Ecological Adaptation in the Chemosensory Gene Repertoire of the Safflower Aphid, Uroleucon gobonis

The red flower aphid (<i>Uroleucon gobonis</i>) is a significant agricultural pest causing damage via direct feeding and virus transmission. Chemical sensory proteins (CSPs) are critical for insecticide resistance, mediating the detection of semiochemicals or the sequestration of neuroactive insecticides. This study provides the first comprehensive identification and functional characterization of chemosensory gene families in <i>Uroleucon gobonis</i> to elucidate their roles in chemoperception and resistance. We conducted de novo transcriptome sequencing and assembly to identify chemosensory genes. Their phylogenetic relationships and structural motifs were analyzed. Developmental expression patterns were assessed via RNA-seq, and tissue-specific expression was validated using quantitative real-time PCR (qRT-PCR). We identified 40 chemosensory genes: 12 odorant-binding proteins (OBPs), 8 CSPs, 14 odorant receptors (ORs), and 6 gustatory receptors (GRs). Phylogenetic analysis revealed species-specific adaptations, including the absence of GR clades 2/4 and minimal representation in CSP Subgroup III. Structural motifs were highly conserved in ORs/OBPs but divergent in CSPs/GRs. RNA-seq identified 1896 differentially expressed genes (DEGs) between instars, including stage-specific regulation of <i>UgobCSP4</i>, <i>UgobCSP6</i>, <i>UgobOBP3</i>, and <i>UgobOBP10</i>. qRT-PCR confirmed extreme spatial expression, such as leg-specific <i>UgobCSP6</i> and antennae-specific <i>UgobOBP10</i>. These findings elucidate key molecular adaptations in chemosensory gene families governing perception and potential insecticide resistance in <i>Uroleucon gobonis</i>. The identified stage- and tissue-specific genes provide targets for developing species-specific pest control strategies.