Identification and Characterization of Olfactory Genes in the Cochineal Scale Insect, Porphyrophora sophorae (Hemiptera: Margarodidae).

Chemosensory systems are essential in insect behavior, with several key genes associated with these systems emerging as potential targets for pest control. Porphyrophora sophorae (Archangelskaya, 1935), a destructive pest of Chinese licorice (Glycyrrhiza uralensis, Fabaceae), poses a significant threat to the healthy cultivation of licorice. However, the molecular mechanisms underlying its host detection and olfactory recognition remain poorly understood. In this study, we present the first identification of odorant-binding proteins (OBPs) and olfactory receptors (ORs) from the transcriptome of P. sophorae. The identified OBPs contain six conserved cysteine residues, while predictive analysis suggests that PsopOrco may contain six transmembrane domains. Phylogenetic analysis demonstrated that the majority of these olfactory proteins are closely related to OBPs and ORs found in other scale insects. Using RT-qPCR, we assessed the anatomical structures expression of these genes and found that PsopOBP3, PsopOBP6, and PsopOrco were predominantly expressed in the antennae. Additionally, expression levels of OBPs and ORs varied across different tissues, suggesting anatomical structure regulation. These findings expand the gene repertoire of P. sophorae and provide valuable resources for further functional analysis of these key olfactory genes.