Deciphering the Olfactory Mechanisms of Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae): Insights from Transcriptome Analysis and Molecular Docking

Olfaction is crucial for insect activities such as host seeking, foraging, oviposition, and predator avoidance. While olfactory proteins have been identified across several insect species, their specific functions are largely enigmatic. In this study, we investigated the olfactory proteins of the Angoumois grain moth, <i>Sitotroga cerealella</i> Olivier. A total of 165 presumptive olfactory genes were identified in the antennal transcriptome of <i>S. cerealella</i>, encompassing 33 odorant-binding proteins (OBPs), 10 chemosensory proteins (CSPs), 58 odorant receptors (ORs), 41 ionotropic receptors (IRs), 21 gustatory receptors (GRs), and 2 sensory neuron membrane proteins (SNMPs). BLASTX and a phylogenetic analysis showed a high similarity of these genes to the orthologs in other model insects. A qRT-PCR analysis demonstrated that ScerOBP15 and ScerOBP23 are specifically and highly expressed in antennae, exhibiting male-biased expression patterns. Moreover, molecular docking revealed their strong binding affinity to the wheat volatiles n-heptadecane and geranyl acetone. Also, the potential active sites within ScerOBP15 and ScerOBP23 that engage with these volatiles have been identified, implying a possible role in host localization. Our findings shed light on the mechanisms underlying the behavioral responses of <i>S. cerealella</i> to wheat odors, enhance our comprehension of their olfactory processes, and pave the way for the development of highly specific and sustainable pest management strategies.