بررسی رابطه تنوع و فراوانی باکتری های همزیست داخلی کنه تار عنکبوتی با فاکتورهای محیطی

Mites of the family Tetranychidae are the most significant herbivorous pest mites affecting agricultural products worldwide, causing damage to crops, trees, and ornamental plants. Among the various species of spider mites, Tetranychus urticae Koch, 1836 has the widest distribution and prevalence globally. Internal symbiotic bacteria play a crucial role in the interactions between herbivores and plants. The diversity, abundance, and distribution of these bacteria, especially the relationship between their distribution and diversity with environmental factors, have not been thoroughly studied. In this study, the relationship between the diversity and abundance of internal symbiotic bacteria in spider mites and environmental factors was examined. Spider mite samples were collected from various agricultural, orchard, and ornamental plant hosts in three provinces: North Khorasan, Razavi Khorasan, and South Khorasan. The results showed that in the populations of spider mites studied on various plant hosts in the three sampled provinces, three types of endosymbiont bacteria—Wolbachia, Rickettsia, and Cardinium—were observed on all or some of the hosts with varying frequencies. In this study, the most common internal symbiont was Wolbachia, with an infection rate ranging from 62.5% to 100% in all T. urticae populations examined. Rickettsia was only observed in populations collected from cucumber, eggplant, and rose in Khorasan Razavi and South Khorasan. The lowest infection rate of Rickettsia was found in cucumber at 12.5% (Khorasan Razavi), while the highest infection rate was in rose at 100% (South Khorasan). The infection rate of Cardinium varied from 12.5% in eggplant to 87.5% in apple. Coinfection of Wolbachia-Cardinium was observed in all three provinces (North, South, and Razavi Khorasan), and Wolbachia-Rickettsia coinfection was observed in Khorasan Razavi and South Khorasan. This study indicates that the prevalence of internal symbiotic bacterial infections may be influenced by environmental factors. In evaluating the impact of environmental factors on the prevalence of internal symbionts, the effect of different hosts showed no significant difference in the infection rates of symbiotic bacteria. The effect of location on the infection of the two-spotted spider mite with Wolbachia was significant, with samples from Khorasan Razavi province having higher infection rates than those from North and South Khorasan provinces. However, there was no significant effect on other bacteria. In this study, latitude and longitude had significant effects on the host's infection intensity with Wolbachia and Rickettsia. Additionally, the relationship between the infection rate of the spider mite with endosymbionts and longitude was negative, while it was positive with latitude. The elevation of the sampling site did not have a significant impact on the host's infection rate with symbiotic bacteria. Definitive conclusions regarding the findings of this study require further investigation.