Volatile Chemicals Research Articles

Functional Analysis of Pheromone Biosynthesis Activating Neuropeptide Receptor Isoforms in Maruca vitrata.

Insect sex pheromones are volatile chemicals that induce mating behavior between conspecific individuals. In moths, sex pheromone biosynthesis is initiated when pheromone biosynthesis-activating neuropeptide (PBAN) synthesized in the suboesophageal ganglion binds to its receptor on the epithelial cell membrane of the pheromone gland. To investigate the function of PBAN receptor (PBANR), we identified two PBANR isoforms, MviPBANR-B and MviPBANR-C, in the pheromone glands of Maruca vitrata. These two genes belong to G protein-coupled receptors (GPCRs) and have differences in the C-terminus but share a 7-transmembrane region and GPCR family 1 signature. These isoforms were expressed in all developmental stages and adult tissues. MviPBANR-C had the highest expression level in pheromone glands among the examined tissues. Through in vitro heterologous expression in HeLa cell lines, only MviPBANR-C-transfected cells responded to MviPBAN (≥5 µM MviPBAN), inducing Ca2+ influx. Sex pheromone production and mating behavior were investigated using gas chromatography and a bioassay after MviPBANR-C suppression by RNA interference, which resulted in the major sex pheromone component, E10E12-16:Ald, being quantitatively reduced compared to the control, thereby decreasing the mating rate. Our findings indicate that MviPBANR-C is involved in the signal transduction of sex pheromone biosynthesis in M. vitrata and that the C-terminal tail plays an important role in its function.

Air-enclosed pores in graphene aerogel inhibit the adsorption of bisphenol A but accelerate the adsorption of naphthalene

Graphene hydrogel (GH) and aerogel (GA) have great application potential as highly effective adsorbents, but the accessibility of their adsorption sites have not yet been identified, restricting our understanding on the adsorption mechanisms and manufacturing. This study comparatively studied the adsorption characteristics of bisphenol A (BPA) and naphthalene (NAP) on GH and GA, focussing on the accessibility of the adsorption sites. The adsorption of BPA on GA was much lower but faster than that on GH. NAP adsorption on GA was very close to that on GH but faster than that on the latter. Considering that NAP is volatilisable, we speculate that some unwetted sites in the air-enclosed pores are available to it, but not to BPA. We applied ultrasonic and vacuum treatments to remove the air in GA pores, which was verified using a CO2 replacement experiment. BPA adsorption was greatly enhanced but slowed, while that of NAP was not enhanced. This phenomenon suggested that some inner pores became accessible in the aqueous phase after air removal from pores. The enhanced accessibility of air-enclosed pores was verified by the increased relaxation rate of surface-bounded water on GA, based on a 1H NMR relaxation analysis. This study highlights that the accessibility of adsorption site plays a crucial role for the adsorption properties of carbon-based aerogel. The volatile chemicals may be quickly adsorbed in the air-enclosed pores, which be useful for immobilizing volatile contaminants.

Ecological risk identification and assessment of land remediation project based on GIS technology.

A land remediation project involves the removal of potentially toxic chemicals from a polluted site. Lands abandoned by industry are often contaminated with heavy metals like mercury, lead, chemicals, arsenic, and other toxins like dichlorodiphenyltrichloroethane biphenyls from electronic devices, and volatile organic chemicals (VOCs) from lubricants and chemicals. Risk assessment in environmental settings requires modernized systematic methodologies due to the complexity of today's environmental problems. When people eat, drink, or work in polluted environments, they put their health at risk and may even get cancer. Integrating geospatial information systems (GIS) with pollutant dispersion models makes environmental risk assessment and early warning possible. This research thus presents a GIS-based ecological risk identification and assessment model (GIS-ERIAM) for assessing risk for efficient land rehabilitation. Environmental cleanup sites' catalog information is the source of these details. With satellite imagery, GIS makes it simple to keep an eye on the environment and track the abundance of different types of plants and animals The ecological risk assessment (ERA) model can support recognition and prioritize risk management. By integrating direct and indirect environment interactions, the risk conditions of the whole ecology and its elements have been quantified and demonstrated in the study. The numerical outcomes illustrate that the recommended GIS-ERIAM model improves the performance by 98.9%, risk level prediction by 97.3%, risk classification by 96.4%, and detection of soil degradation ratio of 95.6% compared to other existing methods.

Exposure to volatile hydrocarbons and neurologic function among oil spill workers up to 6 years after the Deepwater Horizon disaster

BackgroundDuring the 2010 Deepwater Horizon (DWH) disaster, oil spill response and cleanup (OSRC) workers were exposed to toxic volatile components of crude oil. Few studies have examined exposure to individual volatile hydrocarbon chemicals below occupational exposure limits in relation to neurologic function among OSRC workers. ObjectivesTo investigate the association of several spill-related chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e., BTEX-H) and total petroleum hydrocarbons (THC) with neurologic function among DWH spill workers enrolled in the Gulf Long-term Follow-up Study. MethodsCumulative exposure to THC and BTEX-H across the oil spill cleanup period were estimated using a job-exposure matrix that linked air measurement data to detailed self-reported DWH OSRC work histories. We ascertained quantitative neurologic function data via a comprehensive test battery at a clinical examination that occurred 4–6 years after the DWH disaster. We used multivariable linear regression and modified Poisson regression to evaluate relationships of exposures (quartiles (Q)) with 4 neurologic function measures. We examined modification of the associations by age at enrollment (<50 vs. ≥50 years). ResultsWe did not find evidence of adverse neurologic effects from crude oil exposures among the overall study population. However, among workers ≥50 years of age, several individual chemical exposures were associated with poorer vibrotactile acuity of the great toe, with statistically significant effects observed in Q3 or Q4 of exposures (range of log mean difference in Q4 across exposures: 0.13–0.26 μm). We also observed suggestive adverse associations among those ≥ age 50 years for tests of postural stability and single-leg stance, although most effect estimates did not reach thresholds of statistical significance (p < 0.05). ConclusionsHigher exposures to volatile components of crude oil were associated with modest deficits in neurologic function among OSRC workers who were age 50 years or older at study enrollment.

Identifying Toxic Consumer Products: A Novel Data Set Reveals Air Emissions of Potent Carcinogens, Reproductive Toxicants, and Developmental Toxicants.

Consumer products are important sources of exposure to harmful chemicals. Product composition is often a mystery to users, however, due to gaps in the laws governing ingredient disclosure. A unique data set that the California Air Resources Board (CARB) uses to determine how volatile organic chemicals (VOCs) from consumer products affect smog formation holds a partial solution. By analyzing CARB data on VOCs in consumer products, we identified and quantified emissions of volatile chemicals regulated under the California Safe Drinking Water and Toxic Enforcement Act ("Prop 65"). We here highlight individual chemicals as well as consumer product categories that people are likely to be exposed to as individual consumers, in the workplace, and at the population level. Of the 33 Prop 65-listed chemicals that appear in the CARB emissions inventory, we classified 18 as "top tier priorities for elimination". Among these, methylene chloride and N-methyl-2-pyrrolidone were most prevalent in products across all three population groups. Of 172 consumer product categories, 105 contained Prop 65-listed chemicals. Although these chemicals are known carcinogens and reproductive/developmental toxicants, they remain in widespread use. Manufacturers and regulators should prioritize product categories containing Prop 65-listed chemicals for reformulation or redesign to reduce human exposures and associated health risks.

Reproductives signature revealed by protein profiling and behavioral bioassays in termite

Proteins are known to be social interaction signals in many species in the animal kingdom. Common mediators in mammals and aquatic species, they have seldom been identified as such in insects' behaviors. Yet, they could represent an important component to support social signals in social insects, as the numerous physical contacts between individuals would tend to favor the use of contact compounds in their interactions. However, their role in social interactions is largely unexplored: are they rare or simply underestimated? In this preliminary study, we show that, in the termite Reticulitermes flavipes, polar extracts from reproductives trigger body-shaking of workers (a vibratory behavior involved in reproductives recognition) while extracts from workers do not. Molecular profiling of these cuticular extracts using MALDI-TOF mass spectrometry reveals higher protein diversity in reproductives than in workers and a sex-specific composition exclusive to reproductives. While the effects observed with extracts are not as strong as with live termites, these results open up the intriguing possibility that social signaling may not be limited to cuticular hydrocarbons or other non-polar, volatile chemicals as classically accepted. Our results suggest that polar compounds, in particular some of the Cuticular Protein Compounds (CPCs) shown here by MALDI to be specific to reproductives, could play a significant role in insect societies. While this study is preliminary and further comprehensive molecular characterization is needed to correlate the body-shaking triggering effects with a given set of polar compounds, this exploratory study opens new perspectives for understanding the role of polar compounds such as proteins in caste discrimination, fertility signaling, or interspecific insect communication.

Preparation and characterization of emulsions of soy protein isolate-chitosan quaternary ammonium salt complexes and peppermint essential oil with extended release effect

In this study, we report for and first use of soy protein isolate (SPI), chitosan quaternary ammonium salt (HACC), and peppermint essential oil (PMO) to prepare emulsions. Under different SPI/HACC ratios, emulsions with an oil-phase ratio of 60% were produced using the high-speed shearing machine (i.e., 1:0, 1:1, 2:1, and 5:1). The outcome of rheological experiment demonstrated that the addition of HACC boosted the viscosity and improved gel network structure of emulsions. The stability and microstructure of the emulsion also improved as the content of HACC was increased. Also, the evaporation rate of essential oil from the emulsions was examined. The release duration of PMO was also significantly extended by the emulsions, and its capacity to inhibit the growth of three plant pathogenic fungi was enhanced. Therefore, this study suggested that HACC can greatly improved the emulsification stability of SPI as well as essential oil emulsion stabilized by SPI/HACC composite with a ratio of 1:1 had the best slow release effect. The PMO emulsions that were created had great promise for embedding volatile, water-insoluble, and micromolecular chemicals.

Cascading Polymer Macro-Debris Upcycling and Microparticle Removal as an Effective Life Cycle Plastic Pollution Mitigation Strategy.

Plastic pollution caused by material losses and their subsequent chemical emissions is pervasive in the natural environment and varies with age. Cascading the life cycles of plastic losses with solid waste reclamation via re-manufacturing virgin polymers or producing fuels and energy may extend resource availability while minimizing waste generation and environmental exposure. Here, we systematically investigate this cascaded plastic waste processing over other waste end-of-life management pathways by analyzing the environmental consequences of plastic losses across the entire life cycle. Plastic losses can form volatile organic chemicals via photo-degradation and pose non-negligible global warming, ecotoxicity, and air pollution effects that worsen by at least 189% in the long run. These environmental burdens increase by above 9.96% under high ultraviolet radiation levels and participation rates, which facilitate plastic particulate compartment transport and degradation. Cascaded plastic waste processing aided by fast pyrolysis upcycling technologies can effectively cut environmental losses and outperform landfills and incineration in reducing 23.35% ozone formation and 19.91% air pollution by offsetting the external monomer manufacturing and fuels and energy production while saving at least 25.75% fossil fuels.

Thermal properties and kinetic analysis of pyrolysis products of nicotine salts from e-cigarettes using pyrolysis-gas chromatography/mass spectrometry

Volatile organic chemicals (VOCs) released from e-cigarettes are a special source of air pollutants. In this work, we investigated the VOCs released from six nicotine salts (namely, nicotine benzoate, nicotine tartrate, nicotine citrate, nicotine malate, nicotine lactate, and nicotine levulinate) that are commonly used in e-cigarettes. The pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric methods were used to analyze the thermogravimetric characteristics and product release behavior of different nicotine salts. Moreover, the kinetic models and thermodynamic parameters of nicotine salts during the thermal decomposition process were obtained. Thermogravimetric characteristic parameters of six nicotine salts showed significant differences. By the use of Py-GC/MS, our data showed that the pyrolysis products of nicotine salts were mainly from nicotine, acid anhydrides, carboxylic acids, and N-heterocycles, while more than 90% of the nicotine of citrate, tartrate, and malate was transferred to smoke. The result revealed that activation energies of the nicotine salts range from 21.26 to 74.10 kJ mol-1, indicating that the pyrolysis of the nicotine salts is a non-spontaneous heat absorption process, and the organic acid was the key factor affecting the release of nicotine into the ambient air.

Research progress of volatile organic compounds produced by plant endophytic bacteria in control of postharvest diseases of fruits and vegetables

Pathogen infestation results in significant losses of fruits and vegetables during handling, transportation, and storage. The use of synthetic fungicides has been a common measure for controlling plant pathogens. However, their excessive use of chemicals has led to increased environmental pollution, leaving large amounts of chemicals in agricultural products, posing a threat to human and animal health. There is now an increasing amount of research activities to explore safer and more innovative ways to control plant pathogens. In this regard, endophytic bacteria contribute significantly. Endophytic bacteria are ubiquitous in the internal tissues of plants without causing damage or disease to the host. Due to their high volatility and difficulties in residue in fruits and vegetables, volatile organic chemicals (VOCs) produced by endophytic bacteria have received a lot of attention in recent years. VOCs are a potential biofumigant for the effective control of postharvest fruits and vegetables diseases. This review focuses mainly on the recent progress in using endophytic bacteria VOCs to control post-harvest fruits and vegetables disease. This review provides a brief overview of the concept, characteristics, and summarises the types, application effect, and control mechanisms of endophytic bacterial VOCs. The research area that is being developed has great application value in agriculture and living practice.

The Indian perspective on the harmful substances found in sanitary napkins and their effects on the environment and human health.

In this study, hazardous substances in 5 different brands of sanitary napkins being used in India have been analysed through gas chromatography mass spectroscopy (GCMS). Concentration of chemicals such as volatile organic chemicals (VOCs) (acetone, iso propyl alcohol, toluene), persistent organic pollutant (dioxins and furans), phthalates and total chlorine present in sanitary napkin have been reported. Furthermore, amounts of plastic present per sanitary napkin and total plastic waste generation potential have been calculated. Additionally, data analysis was done to understand the health impacts of these hazardous chemicals on users and the environment. It has been found that Indian sanitary pads have higher concentration of hazardous chemicals, as compared to similar product being sold in developed countries like - USA, Europe and Japan. The values of total chlorine observed in 5 different brands were found to be in the range of 170 to 460 ppm; dioxins varied from 0.244 to 21.419 pg/g; furans varied from 0.07 to 0.563 pg/g; acetone varied from 351 to 429 ppm; isopropyl alcohol varied from 125 to 184 ppm; toluene varied from 2.91 to 3.21 ppb; concentration of two phthalates, DBP and DEHP varied from 57.3 to 127.8 and from 146.2 to 188.5, respectively. Plastic pollution potential of this waste is approximately 33,210 tons/year. Daily exposure volume (DEV) of dioxins varied from 2.295 to 2.266 pg TEQ/g and furan from 0.0616 to 0.0738 pg TEQ/kg/day, compared to safe TDI value < 0.7 TEQ/kg/day. Dioxin's value is around 3 times higher than the accepted TDI value, whereas furan is within acceptable limit. Daily exposure doses (DED) of DBP were observed in-between 4.24 and 9.47 μg/kg-bw/day, whereas the DEHP value varied from 0.541 to 0.698 μg/kg-bw/day.

Plant Disease Detection and Solution System

Abstract: For preventing losses in the yield and quantity of the cultural product, Classification is performed, if proper analysis is not taken in this approach or classification, then it produces serious effects on plants and due to ich respective product quality or productivity is affected. Disease classification on the plants is very critical for supportable agriculture. It is very difficult to monitor or treat plant diseases manually. It requires a huge amount of work and also needs excessive processing time, therefore image processing for the detection of plant diseases. Automatic fruit disease detection and grading is a creative strategy.Bacterial Blight, Fruit Spot, Fruit Rot, and Virus Diseases on Fruits are the modules identified in this investigation.For the identification of diseases and their critical processes, including as photosynthesis, transpiration, pollination, fertilisation, germination, and some fruit diseases, molecular methods and profiling of volatile organic chemicals in plants are applied.The classification of plant diseases includes the processes of loading the image, pre-processing, segmenting, feature extraction, and SVM classifier.

Red flour beetle, Tribolium castaneum (Herbst): biology and management

According to an estimate, the world’s population will reach upto 9.1 billion till 2050 and food production is projected to increase up to 70%. Developing countries already facing food scarcity contribute most in population growth. In these countries, one in every six children suffers from hunger and malnutrition. In these critical situation, protection of the grains and food products from insect infestation during pre-harvest and post-harvest is urgently necessary it causes mass losses of grains. In several countries, about 15% of grains are lost harvesting or post-harvesting stages. The Food and Agricultural Organization (FAO) has estimated this loss up to 40% in India. Among the culprits of these losses, coleopteran insect species play major roles. Among coleopterans, red flour beetle, Tribolium castaneum causes loss of grains and food products to larger extent in post-harvest stage. T. castaneum is a secondary pest with a wide host range infesting almong, barley, beans, ground nuts, lentils, maize, oat, peas, rice, rye, sorghum, wheat and other processed grain products. Adults and larvae attack grains already damaged by primary pest and feed mainly on the germ. For the management of T. castaneum population, several approaches including synthetic insecticides have been applied with lots of success but leaving several environmental and human health issues too. To minimize these adverse effects, plant derived volatile chemicals i.e. essential oils and its constituents alone or in combination have been used and got promising results. Since these are volatile, non-persistent and biodegradable, essential oil based formulations can be used for the management of T. castaneum at large as green eco-friendly insecticide

Exploration of seasonal fermentation differences and the possibility of flavor substances as regulatory factors in Daqu

Medium-high temperature Daqu is a characteristic starter for Chinese strong-flavor Baijiu fermentation, and its final quality determines the character and type of Baijiu. Nonetheless, its formation is affected by the interaction of physical and chemical, environmental and microbial interaction, and the differences in seasonal fermentation performance emerge. Here, the differences in the two seasons' Daqu fermentation properties were revealed by the detection of the enzyme activity. The respective dominant enzyme in summer Daqu (SUD) was protease and amylase, while cellulase and glucoamylase in spring Daqu (SPD). The underlying causes of this phenomenon were then investigated through an evaluation of nonbiological variables and microbial community structure. A greater absolute number of microorganisms, particularly Thermoactinomyces, were created in the SPD as a result of the superior growth environment (higher water activity). Additionally, the correlation network and discriminant analysis hypothesized that the volatile organic compound (VOC) guaiacol, which had a different content between SUD and SPD, may be a contributing element to the microbial composition. In contrast to SUD, the enzyme system activity related to guaiacol production in SPD was significantly higher. To support this notion that the volatile flavor chemicals mediate microbial interactions in Daqu, the growth effect of guaiacol on several bacteria isolated from the Daqu was examined in both a contact and non-contact manner. This study emphasized that VOCs not only have the basic characteristics of flavor compounds but also have ecological significance. Because the strains' varied structures and enzyme activities affected how the microorganisms interacted, the VOCs produced in this way ultimately had a synergistic effect on the various effects of Daqu fermentation.

Impact of Marine Chemical Ecology Research on the Discovery and Development of New Pharmaceuticals.

Diverse ecologically important metabolites, such as allelochemicals, infochemicals and volatile organic chemicals, are involved in marine organismal interactions. Chemically mediated interactions between intra- and interspecific organisms can have a significant impact on community organization, population structure and ecosystem functioning. Advances in analytical techniques, microscopy and genomics are providing insights on the chemistry and functional roles of the metabolites involved in such interactions. This review highlights the targeted translational value of several marine chemical ecology-driven research studies and their impact on the sustainable discovery of novel therapeutic agents. These chemical ecology-based approaches include activated defense, allelochemicals arising from organismal interactions, spatio-temporal variations of allelochemicals and phylogeny-based approaches. In addition, innovative analytical techniques used in the mapping of surface metabolites as well as in metabolite translocation within marine holobionts are summarized. Chemical information related to the maintenance of the marine symbioses and biosyntheses of specialized compounds can be harnessed for biomedical applications, particularly in microbial fermentation and compound production. Furthermore, the impact of climate change on the chemical ecology of marine organisms-especially on the production, functionality and perception of allelochemicals-and its implications on drug discovery efforts will be presented.

Improved closed test setup for biodegradation testing of slightly volatile substances in water-sediment systems (OECD 308)

Standardized biodegradation testing methods, like the OECD 308 Aerobic and Anaerobic Transformation in Aquatic Sediment Systems, generate data on biodegradation required during environmental risk and hazard assessment of chemicals under different European and international regulations. However, difficulties arise when applying the OECD 308 guideline for testing hydrophobic volatile chemicals. Especially the use of a co-solvent (like acetone) as a measure to facilitate the application of the test chemical in combination with a closed setup to reduce losses due to volatilization tend to deplete/restrict the amount of oxygen in the test system. The result is a low oxygen or even anoxic water column in the water-sediment system. Thus, the degradation half-lives of the chemical generated from such tests are not directly comparable to the regulatory half-life values for Persistence assessment of the test chemical. The aim of this work was to further develop the closed setup to improve and maintain aerobic conditions in the water phase of the water-sediment systems for testing slightly volatile hydrophobic test chemicals. This improvement was attained by optimizing the test system geometry and agitation technique to maintain aerobic conditions in the water phase in a closed test setup, investigating appropriate co-solvent application strategy, and trialing the resulting test setup. This study shows that when using a closed test setup for OECD 308 tests, agitation of the water phase overlaying the sediment and the test item application using low co-solvent volume is critical for maintaining an aerobic water layer.

Social economic factors and the risk of multiple chemical sensitivity in a Danish population-based cross-sectional study: Danish Study of Functional Disorders (DanFunD)

ObjectivesMultiple chemical sensitivity (MCS) is a rare multisystem and poly-symptomatic disease characterised by a report of various somatic symptoms attributed to inhalation of volatile chemicals in usually harmless doses. The...

Coupling interface design of metal oxide heterostructures derived from MXene@MOFs hybrids for high-sensitivity acetone sensor

Acetone is used in a variety of fields for being highly volatile chemicals that may have detrimental effects on both industrial security and human health. With a view to testing the leak and concentration of acetone, we have successfully developed TiO2/Fe2O3-X (TF-X) sensors via a carboxyl group-shared coordination route. Here, Ti3C2Tx MXene and Fe salt provide chelation sites enabling coordination with carboxyl groups to fabricate two kinds of MOFs (MIL-125(Ti)/MIL-53(Fe)) followed by calcination. The tightly coupled heterogeneous interface between TiO2 and Fe2O3 promotes carrier transfer and elicits sharp resistance variation thereby raising the sensitivity towards acetone. Meantime, the porous TF-X heterostructures generate numerous oxygen vacancies and surface functional groups to be conducive to the gas flow and surface reaction. Accordingly, the optimal TF-400 heterostructure endows the extraordinary sensitivity (R = 446.8) to 100 ppm acetone at 268 ℃, much higher than that of the pristine TiO2 and Fe2O3. Rapid response (15 s) and recovery (7 s) time are implemented, as well as remarkable selectivity and stability. Moreover, the enhanced mechanism of TF-400 heterostructure is presented and studied. It is anticipated to open up a new avenue for the design and synthesis of high-sensitivity acetone sensors.

Design of the 3D Printer Nozzle Cleaning System

Aiming at the problems of low cleaning efficiency, damaged nozzle, and high safety hazard in the traditional cleaning method of the fused deposition modeling (FDM) equipment nozzle, an environmentally friendly nozzle cleaning system was designed by using the chemical solvent and ultrasonic cleaning technology. The modular design of the nozzle clamping module can improve the nozzle loading efficiency and cleaning efficiency. The cleaning liquid circulation device makes the cleaning process automated under the coordination of the control module, which effectively reduces the safety hazards of the cleaning process. A thermal drying device is mainly used to speed up the drying rate of the nozzle. An exhaust gas purification device is used to absorb the volatile chemicals in the cleaning process and reduce pollution in the working environment.

Bark Beetles Utilize Ophiostomatoid Fungi to Circumvent Host Tree Defenses.

Bark beetles maintain symbiotic associations with a diversity of microbial organisms, including ophiostomatoid fungi. Studies have frequently reported the role of ophiostomatoid fungi in bark beetle biology, but how fungal symbionts interact with host chemical defenses over time is needed. We first investigated how inoculations by three fungal symbionts of mountain pine beetle affect the terpene chemistry of live lodgepole pine trees. We then conducted a complimentary laboratory experiment specifically measuring the host metabolite degradation by fungi and collected the fungal organic volatiles following inoculations with the same fungal species on lodgepole pine logs. In both experiments, we analyzed the infected tissues for their terpene chemistry. Additionally, we conducted an olfactometer assay to determine whether adult beetles respond to the volatile organic chemicals emitted from each of the three fungal species. We found that all fungi upregulated terpenes as early as two weeks after inoculations. Similarly, oxygenated monoterpene concentrations also increased by several folds (only in logs). A large majority of beetles tested showed a strong attraction to two fungal species, whereas the other fungus repelled the beetles. Together this study shows that fungal symbionts can alter host defense chemistry, assist beetles in overcoming metabolite toxicity, and provide possible chemical cues for bark beetle attraction.