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Attractiveness of volatile organic compounds on Dermanyssus gallinae (Mesostigmata: Dermanyssidae)
Abstract
The Poultry Red Mite (PRM), Dermanyssus gallinae, is an obligate blood-sucking ectoparasite of economic importance in layer farms. Increasing
acaricide resistance and strengthening of environmental policies make PRM control challenging and require alternative control tools. Whilst the
general life cycle and habits of PRM are well established, determinants of its interaction with environment keep poorly understood. The role of general
host-related stimuli on the behavioral response of the PRM, like CO2 and temperature, was well investigated. However, the role of volatile organic
compounds (VOCs) other than CO2 found in the chemical landscape constituted by the henhouse environment on PRM behaviour received little
attention. The aim of the study was to explore the attractiveness of some of the VOCs present in farm buildings and their interaction with temperature.
We evaluated the attractive response of starved PRM female adults to 8 volatiles compounds commonly found in the farm context, either alone or
associated in a blend, in two choice test bioassays (one performed in a Y-tube olfactometer, another one in a field-mimicking lab design). The impact
of temperature on the attractiveness of VOCs was studied using a heated substrate. Our results showed that a single VOC (ammonia) and one VOC
blend were significantly attractant to PRM in our laboratory conditions. The interaction between VOCs and temperature had a significant impact on
PRM attraction. Our work brings fundamental information on chemical interactions between PRM and its environment in farm buildings. This study
demonstrates the potential of using volatile substances to manipulate the behavior of PRM, combined or not to different stimuli, to elaborate an
attract-and-kill control strategy. The authors would like to thank the European Cooperation in Science and Technology (COST Action (FA1404 -
COREMI) “Improving current understanding and research for sustainable control of the poultry red mite Dermanyssus gallinae”).
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Humans vary in attractiveness to mosquitoes, a phenomenon that is largely attributed to differences in physical cues such as heat and volatile odors emanating from breath and skin. Diet can change human odors but whether specific dietary components alter host attractiveness is largely unexplored. We identified bananas as a target for study following a survey of the internet for advice on avoiding mosquito bites. Human attractiveness to Anopheles stephensi Liston was measured using a glass vial bioassay where mosquito contacts were measured before and 1–3 h after ingestion of bananas or grapes. Consumption of grapes had no effect on the number of contacts but banana ingestion resulted in a significant increase in the overall number of contacts in spite of individual variation that included some subjects who showed no effect or decreases in contacts. Further tests with a single volunteer showed that the effect was repeatable and consistent across 15 trials. The magnitude of the increase was not affected by the number of bananas eaten. Increased contact counts after banana ingestion were also observed when A. gambiae Giles was tested. These results support the hypothesis that diet plays an important role in mediating host attractiveness to anopheline mosquitoes.
The overall interest in environmentally safe pest control methods and the rise of insecticide resistance in pest populations have prompted medical and agricultural entomology research on insect repellents in recent years. However, conducting research on repellent is challenging for several reasons: (1) the different repellent phenomena are not well defined; (2) it is difficult to test for and quantify repellent; (3) the physiological mechanisms are poorly known; (4) the field efficacy appears to be highly variable. Here, we identified five different types of repellent: expellency, irritancy, deterrency, odor masking and visual masking, and described behavioral bioassays to differentiate between them. Although these categories are currently defined by their behavioral response to different stimuli, we suggest new definitions based on their mechanism of action. We put forward three main hypotheses on the physiological mechanism: (1) a dose effect that modifies the behavior, (2) a repellent mechanism with specific receptors, or (3) inhibition of the transduction of neural information.
The economic impact of the poultry red mite, Dermanyssus gallinae, the lack of new acaricides, the occurrence of resistance and tighter legislation have all led to the need to find new ways to control this pest. One promising alternative method of control focuses on employing repellent and/or toxic effects of selected plant essential oils against D. gallinae. Ten essential oils (basil, thyme, coriander, eucalyptus, lavender, lemon, fir tree, oregano, mint, and juniper) were tested for the persistence of toxic and repellent effects. In filter-paper toxicity bioassays against D. gallinae, the best results were observed for lavender (more than 97% mortality after 48 and 72h) and thyme (84% at 72h) at a dose of 0.12mg/cm(2). In addition, two oils showed significant persistent toxic effects 15 and 30 days post application to filter papers. Thyme was the most effective (100% mortality at 72h), followed by lavender (nearly 80% mortality after 72h). Out of the ten oils tested for their repellent effect, thyme was the strongest, with nearly 80% of the tested area avoided by mites; oregano caused a 60% avoidance and lavender exhibited an effect close to 40%. All other oils exhibited a repellent effect of less than 30%. None of the experiments showed a repellent effect for HM (commercial alimentary oil) or negative controls. We found that the thyme and lavender essential oils exhibited promising results when tested in vitro for toxic and repellent effects against D. gallinae; thus, we suggest that future experiments focus on in vivo tests using these oils in farm units.
Currently, the majority of diagnoses of malaria rely on a combination of clinical presentation and visualizing parasites in a stained blood film. Human breath offers an attractive alternative to blood as the basis for simple, non-invasive diagnosis of infectious diseases. In this study, breath samples were taken during controlled human malaria infection in order to determine whether specific malaria associated volatiles could be detected in human breath. We identified nine compounds whose concentrations varied significantly over the course of malaria infection: carbon dioxide, isoprene, acetone, benzene, cyclohexanone and four thioethers. The latter group: allyl methyl sulfide, 1-methylthio-propane, (Z)-1-methylthio-1-propene and (E)-1-methylthio-1-propene had not previously been associated with any disease condition. Before antimalaria-drug treatment, there was evidence of concurrent 48 hour-cyclical changes in both the levels of thioethers and parasitemia. Phase-shifting the values for thioether concentrations by 24 hours, revealed a direct correlation between the parasitemia and volatile levels. Volatile levels declined monotonically ∼6.5 h after initial drug treatment, correlating with clearance of parasitemia. No thioethers were detected in vitro cultures of Plasmodium falciparum. The metabolic origin of the thioethers is not known but results suggest that interplay between host and parasite metabolic pathways is involved in the production of these thioethers.
© The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.
The use of aromatic plants and their essential oils for ectoparasite treatment is a field of growing interest. Several species of birds regularly introduce aromatic herbs into their nests putatively to reduce parasites. The behaviour is most often seen in cavity nesting birds and after nest building has finished. The plants are included in a non-structural manner and are often strongly aromatic. Various different hypotheses have been proposed regarding the function of this behaviour; from the plants altering some non-living factor in the nest (crypsis, water loss and insulation hypotheses) to them being involved in mate selection (mate hypothesis) or even having a beneficial effect, direct or indirect, on chicks (drug or nest protection hypothesis, NPH). Many studies have been carried out over the years observing and experimentally testing these hypotheses. This review focuses on studies involving the most popular of these hypotheses, the NPH: that plants decrease nest parasites or pathogens, thereby conveying positive effects to the chicks, allowing the behaviour to evolve. Studies providing observational evidence towards this hypothesis and those experimentally testing it are discussed.
Sensory cues that predict reward or punishment are fundamental drivers of animal behavior. For example, attractive odors of palatable food or a potential mate predict reward, while aversive odors of pathogen-laced food or a predator predict punishment. Aversive and attractive odors can be detected by intermingled sensory neurons that express highly related olfactory receptors and display similar central projections. These findings raise basic questions of how innate odor valence is extracted from olfactory circuits, how such circuits are developmentally endowed and modulated by state, and how innate and learned odor responses are related. Here, we review odors, receptors and neural circuits associated with stimulus valence, discussing salient principles derived from studies on nematodes, insects and vertebrates. Understanding the organization of neural circuitry that mediates odor aversion and attraction will provide key insights into how the brain functions.
Copyright © 2015 Elsevier Ltd. All rights reserved.
In this paper, we formulate a new model with maturation delay for mosquito population incorporating the impact of blood meal resource for mosquito reproduction. Our results suggest that except for the usual crowded effect for adult mosquitoes, the impact of blood meal resource in a given region determines the mosquito abundance, it is also important for the population dynamics of mosquito which may induce Hopf bifurcation. The existence of a stable periodic solution is proved both analytically and numerically. The new model for mosquito also suggests that the resources for mosquito reproduction should not be ignored or mixed with the impact of blood meal resources for mosquito survival and both impacts should be considered in the model of mosquito population. The impact of maturation delay is also analyzed.
Significance
Recent research suggests that vector-borne pathogens may frequently manipulate host odors to influence vector attraction. Such effects could have implications for the use of olfactory lures or repellents to disrupt vector transmission, as well as for disease diagnosis. We observed enhanced attraction of mosquitoes to mice infected by the rodent malaria parasite Plasmodium chabaudii during a key period after the subsidence of acute malaria symptoms but during which mice remained highly infectious. This attraction appears to be mediated by an overall elevation of volatile emissions from infected individuals and characteristic changes in the levels of individual compounds. Furthermore, clear differences in the odor profiles of healthy and infected individuals persist throughout the course of infection.
Resistance to conventional synthetic pesticides has been widely reported in ticks, parasitic mites and other pests of veterinary and medical significance. New and novel approaches to manage these pests are therefore needed to ensure efficient control programmes that can be implemented now and in the future. Recent research in this area has focused on the pesticidal potential of plant essential oils. These products are attractive as pesticide candidates on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries (limiting the development of pest resistance against them). Although issues may exist concerning reliability in efficacy of essential oils, these may be overcome by identifying and developing bioactive oil components for use in pest management. In the current work, three such components (terpenes) found in essential oils (eugenol, geraniol and citral) were tested against the poultry red mite Dermanyssus gallinae. All provided 100% mortality in toxicity tests when undiluted. Even at 1% of this dose, eugenol was 20% effective against experimental pest populations, although the remaining terpenes were largely ineffective at this concentration.
The poultry red mite, Dermanyssus gallinae, poses a significant threat to poultry production and hen health in many parts of the world. With D. gallinae increasingly suspected of being a disease vector, and reports indicating that attacks on alternative hosts, including humans, are becoming more common, the economic importance of this pest has increased greatly. As poultry production moves away from conventional cage systems in many parts of the world, D. gallinae is likely to become more abundant and difficult to control. Control remains dominated by the use of synthetic acaricides, although resistance and treatment failure are widely reported. Alternative control measures are emerging from research devoted to D. gallinae and its management. These alternative control measures are beginning to penetrate the market, although many remain at the precommercial stage. This review compiles the expanding body of research on D. gallinae and assesses options for its current and future control. We conclude that significant advances in D. gallinae control are most likely to come through an integrated approach adopting recent research into existing and novel control strategies; this is being combined with improved monitoring and modeling to better inform treatment interventions.
BACKGROUND: The essential oils (EO) carvacrol, thymol, eugenol and trans ‐cinnamaldehyde have well‐documented antimicrobial properties and offer therefore an alternative for the antimicrobial growth promoters in pig feeds. The aim of this work was to determine the degradation and kinetics of these EO along the gastrointestinal tract (GIT) of piglets, which is necessary information for correct application in pig feeds.
RESULTS: None of these compounds was significantly degraded in in vitro simulations of pig gastric fermentation. Carvacrol and thymol were not degraded in jejunal simulations, but significant losses of up to 29% were found in caecal simulations. Eugenol and trans ‐cinnamaldehyde showed a more pronounced degradation in jejunal and caecal simulations. A single dose mixed with feed (13.0, 13.2, 12.5 and 12.7 mg kg ⁻¹ body weight for carvacrol, thymol, eugenol and trans ‐cinnamaldehyde respectively) was given orally to piglets. Half‐lives in total digestive tract ranged between 1.84 and 2.05 h, whereby trans ‐cinnamaldehyde showed the fastest disappearance. All of these EO were mainly and almost completely absorbed in the stomach and the proximal small intestine. Plasma concentrations (sum of free and conjugated compound) peaked at 1.39, 1.35 and 0.83 h for carvacrol, thymol and eugenol respectively and this was accompanied by high concentrations in urine.
CONCLUSION: The four compounds were in vitro poorly degraded in the proximal segments of the GIT of piglets, but degradation is expected in more distal segments. In vivo , the EO were mainly and almost completely absorbed in the stomach and the proximal small intestine. Copyright © 2008 Society of Chemical Industry
A primary difference between predators and parasites is the number of victims that an individual attacks throughout a life-history stage. A key division within natural enemies is whether a successful attack eliminates the fitness of the prey or the host. A third distinctive axis for parasites is whether the host must die to further parasite development. The presence or absence of intensity-dependent pathology is a fourth factor that separates macroparasites from microparasites; this also distinguishes between social and solitary predators. Combining these four dichotomies defines seven types of parasitism, seven corresponding parasites, three forms of predation and, when one considers obligate and facultative combinations of these forms, four types of predator. Here, we argue that the energetics underlying the relative and absolute sizes of natural enemies and their victims is the primary selective factor responsible for the evolution of these different trophic strategies.
During the past 2 decades, considerable progress has been made in the study of bird semiochemistry, and our goal was to review and evaluate this literature with particular emphasis on the volatile organic constituents. Indeed, since the importance of social chemosignaling in birds is becoming more and more apparent, the search for molecules involved in chemical communication is of critical interest. These molecules can be found in different sources that include uropygial gland secretions, feather-surface compounds, and molecules from feces and skin. Although many studies have examined the chemical substances secreted by birds, research on bird chemical communication is still at the start, so new strategies for collecting samples and development of new methods of analysis are urgently required. As a first step, we built a database that brings together potential semiochemicals, using a unique chemical nomenclature for comparing different bird species and also for referencing the different classes of substances that can be found in order to adapt future parameters of analysis. The most important patterns of the wax fraction of preen secretions are highlighted and organized in an ordered table. We also draw up a list of various combinations of sampling and analytical techniques, so that each method can be compared at a glance.
Malaria and alcohol consumption both represent major public health problems. Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial. Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes). Water consumption had no effect on human attractiveness to An. gambiae mosquitoes, but beer consumption increased volunteer attractiveness. Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours). The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes. Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.
The poultry red mite, Dermanyssus gallinae, is a parasite of layers in Europe. In order to improve our understanding of the host-searching behaviour of these mites their sensitivity to slowly increasing temperatures was studied under laboratory conditions. Temperatures increasing as slowly as 0.005 degrees C/s (over a one min period) were effective in activating the mites. The speed of the temperature change is more important than the temperature change itself for this activation process. This knowledge of the host-searching process could facilitate the development of new control strategies.
The preference of two allopatric populations of Culex annulirostris mosquitoes in South Australia (SA) for guinea pigs and chickens was investigated using host-baited traps in the field and in a flight tunnel for laboratory assays. Mosquitoes from the Riverland of SA preferred guinea pigs, those from northeast SA preferred chickens. In the field, 2184 Cx. annulirostris were captured during four experiments in each region. The proportion choosing chicken was 0.5393 in northeast SA and 0.4348 in the Riverland. In the laboratory, replicate trials utilizing 15 mosquitoes at a time yielded results concordant with field assays. This study demonstrates variation in Cx. annulirostris host preference throughout this species geographic range. Semiochemical analysis of the two host species was performed on solvent extractions and volatile trapping samples from fur and feathers, respectively. This revealed differences that are likely to be the basis for host discrimination by Cx. annulirostris.
The mosquito repellent activity of 38 essential oils from plants at three concentrations was screened against the mosquito Aedes aegypti under laboratory conditions using human subjects. On a volunteer's forearm, 0.1 mL of oil was applied per 30 cm2 of exposed skin. When the tested oils were applied at a 10% or 50% concentration, none of them prevented mosquito bites for as long as 2 h, but the undiluted oils of Cymbopogon nardus (citronella), Pogostemon cablin (patchuli), Syzygium aromaticum (clove) and Zanthoxylum limonella (Thai name: makaen) were the most effective and provided 2 h of complete repellency.
From these initial results, three concentrations (10%, 50% and undiluted) of citronella, patchouli, clove and makaen were selected for repellency tests against Culex quinquefasciatus and Anopheles dirus. As expected, the undiluted oil showed the highest protection in each case. Clove oil gave the longest duration of 100% repellency (2–4 h) against all three species of mosquito. Copyright
Axillary body odor is individually specific and potentially a rich source of information about its producer. Odor individuality partly results from genetic individuality, but the influence of ecological factors such as eating habits are another main source of odor variability. However, we know very little about how particular dietary components shape our body odor. Here we tested the effect of red meat consumption on body odor attractiveness. We used a balanced within-subject experimental design. Seventeen male odor donors were on "meat" or "nonmeat" diet for 2 weeks wearing axillary pads to collect body odor during the final 24 h of the diet. Fresh odor samples were assessed for their pleasantness, attractiveness, masculinity, and intensity by 30 women not using hormonal contraceptives. We repeated the same procedure a month later with the same odor donors, each on the opposite diet than before. Results of repeated measures analysis of variance showed that the odor of donors when on the nonmeat diet was judged as significantly more attractive, more pleasant, and less intense. This suggests that red meat consumption has a negative impact on perceived body odor hedonicity.
This report presents the first quantitative estimates of emission rates for chemical signals in a bird—the crested auklet (Aethia cristatella). Volatile emissions from live birds were captured in a purified airstream onto polymer traps. Traps were eluted with methanol and analyzed with gas chromatography-mass spectrometry. The volatile collection chamber was field-calibrated with an in-line bubbler and synthetic octanal, the dominant constituent of the crested auklet’s citruslike odor. The result is an index of volatile chemical emissions within a small population of wild crested auklets at Big Koniuji Island, AK, USA. The average emission rate for octanal was 5.7 μl/50 min. Males and females did not differ in their emission rates (t
(0.05)two-tailed = 0.44, P = 0.66). There was a sevenfold difference between minimum and maximum emission rates. Prevalence of tick infection (2%) was low despite the high abundance of ticks in the colony. The crested auklet with the lowest chemical emission rate was heavily parasitized by ticks.
The reproductive organs of some plants self-heat, release scent, and attract pollinators. The relations among these processes
are not well understood, especially in the more ancient, nonflowering gymnosperm lineages. We describe the influence of plant
volatiles in an obligate pollination mutualism between an Australian Macrozamia cycad (a gymnosperm with male and female individuals)
and its specialist thrips pollinator, Cycadothrips chadwicki. Pollen-laden thrips leave male cycad cones en masse during the
daily thermogenic phase, when cone temperatures and volatile emissions increase dramatically and thrips are repelled. As thermogenesis
declines, total volatile emissions diminish and cones attract thrips, resulting in pollination of female cones. Behavioral
and electrophysiological tests on thrips reveal that variations in b-myrcene and ocimene emissions by male and female cones
are sufficient to explain the observed sequential thrips' repellence (push) and attraction (pull). These dynamic interactions
represent complex adaptations that enhance the likelihood of pollination and may reflect an intermediate state in the evolution
of biotic pollination.
This study evaluated the repellency effect of 3 topical repellents (permethrin, DEET and neem tree extract) against 3-5 day old females of laboratory and field strains of Anopheles stephensi. Probing/biting rates on the shaved belly of white rabbits were counted. Effective dose (ED) 50 and ED95 values were calculated by probit statistic software. The results revealed ED50 values of 0.007, 0.005 and 0.191 mg/cm2 for permethrin, DEET and neem, respectively, against the field strain. The figures for the laboratory strain were 0.006, 0.007, 0.156 mg/cm2. Major heterogeneity of response was observed using DEET. Although neem was the least effective agent, extracts of locally produced neem oil offer a promising repellent against mosquito biting.
Covering: up to 2017
The review summarizes results up to 2017 on chemosensory cues occurring in both aquatic and terrestrial environments. The chemicals are grouped by their physicochemical properties to compare their potential mobility in the different media. In contrast to what is widely asserted in the literature, the report emphasizes that living organisms encounter and sense molecules of various degrees of solubility and volatility both on land and in aquatic environments. The picture that emerges from the review suggests a substantial revision of the traditional definitions of the chemical senses based on their spatial range, which is currently orienting the literature on chemosensory signaling, in favor of a new vision based on the natural products that are the actual mediators of the chemosensory perceptions. According to this perspective, natural product chemistry is a powerful tool with which to explore the evolutionary history of the chemical senses.
Under arm odour [axillary odour AO, bromidrosis] is a deeply unpleasant problem that can affect a person's self confidence and esteem and reduce social interaction. It is generally managed by good hygiene along with antiperspirants and deodorants, but the axillary apocrine glands may need surgical removal in severe cases of odour. The odour comes from microbial conversion of the apocrine secretions into short chain fatty acids like isovaleric acid and volatile sulphur compounds like 3-sulphanylhexan-1-ol. These can be detected at a few parts per billion to parts per trillion by the human nose so an unhygienic state is soon apparent. Recently genetics have been found to play an important role too as people with the AA variant of the ATP-binding cassette (ABC) transporter gene, ABCC11, do not secrete preodour substrates for bacterial conversion, while those with GA or GG variants do. Hygiene and genetics, are an incomplete explanation though, because the longitudinal ALSPAC study found that there is a mismatch between patients' secretory status, as determined by genetics, and their use of deodorants. This suggests that other metabolic pathways or compounds contribute to the odour. In this paper I propose that under arm odour is commonly caused by terpenes excreted via the axillary apocrine glands. I also show that these come from terpene and carotenoid-rich dietary sources including lycopene, tomatoes, orange peel and the glandular trichomes of tomato plants. These observations suggest that the axillary apocrine glands are a prominent excretory route for terpenes. Considering the quantities eaten, tomatoes are likely to be the main source of dietary terpenes, and under arm odour in turn. This study also shows that lycopene is probably metabolised by β-carotene 9 10 monooxygenase which cleaves β-carotene eccentrically at the 9 10 or 9'10' position of the chain. Direct evidence of lycopene metabolism by β-carotene 9 10 monooxygenase has hitherto been lacking. The study of terpene and carotenoid metabolism can be greatly advanced by analysing the content of axillary gland excretions.
1. Sophisticated and sensitive technologies now allow separation, quantification and chemical characterization of numerous compounds that play roles in chemical communication, chemical defence and aggression, in interactions between conspecific or heterospecific individuals. In the particular subfield of mammalian chemical communication, these rapid technological advances, combined with a frequent lack of technical background, have led to important errors in both chemical characterization of molecules and interpretation of their roles as chemical mediators of communication.
2. The aim of this article is to highlight some of these methodological and analytical pitfalls and to provide a basis for better understanding of chemical mediation of communication in mammals. We compiled the recent literature treating molecules found in mammalian secretions and having putative roles in communication. A selection of 41 published studies dealing with 33 mammal species revealed reports of 857 different molecules. Based on the five main metabolic pathways responsible for the biosynthesis of most known secondary metabolites, we propose nine general biochemical rules that will help researchers to avoid errors of chemical characterization and to aid in interpreting the possible functional role of identified molecules as chemical mediators of mammal communication.
3. Following these nine rules, we show that published studies include reports of molecules that are incorrectly or ambiguously named, molecules of exclusively non-natural origin, molecules produced by other organisms but not directly by mammals, and molecules of biological origin and possibly produced by mammals. Only the last two of these classes could conceivably play roles as mediators of mammalian communication. We discuss the potential roles of these compounds as reported in the publications we reviewed.
4. Our recommendations concerning technical, analytical and statistical aspects of the identification of compounds and interpretation of their roles should help chemical ecologists ask the appropriate questions about the accuracy of their identifications of molecules, the biological relevance of molecules they do identify and the possible functional roles of these molecules in mammalian communication.
In this study, the strong “maple-syrup” odour which appears after fenugreek ingestion was investigated. Headspace solid-phase microextraction (HS-SPME) was applied to extract volatile odourant compounds from human male armpit sweat samples. Two male volunteers were considered who have similar diet; they had to ingest fenugreek infusion over the same period of time. The HS-SPME extracts obtained were then analysed by gas chromatography coupled either to mass spectrometry (GC–MS) or flame ionisation detection and olfactometry (GC–O). In that latter case, a panel of eight assessors was used, and the detection frequency methodology was applied. A total of 44 compounds could be identified in sweat samples, with a wide range of chemical structures, some of them being reported for the first time in human armpit sweat. Eight compounds appearing only after fenugreek ingestion could be identified: 2,5-dimethylpyrazine, β-pinene, 3-octen-2-one, camphor, terpinen-4-ol, 4-isopropyl-benzaldehyde, neryl acetate and β-caryophyllene. Due to their odourant notes, such compounds should be responsible for the strong “maple-syrup” odour present in sweat after fenugreek ingestion. GC–O confirmed the role of some odourant compounds in the “maple-syrup” odour of sweat, especially 2,5-dimethylpyrazine which was the best perceived odour. Among these eight compounds, some of them were previously reported in the fenugreek seeds, namely β-pinene, 3-octen-2-one and camphor.
On-site sampling and sample preparation favor portable, solventless or even solvent-free techniques. Solid-phase microextraction (SPME) has these advantages. This review focuses on developments between 2007 and early 2011 in microextraction techniques for on-site sampling and sample preparation, including fiber SPME, stir-bar sorptive extraction (SBSE), thin-film microextraction (TFME) and different types of in-needle SPME. The major trends in on-site applications of SPME appear to be fiber and thin-film SPME, microextraction by packed sorbent (MEPS) and the sorbent-packed needle-trap device (NTD). We discuss and compare several aspects of these types of SPME in on-site applications. We also describe sorbent phases for SPME that benefit on-site applications. Finally, we provide a perspective on SPME-based techniques for on-site applications.
The terms "attractant" and "repellent" only have commonly Been employed to describe chemicals in terms of their effect on the behavior of insects. The two terms as defined in their strictest sense do not apply to all possible types of reactions of insects to chemicals. There is a genuine need to clarify the use of terminology in this subject. An analysis of the behavioral effects of chemicals on locomotion, feeding, and oviposition has led to the designation and definition of five terms; namely, arrestant, stimulant (locomotor, feeding, ovipositional),attractant, repellent, deterrent. It is proposed that these five be employed as standard terms within the limits of the definitions given.
Experiments on the biological measurement of toxicities, and others requiring the use of the probit transformation in the statistical analysis, have in die past been largely of a unifactorial nature. In order to reach a fuller understanding of the action of insecticides and other poisons it is necessary that experiments be performed in‐which two or more factors relating to the dosage are subjected to variation. Bliss has recently described methods for the analysis of two‐factor experiments, but his technique is not a direct extension of the simple case for the fitting of a probit regression line, nor will it generalize easily when more factors are involved.
In the present paper it is shown that probit regression planes and hyper‐planes can be fitted in a way exactly analogous to that used for the regression line. Tests of heterogeneity and of parallelism, and standard errors of parameters are readily derived. The notion of relative potency of two poisons does not extend so easily, and it is suggested that the mean probit difference should be used in its stead as a measure of their relative effectiveness. As in the unifactorial analysis, the routine of fitting the. regression equations may be repeated until satisfactory accuracy in the estimation of the parameters is attained, but usually one, or at the most two, cycles of the process gives values sufficiently near to the maximum likelihood solution for practical purposes.
A more general class of equations is introduced for use when the probit mortality is linearly related to each dosage factor separately, but the individual effects are not additive. The suggestion made by Bliss (1040) for this case lacks symmetry and does not completely fulfil the linearity conditions, but the present proposal avoids these defects and permits the making of tests for the significance of the im‐proval in fit effected by the additional parameters.
The arithmetical procedure for the fitting of a probit plane is described in detail for data on the toxicity to Tribolium castameion of a pyrethrin oil spray at various levels of concentration and deposit weight. Two methods of applying the poison were compared in this experiment, and the two series of results were excellently fitted by parallel probit planes. Direct spraying gave slightly, but not significantly, higher kills than the film method of application, and under the particular conditions obtaining, increasing the concentration of pyrethrin in the spray was a far more effective means of increasing kill than was a proportionate increase in the total amount of spray available to the insects. Numerical examples used by Bliss are also discussed in relation to die methods of fitting and forms of equation given in this paper.
In this review, we describe technical developments in breath analysis and its applications in clinical diagnosis, monitoring disease state, and assessing environmental exposure. Breath tests have been successfully employed in clinical analyses for symptoms including lung disease, oxidative stress, gastrointestinal disease, metabolic disorders, and Helicobacter pylori infection. Although gas chromatography has been used mainly for the analysis of volatile constituents in breath samples, other techniques (e.g., sensors and lasers) have also been used satisfactorily. The analytical results of breath analysis can be derived both qualitatively and quantitatively. However, evaluation of the data from different approaches remains insufficient because of the lack of standardized procedures and poor methods of validation. Further research is therefore required to expand the applicability of breath analysis in clinical diagnosis of diseases.
Lung cancer diagnosis via breath analysis has to overcome some issues that can be summarized by two crucial points: (1) further developments for more performant breath sampling technologies; (2) discovering more differentiated volatile fingerprints to be ascribed to specific altered biological mechanisms. The present work merges these two aspects in a pilot study, where a breath volume, sampled via endoscopic probe, is analyzed by an array of non-selective gas sensors. Even if the original non-invasive methods of breath analysis has been laid in favour of the endoscopic means, the innovative technique here proposed allows the analysis of the volatile mixtures directly sampled near the tumor mass. This strategy could open the way for a better understanding of the already obtained discrimination among positive and negative cancer cases. The results obtained so far confirm the established discrimination capacity. This allows to discriminate the different subtypes of lung cancer with 75% of correct classification between adenocarcinoma and squamous cell carcinoma. This result suggests that a 'zoom-in' on the cancer settled inside the human body can increase the resolution power of key-volatiles detection, allowing the discrimination among different cancer fingerprints. We report this novel technique as a robust support for a better comprehension of the promising results obtained so far and present in literature; it is not to be intended as a replacement for non-invasive breath sampling procedure with the endoscope.
Hundreds of volatile organic compounds (VOCs) are emitted from the human body, and the components of VOCs usually reflect
the metabolic condition of an individual. Therefore, contracting an infectious or metabolic disease often results in a change
in body odour. Recent progresses in analytical techniques allow rapid analyses of VOCs derived from breath, blood, skin and
urine. Disease-specific VOCs can be used as diagnostic olfactory biomarkers of infectious diseases, metabolic diseases, genetic
disorders and other kinds of diseases. Elucidation of pathophysiological mechanisms underlying production of disease-specific
VOCs may provide novel insights into therapeutic approaches for treatments for various diseases. This review summarizes the
current knowledge on chemical and clinical aspects of body-derived VOCs, and provides a brief outlook at the future of olfactory
diagnosis.
The repellent activity of the essential oil of the catmint plant, Nepeta cataria (Lamiaceae), and the main iridoid compounds (4aS,7S,7aR) and (4aS,7S,7aS)-nepetalactone, was assessed against (i) major Afro-tropical pathogen vector mosquitoes, i.e. the malaria mosquito, Anopheles gambiae s.s. and the Southern house mosquito, Culex quinquefasciatus, using a World Health Organisation (WHO)-approved topical application bioassay (ii) the brown ear tick, Rhipicephalus appendiculatus, using a climbing repellency assay, and (iii) the red poultry mite, Dermanyssus gallinae, using field trapping experiments. Gas chromatography (GC) and coupled GC-mass spectrometry (GC-MS) analysis of two N. cataria chemotypes (A and B) used in the repellency assays showed that (4aS,7S,7aR) and (4aS,7S,7aS)-nepetalactone were present in different proportions, with one of the oils (from chemotype A) being dominated by the (4aS,7S,7aR) isomer (91.95% by GC), and the other oil (from chemotype B) containing the two (4aS,7S,7aR) and (4aS,7S,7aS) isomers in 16.98% and 69.83% (by GC), respectively. The sesquiterpene hydrocarbon (E)-(1R,9S)-caryophyllene was identified as the only other major component in the oils (8.05% and 13.19% by GC, respectively). Using the topical application bioassay, the oils showed high repellent activity (chemotype A RD(50)=0.081 mg cm(-2) and chemotype B RD(50)=0.091 mg cm(-2)) for An. gambiae comparable with the synthetic repellent DEET (RD(50)=0.12 mg cm(-2)), whilst for Cx. quinquefasciatus, lower repellent activity was recorded (chemotype A RD(50)=0.34 mg cm(-2) and chemotype B RD(50)=0.074 mg cm(-2)). Further repellency testing against An. gambiae using the purified (4aS,7S,7aR) and (4aS,7S,7aS)-nepetalactone isomers revealed overall lower repellent activity, compared to the chemotype A and B oils. Testing of binary mixtures of the (4aS,7S,7aR) and (4aS,7S,7aS) isomers across a range of ratios, but all at the same overall dose (0.1 mg), revealed not only a synergistic effect between the two, but also a surprising ratio-dependent effect, with lower activity for the pure isomers and equivalent or near-equivalent mixtures, but higher activity for non-equivalent ratios. Furthermore, a binary mixture of (4aS,7S,7aR) and (4aS,7S,7aS) isomers, in a ratio equivalent to that found in chemotype B oil, was less repellent than the oil itself, when tested at two doses equivalent to 0.1 and 0.01 mg chemotype B oil. The three-component blend including (E)-(1R,9S)-caryophyllene at the level found in chemotype B oil had the same activity as chemotype B oil. In a tick climbing repellency assay using R. appendiculatus, the oils showed high repellent activity comparable with data for other repellent essential oils (chemotype A RD(50)=0.005 mg and chemotype B RD(50)=0.0012 mg). In field trapping assays with D. gallinae, addition of the chemotype A and B oils, and a combination of the two, to traps pre-conditioned with D. gallinae, all resulted in a significant reduction of D. gallinae trap capture. In summary, these data suggest that although the nepetalactone isomers have the potential to be used in human and livestock protection against major pathogen vectors, intact, i.e. unfractionated, Nepeta spp. oils offer potentially greater protection, due to the presence of both nepetalactone isomers and other components such as (E)-(1R,9S)-caryophyllene.
One mechanism by which the action of semiochemicals can be classified is based on the behavioral impact within or external to the species of interest. As such, one can classify a chemical as one of the following2,3:
1. Pheromone, if it results in response between insects of the same species 2. Kairomone, if it results in response in another species that benefits the species receiving the chemical cue 3. Allomone, if it results in response in another species that benefits the species releasing the chemical cue
However, the distinctions can be more specific by classification of chemical cues through the imparted behavioral effect: attractant; repellent; arrestant; locomotory stimulant; feeding, mating, or oviposition stimulant; and feeding, mating, or oviposition deterrent.2,4 Karlson and Lu¨ scher first proposed the term “pheromone” to describe chemicals with instraspecific species activity.5,6 Chemicals with interspecific species activity are allelochemicals.3 Allelochemicals can be separated further into kairomones, of which attractants are a category of, and allomones, which are the primary focus of both this book and chapter, and the class that repellents are a part of. Furthermore, attraction-inhibitors, are classified by us as a category of repellents. Ironically, many of the attraction-inhibitors have been discovered in a search for kairomones used by mosquitoes to locate human hosts. Attraction-inhibitors may not repel by the traditional mechanisms, but they do interfere, or act as an antagonist to the normal attraction response of an insect to attractive odor(s).
The proper name for the behavioral actions that are described in this chapter can be debated extensively and additional discussion of terminology is found in Chapter 2 by White. In this short prequel to the main body of our contribution on human and other compounds that interfere with mosquito host-finding, we put forth our rationale supporting the terms used to describe behaviors reported in this chapter.
The toxicity of a range of plant essential oils to the poultry red mite, Dermanyssus gallinae (De Geer) (Acari: Dermanyssidae), a serious ectoparasitic pest of laying hens throughout Europe and elsewhere, was assessed in the laboratory. Dermanyssus gallinae may cause losses in egg production, anaemia and, in extreme cases, death of hens. With changes in legislation and consumer demand, alternatives to synthetic acaricides are needed to manage this pest. Fifty plant essential oils were selected for their toxicity to arthropods reported in the literature. Twenty-four of these essential oils were found to kill > 75% of adult D. gallinae in contact toxicity tests over a 24-h period at a rate of 0.21 mg/cm(2). Subsequent testing at lower rates showed that the essential oils of cade, manuka and thyme were especially toxic to adult D. gallinae. The toxicity of the seven most acaricidal essential oils was found to be stable at different temperatures likely to be encountered in commercial poultry housing (15 degrees C, 22 degrees C and 29 degrees C), although results suggest that humidity and dust might influence the toxicity of some of the oils tested. The toxicity of clove bud essential oil to D. gallinae, for example, was increased at high humidity and dust levels compared with ambient levels. The results suggest that certain essential oils may make effective botanical pesticides for use against D. gallinae, although it is likely that issues relating to the consistency of the toxic effect of some oils will determine which oils will be most effective in practice.
Infections are often followed by a change in body odours. For a long time, these changes were considered as non-specific (with no adaptive value) but recent evidences suggest that this may not always be true. Odour modifications due to an infection may either be of adaptive value for the parasite or the host. Here, we describe the observations in support of this idea, discuss the potential roles these modifications may play for the parasite and the host and propose a set of future directions that we think should allow to better understand the mechanisms at the origin of these modifications and how they may be used by both parasites and their human hosts.
1. The metabolism of eugenol (4-hydroxy-3-methoxy-allylbenzene) was investigated in male and female healthy volunteers. It was rapidly absorbed and metabolized after oral administration and was almost completely excreted in the urine within 24 h. Unmetabolized eugenol excreted in urine amounted to less than 0.1% of the dose. 2. The urine contained conjugates of eugenol and of nine metabolites. The structures of these metabolites, elucidated using g.l.c.-mass spectrometry, and by comparison with synthetic reference compounds, were identified as: eugenol, 4-hydroxy-3-methoxyphenyl-propane, cis- and trans-isoeugenol, 3-(4-hydroxy-3-methoxyphenyl)-propylene-1,2-oxide, 3-(4-hydroxy-3-methoxyphenyl)-propane-1,2-diol, and 3-(4-hydroxy-3-methoxyphenyl)-propionic acid. 3. The structures of the following metabolites were tentatively deduced from mass spectra only, as reference compounds were not available: 3-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-allylbenzene, 3-(6?-mercapto-4-hydroxy-3-methoxyphenyl)-propane, and 2-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-propionic acid. 4. The amounts of the individual metabolites excreted were determined by g.l.c. Some 95% of the dose was recovered in the urine, most of which (greater than 99%) consisted of phenolic conjugates; 50% of the conjugated metabolites were eugenol-glucuronide and sulphate. Other metabolic routes observed were the epoxide-diol pathway, synthesis of a thiophenol and of a substituted propionic acid, allylic oxidation, and migration of the double bond.
This review discusses the most recent developments and future challenges in the application of solid phase microextraction (SPME) for sampling of live biological samples. The emphasis is placed on applications of fiber SPME for analysis of volatile emissions and drugs in biological fluids. The method development section highlights the main parameters that need to be considered in the case of in vivo experiments: extraction techniques, selection of extraction phases, calibration procedures, determination of free concentrations, and automation.
Candidate kairomones of ornithophilic mosquito species are reported from GC/MS analysis of compounds from the skin on the back, the feet, and feathers from the back of White Leghorn chickens (Gallus gallus domesticus). Hexane and ether extracts of chicken feathers differ significantly in attractiveness of Culex spp. mosquitoes. The active (hexane) extracts contained an abundance of alcohols, ketones, and diones. The inactive (ether) extracts contained aldehydes, which also were in the hexane extracts. Analysis of hexane extracts from chicken feet, skin, and feathers demonstrated the qualitative similarity in the compounds collected with subtle differences observed in the quantitative amounts of these compounds. Aldehydes and carboxylic acids were detected in a concentrated ether extract of feathers in quantitatively similar ratios within each compound class for the corresponding series of C(6)-C(9 )aldehydes and acids.
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Plant extracts repellent against Dermanyssus gallinae
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Plant extracts: a new tool for the poultry red mite issue
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