Characterization of the Bacterial Microbiome in Natural Populations of Barley Stem Gall Midge, Mayetiola hordei, in Morocco

SIMPLE SUMMARY: Barley stem gall midge, Mayetiola hordei (Kieffer), is one of the most devastating barley pests in many regions of the world, causing significant losses to agricultural output. In this work, we explore the presence of reproductive symbionts, including Wolbachia, Spiroplasma, Cardinium, and Arsenophonus, which can be employed as a substitute for chemical pesticides in pest management, in addition to the impact of their geographic origin on bacterial composition, as well as the diversity of the natural populations of barley stem gall midges detected in four Moroccan barley-growing regions. The screening revealed the presence of Wolbachia; in contrast, none of the samples analyzed had Spiroplasma, Cardinium, or Arsenophonus infections. Overall, 5 phyla, 7 classes, and 42 genera were detected throughout all samples, with a significant environmental influence on the taxonomic assortment of the microbiota. ABSTRACT: Mayetiola hordei (Kieffer), known as barley stem gall midge, is one of the most destructive barley pests in many areas around the world, inflicting significant qualitative and quantitative damage to crop production. In this study, we investigate the presence of reproductive symbionts, the effect of geographical origin on the bacterial microbiome’s structure, and the diversity associated with natural populations of M. hordei located in four barley-producing areas in Morocco. Wolbachia infection was discovered in 9% of the natural populations using a precise 16S rDNA PCR assay. High-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene indicated that the native environments of samples had a substantial environmental impact on the microbiota taxonomic assortment. Briefly, 5 phyla, 7 classes, and 42 genera were identified across all the samples. To our knowledge, this is the first report on the bacterial composition of M. hordei natural populations. The presence of Wolbachia infection may assist in the diagnosis of ideal natural populations, providing a new insight into the employment of Wolbachia in the control of barley midge populations, in the context of the sterile insect technique or other biological control methods.