Host-specific and deterministic microbiome assembly in major coleopteran stored-grain pests.

Dual DNA- and RNA-based sequencing profiled the microbiomes of five major coleopteran stored-grain pests and their wheat flour substrate. The microbiomes differed significantly among hosts and from flour, yet 11 core bacterial and 9 core fungal taxa were shared across hosts. RNA data revealed host-specific active microbiota. Deterministic processes dominated community assembly, exceeding 90% in Rhyzopertha dominica and Oryzaephilus surinamensis. Homogeneous selection identified eight conserved bacterial clades. Although microbiomes were strongly host-specific, they showed no significant correlation with host phylogeny, indicating that environmental filtering and deterministic selection, rather than evolutionary relatedness, are the dominant forces shaping these pest-associated communities.