Insect-associated microorganisms play important roles in the health and development of insects. This study aimed to investigate the similarities and differences in bacterial community structure and composition between the larval gut of Osmia excavata, nest soil, and brood provision from the nest tube. We sequenced larvae gut and their environments’ microorganisms of O. excavata from four locations based on full-length 16S rRNA gene amplicons. The results showed 156, 280, and 366 bacterial OTUs from gut, brood provision, and nest soil, respectively, and three groups shared 131 bacterial OTUs. In the gut, the top two dominant bacteria were Sodalis praecaptivus (68.99%), Lactobacillus micheneri (17.95%). In the brood provision, the top two dominant bacteria were S. praecaptivus (26.66%), Acinetobacter nectaris (13.05%), and in the nest soil, the two most abundant bacteria were Gaiella occulta (4.33%), Vicinamibacter silvestris (3.88%). There were significant differences in diversity between the brood provision groups and the nest soil groups, respectively. Three of the four locations did not differ for gut microbial diversity. Bacteria similar to other solitary bees also existed in the gut of the larvae. Results indicated when the habitat environments were similar, the bacterial community diversity of the gut of O. excavata was similar, despite significant differences among brood provisions and soils, respectively.

The subfamily Lamiinae is the most taxonomically diverse subfamily of Cerambycidae, but relationships between tribes of Lamiinae are still unresolved. In order to study the characteristics of the mitogenomes of Lamiinae and the tribal-level phylogenetic relationships, we sequenced the mitogenomes of two species representing two tribes, Agapanthia amurensis (Agapanthiini) and Moechotypa diphysis (Ceroplesini), with a total length of 15,512 bp and 15,493 bp, respectively. The gene arrangements of these two new mitogenomes were consistent with the inferred ancestral insect mitogenomes. Each species contained 37 typical mitochondrial genes and a control region (A + T-rich region), including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNAs). All PCGs initiated with the standard start codon ATN, and terminated with the complete stop codons of TAA and TAG, or incomplete stop codon T. All tRNAs could be folded into a clover-leaf secondary structure except for trnS1, in which the dihydrouridine (DHU) arm was reduced. Moreover, we studied the phylogenetic relationships between some tribes of Lamiinae based in mitochondrial PCGs in nucleotides; our results show that the relationships were as follows: (Onciderini + ((Apomecynini + Acanthocinini) + ((Ceroplesini + Agapanthiini) + ((Mesosini + Pteropliini) + ((Dorcaschematini + (Saperdini 1 + (Phytoeciini + Saperdini 2))) + (Batocerini + Lamiini)))))).

Bees (Hymenoptera, Apoidea and Anthophila) are distributed worldwide and considered the primary pollinators of angiosperm. Megachilidae is one of the largest families of Anthophila. In this study, two complete mitogenomes of cuckoo bees in Megachilidae, namely Coelioxys fenestrata and Euaspis polynesia, were amplified and sequenced, with a length of 17,004 bp (C. fenestrata) and 17,682 bp (E. polynesia). The obtained results show that 37 mitogenomic genes and one putative control region were conserved within Hymenoptera. Truncated stop codon T was found in the cox3 gene of E. polynesia. The secondary structure of small (rrnS) and large (rrnL) rRNA subunits contained three domains (28 helices) and five domains (44 helices) conserved within Hymenoptera, respectively. Compared with ancestral gene order, gene rearrangement events included local inversion and gene shuffling. In order to reveal the phylogenetic position of cuckoo bees, we performed phylogenetic analysis. The results supported that all families of Anthophila were monophyletic, the tribe-level relationship of Megachilidae was Osmiini + (Anthidiini + Megachilini) and Coelioxys fenestrata was clustered to the Megachile genus, which was more closely related to Megachile sculpturalis and Megachile strupigera than Euaspis polynesia.

The mitogenome of Habropoda rodoszkowskii, the first complete mitogenome sequence of the genus Habropoda (hymenoptera: Apidae), was sequenced. The mitogenome is 18,497 bp (The proportion of A + T in 80.7%) long, with 37 classic eukaryotic mitochondrial genes (including 13 PCGs, 22 tRNAs, and 2 rRNAs) and an AT-rich region (The proportion of A + T in 78.2%). The Bayesian-inference and Maximum-likelihood phylogenetic relationship was constructed using 15 species from Hymenoptera. According to the phylogenetic tree, Habropoda rodoszkowskii converges with genus Nomada bees (Nomada flava and Nomada flavoguttata) to be supported. In addition, Habropoda rodoszkowskii is more closely related to Apidae than to Megahilidae and Colletidae.

The complete mitogenome of Lasioglossum affine (Hymenoptera: Halictidae) was sequenced and analyzed. The whole mitogenome is 17,352 bp (AT%=84.1%) and encodes 37 typical eukaryotic mitochondrial genes, including 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and an AT-rich region. Further analysis found three gene rearrangements, where trn I-Q-M → trn M-I-Q, trn W-C-Y → trn C-W-Y, and trn K-D → trn D-K were shuffled. The phylogenetic relationships of 19 species of Hymenoptera were established using maximum-likelihood method based on 13 concatenated PCGs. The result showed that Lasioglossum affine is a sister of Lasioglossum sp. SJW-2017.

The complete mitogenome of Nomia chalybeata was sequenced. The mitochondrial length of N. chalybeata was 16,692 bp (AT content 85.4%), with 37 classic invertebrate mitochondrial genes (including 13 protein-coding genes, 22 transporter RNAs, and two ribosomal RNAs) and AT-rich region (AT content 91.7%). The maximum-likelihood phylogenetic relationship was constructed using 11 species from Hymenoptera. Through the phylogenetic relationship, our research team successfully used the molecular data of the mitochondrial genome to verify that N. chalybeata belongs to the family Halictidae, and also provides molecular data for the database of the family Halictidae.