Expression Profiles and Functional Characterization of Chemosensory Protein 15 (HhalCSP15) in the Brown Marmorated Stink Bug Halyomorpha halys

Involvement of three chemosensory proteins in perception of host plant volatiles in the tea green leafhopper, Empoasca onukii

Chemosensory proteins (CSPs) can bind and transport odorant molecules, which are believed to be involved in insect chemoreception. Here, we investigated three CSPs in perception of volatiles in Empoasca onukii. Expression profiles showed that although EonuCSP4, EonuCSP 6-1 and EonuCSP6-2 were ubiquitously expressed in heads, legs, thoraxes and abdomen, they were all highly expressed in the antennae of E. onukii. Further, fluorescence competitive binding assays revealed that EonuCSP4 and 6-1 had binding affinities for three plant volatiles, suggesting their possible involvement in the chemosensory process. Among them, EonuCSP6-1 showed relatively high binding affinities for benzaldehyde. Behavioral assays revealed that the adults of E. onukii showed a significant preference for two compounds including benzaldehyde. The predicted three-dimensional (3D) structures of these 3 CSP have the typical six α-helices, which form the hydrophobic ligand-binding pocket. We therefore suggest that Eoun6-1 might be involved in the chemoreception of the host-related volatiles for E. onukii. Our data may provide a chance of finding a suitable antagonist of alternative control strategies which block the perception of chemosensory signals in pest, preventing the food- orientation behaviors.

Identification and Expression Profiles of Putative Soluble Chemoreception Proteins from Lasioderma serricorne (Coleoptera: Anobiidae) Antennal Transcriptome

The cigarette beetle, Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae), is a destructive stored product pest worldwide. Adult cigarette beetles are known to rely on host volatiles and pheromones to locate suitable habitats for oviposition and mating, respectively. However, little is known about the chemosensory mechanisms of these pests. Soluble chemoreception proteins are believed to initiate olfactory signal transduction in insects, which play important roles in host searching and mating behaviors. In this study, we sequenced the antennal transcriptome of L. serricorne and identified 14 odorant-binding proteins (OBPs), 5 chemosensory proteins (CSPs), and 2 Niemann-Pick C2 proteins (NPC2). Quantitative realtime PCR (qPCR) results revealed that several genes (LserOBP2, 3, 6, and 14) were predominantly expressed in females, which might be involved in specific functions in this gender. The five LserOBPs (LserOBP1, 4, 8, 10, and 12) that were highly expressed in the male antennae might encode proteins involved in specific functions in males. These findings will contribute to a better understanding of the olfactory system in this stored product pest and will assist in the development of efficient and environmentally friendly strategies for controlling L. serricorne.

Identification and functional analysis of a chemosensory protein from Bactrocera minax (Diptera: Tephritidae)

BACKGROUND

Olfaction has an indispensable role in insect behavior, enabling location of suitable host plants and oviposition sites, finding mates and evasion of natural enemies. Chemosensory proteins (CSPs) function to screen external odorants and transport them to olfactory receptor neurons, thereby increasing the sensitivity of the olfactory system. At present, CSP genes have been identified in many insect species, but there are relatively few studies on the function of CSP, especially in Tephritidae.

RESULTS

In this study, we sequenced and analyzed 12 transcriptomes of Bactrocera minax and identified five CSP genes. The results of polymerase chain reactions with reverse transcription showed that BminCSP3 was highly expressed only in antennae. Results from competitive binding experiments showed that BminCSP3 has good binding ability to citral compared with 23 other volatile organic compounds. The docking model with citral showed hydrogen bond formation with residues (ARG97); however, no hydrogen bonds were formed in the docking of five other ligands (furfuryl alcohol, linalool, cis-3-hexenyl acetate, (R)-(+)-limonene and (+)-carvone). Electroantennogram (EAG) analyses revealed that citral was active in B. minax at the antennal level, and the EAG response value of female adults was significantly higher than that of male adults. Furthermore, the results of behavioral bioassays showed that females were significantly attracted to citral.

CONCLUSION

Our results suggest that BminCSP3 plays an important role in the recognition of citral by B. minax adults. © 2022 Society of Chemical Industry.