Odorant-Binding and Chemosensory Proteins in Fig Wasps: Evolutionary Insights From Comparative Studies.

Fig wasps (Agaonidae; Hymenoptera) are the only pollinating insects of fig trees (Ficus; Moraceae), forming the most closely and highly specific mutualism with the host. We used transcriptome sequences of 25 fig wasps from six genera to explore the evolution of key molecular components of fig wasp chemosensory genes: odorant-binding proteins (OBPs) and chemosensory proteins (CSPs). We identified a total 321 OBPs and 240 CSPs, with each species recording from 6 to 27 OBP genes and 6-19 CSP genes. 318 OBP genes are clustered into 17 orthologous groups and can be divided into two groups: PBP sensitive to pheromone and GOBP sensitive to general odor molecules, such as alcohols, esters, acids, ketones, and terpenoids. 240 CSP genes are clustered into 12 orthologous groups, which can be divided into three major groups and have functions, such as olfactory, tissue formation and/or regeneration, developmental, and some specific and unknown function. The gene sequences of most orthologous groups vary greatly among species and are consistent with the phylogenetic relationships between fig wasps. Strong purifying selection of both OBP and CSP genes was detected, as shown by low ω values. A positive selection was detected in one locus in CSP1. In conclusion, the evolution of chemosensory proteins OBPs and CSPs in fig wasps is relatively conservative, and they play an indispensable role in the life activities of fig wasps. Our results provide a starting point for understanding the molecular basis of the chemosensory systems of fig wasps.

The effects of mepiquat chloride (DPC) on the soluble protein content and the activities of protective enzymes in cotton in response to aphid feeding and on the activities of detoxifying enzymes in aphids.

BACKGROUND: Mepiquat chloride (DPC) enhances the resistance of cotton plants, and it is widely used as a growth regulator. DPC can stimulate photosynthesis, stabilize the structure of cotton leaves, and affect population reproduction and energy substances in Aphis gossypii Glover (cotton aphids), but interactions between DPC and cotton aphids remain unclear. In this study, we analyzed the physiological responses of cotton to DPC, and the toxicity of DPC toward cotton aphids, before and after feeding, to explore the DPC-induced defense mechanism against cotton aphids. RESULTS: Measurements of protective enzyme activity in cotton showed that the soluble protein contents, peroxidase (POD) activity, and catalase (CAT) activity in cotton treated with different concentrations of DPC were higher than in the control. Superoxide dismutase (SOD) activity was higher than that of the control when the concentration of DPC was < 0.1 g/L. Under aphid feeding stress, POD activity in cotton treated with a low insect population density was significantly lower than in the controls, but the reverse was true for cotton treated with a high insect population density, and SOD activity was positively correlated with population density. The activities of detoxification enzymes in field and laboratory experiments showed that DPC promoted the specific activity of glutathione S-transferase (GST) in cotton aphids, while the specific activities of carboxylesterase (CarE) and acetylcholinesterase (AchE) were decreased. CONCLUSIONS: DPC enhanced the aphid resistance in cotton by increasing the soluble protein content and the activity of protective enzymes. It also had a toxic effect on cotton aphids by increasing GST activity (the main DPC target). DPC increased the soluble protein content and protective enzymes activity in cotton under aphid stress, and thereby enhanced tolerance to cotton aphids. It conclude that DPC interferes with cotton aphids through indirect (DPC induced cotton defense responses) and direct (DPC toxicity to cotton aphids) ways, which plays a positive role in interfering with cotton aphids.

Low host specificity and broad geographical ranges in a community of parasitic non-pollinating fig wasps (Sycoryctinae; Chalcidoidea).

Plants, phytophagous insects and their parasitoids form the most diverse assemblages of macroscopic organisms on earth. Enclosed assemblages in particular represent a tractable system for studying community assembly and diversification. Communities associated with widespread plant species are especially suitable as they facilitate a comparative approach. Pantropical fig-wasp communities represent a remarkably well-replicated system, ideal for studying these historical processes. We expect high dispersal ability in non-pollinating fig wasps to result in lower geographical turnover in comparison to pollinating fig wasps. The ability of non-pollinating wasps to utilise a number of hosts (low host specificity) is a key determinant of overall geographical range, with intraspecific competition becoming a constraining factor should diet breadth overlap among species. Finally, we expect conserved community structure throughout the host range. We aim to test these expectations, derived from population genetic and community studies, using the multi-trophic insect community associated with Ficus hirta throughout its 3,500 km range across continental and insular Asia. We collect molecular evidence from one coding mitochondrial gene, one non-coding nuclear gene and multiple microsatellites across 25 geographical sites. Using these data, we establish species boundaries, determine levels of host specificity among non-pollinating fig wasps and quantify geographical variation in community composition. We find low host specificity in two genera of non-pollinating fig wasps. Functional community structure is largely conserved across the range of the host fig, despite limited correspondence between the ranges of non-pollinator and pollinator species. While nine pollinators are associated with Ficus hirta, the two non-pollinator tribes developing in its figs each contained only four species. Contrary to predictions, we find stronger isolation by distance in non-pollinators than pollinators. Long-lived non-pollinators may disperse more gradually and be less reliant on infrequent long-distance dispersal by wind currents. Segregation among non-pollinating species across their range is suggestive of competitive exclusion and we propose that this may be a result of increased levels of local adaptation and moderate, but regular, rates of dispersal. Our findings provide one more example of lack of strict codiversification in the geographical diversification of plant-associated insect communities.

Multiple parapatric pollinators have radiated across a continental fig tree displaying clinal genetic variation.

The ways that plant-feeding insects have diversified are central to our understanding of terrestrial ecosystems. Obligate nursery pollination mutualisms provide highly relevant model systems of how plants and their insect associates have diversified and the over 800 species of fig trees (Ficus) allow comparative studies. Fig trees can have one or more pollinating fig wasp species (Agaonidae) that breed within their figs, but factors influencing their number remain to be established. In some widely distributed fig trees, the plants form populations isolated by large swathes of sea, and the different populations are pollinated by different wasp species. Other Ficus species with continuous distributions may present genetic signatures of isolation by distance, suggesting more limited pollinator dispersal, which may also facilitate pollinator speciation. We tested the hypothesis that Ficus hirta, a species for which preliminary data showed genetic isolation by distance, would support numerous pollinator species across its range. Our results show that across its range F. hirta displays clinal genetic variation and is pollinated by nine parapatric species of Valisia. This is the highest number of pollinators reported to date for any Ficus species, and it is the first demonstration of the occurrence of parapatric pollinator species on a fig host displaying continuous genetic structure. Future comparative studies across Ficus species should be able to establish the plant traits that have driven the evolution of pollinator dispersal behaviour, pollinator speciation and host plant spatial genetic structure.

Myricetin ameliorates the symptoms of collagen-induced arthritis in mice by inhibiting cathepsin K activity.

Myricetin, a common dietary flavonoid, is widely distributed in fruits and vegetables. It is known to be a food supplement contributing to human health because of its immune modulatory function, and its antioxidation, antitumor, and anti-inflammatory properties. In the present study, myricetin was shown to directly inhibit cathepsin K activity, a highly potent collagenase, which is the predominant papain-like cysteine protease expressed in osteoclasts and synovial fibroblasts. It was shown that the IC50 of myricetin for the recombinant human cathepsin was 585.3 µmol/L. Also, myricetin proved to have positive effects in murine collagen-induced arthritis (CIA). Mice suffering from CIA received a daily dose of myricetin (25 mg/kg, per os). During the study, the clinical severity of the CIA and the histopathology were evaluated. Biomarkers related to the histological evaluation of cartilage degradation, namely deoxypyridinoline, cartilage oligomeric matrix protein and C-terminal telopeptide degradation product of type I collagen (CTX-I), were analyzed. Myricetin treatment reduced the levels of biomarkers indicative of cartilage degradation (p < 0.05) and ameliorated the symptoms of CIA in mice at the clinical level (p < 0.01). As the inhibitory effect of myricetin on cathepsin K activity induced beneficial effects on CIA in mice, further investigation of therapeutic interventions with myricetin in other mammals or in human rheumatoid arthritis is recommended.

Characterization of a novel exported esterase Rv3036c from Mycobacterium tuberculosis.

Mycobacterium tuberculosis possesses an unusually high number of genes involved in the metabolism of lipids. Driven by a newly described esterase motif SXXK in the amino acid sequence and a predicted signal peptide, the gene rv3036c from M. tuberculosis was cloned and characterized biochemically. Rv3036c efficiently hydrolyzes soluble p-nitrophenyl esters but not emulsified lipid. The highest activity of this enzyme was observed when p-nitrophenyl acetate (C2) was used as the substrate. Based on the activities, Rv3036c was classified as a nonlipolytic hydrolase. The results of immunoreactivity studies on the subcellular mycobacterial fractions suggested that the enzyme was present in the cell wall and cell membrane in mycobacteria. In summary, Rv3036c was characterized as a novel cell wall-anchored esterase from M. tuberculosis.

Prognostic model for hepatocellular carcinoma based on necroptosis-related genes and analysis of drug treatment responses.

Objective: Recent studies reveal that necroptosis is pivotal in tumorigenesis, cancer metastasis, cancer immunity, and cancer subtypes. Apoptosis or necroptosis of hepatocytes in the liver microenvironment can determine the subtype of liver cancer. However, necroptosis-related genomes have rarely been analyzed in hepatocellular carcinoma (HCC). Therefore, this study aims to construct an HCC risk scoring model based on necroptosis-related genes and to validate its predictive performance in overall survival prediction and immunotherapy efficacy evaluation in HCC, as well as to analyze drug treatment responses. Methods: This study analyzed clinical information and RNA-seq expression data of liver cancer patients from TCGA public data, identified necroptosis-related genes, and conducted GO and KEGG enrichment analyses. Using Cox regression analysis and LASSO analysis to identify independent prognostic factors, a predictive model was established and validated in clinical subgroups, and correlation analysis with immune cells and ssGSEA differential analysis were conducted. Finally, potential drugs for HCC were screened to explore the drug sensitivity of different subtypes. Results: We identified 19 differentially expressed necroptosis-related genes and constructed a predictive model with 3 independent prognostic factors through stepwise Cox regression. Validation results from clinical subgroups showed that the constructed model performed well in risk prediction, and ssGSEA differential analysis results were significant. We analyzed 55 immunotherapy drugs, and clustered them by distinct IC50 values to guide drug selection for HCC patients. Notable, Bleomycin, Obatoclax. Mesylate, PF.562271, PF.02341066, QS11, X17. AAG, and Bl. D1870 exhibited significantly different sensitivities in different subtypes, providing references for clinical practice in HCC patients.

Effectiveness of Paxlovid in the treatment of the SARS-CoV-2 Omicron variant infection in children with hematologic malignancies: a retrospective cohort study.

Background: Patients with hematologic malignancies (HMs) may be immunocompromised after receiving anti-tumor therapy. Those who also have the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infection face many challenges, including a lack of effective antiviral drugs. This study aimed to investigate the clinical features of the SARS-CoV-2 Omicron variant infection in children with HMs, and the effectiveness of Paxlovid. Methods: A retrospective, non-randomized study was conducted on pediatric patients with HMs infected with the SARS-CoV-2 Omicron variant who had been admitted to the Shanghai Children's Medical Center, Shanghai, China from December 1, 2022 to March 1, 2023. The Paxlovid-treated group (Group P) comprised 21 patients, and the non-Paxlovid-treated group (Group N) comprised 21 patients. The patients' demographic data, clinical features, and therapeutic outcomes were collected. Statistical tests were used to evaluate the effectiveness of the treatment and related factors. Results: The clinical course of the SARS-CoV-2 Omicron variant infection for most of the children with HMs was non-severe (97.6%), and only one child progressed to severe disease (2.4%). The most common symptoms were fever (66.7%) and cough (52.4%). Compared with the children in Group N, those in Group P had worse clinical characteristics, including those who previously underwent hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor T (CAR-T) cell treatment (71.4% vs. 28.6%, P=0.005), and those in the myelosuppressive phase (57.1% vs. 4.8%, P<0.001). Most of the children in Group P were treated with more than two types of antibiotics (76.2% vs. 42.9%, P=0.02). The patients treated with Paxlovid within 5 days of diagnosis had a median viral clearance time of 5 days [interquartile range (IQR), 4-8 days], which was significantly shorter than that of the patients who were not treated with Paxlovid (P=0.03). There were no significant differences in the clinical outcomes between the two groups after the propensity score matching (PSM) analyses. Eight patients (19%) had repeat-positive (re-positive) test results. No factor was found to be statistically significant in predicting re-positive test results based on the binary logistic regression analysis. Conclusions: Administering Paxlovid within 5 days of the diagnosis of the SARS-CoV-2 Omicron variant infection in children may effectively shorten the clearance time of the virus, but there is still the possibility the patients may have re-positive test results.

Janus mesoporous organosilica/platinum nanomotors for active treatment of suppurative otitis media.

We report a Janus mesoporous organosilica/platinum (MOS/Pt) nanomotor for active targeted treatment of suppurative otitis media, as a new type of multi-functional ear drop. The efficient propulsion of MOS/Pt nanomotors in hydrogen peroxide ear-cleaning drops significantly improves their binding efficiency with Staphylococcus aureus and enhances their antibacterial efficacy.

Crizotinib resistance reversal in ALK-positive lung cancer through zeolitic imidazolate framework-based mitochondrial damage.

Crizotinib (CRZ), one of anaplastic lymphoma kinase tyrosine kinase inhibitors (ALK-TKIs), has emerged as a frontline treatment for ALK-positive (ALK+) lung adenocarcinoma. However, the overexpression of P-glycoprotein (P-gp, a mitochondrial adenosine triphosphate (ATP)-dependent protein) in lung adenocarcinoma lesions causes multidrug resistance (MDR) and limits the efficacy of CRZ treatment. Herein, a mitochondria-targeting nanosystem, zeolitic imidazolate framework-90@indocyanine green (ZIF-90@ICG), was fabricated to intervene in mitochondria and overcome drug resistance. Due to the zinc ion (Zn2+) interference of ZIF-90 and the photodynamic therapy (PDT) of ICG, this nanosystem is well suited for damaging mitochondrial functions, thus downregulating the intracellular ATP level and inhibiting P-gp expression. In addition, systematic bioinformatics analysis revealed the upregulation of CD44 in CRZ-resistant cells. Therefore, hyaluronic acid (HA, a critical target ligand of CD44) was further modified on the surface of ZIF-90@ICG for active targeting. Overall, this ZIF-90@ICG nanosystem synergistically increased the intracellular accumulation of CRZ and reversed CRZ resistance to enhance its anticancer effect, which provides guidance for nanomedicine design to accurately target tumours and induce mitochondrial damage and represents a viable regimen for improving the prognosis of patients with ALK-TKIs resistance. STATEMENT OF SIGNIFICANCE: The original aim of our research was to combat multidrug resistance (MDR) in highly aggressive and lethal lymphoma kinase-positive (ALK+) lung adenocarcinoma. For this purpose, a cascade-targeted system was designed to overcome MDR, integrating lung adenocarcinoma-targeted hyaluronic acid (HA), mitochondrion-targeted zeolitic imidazolate framework-90 (ZIF-90), the clinically approved drug crizotinib (CRZ), and the fluorescence imaging agent/photosensitizer indocyanine green (ICG). Moreover, using a "two birds with one stone" strategy, ion interference and oxidative stress induced by ZIF-90 and photodynamic therapy (PDT), respectively, disrupt mitochondrial homeostasis, thus downregulating adenosine triphosphate (ATP) levels, inhibiting MDR-relevant P-glycoprotein (P-gp) expression and suppressing tumour metastasis. Overall, this research represents an attempt to implement the concept of MDR reversal and realize the trade-offs between MDR and therapeutic effectiveness.

The genetic structuring in pollinating wasps of Ficus hispida in continental Asia.

The interaction between figs and fig wasps provides a striking example of obligate brood site pollination mutualism. Monoecious figs, constituting independent radiations in each tropical biome, are present in significant proportions worldwide, but in continental Asia, dioecious figs have diverged into various niches, making the region's assemblage remarkably diverse. However, the reproductive success of figs and fig wasps largely depends on the fig wasp dispersal process. Monoecious fig pollinators in continental Asian tropical rain forests exhibit high gene flow of the plant, while many dioecious fig pollinators have a more restricted gene flow. However, there are limited studies on the genetic structure of dioecious Ficus pollinators that pollinate figs with intermediate gene flow. Here, we used molecular methods to investigate the genetic structure of pollinating wasps of the widely distributed dioecious Ficus hispida in China and Southeast Asia. Sequence data from two gene regions were used: the mitochondrial protein-coding gene cytochrome c oxidase subunit I (COI) and the nuclear 28S genes. Both molecular and morphological results support two fig wasp species at our sampling sites. Our findings suggest that for widely sympatric Ficus species in continental Asia, monoecious figs presenting long gene glow have the fewest fig wasp species, followed by dioecious figs presenting intermediate gene flow, and dioecious figs presenting local gene flow have the most fig wasp species.

Efficacy of ß2-adrenergic receptor agonist combined with corticosteroid in the treatment of children with cough variant asthma.

BACKGROUND: Cough variant asthma (CVA) is one of the most common respiratory diseases in children, which has a serious impact on the quality of life and daily activities of children. For severe CVA, immunomodulatory drugs are needed. AIM: To evaluate the efficacy of salmeterol combined with budesonide in the treatment of pediatric CVA. METHODS: 130 children with CVA from January 2020 to December 2022 were prospectively selected and randomly divided into an observation group (salmeterol combined with budesonide) and a control group (budesonide combined with a placebo). Compare the clinical efficacy of two groups before and after intervention. The evaluation parameters include cough frequency score, nocturnal cough arousal, and lung function indicators. Serum inflammatory markers, immune function markers and airway anatomical indicators were also measured. RESULTS: After the intervention, the total effective rate of the observation group was significantly higher than that of the control group, and the cough frequency score and the night cough wake rate of the observation group were lower than that of the control group, with a statistically significant difference. In addition, the changes of lung function indicators, serum markers and immune function markers in the observation group were better than those in the control group. CONCLUSION: The clinical efficacy of salmeterol combined with Budesonide in the treatment of CVA is better than that of Budesonide alone.

Olfactory and gustatory receptor genes in fig wasps: Evolutionary insights from comparative studies.

The mechanisms of chemoreception in fig wasps (Hymenoptera, Agaonidae) are of primary importance in their co-evolutionary relationship with the fig trees they pollinate. We used transcriptome sequences of 25 fig wasps in six genera that allowed a comparative approach to the evolution of key molecular components of fig wasp chemoreception: their odorant (OR) and gustatory (GR) receptor genes. In total, we identified 311 ORs and 47 GRs, with each species recording from 5 to 30 OR genes and 1-4 GR genes. 304 OR genes clustered into 18 orthologous groups known to be sensitive to cuticular hydrocarbons (CHC), pheromones, acids, alcohols and a variety of floral scents such as cineole, Linalool, and Heptanone. 45 GR genes clustered into 4 orthologous groups that contain sweet, bitter, CO2 and undocumented receptors. Gene sequences in most orthologous groups varied greatly among species, except for ORco (60.0% conserved) and sweet receptors (30.7% conserved). Strong purifying selection of both odorant and gustatory genes was detected, as shown by low ω values. Signatures of positive selection were detected in loci from both OR and GR orthologous groups. Fig wasps have relatively few olfactory and especially gustatory receptors, reflecting the natural history of the system. Amino acid sequences nonetheless vary significantly between species and are consistent with the phylogenetic relationships among fig wasps. The differences in ORs within some orthologous groups from the same species, but different hosts and from closely related species from one host can reach as low as 49.3% and 9.8% respectively, implying the ORs of fig wasps can evolve rapidly to novel ecological environments. Our results provide a starting point for understanding the molecular basis of the chemosensory systems of fig wasps.

CoVnita, an end-to-end privacy-preserving framework for SARS-CoV-2 classification.

Classification of viral strains is essential in monitoring and managing the COVID-19 pandemic, but patient privacy and data security concerns often limit the extent of the open sharing of full viral genome sequencing data. We propose a framework called CoVnita, that supports private training of a classification model and secure inference with the same model. Using genomic sequences from eight common SARS-CoV-2 strains, we simulated scenarios where the data was distributed across multiple data providers. Our framework produces a private federated model, over 8 parties, with a classification AUROC of 0.99, given a privacy budget of [Formula: see text]. The roundtrip time, from encryption to decryption, took a total of 0.298 s, with an amortized time of 74.5 ms per sample.

A chromosome-level genome assembly of the pollinating fig wasp Valisia javana.

Fig wasp has always been thought the species-specific pollinator for their host fig (Moraceae, Ficus) and constitute a model system with its host to study co-evolution and co-speciation. The availability of a high-quality genome will help to further reveal the mechanisms underlying these characteristics. Here, we present a high-quality chromosome-level genome for Valisa javana developed by a combination of PacBio long-read and Illumina short-read. The assembled genome size is 296.34 Mb from 13 contigs with a contig N50 length of 26.76 kb. Comparative genomic analysis revealed expanded and positively selected genes related to biological features that aid fig wasps living in syconium of its highly specific host. Protein-coding genes associated with chemosensory, detoxification and venom genes were identified. Several differentially expressed genes in transcriptome data of V. javana between odor-stimulated samples and the controls have been identified in some olfactory signal transduction pathways, e.g. olfactory transduction, cAMP, cGMP-PKG, Calcim, Ras and Rap1. This study provides a valuable genomic resource for a fig wasp, and sheds insight into further revealing the mechanisms underlying their adaptive traits to their hosts in different places and co-speciation with their host.

Asymmetric sharing of pollinator fig wasps between two sympatric dioecious fig trees: a reflection of supply and demand or differences in the size of their figs?

BACKGROUND: Host specificity among pollinator fig wasps (Agaonidae) depends on host plant specific volatile cues, but fig wasps must also pass through a narrow physical barrier (the ostiole) if they are to pollinate and oviposit. Across South East Asia the dioecious shrub Ficus hirta is associated with at least ten pollinator species allied to Valisia javana. Ficus triloba has a single recorded pollinator, Valisia esquirolianae. Receptive figs of F. hirta are usually much smaller than those of F. triloba, but at a mainland site where F. hirta has atypically large figs we identified both V. esquirolianae and V. javana from both Ficus species using COI and ITS2 sequencing. To investigate whether this host overlap was exceptional we reared fig wasps from the two trees elsewhere and recorded features that may facilitate host transfer between them, including attractant volatiles, reproductive phenology and the sizes of their figs and fig wasps. RESULTS: The two Ficus species were found to support both Valisia species at several of the sites, suggesting that the differences we detected in volatile profiles, ostiole sizes and pollinator head sizes are not strict barriers to host sharing. Valisia javana colonised F. triloba more frequently than V. esquirolianae colonised F. hirta. CONCLUSIONS: This asymmetric sharing of pollinators may reflect the relative abundance of the two species of fig wasps and differences in host reproductive phenology. Asynchronous flowering of individual F. hirta may favor local retention of pollinators, in contrast to the tree-wide synchrony of F. triloba figs, which can generate local shortages of V. esquirolianae. If the pollinator sharing by male figs of F. triloba and F. hirta also occurs in female figs then this could result in gene flow between them.

[Advances in the mechanism of plant adaptation to acid aluminum stress].

The aluminum stress in acidic soil areas of China is an important abiotic stress factor that hampers the normal growth and development of plants and seriously affects the agricultural yield. The forms of plant resistance to aluminum stress are complex and diverse, which include secretion of organic acids, increase of rhizosphere pH, secretion of mucus, cell wall fixation of Al3+, organic acid chelation of Al3+ in cell solute, and vacuolar area isolation. Most of studies focus on analyzing conventional physiological characteristics, but in-depth molecular biological analyses are lacking. This review summarizes the mechanisms how plants adapt to acidic aluminum stress. This includes the effect of acid aluminum stress on plant growth and physiological metabolism, the two main physiological mechanisms of plant adaptation to acid aluminum stress (aluminum exclusion mechanism, aluminum tolerance mechanism), and the aluminum resistance related genes. Finally, this paper puts forward some prospects for further revealing the mechanism of plant adaptation to acid aluminum stress and excavating high-quality crops suitable for cultivation in acidic soils.

Overlaps in olfactive signalling coupled with geographic variation may result in localised pollinator sharing between closely related Ficus species.

BACKGROUND: In brood site pollination mutualisms, pollinators are attracted by odours emitted at anthesis. In Ficus, odours of receptive figs differ among species and the specific pollinators generally only enter figs of their host species ensuring a pre-zygotic barrier to plant interspecific hybridisation. However, field observations recorded that, in Guangdong province in China, Valisia javana hilli, the local pollinator of F. hirta, entered and reproduced successfully in the figs of the closely related F. triloba on a regular basis. We propose that closely related Ficus species produce similar receptive fig odours. Under particular contexts of odours locally present, the receptive fig odours of non-host figs of a Ficus species may become attractive to pollinators of closely related Ficus species. We used the headspace technique to collect in situ receptive fig odours of F. triloba in a series of locations in China. Under controlled conditions, we tested the attraction of fig pollinating wasps from F. hirta and F. triloba to host figs and non-host figs in Y tube experiments. RESULTS: Receptive fig odours of F. triloba though different from those of F. hirta, were mainly composed of a same set of volatile organic compounds. When given the choice between receptive fig odours and air, the pollinating wasps were only attracted by their host's odours. However, when given a choice between host and non-host figs the pollinators of F. hirta were equally attracted by the two odours while the pollinators of F. triloba tended to be more attracted by their host's fig odours. CONCLUSIONS: Receptive fig odours vary geographically within species and the differentiation of receptive fig odours between closely related Ficus species is often incomplete. This allows localised or occasional pollinator sharing following different modalities. Cross stimulation when wasps are exposed simultaneously to odours of host and non-host species may be important. While occasional pollinator sharing may play a marginal role when wasp populations are robust, it may ensure the provisioning of new pollinators from the closest relative of a Ficus species if its pollinators go extinct.

Author Correction: Chemical signal is in the blend: bases of plant-pollinator encounter in a highly specialized interaction.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Chemical signal is in the blend: bases of plant-pollinator encounter in a highly specialized interaction.

In several highly specialized plant-insect interactions, scent-mediated specificity of pollinator attraction is directed by the emission and detection of volatile organic compounds (VOCs). Although some plants engaged in such interactions emit singular compounds, others emit mixtures of VOCs commonly emitted by plants. We investigated the chemical ecological bases of host plant recognition in the nursery pollination mutualism between the dioecious Ficus carica and its specific pollinator Blastophaga psenes. Using Y-tube olfactometer tests, we show that B. psenes females are attracted by VOCs of receptive figs of both sexes and do not exhibit preference for VOCs of either male or female figs. Electrophysiological tests and chemical analysis revealed that of all the VOCs emitted by receptive figs, only five were found to be active on female antennae. Behavioural tests show that, in contrast to VOCs presented alone, only a blend with a particular proportion of four of these VOCs is as attractive as the odour of receptive figs, and that if there is a very small change in this blend proportion, the pollinator is no longer attracted. This study revealed that in highly specialized mutualistic interactions specificity could be mediated by a particular blend of common compounds emitted by plants.