Phosphine Resistance in Turkish Populations of Sitophilus oryzae (L., 1763) (Coleoptera: Curculionidae)
In this study, the status of phosphine resistance in Sitophilus oryzae (L.,1763) (Coleoptera: Curculionidae) populations collected from Şanlıurfa, Adana and Kahramanmaraş province in Turkey were investigated by conducting the discriminating concentration tests and the concentration–mortality bioassays. Low (0.04 mg/L) and high (0.20 mg/L) discriminating concentration tests indicated that there was phosphine resistance of S. oryzae. The survival rates of field population of S. oryzae in Şanlıurfa, Adana and Kahramanmaraş ranged from 0 to 99%, 0 to 90% and 0 to 89% at the low discriminating concentration while it ranged from 0 to 83%, 0 to 46.5% and 0 to 28.5% at the high discriminating concentration respectively. Based on 50% mortality level (LC50), the Şanlıurfa 4, Adana 7 and Kahramanmaraş 8 populations were 57.5, 28.9, and 16.3 times more resistant, respectively, than the susceptible population (Kahramanmaraş 4). In conclusion, this study revealed that phosphine resistance in S. oryzae is high in the examined areas of Turkey and some populations have levels of resistance that may pose challenges to the continued use of phosphine for their management.