Toxicity and Repellency Effects of Three Plant Esse ntial Oils Against Two-spotted Spider Mite, Tetranychus urticae (Acari: Tetranychidae)

Abstract

To introduce ecologically safe acaricide, effects o f essential oils derived from Cuminum cyminum (Cumin), Syzygium aromaticum (Clove), and Mentha spicata (Spearmint) were determined on Tetranychus urticae at 25±1 ◦ C, 65±5% RH and a photoperiod of 16:8 (L:D) hour. The essential oils extracted by hydro-distill ation were characterized by means of GC and GC–MS. Bioassays were performed by filter pa per diffusion without allowing direct contact. Cumin, clove, and spearmint oils co ntained α - Pinene (29.1% ), eugenol (78.5% ) and carvone (59.4% ), respectively, as the major compounds. The lowest LC 50 value for adults was recorded for cumin oil (3.74 μ L L -1 air) followed by clove (6.13 μ L L -1 air) and spearmint (7.53 μ L L -1 air). The highest ovicidal activity was recorded f or cumin oil (LC 50 = 7.65 μ L L -1 air) followed by clove (LC 50 = 8.73 μ L L -1 air) and spearmint (LC 50 = 9.01 μ L L -1 air). According to repellency tests, by increasing concentration of oils, the repellency effects were increased. The most potent repellency effect was recorded for clove, followed by spearmint and cumin oils. The th ree extracted essential oils seem to be suitable sources of active vapors that can be used as alternatives for chemical pesticides for controlling this pest. Keywords: Clove, Cumin , Ovicidal activity, Spearmint.