), jojoba (0.25%) and the fixed vegetable oil (soyabean and sunflower oil (0.125%)) were tested in this study. The acaricidal activity was evaluated by studying the mortality, fecundity and fertility rates of the adult females at three different temperatures. Results showed that highest mortality rates among T. urticae were recorded for garlic oil followed by vegetable, jojoba and rosemary oils at 15 degrees C and for garlic, jojoba, rosemary and vegetable oils at 35 degrees C. Interestingly, no mortality rates were recorded for all the tested oils at 27 degrees C. At 15 degrees C, garlic oil caused a significant effect on both the fecundity and fertility rates as compared to the other oils. On the other hand, at 27 degrees C and 35 degrees C, most of the tested oils caused significant effects on the fecundity and fertility rates. In conclusion, the temperature is apparently a key factor regulating the acaricidal activity of the tested oils and attention must be given to this factor during field applications.