Abstract: Objective To investigate the composition and diversity of the symbiotic microorganisms of adult Cheyletus malaccensis for biological data for large-scale breeding of Cheyletus malaccensis and its application in biological control of stored grain pests. Methods Specimens of C. malaccensis were captured in 2022 from the stored grain in a farm granary in Wuhu City, Anhui Province, and purely cultivated after morphological identification. Then total DNA was extracted from adult mites, and subjected to high-throughput sequencing at the V4 region of bacterial 16S rRNA and the ITS1 region of fungal. Operational taxonomic units (OTUs) of symbiotic microorganisms were annotated, and their community composition and diversity were systematically analyzed. Results A total of 190 788 valid sequences at V4 region of bacterial 16S rRNA and 20 1736 valid sequences at ITS1 region of fungal were obtained, which were clustered into 469 and 270 OTUs, respectively. The bacterial sequences fell into 27 phyla, 50 classes, 119 orders, 200 families and 337 genera, while the fungal sequences were assigned to 4 phyla, 18 classes, 41 orders, 85 families, and 137 genera. At the phylum level, the dominant bacterial groups were Pseudomonadota (45.23%), Verrucomicrobiota (20.98%) and Bacillota (16.42%), whereas Ascomycota (93.86%) was the predominant fungal phylum. At the genus level, the most abundant bacterial genera were Izhakiella (35.62%), Candidatus Fritschea (20.95%) and Candidatus Cardinium (13.12%). The dominant fungal genera were Aspergillus (32.11%), Acremonium (14.72%) and an indeterminate genus within Hypocreales (11.20%). Alpha diversity analysis indicated the bacteria and fungi are diverse associated with adult C. malaccensis. Conclusion This study revealed the compositional structure and high diversity of the symbiotic bacteria and fungi associated with adult C. malaccensis, which can provide theoretical basis and propagation technology for artificial rearing of C. malaccensisin large scale. 

Key words: Cheyletus malaccensis, High-throughput sequencing, Symbiotic microorganisms, Diversity