Olfactory proteins form the basis of insect olfactory recognition, which is crucial for host identification, mating, and oviposition. Using transcriptome analysis of Anoplophora glabripennis antenna, we identified 42 odorant-binding proteins (OBPs), 12 chemosensory proteins (CSPs), 14 pheromone-degrading enzymes (PDEs), 1 odorant-degrading enzymes (ODE), 37 odorant receptors (ORs), 11 gustatory receptors (GRs), 2 sensory neuron membrane proteins (SNMPs), and 4 ionotropic receptor (IR). All CSPs and PBPs were expressed in antennae, confirming the authenticity of the transcriptome data. CSP expression profiles showed that AglaCSP3, AglaCSP6, and AglaCSP12 were expressed preferentially in maxillary palps and AglaCSP7 and AglaCSP9 were strongly expressed in antennae. The vast majority of CSPs were highly expressed in multiple chemosensory tissues, suggesting their participation in olfactory recognition in almost all olfactory tissues. Intriguingly, the PBP AglaPBP2 was preferentially expressed in antenna, indicating that it is the main protein involved in efficient and sensitive pheromone recognition. Phylogenetic analysis of olfactory proteins indicated AglaGR1 may detect CO₂. This study establishes a foundation for determining the chemoreception molecular mechanisms of A. glabripennis, which would provide a new perspective for controlling pest populations, especially those of borers.

Eogystia hippophaecolus (Hua et al.) (Lepidoptera: Cossidae) is the major threat to seabuckthorn plantations in China. Specific and highly efficient artificial sex pheromone traps was developed and used to control it. However, the molecular basis for the pheromone recognition is not known. So we established the antennal transcriptome of E. hippophaecolus and characterized the expression profiles of odorant binding proteins. These results establish and improve the basis knowledge of the olfactory receptive system, furthermore provide a theoretical basis for the development of new pest control method. We identified 29 transcripts encoding putative odorant-binding proteins (OBPs), 18 putative chemosensory proteins (CSPs), 63 odorant receptors (ORs), 13 gustatory receptors (GRs), 12 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Based on phylogenetic analysis, we found one Orco and three pheromone receptors of E. hippophaecolus and found that EhipGR13 detects sugar, EhipGR11 and EhipGR3 detect bitter. Nine OBPs expression profile indicated that most were the highest expression in antennae, consistent with functions of OBPs in binding and transporting odors during the antennal recognition process. OBP6 was external expressed in male genital-biased in, and this locus may be responsible for pheromone binding and recognition as well as mating. OBP1 was the highest and biased expressed in the foot and may function as identification of host plant volatiles. One hundred thirty-seven chemosensory proteins were identified and the accurate functions and groups of part proteins were obtained by phylogenetic analysis. The most OBPs were antenna-biased expressed, which are involved in antennal recognition. However, few OBP was detected biased expression in the foot and external genitalia, and these loci may function in pheromone recognition, mating, and the recognition of plant volatiles.

Sirex noctilio F. (Hymenoptera: Siricidae: Siricinae), a new invasive species in China, is a significant international forestry quarantine pest. Transportation of Sirex in logs, and related wood packing materials, has led to environmental damage and substantial economic loss in many countries around the world. Traditional morphological characteristics are not reliable for identification of the Siricidae family, particularly the larvae. Furthermore, specimens are frequently not in a suitable condition to permit morphological identification. The majority of damage is caused by the larval stage, which excavates galleries that can penetrate to the center of tree boles. Thus, development of a rapid, accurate, and effective molecular identification technique for S. noctilio , which does not require expert morphological knowledge, is necessary. Here, we describe a molecular identification tool based on the mitochondrial DNA gene, cytochrome C oxidase subunit I (COI). We designed a species-specific COI (SS-COI) PCR assay, which allows direct identification of S. noctilio , regardless of developmental stage. Six woodwasp species commonly found in China, Sirex noctilio , Sirex nitobei , Sirex sp., Tremex fuscicornis Fabr., Tremex apicalis Matsumura, and Xeris spectrum , were included in our analyses . Moreover, specimens of S. noctilio from 16 different areas were analyzed. The results demonstrate that our molecular assay is effective and accurate, regardless of developmental stage or type of specimen, consistent with use for quarantine purposes, to prevent the harmful consequences of S. noctilio spread.

Olfaction in insects is essential for host identification, mating and oviposition, in which olfactory proteins are responsible for chemical signaling. Here, we determined the transcriptomes of male and female adult antennae of Anoplophora chinensis, the citrus longhorned beetle. Among 59,357 unigenes in the antennal assembly, we identified 46 odorant-binding proteins, 16 chemosensory proteins (CSPs), 44 odorant receptors, 19 gustatory receptors, 23 ionotropic receptors, and 3 sensory neuron membrane proteins. Among CSPs, AchiCSP10 was predominantly expressed in antennae (compared with legs or maxillary palps), at a significantly higher level in males than in females, suggesting that AchiCSP10 has a role in reception of female sex pheromones. Many highly expressed genes encoding CSPs are orthologue genes of A. chinensis and Anoplophora glabripennis. Notably, AchiPBP1 and AchiPBP2 showed 100% and 96% identity with AglaPBP1 and AglaPBP2 from A. glabripennis, with similar expression profiles in the two species; PBP2 was highly expressed in male antennae, whereas PBP1 was expressed in all three tissues in both males and females. These results provide a basis for further studies on the molecular chemoreception mechanisms of A. chinensis, and suggest novel targets for control of A. chinensis.