Olfactory Responses of Tomicus yunnanensis to Different Non-host Plants

[ Objective ] With Cupressustorulosa, Cinnamomum camphora and Cyclobalanopsis Oerst as test materials, the paper studied the effects of different non- host plants on olfactory responses of Tomicus yunnanensis. [ Method ] The needles of Pinus yunnanensis were mixed with the leaves of Cupressustondosa, C. cam- phora and C. Oerst according to the ratios of 0 g ： 6 g, 1 g ： 5 g, 2 g ： 4 g, 3 g ： 3 g, 4 g ： 2 g, 5 g ： 1 g and 6 g ： 0 g, and the mixtures were put in the re- spanse arm of Y-tube olfactometer as odor source to observe the olfactory behavior of T. yunnanensis, the empty arm was set as control. [ Result ] When the needles of P. yunnanensis were mixed with the leaves of non-hest plants according to the ratio of 1 g ： 5 g and 2 g ： 4 g, they had less difference on attractive rate to T. yun- nanensis compared with complete P. yunnanensis needles in mixture （ratio： 6 g ： 0 g）, and the maximum difference was 14%. When the needles ofP. yunnanen- sis were mixed with non-host leaves according to the ratio of 1 g ： 5 g, 2 g ： 4 g, the attractive rate to T. yunnanensis decreased compared with complete P. yun- nanensis needles in mixture （ ratio： 6 g ： 0 g）, and the decrease value in maximum was 40%. [ Conclusion] When the ratio of non-host plants was relatively small in mixed leaves, non-host had less impact on olfactory responses of T. yunnanensis. As the proportion of non-hest leaves gradually increased, the attractive rate of leaf mixtures to T. yunnanensis was gradually small. The results could provide reference for determination of mixed ratio in construction of mixed forest and the de- velopment of botanical attractive and repellent of T. yunnanensis.

Roles of the main olfactory and vomeronasal systems in the detection of androstenone in inbred strains of mice

We investigated the role of the main olfactory and accessory olfactory systems （MOS and AOS respectively） in the detection of androstenone. We used the following experimental approaches： behavioral, surgical removal of the vomeronasal organ （VNX） followed by histochemical verification and Fos immunohistochemistry. Using a Y-maze paradigm we estimated sensitivity of NZB/B1NJ and CBA/J mice to androstenone. CBA mice were 2,000-fold more sensitive to androstenone than NZB mice. VNX caused a 4-tol6-fold decrease in sensitivity to androstenone in highly-sensitive CBA mice, but did not affect thresholds in NZB mice. Results indicate the involvement of the MOS and AOS in the detection of androstenone. We observed a specific pattern of Fos-positive cells in the main olfactory bulb of CBA mice but not in NZB mice subsequent to exposure of mice to androstenone; the compound activated cells in the accessory olfactory bulb in both strains of mice, indicating the involvement of the vomeronasal organ. Patterns of Fos-positive cells in the vomeronasal organ were recorded subsequent to exposure to androstenone. Fos-positive receptor cells in the vomeronasal organ of CBA and NZB mice were different, in CBA mice Fos-positive cells were noted in both the basal and apical zones, however, in NZB mice activation was observed only in the apical zone [Current Zoology 56 （6）： 813-818, 2010].

Mutagenesis of odorant coreceptor Orco reveals the distinct role of olfaction between sexes in Spodoptera frugiperda

Odorant receptor(OR)is crucial for insects to detect and recognize external chemical cues closely related to their survival.The insect OR forms a heteromeric complex composed of a ligand-specific receptor and a ubiquitously odorant receptor coreceptor(Orco).This study used the CRISPR/Cas9 technique to knock out(KO)Orco and reveal its essential role in acting on OR-meditated olfactory behavior in a critical invasive agricultural pest,the fall armyworm(FAW),Spodoptera frugiperda.Electroantennogram(EAG)results suggested that the Orco mutants of both male and female moths severely reduced their electrophysiological responses to the eight tested plant volatiles and two sex pheromones.However,the Orco gene played distinct roles in mating behavior between sexes:the mating behavior was fully disrupted in mutated males but not in mutated females.The oviposition result indicated that the Orco KO females displayed reduced egg laying by 24.1%compared with the mated wild type(WT)females.Overall,these results strongly suggest that Orco is an excellent target for disrupting FAW’s normal behavior and provides a feasible pest control approach.

Expression and functional characterization of odorant-binding protein 2 in the predatory mite Neoseiulus barkeri

Olfaction plays a crucial role for arthropods in foraging,mating,and oviposition.The odorant-binding protein(OBP)gene is considered one of the most important olfactory genes.However,little is known about its functions in predatory mites.Here,we used Neoseiulus barkeri,an important commercialized natural pest control,to explore the chemosensory characteristics of OBP.In this study,N.barkeri was attracted by methyl salicylate(MeSA)and showed higher crawling speeds under MeSA treatment.Then,we identified and cloned an OBP gene named Nbarobp2 and analyzed its expression profiles in the predatory mite.Nbarobp2 was 663 bp,was highly expressed in larval and nymphal stages,and was significantly upregulated in N.barkeri under MeSA treatment.Nbarobp2 encoded 202 amino acid residues with a molecular weight of 23 kDa(after removing the signal peptide).Sequence comparisons revealed that the OBPs in Arachnida shared 6 conserved cysteine sites,but were distinguishable from the OBPs of Insecta on the phylogenetic tree.RNA interference,Western blotting,and binding affinity assays further proved that Nbarobp2 was involved in volatile perception in predatory mites.This study shed light on the functional characteristics of OBPs in predatory mites,providing a new insight for better biological control.