Screening stored wheat beetles for reproductive parasitic endosymbionts in central Turkey

Abstract

Stored-product pest insects cause significant loss in stored wheat worldwide. In Turkey, an important wheat producer and historic centre of wheat domestication, almost 60 stored-product pest insects have been reported so far, most of them being coleopteran species. Using reproductive parasitic endosymbionts (RPEs) is a promising recent approach among control methods alternative to insecticides. For planning and studying pest management with these bacteria, first of all, their presence in the natural pest populations should be investigated. The present study focused on screening the RPEs in Central Anatolian stored wheat pests. We collected pests in granaries in Kırşehir province and identified 10 coleopteran species both morphologically and genetically; namely, Ahasverus advena, Cryptolestes ferrugineus, C. pusillus, Carpophilus obsoletus, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus granarius, S. oryzae, S. zeamais, and Tribolium castaneum. In these pests, we screened the most commonly studied RPEs worldwide, Arsenophonus, Cardinium, Fritschea, Hamiltonella, Rickettsia, Spiroplasma, and Wolbachia, by using specific genetic primers. As a result, we detected RPE presence in almost all sampling localities visited. The RPEs that we found were Rickettsia, Spiroplasma, and Wolbachia. We found no infection caused by Arsenophonus, Cardinium, Fritschea, nor Hamiltonella. Rickettsia presence was only in S. granarius populations, whereas Spiroplasma and Wolbachia presence were not species specific. 22% of all sampled beetle individuals were Wolbachia positive. The highest detection rate per granary was that of Spiroplasma (80%). Wolbachia and Spiroplasma were the most frequently detected RPEs per insect species. We also found several cases of coinfections. This study is the first attempt to screen stored-product pests for seven RPEs together.