Different responses of soil fauna gut and plant rhizosphere microbiomes to manure applications

• Microbial attributes were compared between soil fauna gut and plant rhizosphere. • Manure applications decreased or increased gut or rhizosphere bacterial diversity. • Stochastic or deterministic processes drove gut or rhizosphere bacterial assembly. • Manure applications increased bacterial network complexity of gut and rhizosphere. Diverse microbes inhabit animals and plants, helping their hosts perform multiple functions in agricultural ecosystems. However, the responses of soil fauna gut and plant rhizosphere microbiomes to livestock manure applications are still not well understood. Here we fed Protaetia brevitarsis larvae (PBL) with chicken manure and collected their frass. The frass and manure were applied as fertilizers to lettuce pots. We then compared the changes of microbial diversity, community assembly, and potential functions between the gut group (i.e., all PBL gut and frass samples) and the rhizosphere group (i.e., all rhizosphere soil samples). We revealed that manure applications (i.e., feeding or fertilization) decreased bacterial diversity in the gut group but increased that in the rhizosphere group. Particularly, the proportions of Bacilli in the gut group and Gammaproteobacteria in the rhizosphere group were increased (up to a maximum of 33.8% and 20.4%, respectively) after manure applications. Stochastic and deterministic processes dominated community assembly in the gut and rhizosphere microbiomes, respectively. Manure applications increased the microbial co-occurrence network complexity of both the gut and rhizosphere groups. Moreover, the proportions of functional taxa associated with human/animal pathogens in the gut group and carbon/nitrogen cycling in the rhizosphere group were enhanced (up to 2.6-fold and 24.6-fold, respectively). Our findings illustrate the different responses of microbial diversity, community assembly, and potential functions in soil fauna gut and plant rhizosphere to manure applications. The results could enhance our knowledge on the reasonable utilization of animal and plant microbiomes in agricultural management.