Biological activity of the Litsea cubeba essential oil and citral against the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae)

Abstract

Investigation of the biological activity of Litsea cubeba essential oil and its main component citral to assess the possibility of their use in biologized protection of greenhouse crops was the aim of this research. The study was carried out on a laboratory population of the two-spotted spider mite on bean plants. The toxic action under the contact-intestinal application and fumigation, and repellent action against the spider mite females and their o spring were evaluated. When using L. cubeba oil and citral at a concentration of 0.25%, a signi cant decrease in the reproduction index by 2.8 and 2.5 times, respectively, was recorded. The activity of the essential oil under fumigation at doses of 7.5 and 6.0 μl/l of air was close to 100%. After reducing the dosage to 4.5 μl/l, the mortality in the experiment exceeded 50%, and the suppression rate of reproduction was 84.5%. The negative e ect on fertility remained above 60% at 3.75 μl/l. The citral application at a dosage of 3.0 μl/l resulted in the mite mortality above 80% and a decrease in the number of eggs laid by female by more than 90%. Females ignored leaves treated with 0.25% solutions of the studied substances, and the decrease in the number of eggs was more than 90% (repellent e ect). The use of citral at 0.125 and 0.06 % concentrations prevented the colonization of leaves by mites also, and at a concentration of 0.045 %, it reduced the number of eggs laid by 3.1 times. Thus, L. cubeba oil and citral may be perspective as natural acaricidal agents with di erent modes of action.