The interactions between the host and associated microorganisms could affect the host. One of the emerging studies in this field is the effects of symbiotic bacteria on insect vectors and the transmission of plant viruses. For this purpose,Toya propinquawas collected from weed around the fields, mostly bermudagrass in Isfahan, Mobarakeh, Zarrinshahr and Golpayegan. After a preliminary study of morphological characteristics, the collected planthoppers were released into the aluminum boxes containing bermudagrass for propagation. Morphological characteristics of the body, the male genitalia, and the cytochrome oxidase gene sequence confirmed the collected planthoppers aToya propinqua. To identify culturable bacterial symbionts ofToya propinqua, the body suspension of planthoppers was cultured on NA medium. The colonies were subcultured, and DNA was extracted from purified colonies. PCR was performed using 27F/1492R primer pair. Sequencing of amplified bands and BLAST search led to identifying two bacteria,aenibacillu. andAcinetobacter. In order to identify non-culturable prokaryotic symbionts, extracted DNA of planthoppers was subjected to PCR using specific primers ofWolbachia. (81F/691R),Cardinium. (CLOF/CLOR1),Rickettsia. (RBF/RBR), andiroplasma. (Spi-f1/Spi-r3). Sequencing the amplified segments and BLAST search revealed the association ofWolbachia.,Cardinium.,Rickettsia.,Cardiobacter. andiroplasma. withT. propinqua. According to our information, exceptingWolbachia, other symbionts are reported fromT. propinquafor the first time. Sequencing the amplicon and BLAST search showed the presence of YLS iT. propinqua.For determining the frequency ofWolbachia,Cardinium, andRickettsiaymbionts iT. propinquaopulations, planthoppers were collected from Isfahan, Golpayegan, Zarrinshahr, and Mobarakeh and were tested by PCR. In total,Wolbachia.,Cardinium. andRickettsia. were found in 75% of the planthoppers. About 94.4% of males and 59.1% of females showed to have symbionts. The frequency ofWolbachia.was 72.5%,Cardinium.45%, andRickettsia.42.5%. Single infection ofWolbachia.was calculated in 15%,Wolbachia.+Cardinium.in 17%, andWolbachia.+Rickettsia.in 15%, and three symbionts were in 25% of the planthoppers. In general, the presence ofWolbachia.was estimated at 82.3%, andRickettsia. at 73.4%, double infection ofWolbachia. +Rickettsia. was estimated at 70%, and 8.9% of the planthoppers lackedWolbachia. andRickettsia. The transmission efficiency of cynodon chlorotic streak virus (CCSV) byT. propinquafrom bermudagrass to oat plants was calculated 54.21%. To determine the effect ofWolbachia. andRickettsia. on the transmission efficiency of CCSV byT. propinqua, the planthoppers were examined in the transmission test. The planthoppers were first placed on infected bermudagrasses for three days and then maintained on healthy bermudagrasses for one month. By the end of the incubation period, the planthoppers were placed individually on the oat plants in the coleoptile stage. The planthoppers were transferred into the -80 °C freezer after three days. Total RNA was extracted from plant leaves one month after transmission feeding and analyzed by RT-PCR with CCSVIrF/CCSVIrR primer pair. Total DNA was extracted from the planthoppers, and theymbionts were detected using specific primers. Data analysis using the t-test showed the effect ofWolbachia. andRickettsia. in decreasing and increasing CCSV transmission efficiency byT. propinqua, respectively. The focus of future researches on the four plant-virus-vector-symbiont interactions will increase our insight into this field. Key Words Toya propinqua , Symbionts, Paenibacillus , Acinetobacter , Wolbachia , Cardinium , Rickettsia , Spiroplasma , YLS, CCSV, Transmission Efficiency