Efficacy of microcapsule essential oil of peppermint (Mentha piperita L.) on biological parameters of two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

Background and Objectives Tetranychus urticae, as the two-spotted spider mite, is considered as one of the most important and destructive herbivorous mites in farms and greenhouses, which is very important to control due to its wide host range. The damage caused by agricultural pests combined with the harmful effects of synthetic chemicals used in their control can be mitigated or eliminated by using botanicals, which are derived from renewable resources including a mixture of various bioactive ingredients. Therefore, finding a suitable alternative way for controlling this pest is necessary by considering the resistance to acaricides, as well as undesirable effects of chemical compounds. The present work aims to evaluate microcapsule essential oil of Mentha piperita and its lethal and sublethal toxicity to T. urticae. Materials and Methods Laboratory bioassays were used for evaluating the sublethal effects of peppermint essential oil microcapsules on biological and population parameters of T. urticae. The life table parameters of T. urticae were conducted on leaf discs under laboratory conditions at 25 ± 2°C, 60 ± 5% relative humidity, and a photoperiod of 16:8 (L: D) hours. Then, the duration of each stage, developmental time, and survival were observed and recorded daily. In addition, the raw data were analyzed based on age stage two-sex life table theory with MS-Chart. Results Based on the results, microcapsules of Menthe piperita caused a significant reduction in fecundity and longevity. Those treated with LC20 and LC30 had a significant reduction at net reproductive rate, compared to those treated with LC10 and untreated ones. The intrinsic and finite rate of increase reduced significantly in higher concentration compared to the control. In addition, the mean generation time decreased significantly at the upper dose, compared with LC10. Discussion Botanic acaricides can be used for controlling Tetranychus urticae, and the microencapsulated formulation of these products makes them more stable. Familiarity with the chemical nature of the bio-active pesticide/acaricidal compound can be considered in future research which can play a role in developing an effective and environmentally friendly treatment against spider mites, leading to a decrease in reliance on synthetic pesticides/acaricides. The results of this study can be used in designing the mentioned pest management programs by considering the detrimental effects of M. piperita essential oil microcapsule on some biological parameters of T. urticae.