Fig. 3

Bacterial communities associated with IJs from different species of Steinernema. a Simplified phylogeny of Steinernema. Phylogenetic relationships between 16 Steinernema strains based on a maximum likelihood (ML) analysis of partial internal transcribed spacer (ITS) regions (~ 850 bp). Heterorhabditis bacteriophora was used as outgroup. Branch support values (estimated by the aLRT [SH-like] method) are shown at the nodes (percentages of 100 replicates). The branch length scale bar below the phylogenetic tree indicates the number of nucleotide substitutions per site. The accession numbers of the sequences are indicated after the names of the nematodes. The sequences of strains used for metabarcoding studies are shown in colour. b Principal co-ordinates analysis (PCoA) based on Bray-Curtis distances for the IJ microbiota. Heterorhabditis and Steinernema samples are indicated by circles and triangles, respectively. Colours indicate the different Steinernema species. Each point represents a technical replicate. The proportion of the variance explained by each axis is shown. The five samples are significantly different (Permanova rpoB, Df = 4, R² = 0.73, p value = 10⁻⁴). c Heatmap showing the microbiota composition of IJ samples. Each column represents an IJ species. The 30 most abundant OTUs across the samples at the genus level of affiliation (Top30 Genus) are listed on the left. The percentage relative abundance is indicated by the gradient of blue hues. For b and c, IJ microbiota were described by metabarcoding with the 435 bp rpoB region. The EPN strains used here belong to the following batches: S. carpocapsae SK27_23_08_16 and B10_27_04_16; S. weiseri 583_09_06_15, TCH02_11_08_16 (t1), S. glaseri SK39_09_06_15; S. feltiae FRA200_09_06_15 and FRA200_12_08_15 and H. bacteriophora TT01_22_06_16 and TT01_15_03_16. Three to six technical replicates per batch were performed