Identification and functional analysis of odorant-binding proteins of the parasitoid wasp Scleroderma guani reveal a chemosensory synergistic evolution with the host Monochamus alternatus.

Scleroderma guani is a generalist ectoparasitoid of wood-boring insects. The chemosensory genes expressed in its antennae play crucial roles in host-seeking. In the present study, we identified 14 OBP genes for the first time from the antennae transcriptomes and genomic data of S. guani. The expression profiles of 14 OBPs were tested by RT-qPCR, and the RT-qPCR results showed that SguaOBP2/5/6/11/12/13 were specifically highly expressed in the female antennae. Then we performed ligand binding assays to test the interactions between six selected SguaOBPs with host specific chemical compounds from M. alternatus and pines. The binding results indicated that SguaOBP12 had a higher binding affinity with longifolene, ß-caryophyllene, α-pinene, ß-pinene, myrcene, butylated hydroxytoluene, and 3-carene. SguaOBP11 had a high or medium binding affinity with them. Furthermore, both SguaOBP11 and SguaOBP12 had a medium binding affinity with the aggregation pheromone of Monochamus species, 2-undecyloxy-1-ethanol. Finally, by using molecular docking and RNAi, we further explored the molecular interactions and behavioral functions of SguaOBP11 and SguaOBP12 with these vital odor molecules. Our study contributes to the further understanding of chemical communications between S. guani and its host, and further exploration for its role as a more effective biological control agent.

Expressional and functional comparisons of two general odorant binding proteins in Agrotis ipsilon.

Insect general odorant binding proteins (GOBPs) have been long thought to bind and transport host plant volatiles to the olfactory receptors on the dendrite membrane of the olfactory neurons. Recent studies indicate that they can also bind female sex pheromones. In present study, two GOBP genes, AipsGOBP1 and AipsGOBP2 were cloned from the adult antennae of Agrotis ipsilon. Tissue expression profiles indicated that both of them are antennae-specific and more abundant in the female antennae than in the male antennae. Temporal expression profiles showed that both AipsGOBP1 and AipsGOBP2 began to express in antennae 3 days prior to adult emergence from pupae, and reached their highest expression level 3 and 4 days after adult emergence, respectively. Mating increased their expression in the female antennae but reduced their expression in the male antennae. In situ hybridization and immunolocalization demonstrated that both AipsGOBP1 and AipsGOBP2 are expressed and co-localized in sensilla basiconica and sensilla trichodea of both sexes. AipsGOBP2 exhibited a high binding affinity in vitro with the two major sex pheromone components Z7-12:Ac and Z9-14:Ac and the four plant volatiles cis-3-hexen-1-ol, oleic acid, dibutyl phthalate and ß-caryophyllene with Ki values less than 5 µM. AipsGOBP1, on the other hand, showed medium binding affinities with the five A. ipsilon sex pheromones and six plant volatiles. AipsGOBP2 also showed a broader ligand-binding spectrum and a greater ligand-binding affinity than AipsGOBP1 with the tested aldehyde and alcohol sex pheromones of Lepidoptera species. Taken together, our results indicate that AipsGOBP2 may play greater roles than AipsGOBP1 does in binding sex pheromones and host plant volatiles.

Taxonomy of Aulacochilus (Coleoptera: Erotylidae: Erotylinae) From China, with a Key Based on Adult Characters.

The history of taxonomy of Aulacochilus from China was reviewed. A key based on adult characters to separate the Chinese species of this genus is presented. A map of the collecting sites in China is given. One new species, Aulacochilus xingtaiensis sp. nov., from China is described and illustrated.