Effect of six ethanolic plant derived products on the pre-imago two-spotted spider mite

Abstract:

Background: Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most destructive cosmopolitan pests of many plant families. This pest has shown resistance to many synthetic acaricides applied in the field and glasshouse. Consequently, increased global efforts have been undertaken to develop other methods of pest control such as botanical insecticides. Methods: The effects of ethanol (95%) and ethanolic extract of six plant species (Aloe vera, Calendula officinalis, Melia azedarach, Peganum harmala, Syzygium aromaticum and Juglans regia) on T. urticae were investigated under laboratory condition. Leaf disks of bean (3.3 cm diameter) were sprayed by ethanol, as negative control, control without spray and plant extracts with 5 mg.mL–1 concentration as treatments. Then new hatched larva were placed on the leaves and surveyed daily. Developmental times and mortalities of each treatment were evaluated until adult emergence. Results: The susceptibility of each developmental stage fluctuated for each plant extract. Among the applied plant derived chemicals, the greatest total mortality was recorded in M. azedarach (87.5%) and P. harmala (81.25%) treatments. Moreover, larval developmental time of the spider mite significantly increased in the both above-mention extracts.

KEY WORDS: Tetranychus urticae, plant extracts, mortality, acaricidal activity, developmental times.