Odorant-binding proteins involved in sex pheromone and host-plant recognition of the sugarcane borer Chilo infuscatellus (Lepidoptera: Crambidae).

BACKGROUND: Pheromone-binding proteins (PBPs) are responsible for transporting sex pheromones and general odorant-binding proteins (GOBPs) have been proposed to transport host-plant volatiles. A large number of OBPs have been identified from Lepidoptera species. However, olfactory molecular biology and physiology studies on PBP and GOBP in sugarcane pests are limited. Chilo infuscatellus is one of the most widely distributed pests in sugarcane-producing areas. RESULTS: Three PBPs (CinfPBP1, CinfPBP2 and CinfPBP3) and two GOBPs (CinfGOBP1 and CinfGOBP2) were identified, and five olfactory gene transcripts were abundantly expressed in antennae of C. infuscatellus. Binding assays showed that CinfPBP1-3 exhibited strong binding affinity for the sex pheromone components Z11-16:OH and 16:OH of C. infuscatellus. Meanwhile, CinfGOBP1-2 had high binding affinity with host-plant volatiles from sugarcane (Saccharum officinarum). Field-trapping results suggested that four volatile components, octadecane, (Z)-3-hexen-1-ol, α-terpineol and hexadecane from host plants and sex pheromone mixed baits have synergistic roles in attracting C. infuscatellus adult moths. CONCLUSION: Functional characterization of CinfPBPs and CinfGOBPs in C. infuscatellus could help us find new environmentally friendly alternatives to conventional pest control using pesticides in sugarcane fields. © 2020 Society of Chemical Industry.

Field evaluation of sex pheromones and binding specificity of pheromone binding protein 4 in Tryporyza intacta (Lepidoptera: Crambidae).

The recognition of chemical signal including volatile odorants and pheromones is very important in the olfactory physiological behaviors of insects, such as avoiding predators, seeking food and mating partners. The sugarcane borer, Tryporyza intacta is the most harmful insect in sugarcane region in Southeast Asia and Southern China, however, the study of their molecular biology and physiology was limited. Here we demonstrated that the sex pheromone (E11-16:Ald: Z11-16:Ald = 7:3) were most effective to T. intacta. In addition, compared the traditional rubber lure, a new microsphere formulation lure can optimize the trapping effect and might be widely used in the sugarcane growing area. To obtain a better understanding of the olfactory molecular mechanism of pheromone-based mate recognition system, we have cloned the full-length gene of the TintPBP4 and expressed in Escherichia coli. Our phylogenetic analysis highlighted that the TintPBP4 was highly conserved among diverse species of Lepidoptera. Furthermore, the results of QRT-PCR demonstrated that TintPBP4 transcripts were abundantly expressed in the antennae of T. intacta, especially in the male adults. The fluorescence binding experiments showed the TintPBP4 exhibited strong binding capacities to the sex pheromone components. These results will not only provide more understanding for the functional analysis of olfactory proteins from T. intacta, but also assist in the exploitation and development of sex pheromones in the integrated biological control of this pest.

Molecular characterization and functional differentiation of three pheromone-binding proteins from Tryporyza intacta.

Insect pheromone-binding proteins (PBPs) have been proposed to capture and transport hydrophobic sex pheromone components emitted by con-specific insects to pheromone receptors in the hemolymph of male antennal sensilla. In this study, field trapping results indicate that a mixture of E11-16: Ald and Z11-16: Ald can effectively attract a great number of male Tryporyza intacta. Real-time PCR results suggest that the transcript levels of three TintPBP1-3 genes are mainly expressed in the adult antennae. Fluorescence competitive binding experiments show that TintPBP1-3 proteins have great binding affinities to their major sex pheromones. Moreover, TintPBPs clearly cannot bind to other four kinds of sex pheromone components released by another sugarcane borer, Chilo venosatus and Chilo infuscatellu, which have the same host plant and live in similar habitats like T. intacta. The molecular docking results demonstrate that six amino acid residues of the three TintPBPs are crucial for the specific perception of the sex pheromone components. These results will provide a foundation for the development of novel sex pheromone analogues and blocking agents for biological control of sugarcane pests, improving their efficient monitoring and integrated management strategies in the sugarcane field.