Population genetic differentiation and phenotypic plasticity of Ambrosia artemisiifolia under different nitrogen levels.

Rapid adaptive evolution and phenotypic plasticity are two mechanisms that often underlie invasiveness of alien plant species, but whether they can co-occur within invasive plant populations under altered environmental conditions such as nitrogen (N) enrichment has seldom been explored. Latitudinal clines in plant trait responses to variation in environmental factors may provide evidence of local adaptation. Here, we inferred the relative contributions of phenotypic plasticity and local adaptation to the performance of the invasive plant Ambrosia artemisiifolia under different soil N levels, using a common garden approach. We grew A. artemisiifolia individuals raised from seeds that were sampled from six invasive populations along a wide latitudinal cline in China (23°42' N to 45°43' N) under three N (0, 5, and 10 g N m-2 ) levels in a common garden. Results show significant interpopulation genetic differentiation in plant height, number of branches, total biomass, and transpiration rate of the invader A. artemisiifolia across the N treatments. The populations also expressed genetic differentiation in basal diameter, growth rate, leaf area, seed width, root biomass, aboveground biomass, stomatal conductance, and intercellular CO2 concentration regardless of N treatments. Moreover, plants from different populations of the invader displayed plastic responses in time to first flower, hundred-grain weight, net photosynthetic rate, and relative biomass allocation to roots and shoots and seed length under different N treatments. Additionally, individuals of A. artemisiifolia from higher latitudes grew shorter and allocated less biomass to the roots regardless of N treatment, while latitudinal cline (or lack thereof) in other traits depended on the level of N in which the plants were grown. Overall, these results suggest that rapid adaptive evolution and phenotypic plasticity in the various traits that we quantified may jointly contribute to invasiveness of A. artemisiifolia under different levels of N availability. More broadly, the results support the idea that phenotypic plasticity and rapid adaptive evolution can jointly enable invasive plants to colonize a wide range of environmental conditions.

Sublingual immunotherapy tablets in monosensitized and polysensitized adults with allergic rhinoconjunctivitis.

Background: Most patients with allergic rhinitis/conjunctivitis (AR/C) are sensitized to more than one allergen. An ongoing question is the efficacy of single-allergen immunotherapy in patients who are polysensitized. Objective: To evaluate the efficacy and safety of grass, ragweed, tree, and house-dust mite (HDM) sublingual immunotherapy (SLIT) tablets in adults with AR/C who are mono- or polysensitized. Methods: Data from adults (ages ≥ 18 years) with AR/C who participated in phase III double-blind, placebo controlled field trials (four grass, two ragweed, two HDM, one tree) were included in the post hoc analyses. Efficacy was assessed by the total combined score (TCS) (sum of AR/C daily symptom and medication scores) during the entire pollen season for grass and tree trials, and peak pollen season for ragweed trials versus placebo. Efficacy for the HDM SLIT-tablet was assessed by the total combined rhinitis score (TCRS) (sum of rhinitis daily symptom and medication scores) during the last 8 weeks of treatment versus placebo. Results: For the grass SLIT-tablet, TCS improved by 20% (mean difference 1.33 [95% confidence interval {CI}, 0.44-2.22]) in the subjects who were monosensitized (n = 442) and 20% (mean difference 1.28 [95% CI, 0.90-1.67]) in the subjects who were polysensitized (n = 1857). For the ragweed SLIT-tablet, TCS improved by 19% (mean difference 1.72 [95% CI, -0.20 to 3.63]) in the subjects who were monosensitized (n = 115) and 27% (mean difference 2.27 [95% CI, 1.28-3.27]) in the subjects who were polysensitized (n = 528). For the tree SLIT-tablet, TCS improved by 54% (mean difference 4.65 [95% CI, 2.48-6.82]) in the subjects who were monosensitized (n = 138) and 34% (mean difference 2.51 [95% CI, 1.34-3.69]) in the subjects who were polysensitized (n = 437). For the HDM SLIT-tablet, TCRS improved by 20% (mean difference 1.24 [95% CI, 0.48-1.99]) in the subjects who were monosensitized (n = 468) and 17% (mean difference 0.85 [95% CI, 0.43-1.28]) in the subjects who were polysensitized (n = 1294). The overall safety profile was not qualitatively different between the subjects who were monosensitized and the subjects who were polysensitized. Conclusion: Grass, ragweed, tree, or HDM SLIT-tablet treatment is effective for the specific allergen in question in adults with AR/C and who are monosensitized or polysensitized. Targeting one relevant allergen with SLIT-tablets induces a clinical effect for that allergen in patients who were polysensitized.

Radiation-Detoxified Form of Endotoxin Effectively Activates Th1 Responses and Attenuates Ragweed-Induced Th2-Type Airway Inflammation in Mice.

Urbanization with reduced microbial exposure is associated with an increased burden of asthma and atopic symptoms. Conversely, environmental exposure to endotoxins in childhood can protect against the development of allergies. Our study aimed to investigate whether the renaturation of the indoor environment with aerosolized radiation-detoxified lipopolysaccharide (RD-LPS) has a preventative effect against the development of ragweed-induced Th2-type airway inflammation. To explore this, cages of six-week-old BALB/c mice were treated daily with aerosolized native LPS (N-LPS) or RD-LPS. After a 10-week treatment period, mice were sensitized and challenged with ragweed pollen extract, and inflammatory cell infiltration into the airways was observed. As dendritic cells (DCs) play a crucial role in the polarization of T-cell responses, in our in vitro experiments, the effects of N-LPS and RD-LPS were compared on human monocyte-derived DCs (moDCs). Mice in RD-LPS-rich milieu developed significantly less allergic airway inflammation than mice in N-LPS-rich or common environments. The results of our in vitro experiments demonstrate that RD-LPS-exposed moDCs have a higher Th1-polarizing capacity than moDCs exposed to N-LPS. Consequently, we suppose that the aerosolized, non-toxic RD-LPS applied in early life for the renaturation of urban indoors may be suitable for the prevention of Th2-mediated allergies in childhood.

Insect Cell-Expressed Major Ragweed Allergen Amb a 1.01 Exhibits Similar Allergenic Properties to Its Natural Counterpart from Common Ragweed Pollen.

Common ragweed pollen allergy has become a health burden worldwide. One of the major allergens in ragweed allergy is Amb a 1, which is responsible for over 90% of the IgE response in ragweed-allergic patients. The major allergen isoform Amb a 1.01 is the most allergenic isoform in ragweed pollen. So far, no recombinant Amb a 1.01 with similar allergenic properties to its natural counterpart (nAmb a 1.01) has been produced. Hence, this study aimed to produce a recombinant Amb a 1.01 with similar properties to the natural isoform for improved ragweed allergy management. Amb a 1.01 was expressed in insect cells using a codon-optimized DNA construct with a removable N-terminal His-Tag (rAmb a 1.01). The recombinant protein was purified by affinity chromatography and physicochemically characterized. The rAmb a 1.01 was compared to nAmb a 1.01 in terms of the IgE binding (enzyme-linked immunosorbent assay (ELISA), immunoblot) and allergenic activity (mediator release assay) in well-characterized ragweed-allergic patients. The rAmb a 1.01 exhibited similar IgE reactivity to nAmb a 1.01 in different IgE-binding assays (i.e., IgE immunoblot, ELISA, quantitative ImmunoCAP inhibition measurements). Furthermore, the rAmb a 1.01 showed comparable dose-dependent allergenic activity to nAmb a 1.01 regarding basophil activation. Overall, the results showed the successful expression of an rAmb a 1.01 with comparable characteristics to the corresponding natural isoform. Our findings provide the basis for an improvement in ragweed allergy research, diagnosis, and immunotherapy.

Non-Specific Lipid Transfer Protein Amb a 6 Is a Source-Specific Important Allergenic Molecule in Ragweed Pollen.

Pollen from common ragweed is an important allergen source worldwide and especially in western and southern Romania. More than 100 million patients suffer from symptoms of respiratory allergy (e.g., rhinitis, asthma) to ragweed pollen. Among the eleven characterized allergens, Amb a 6 is a non-specific lipid transfer protein (nsLTP). nsLTPs are structurally stable proteins in pollen and food from different unrelated plants capable of inducing severe reactions. The goal of this study was to produce Amb a 6 as a recombinant and structurally folded protein (rAmb a 6) and to characterize its physicochemical and immunological features. rAmb a 6 was expressed in Spodoptera frugiperda Sf9 cells as a secreted protein and characterized by mass spectrometry and circular dichroism (CD) spectroscopy regarding molecular mass and fold, respectively. The IgE-binding frequency towards the purified protein was evaluated using sera from 150 clinically well-characterized ragweed-allergic patients. The allergenic activities of rAmb a 6 and the nsLTP from the weed Parietaria judaica (Par j 2) were evaluated in basophil activation assays. rAmb a 6-specific IgE reactivity was associated with clinical features. Pure rAmb a 6 was obtained by insect cell expression. Its deduced molecular weight corresponded to that determined by mass spectrometry (i.e., 10,963 Da). rAmb a 6 formed oligomers as determined by SDS-PAGE under non-reducing conditions. According to multiple sequence comparisons, Amb a 6 was a distinct nsLTP with less than 40% sequence identity to currently known plant nsLTP allergens, except for nsLTP from Helianthus (i.e., 52%). rAmb a 6 is an important ragweed allergen recognized by 30% of ragweed pollen allergic patients. For certain patients, rAmb a 6-specific IgE levels were higher than those specific for the major ragweed allergen Amb a 1 and analysis also showed a higher allergenic activity in the basophil activation test. rAmb a 6-positive patients suffered mainly from respiratory symptoms. The assumption that Amb a 6 is a source-specific ragweed allergen is supported by the finding that none of the patients showing rAmb a 6-induced basophil activation reacted with Par j 2 and only one rAmb a 6-sensitized patient had a history of plant food allergy. Immunization of rabbits with rAmb a 6 induced IgG antibodies which strongly inhibited IgE binding to rAmb a 6. Our results demonstrate that Amb a 6 is an important source-specific ragweed pollen allergen that should be considered for diagnosis and allergen-specific immunotherapy of ragweed pollen allergy.

The Essential Oil Compositions of Ambrosia acanthicarpa Hook., Artemisia ludoviciana Nutt., and Gutierrezia sarothrae (Pursh) Britton & Rusby (Asteraceae) from the Owyhee Mountains of Idaho.

As part of our interest in the volatile phytoconstituents of aromatic plants of the Great Basin, we have obtained essential oils of Ambrosia acanthicarpa (three samples), Artemisia ludoviciana (12 samples), and Gutierrezia sarothrae (six samples) from the Owyhee Mountains of southwestern Idaho. Gas chromatographic analyses (GC-MS, GC-FID, and chiral GC-MS) were carried out on each essential oil sample. The essential oils of A. acanthicarpa were dominated by monoterpene hydrocarbons, including α-pinene (36.7-45.1%), myrcene (21.6-25.5%), and ß-phellandrene (4.9-7.0%). Monoterpene hydrocarbons also dominated the essential oils of G. sarothrae, with ß-pinene (0.5-18.4%), α-phellandrene (2.2-11.8%), limonene (1.4-25.4%), and (Z)-ß-ocimene (18.8-39.4%) as major components. The essential oils of A. ludoviciana showed wide variation in composition, but the relatively abundant compounds were camphor (0.1-61.9%, average 14.1%), 1,8-cineole (0.1-50.8%, average 11.1%), (E)-nerolidol (0.0-41.0%, average 6.8%), and artemisia ketone (0.0-46.1%, average 5.1%). This is the first report on the essential oil composition of A. acanthicarpa and the first report on the enantiomeric distribution in an Ambrosia species. The essential oil compositions of A. ludoviciana and G. sarothrae showed wide variation in composition in this study and compared with previous studies, likely due to subspecies variation.

Host switching by an ambrosia beetle fungal mutualist: Mycangial colonization of indigenous beetles by the invasive laurel wilt fungal pathogen.

Ambrosia beetles require their fungal symbiotic partner as their cultivated (farmed) food source in tree galleries. While most fungal-beetle partners do not kill the host trees they inhabit, since their introduction (invasion) into the United states around ~2002, the invasive beetle Xyleborus glabratus has vectored its mutualist partner (but plant pathogenic) fungus, Harringtonia lauricola, resulting in the deaths of over 300 million trees. Concerningly, indigenous beetles have been caught bearing H. lauricola. Here, we show colonization of the mycangia of the indigenous X. affinis ambrosia beetle by H. lauricola. Mycangial colonization occurred within 1 h of feeding, with similar levels seen for H. lauricola as found for the native X. affinis-R. arxii fungal partner. Fungal mycangial occupancy was stable over time and after removal of the fungal source, but showed rapid turnover when additional fungal cells were available. Microscopic visualization revealed two pre-oral mycangial pouches of ~100-200 × 25-50 µm/each, with narrow entry channels of 25-50 × 3-10 µm. Fungi within the mycangia underwent a dimorphic transition from filamentous/blastospore growth to yeast-like budding with alterations to membrane structures. These data identify the characteristics of ambrosia beetle mycangial colonization, implicating turnover as a mechanism for host switching of H. lauricola to other ambrosia beetle species.

A high diversity of non-target site resistance mechanisms to acetolactate-synthase (ALS) inhibiting herbicides has evolved within and among field populations of common ragweed (Ambrosia artemisiifolia L.).

BACKGROUND: Non-target site resistance (NTSR) to herbicides is a polygenic trait that threatens the chemical control of agricultural weeds. NTSR involves differential regulation of plant secondary metabolism pathways, but its precise genetic determinisms remain fairly unclear. Full-transcriptome sequencing had previously been implemented to identify NTSR genes. However, this approach had generally been applied to a single weed population, limiting our insight into the diversity of NTSR mechanisms. Here, we sought to explore the diversity of NTSR mechanisms in common ragweed (Ambrosia artemisiifolia L.) by investigating six field populations from different French regions where NTSR to acetolactate-synthase-inhibiting herbicides had evolved. RESULTS: A de novo transcriptome assembly (51,242 contigs, 80.2% completeness) was generated as a reference to seek genes differentially expressed between sensitive and resistant plants from the six populations. Overall, 4,609 constitutively differentially expressed genes were identified, of which none were common to all populations, and only 197 were shared by several populations. Similarly, population-specific transcriptomic response was observed when investigating early herbicide response. Gene ontology enrichment analysis highlighted the involvement of stress response and regulatory pathways, before and after treatment. The expression of 121 candidate constitutive NTSR genes including CYP71, CYP72, CYP94, oxidoreductase, ABC transporters, gluco and glycosyltransferases was measured in 220 phenotyped plants. Differential expression was validated in at least one ragweed population for 28 candidate genes. We investigated whether expression patterns at some combinations of candidate genes could predict phenotype. Within populations, prediction accuracy decreased when applied to an additional, independent plant sampling. Overall, a wide variety of genes linked to NTSR was identified within and among ragweed populations, of which only a subset was captured in our experiments. CONCLUSION: Our results highlight the complexity and the diversity of NTSR mechanisms that can evolve in a weed species in response to herbicide selective pressure. They strongly point to a non-redundant, population-specific evolution of NTSR to ALS inhibitors in ragweed. It also alerts on the potential of common ragweed for rapid adaptation to drastic environmental or human-driven selective pressures.

Distinctive foliar features and volatile profiles in three Ambrosia species (Asteraceae).

MAIN CONCLUSION: Ambrosia species differ both in their trichome types and in metabolic profiles of leaf volatiles. The current study provides tools for easier taxonomic identification of ragweed species. The genus Ambrosia (Asteraceae) includes some of the most noxious allergenic invasive weeds in the world. Due to high polymorphism in this genus, identification of species is often difficult. This study focuses on microscopic investigation of foliar features and GC-MS identification of the main leaf volatile components of three Ambrosia species currently found in Israel-invasive species Ambrosia confertiflora and A. tenuifolia, and transient A. grayi. A. confertiflora and A. tenuifolia have three trichome types: non-glandular trichomes, capitate glandular trichomes and linear glandular trichomes. Their non-glandular trichomes and capitate trichomes have distinct structures and can serve as taxonomic characters. A. grayi (the least successful invader) has only very dense covering trichomes. All three Ambrosia species have secretory structures in their leaf midrib. A. confertiflora, the most problematic invasive plant in Israel, had a ten times higher volatiles content than the other two species. In A. confertiflora, the most abundant volatiles were chrysanthenone (25.5%), borneol (18%), germacrene D and (E)-caryophyllene (both around 12%). In A. tenuifolia, the most abundant volatiles were ß-myrcene (32.9%), (2E)-hexenal (13%) and 1,8-cineole (11.7%). In A. grayi, the most abundant volatiles were ß-myrcene (17.9%), germacrene D (17.8%) and limonene (14%). The three examined species have distinct trichome types and metabolic profiles. Non-glandular trichomes show structural diversification between species and are a good descriptive character. Considering the anthropocentric significance of this highly problematic genus, the current study provides tools for easier identification of ragweed species.

The worldwide invasion history of a pest ambrosia beetle inferred using population genomics.

Xylosandrus crassiusculus, a fungus-farming wood borer native to Southeastern Asia, is the most rapidly spreading invasive ambrosia species worldwide. Previous studies focusing on its genetic structure suggested the existence of cryptic genetic variation in this species. Yet, these studies used different genetic markers, focused on different geographical areas and did not include Europe. Our first goal was to determine the worldwide genetic structure of this species based on both mitochondrial and genomic markers. Our second goal was to study X. crassiusculus' invasion history on a global level and identify the origins of the invasion in Europe. We used a COI and RAD sequencing design to characterize 188 and 206 specimens worldwide, building the most comprehensive genetic data set for any ambrosia beetle to date. The results were largely consistent between markers. Two differentiated genetic clusters were invasive, albeit in different regions of the world. The markers were inconsistent only for a few specimens found exclusively in Japan. Mainland USA could have acted as a source for further expansion to Canada and Argentina through stepping stone expansion and bridgehead events. We showed that Europe was only colonized by Cluster II through a complex invasion history including several arrivals from multiple origins in the native area, and possibly including bridgehead from the United States. Our results also suggested that Spain was colonized directly from Italy through intracontinental dispersion. It is unclear whether the mutually exclusive allopatric distribution of the two clusters is due to neutral effects or due to different ecological requirements.

Antifungal and Insecticidal Activities of Selected Plant Species from Cloud Forest of Veracruz, Mexico: A Contribution to the Search of Novel Control Agents against Ambrosia Pest Complexes.

The antifungal and insecticidal activities of 34 extracts from 27 plant species were evaluated against fungal phytopathogens of the genus Fusarium and Xyleborus Scolytine ambrosia beetles involved in Fusarium dieback (FD) and laurel wilt (LW) diseases. Sixteen extracts caused mycelial growth inhibition (MGI) above 23 % at 2 mg mL-1 against F. solani, those from S. nudum and M. argyrophylla exhibited the highest MGI (57 % and 49 %, respectively). Thirteen extracts displayed significant antifungal activity against F. kuroshium, those from C. nocturnum and M. argyrophylla exhibited the highest MGI (100 % and 54.9 %, respectively). Additionally, ten plants extracts caused mortality in at least one of the beetle species tested, mainly from Solanaceae species. In the most active species, 39 phenolics were identified that may have contributed to their biological effects. This study is one of the first to report the potential of plant-derived natural products against the causative agents of FD and LW.

Acibenzolar-S-methyl induces resistance against ambrosia beetle attacks in dogwoods exposed to simulated flood stress.

Xylosandrus spp. ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are important wood-boring pests of nursery trees weakened by abiotic and biotic stressors. Acibenzolar-S-methyl (ASM), a plant defense elicitor, was tested for inhibiting Xylosandrus spp. tunneling (i.e., attacks) into flood-stressed flowering dogwoods (Cornus florida L. (Cornales: Cornaceae)). Container-grown dogwoods were treated with ASM substrate drench + flooding, ASM foliar spray + flooding, ASM drench + no flooding, ASM foliar + no flooding, no ASM + flooding, or no ASM + no flooding at 3 days before flood stress in a completely randomized design under field conditions. Trees were flooded for 14 days and then drained and watered as needed. Attacks were counted every 2 days for 28 days. Plant tissue samples were collected at 7 and 14 days after flooding to determine ethanol content using solid-phase microextraction-gas chromatography-mass spectrometry. Trees were dissected to determine gallery formation and depth, fungal colonization, and the presence of eggs, larvae, and adults. The highest number of Xylosandrus beetle species attacks were recorded from plants exposed to no ASM + flooding, but attacks were reduced in ASM treated trees (drench or foliar) + flooding. Trees treated with drenches had fewer attacks than foliar sprays. Plants assigned to no flood had the fewest beetle attacks. Moreover, ASM reduced Xylosandrus spp. gallery formation and depth, fungal colonization, and presence of eggs, larvae, and adults. All flooded trees produced ethanol. In conclusion, ASM induced a plant defense response to Xylosandrus spp. tunneling in dogwoods under flood stress conditions.

Effects of permethrin on ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) in ornamental nurseries.

Exotic ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), such as Xylosandrus crassiusculus (Motschulsky), Xylosandrus germanus (Blandford), and Xylosandrus compactus (Eichoff) are serious pests in southeastern ornamental nurseries. Preventative pyrethroid trunk sprays effectively reduce boring damage. However, it is unclear how pyrethroids such as permethrin prevent attack. Thus, the objective was to determine how permethrin-treated bolts interact with invading ambrosia beetles. In 2022, a study with 2 independent trials was conducted in a nursery on red maple (Acer rubrum L.), bolts during March and April, respectively. The treatments were (i) nonbaited, nontreated bolt, (ii) ethanol baited bolt, (iii) nonbaited bolt + glue [painted on bolt], (iv) ethanol baited bolt + glue, (v) ethanol baited bolt + glue + permethrin, (vi) ethanol baited bolt + glue + permethrin + verbenone, and (vii) ethanol baited bolt + glue + verbenone. Ambrosia beetles trapped on glue, beetles which fell into the pail with soap solution under the bolts, and entry holes on bolts were quantified. Permethrin prevented beetle attacks but did not reduce the number of ambrosia beetles landing on the treated bolts. Verbenone reduced ambrosia beetles from landing on the bolts but did not prevent boring into bolts. The numbers of ambrosia beetles in soapy water were not significantly different among treatments. Ambrosia beetles are landing on permethrin-treated bolts but not boring into the bolts, implying that fresh permethrin residues may not be necessary for ambrosia beetle management.

Relationship between IgE Levels Specific for Ragweed Pollen Extract, Amb a 1 and Cross-Reactive Allergen Molecules.

Ragweed (Ambrosia artemisiifolia) pollen is a major endemic allergen source responsible for severe allergic manifestations in IgE-sensitized allergic patients. It contains the major allergen Amb a 1 and cross-reactive allergen molecules, such as the cytoskeletal protein profilin, Amb a 8 and calcium-binding allergens Amb a 9 and Amb a 10. To assess the importance of Amb a 1, profilin and calcium-binding allergen, the IgE reactivity profiles of clinically well-characterized 150 ragweed pollen-allergic patients were analysed regarding specific IgE levels for Amb a 1 and cross-reactive allergen molecules by quantitative ImmunoCAP measurements, IgE ELISA and by basophil activation experiments. By quantifying allergen-specific IgE levels we found that Amb a 1-specific IgE levels accounted for more than 50% of ragweed pollen-specific IgE in the majority of ragweed pollen-allergic patients. However, approximately 20% of patients were sensitized to profilin and the calcium-binding allergens, Amb a 9 and Amb a 10, respectively. As shown by IgE inhibition experiments, Amb a 8 showed extensive cross-reactivity with profilins from birch (Bet v 2), timothy grass (Phl p 12) and mugwort pollen (Art v 4) and was identified as a highly allergenic molecule by basophil activation testing. Our study indicates that molecular diagnosis performed by the quantification of specific IgE to Amb a 1, Amb a 8, Amb a 9 and Amb a 10 is useful to diagnose genuine sensitization to ragweed pollen and to identify patients who are sensitized to highly cross-reactive allergen molecules present in pollen from unrelated plants, in order to enable precision medicine-based approaches for the treatment and prevention of pollen allergy in areas with complex pollen sensitization.

Integrating biogeographic approach into classical biological control: Assessing the climate matching and ecological niche overlap of two natural enemies against common ragweed in China.

Plant invasion is considered a high priority threat to biodiversity, ecosystems, the environment, and human health worldwide. Classical biological control (biocontrol) is a generally safer and more environmentally benign measure than chemical controls in managing invasive alien plants (IAPs). However, the impacts of climate change and the importance of climate matching in ensuring the efficiency of biocontrol candidates in controlling IAPs are likely to be underestimated. Here, based on the ensemble model and n-dimensional hypervolumes concepts, we estimated the overlapping areas between Ambrosia artemisiifolia and its two most effective natural enemies (Ophraella communa and Epiblema strenuana) under climate change in China. Moreover, we compared their ecological niches, further assessing the impact of climate change on the efficiency of two natural enemies in controlling A. artemisiifolia in China. We found that the potentially suitable areas of the two natural enemies and A. artemisiifolia were primarily influenced by temperature and human influence index variables. Under near-current climate, the overlapping area between O. communa and A. artemisiifolia was the largest, followed by E. strenuana and A. artemisiifolia, and both two natural enemies and A. artemisiifolia. The ecological niche between A. artemisiifolia and O. communa was most similar (0.64), followed by A. artemisiifolia and E. strenuana (0.55). The separate control (the niche separation areas of the two natural enemies against A. artemisiifolia) and joint-control (the niche overlap areas of the two natural enemies against A. artemisiifolia) efficiencies of the two natural enemies against A. artemisiifolia will both increase in future climates (the 2030s and 2050s) in northern and northeastern China. Our findings demonstrate a new approach to assess control efficiency and screen potential release areas of two natural enemies against A. artemisiifolia in China without the need for actual field release or experimentation. Moreover, our findings provide important clues for ensuring the classical biocontrol of IAPs worldwide.

Nitrogen deposition further increases Ambrosia trifida root exudate invasiveness under global warming.

Invasive plants can change the soil ecological environment in the invasion area to adapt to their growth and reproduction through root exudates. Root exudates are the most direct manifestation of plant responses to external environmental changes, but there is a lack of studies on root exudates of invasive plants in the context of inevitable global warming and nitrogen deposition. In this research, we used widely targeted metabolomics to investigate Ambrosia trifida root exudates during seedling and maturity under warming and nitrogen deposition to reveal the possible mechanisms of A. trifida adaptation to climate change. The results showed that the organic acids increased under warming condition but decreased after nitrogen addition in the seedling stage. Phenolic acids increased greatly after nitrogen addition in the mature stage. Most phenolic acids were annotated in the phenylpropane metabolic pathway and tyrosine metabolism. Therefore, nitrogen deposition may increase the adaptability of A. trifida through root exudates, making it more invasive under global warming. The results provide new ideas for preventing and controlling the invasion of A. trifida under climate change.

Climate warming can reduce biocontrol efficacy and promote plant invasion due to both genetic and transient metabolomic changes.

Climate change may affect plant-herbivore interactions and their associated ecosystem functions. In an experimental evolution approach, we subjected replicated populations of the invasive Ambrosia artemisiifolia to a combination of simulated warming and herbivory by a potential biocontrol beetle. We tracked genomic and metabolomic changes across generations in field populations and assessed plant offspring phenotypes in a common environment. Using an integrated Bayesian model, we show that increased offspring biomass in response to warming arose through changes in the genetic composition of populations. In contrast, increased resistance to herbivory arose through a shift in plant metabolomic profiles without genetic changes, most likely by transgenerational induction of defences. Importantly, while increased resistance was costly at ambient temperatures, warming removed this constraint and favoured both vigorous and better defended plants under biocontrol. Climate warming may thus decrease biocontrol efficiency and promote Ambrosia invasion, with potentially serious economic and health consequences.

First experimental evidence for active farming in ambrosia beetles and strong heredity of garden microbiomes.

Fungal cultivation is a defining feature for advanced agriculture in fungus-farming ants and termites. In a third supposedly fungus-farming group, wood-colonizing ambrosia beetles, an experimental proof for the effectiveness of beetle activity for selective promotion of their food fungi over others is lacking and farming has only been assumed based on observations of social and hygienic behaviours. Here, we experimentally removed mothers and their offspring from young nests of the fruit-tree pinhole borer, Xyleborinus saxesenii. By amplicon sequencing of bacterial and fungal communities of nests with and without beetles we could show that beetles are indeed able to actively shift symbiont communities. Although being consumed, the Raffaelea food fungi were more abundant when beetles were present while a weed fungus (Chaetomium sp.) as well as overall bacterial diversity were reduced in comparison to nests without beetles. Core symbiont communities were generally of low diversity and there were strong signs for vertical transmission not only for the cultivars, but also for secondary symbionts. Our findings verify the existence of active farming, even though the exact mechanisms underlying the selective promotion and/or suppression of symbionts need further investigation.

Symbiotic Fungi of an Ambrosia Beetle Alter the Volatile Bouquet of Cork Oak Seedlings.

In Portugal, fungal symbionts of the ambrosia beetle Platypus cylindrus affect tree vigor of cork oak (Quercus suber) and are linked with the cork oak decline process. Fungal symbionts play crucial roles in the life history of bark and ambrosia beetles and recent work indicates complex interactions on the fungal and plant metabolic level. Colonized trees may respond with an array of currently unknown volatile metabolites being indicative of such interactions, acting as infochemicals with their environment. In this study, we examined volatile organic compounds (VOCs) of cork oak seedlings wound inoculated with strains of three fungal associates of P. cylindrus (Raffaelea montetyi, R. quercina, and Ceratocystiopsis sp. nov.) over a 45-day period by means of thermodesorption gas chromatography-mass spectrometry techniques. Fungal strains induced largely quantitative but species-specific changes among the 58 VOCs characterized. Overall, monoterpenes-the major volatiles of cork oak foliage-were significantly reduced, possibly a result of fungal biotransformation. Acetophenone, sulcatone, and nonanal-volatiles known for mediating ambrosia beetle behavior-increased in response to fungal inoculation. Qualitative VOC profiles of excised tissue of wood lesions (21 VOCs) and pure fungal cultures (60 VOCs) showed little overlap with seedling VOCs, indicating their plant-derived but fungal-induced origin. This chemoecological study expands on the limited knowledge of VOCs as infochemicals emitted from oak trees threatened by oak decline in relation to beetle-vectored ophiostomatoid fungi. It opens new avenues of research to clarify mutualistic or pathogenic aspects of these complex symbiotic interactions and develop new control strategies for P. cylindrus, including its mycobiota.

Standardized allergen extracts for allergen immunotherapy.

Nineteen U.S. allergen extracts were standardized by the U.S. Food and Drug Administration (FDA) between 1987 and 1998, including of two house-dust mites, short ragweed, cat hair and cat pelt, seven temperate and one southern grass, and six Hymenoptera venom preparations. Relevant literature was reviewed. For each allergen, a "representative" extract was established; the potency of each representative extract was determined by measurement of the total protein content (Hymenoptera venom), radial diffusion measurement of the dominant allergen (short ragweed and cat), or, if there was no dominant allergen, then by quantitative skin testing by using the ID50EAL (intradermal dilution for 50 mm sum of erythema determines the bioequivalent allergy units) method. In vitro tests were developed to allow the manufacturer to demonstrate that each lot of its extract was statistically identical, within defined limits, to the FDA reference extract. These tests included radial immunodiffusion, competitive enzyme-linked immunosorbent assay, and isoelectric focusing. The standardized extracts offer the advantage of consistent potency from lot to lot for each manufacturer and also from manufacturer to manufacturer, and assure the presence of recognized significant allergens within the extract. Therefore, standardized extracts offer improved safety and efficacy over their nonstandardized predecessors.