Determination of malathion resistance in Sitophilus oryzae L., 1763 and Sitophilus granarius L., 1758 (Coleoptera: Curculionidae) populations in

This study was conducted to determine the malathion resistance levels of two important stored grain pest beetles, Sitophilus oryzae L., 1763 and Sitophilus granarius L., 1758 (Coleoptera: Curculionidae), collected from different provinces of Turkiye in the years 2017-2018. To control these pests, chemical insecticides have been widely used for a long time as a grain protectant in farmer warehouses, flour mills, or silos in many countries, including Turkiye. In the current study, insects were exposed to malathion for 24 hours to determine resistance rates. The highest resistance ratio to malathion in S. oryzae was found in the Adana-Kartepe population with 5.73-fold, and the lowest resistance was found in the Istanbul- Buyukcekmece population with 1.57-fold. While the Konya-Alibeyhoyugu population of S. granarius had the highest resistance ratio of 6-fold, the lowest resistance rate of 2.54-fold was found in the population obtained from the same location but from a different warehouse. According to this study, we found that slight resistance developed in the populations of S. oryzae and S. granarius in Turkiye. In order to prevent the occurrence of resistance due to synthetic insecticides used against stored product pests, it is thought that various insecticide groups with different mechanisms of action should be used.