Metagenomic analysis of the microbiota of a laboratory mite population of Neoseiulus californicus (mesostigmata, phytoseiidae) and the optimisation of microbiota composition to improve mite breeding efficiency

Abstract

Experimental modelling of the microbiota of a biocontrol population of the predatory mite, Neoseiulus californicus bred on the spider mite, Tetranychus urticae was carried out to both eliminate bacterial pathogens and increase the viability of the mite line. We produced an isofemale line of N. californicus BioDefence2 and a derived line with an optimised microbiota BioDefence3. The microbiota was optimised by a sequential treatment of the mite line with tetracycline to eliminate pathogenic bacteria, followed by a treatment with the probiotic bacterium, Bacillus subtilis to restore the viability of the mite line. The microbiotas of the BioDefence2 and BioDefence3 mite lines were compared using metagenomic 16S rRNA gene data. The metagenomic data were extracted from the hologenomes of the mite lines obtained through Oxford Nanopore long read sequencing. The bacterial species comprising the microbiotas of the original and optimised mite lines were identified. The saprophytic soil bacteria, Stenotrophomonas maltophilia, Acinetobacter johnsonii and Enterobacter hormaechei, also known as opportunistic human pathogens, form the basis of the N. californicus microbiota. The optimization of the microbiota eliminates the intracellular bacterium, Renibacterium salmoninarum, a well-known fish pathogen. The effect of mite microbiota optimisation on the viability of the biocontrol population of N. californicus is discussed. The results obtained may provide a basis for improving the technology of N. californicus rearing.