In this study, using PCR-RFLP molecular identification methods, the species composition was determined in populations of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) which were collected from greenhouses located in the Akdeniz, Aydincik, Bozyazi, Erdemli, Gulnar, Silifke, and Tarsus districts of Mersin Province. For this purpose, adult whiteflies were collected from the greenhouses during the spring and autumn growing seasons of 2016 and 2017. In order to determine the species status in the off-season, samples were also collected from field crops around greenhouses during summer 2016. In all, 219, 195, and 129 females were analyzed from samples collected in spring, autumn, and off-seasons, respectively. According to the results of analysis, the species status of B. tabaci did not vary depending on location and season. Overall, MEAM1 and MED (with subgroups Q1 and Q2) species were found. The abundance rates of MEAM1 species were found to be very high in all locations, with values of 97.7% and 99.5% during spring and autumn, respectively. Similar to the greenhouse-collected populations, the MEAM1 species whiteflies collected from open field crops during the off-season were found to have a higher abundance rate (99.2%). The highest abundance rate for MED species (12.8%) was determined in Erdemli district during spring. The results of this study indicate that B. tabaci belonging to the MEAM1 is the most dominant species in greenhouses and open fields (off-season) of Mersin, Turkey, in both spring and autumn, and these results are also discussed aiming at contributing to B. tabaci management in greenhouses.