Effects of strip intercropping of eggplant with soybean on densities of two-spotted spider mite Tetranychus urticae, species diversity of its natural enemies, and crop yield

In this research, the influence of eggplant monoculture (E), soybean monoculture (S), and three intercropping systems including two rows of eggplant with four rows of soybean (2E: 4S), two rows of eggplant with two rows of soybean (2E: 2S) and four rows of eggplant with two rows of soybean (4E: 2S) were studied on population densities of Tetranychus urticae Koch, diversity and abundance of its predators, and yield of both crops in an experimental field based on a randomized block design with four blocks during two cropping seasons (2016 - 2017). In both years, the densities of T. urticae eggs and mobile forms on eggplant and soybean were significantly lower in the three intercrops compared to monoculture systems (P < 0.05). Moreover, the densities of T. urticae eggs and mobile forms were significantly higher on the soybean than the eggplant in each monoculture and intercrop system. The Shannon’s diversity indexes (H') for T. urticae predators on eggplants were significantly higher in the three intercrops compared to the monoculture. Furthermore, the values of this index were greater in soybean monoculture and 2E: 4Sintercrop than 2E: 2Sand 4E: 2S systems (P < 0.05). Values of the land equivalent ratio (LER) were higher in 2E: 4S relative to other intercrop systems in both years. Therefore, it could be concluded that 2E: 4S intercrop is the most suitable cropping system for using in integrated management of T. urticae in eggplant and soybean fields.