Evaluating the Diversity of Oribatida Mites affected by Several Cropping Systems and Soil Types

Abstract Objectives: Investigating the relationship between diversity, total number of mites and number of adult and immature mites with the type of culture were the main objective of this experiment.   Materials and Methods: In order to determine the frequency and diversity of Oribatida mites, regular and random sampling of different soil horizons belonging to 21 habitats of Marand region of East Azerbaijan province was performed in the summer of 2014. Sampling was performed by digging soil profiles and sampling from different horizons. After extracting the mites from the soil samples, microscopic slides of them were prepared and identified. Then, the texture type of the studied soils was determined. Finally, after calculating the Shannon-Wiener diversity index, the relationship between diversity, total number of mites and number of adult and immature mites with the type of culture was investigated using MSTAT-C software.   Results: 59 species belonging to 44 genera and 28 families were collected and identified, most of which were adults. Among them Epilohmania cylindrica cylindrica and Discoppia (Cylindrappia) cylindrica species have the highest relative abundance. The dominant mite D. (Cylindroppia) cylindrica had the highest percentage in wheat fields. 9 species were collected only from pastures, 11 species only from wheat fields, 4 species only from sunflower fields and 4 species only from gardens. The highest diversity indices were obtained in mixed garden 3, sunflower fields and pastures and the lowest diversity indices were obtained in wheat fields. The diversity and number of adult and immature mites did not show significant differences in different cultures and horizons. The total number of mites did not show a significant difference in different cultures, but different horizons showed a significant difference in the total number of mites at a probability level of 5%. The second horizon had the highest number of mites and the third horizon showed a smaller number. The highest variability was observed in the second horizon and the lowest variability was observed in the third horizon. Among the cultures, sunflower had the highest number of mites. The interaction effect of cultivation and horizon was not significant in any of traits. The highest total number of mites was observed in the second horizon with clay loam texture in which the number of adult mites was more than immature mites. The greatest variability was observed in the first horizon with sandy clay loam texture.   Conclusion: Based on the index of species diversity and frequency of mites obtained, it can be concluded that the types of crops and localities studied are on the same level in terms of contamination or non-contamination with chemicals and heavy metals. The difference in the frequency and variety of oribatid mites in different horizons is due to the sensitivity of these mites to moisture. Moisture in the upper soil horizon at the time of sampling has led to the migration of these mites to the second horizon with higher moisture content.