De novo RNA-Seq and Annotation of Sesquiterpenoid and Ecdysteroid Biosynthesis Genes and MicroRNAs in a Spider Mite Eotetranychus kankitus

RNAi-mediated knockdown of juvenile hormone acid methyltransferase depresses reproductive performance in female Aethina tumida

Small hive beetles, Aethina tumide, are free-flying parasites of social bee colonies where they feed and reproduce. In case of mass infestation, A. tumida can cause significant economic losses. There is an urgent need to explore novel green molecular approaches for sustainable control of A. tumida. It has been confirmed that juvenile hormone acid methyl transferase (JHAMT) plays a crucial role in regulating the synthesis of juvenile hormone (JH). However, its impact on female reproduction of A. tumida remains unclear. In the present study, a novel JHAMT gene was identified from A. tumida with an open reading frame of 978 bp, encoding a polypeptide of 325 amino acids containing a Methyltransferase domain. The deduced amino acid sequence of AtJHAMT shared 60 % and 33 % identity with homologs from Brassicogethes aeneus and Apis mellifera, respectively. The expression profile indicates that the transcription level of AtJHAMT increases in the adult stages, reaching its peak in 5-day-old female adults. AtJHAMT exhibits the highest expression levels in the ovaries, and fluorescence in situ hybridization (FISH) demonstrates that this gene shows a significant number of positive signals in the ovarian ducts and the head region. Furthermore, we investigated the function of AtJHAMT through RNA interference and methoprene rescue experiments. We also investigeted the off-target effects of the dsJHAMT. The results showed that silencing AtJHAMT through oral dsRNA delivery (feeding dsRNA-SPc mix) affected ovarian development and significantly reduced JH titers, female fecundity, female fertility, and egg hatchability. The application of methoprene partially rescued the negative effect of silencing AtJHAMT on reproduction. Several genes associated with ovarian development were significantly downregulated following interference with AtJHAMT, but their expression levels were restored after complementation experiments. Additionally, the off-target effects experiment showed that dsJHAMT from A. tumida had no adverse effects on ovaries development in honey bee queens. Overall, this study illustrates the functions of the JHAMT in A. tumida, which can serve as a potential target for controlling the reproduction of the most deleterious bee parasites, A. tumida.

Complete mitochondrial genomes of Thyreophagus entomophagus and Acarus siro (Sarcoptiformes: Astigmatina) provide insight into mitogenome features, evolution, and phylogeny among Acaroidea mites

Mites from the Acaroidea (Sarcoptiformes: Astigmatina) are important pests of various stored products, posing potential threats to preserved foods. In addition, mites can cause allergic diseases. Complete mitochondrial genomes (mitogenomes) are valuable resources for different research fields, including comparative genomics, molecular evolutionary analysis, and phylogenetic inference. We sequenced and annotated the complete mitogenomes of Thyreophagus entomophagus and Acarus siro. A comparative analysis was made between mitogenomic sequences from 10 species representing nine genera within Acaroidea. The mitogenomes of T. entomophagus and A. siro contained 37 genes, including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs), and one control region. In Acaroidea species, mitogenomes have highly conserved gene size and order, and codon usage. Among Acaroidea mites, most PCGs were found to be under purifying selection, implying that most PCGs might have evolved slowly. Our findings showed that nad4 evolved most rapidly, whereas cox1 and cox3 evolved most slowly. The evolutionary rates of Acaroidea vary considerably across families. In addition, selection analyses were also performed in 23 astigmatid mite species, and the evolutionary rate of the same genes in different superfamilies exhibited large differences. Phylogenetic results are mostly consistent with those identified by previous phylogenetic studies on astigmatid mites. The monophyly of Acaroidea was rejected, and the Suidasiidae and Lardoglyphidae appeared to deviate from the Acaroidea branch. Our research proposed a review of the current Acaroidea classification system.