Molecular characterization and evolutionary insights into potential sex-determination genes in the western orchard predatory mite <i>Metaseiulus occidentalis</i> (Chelicerata: Arachnida: Acari: Phytoseiidae)

<div><p>Little is known about the process of sex determination at the molecular level in species belonging to the subclass Acari, a taxon of arachnids that contains mites and ticks. The recent sequencing of the transcriptome and genome of the western orchard predatory mite <i>Metaseiulus occidentalis</i> allows investigation of molecular mechanisms underlying the biological processes of sex determination in this predator of phytophagous pest mites. We identified four <i>doublesex</i>-<i>and</i>-<i>mab</i>-<i>3</i>-<i>related transcription factor</i> (<i>dmrt</i>) genes, one <i>transformer</i>-<i>2</i> gene, one <i>intersex</i> gene, and two <i>fruitless</i>-like genes in <i>M. occidentalis</i>. Phylogenetic analyses were conducted to infer the molecular relationships to sequences from species of arthropods, including insects, crustaceans, acarines, and a centipede, using available genomic data. Comparative analyses revealed high sequence identity within functional domains and confirmed that the architecture for certain sex-determination genes is conserved in arthropods. This study provides a framework for identifying potential target genes that could be implicated in the process of sex determination in <i>M. occidentalis</i> and provides insight into the conservation and change of the molecular components of sex determination in arthropods.</p>