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Simple Summary: The negative impact of numerous chemical compounds entering the environment from various anthropogenic sources is one of the reasons for the decline in populations and biodiversity of aboveground invertebrates. Chemical compounds can cause various effects (attracting or repelling) on insects. In laboratory conditions, the motor response of 1802 adult Philonthus decorus Gravenhorst beetles to 40 organic compounds and mixtures of compounds (acids, alcohols, ketones, phenols, aldehydes, aromatic carbohydrates solvents, and vehicle fuels) was revealed. It has been established that females of this rove species are generally less sensitive to odors. Organic acids in most cases were characterized by a repellent (oleic, acetic, oxalic, citric, formic acids) or neutral effect on beetles. The exception was some amino acids that have a moderate attractive effect. Alcohols most often exhibited the properties of moderate repellents or neutral substances for Ph. decorus imagoes. The exceptions were butyl alcohol (strong repellent of females), and methyl alcohol (moderate attractant of females). Aldehydes showed a moderate repellent effect on males and did not affect females. Aromatic hydrocarbons had a weak repellent effect on rove beetles. Organic solvents and fuels exerted no repellent or attractant effects on Ph. decorus. In most cases, they had a moderate repellent or neutral effect on these insects, with the exception of diesel fuel. This type of fuel attracted females. The majority (55%) of the chemical compounds and mixtures of compounds participating in the experiment had no attractant or repellent effect on the staphylinids. The use of organic compounds in different spheres of human activity is accompanied by their influx to and accumulation in the environment. The negative impact of those compounds can be one of the reasons for a decline in populations and biodiversity of aboveground invertebrates. Chemical compounds can potentially cause a variety of effects (attractant or repellent) on insects, including species of the Staphylinidae family. In a laboratory experiment, we identified repellent and attractant influence of 40 organic compounds and mixtures of compounds (acids, alcohols, ketones, phenols, aldehydes, aromatic carbohydrates solvents, and vehicle fuels) on Philonthus decorus Gravenhorst, 1802. The ambulatory responses of the males and females to the same chemical compounds most often varied. A strong repellent activity against both sexes of Ph. decorus was caused by oleic acid, while hexane repelled the males. Acetic acid, 1-butanol, and ammonia solution were found to be strongly repellent against females. A moderate (average) repellent activity towards male Ph. decorus was displayed by organic solvents and fuels, some alcohols (isopropanol, isoamyl alcohol, methanol, ethanol), acids (acetic, formic acid), aromatic carbohydrates (toluene, xylene), and formaldehyde. Female Ph. decorus in general were less sensitive to the odors. The list of repellents with moderate activity against the females was much shorter: solvent 646, white spirit, toluene, isopropanol, isoamyl alcohol, citric and oxalic acids, and glycerol. Moderate attractant activity for Ph. decorus was exhibited by some amino acids, alcohols, and fuel mixes: glycine and L-cysteine (for the males), and phenylalanine, methanol, and diesel fuel (for the females). The rest of the 40 chemical compounds we studied caused no ambulatory responses in Ph. decorus. The difficulties we encountered in the interpretation of the results suggest a need for further experimental studies that would expand the knowledge of the chemoecology of insects. [ABSTRACT FROM AUTHOR]

The push–pull approach using semiochemicals in pest control requires both an attractant and a repellent. Many previous studies have arbitrarily tested one or more known insect repellents or plant essential oils (EOs) hoping to find repellents of an insect pest. We used a comprehensive approach that synergistically tests in the field numerous natural volatiles from commercial EOs to identify repellents of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae), a worldwide pest of palms and date palms. Volatiles from 79 EOs in slow-release devices were divided into five groups and tested in traps with attractive pheromone compared to traps with pheromone alone. EO-treatment groups exhibiting repellency due to significant trap shutdown, were further subdivided into subgroups of four EOs each and tested further. Two groups of four EOs (cypress, desert wormwood, elemi, and Eucalyptus citriodora) and (niaouli, nutmeg, oregano, and orange sweet), or their corresponding mixtures of major volatiles, caused pheromone trap reductions of up to 92%. Further tests showed that seven of the eight EOs are similarly repellent as the corresponding subgroup. This systematic approach of successively testing sub-fractions of EOs in the field for trap shutdown should be useful to identify repellents of other insect pests of crops. [ABSTRACT FROM AUTHOR]

In recent years, a large number of insect repellents have been developed with the idea of consumer benefits. In addition to already known advantageous application of insect repellents, there is increasing concern about the potential toxicity in environment leading to health caused by random use of these compounds. An increasing number of evidence suggests that insect repellents may trigger undesirable hazardous interactions with biological systems with a potential to generate harmful effects including intermediate metabolites. Biotransformation followed by bioaccumulation ( vice e versa ) may be an important phenomenon for toxic response of this chemicals. In this review, we have summarized the current state of knowledge on the insect repellent toxicity, including biochemical pathway alteration under in vitro and in vivo conditions considering different classes of organisms, from lower to higher vertebrate. Furthermore, we have tried to incorporate the effects of insect repellent in light of some clinical reports. We hope this review would provide useful information on potential side effects of uncontrolled use of insect repellents. [ABSTRACT FROM AUTHOR]

Mosquitoes (Diptera: Culicidae) represent a huge threat for millions of humans and animals worldwide, since they act as vectors for important parasites and pathogens, including malaria, filariasis and important arboviruses, such as dengue, West Nile and Zika virus. No vaccines or other specific treatments are available against the arboviruses transmitted by mosquitoes, and avoidance of mosquito bites remains the best strategy. African regions are usually hit most whose inhabitants are poor, and the use of repellent plants is the only efficient protection against vectors they have. Ethnobotanical knowledge of such plants and their use is usually passed on orally from one generation to another. However, it is also important to preserve this information in a written form, as well. Ethnobotanical research projects carried out in the regions of today’s Ethiopia, South Africa, Nigeria, Kenya, and Tanzania indicate that the native inhabitants of the African study regions traditionally use 64 plant species, belonging to 30 families. Aromatic plants (i.e., Citrus spp., Eucalyptus spp., Lantana camara , Ocimum spp. and Lippia javanica ) the most commonly used in all the study regions. Native people know three major methods of using repellent plants: ( i ) production of repellent smoke from burning plants, ( ii ) hanging plants inside the house or sprinkling leaves on the floor, ( iii ) the use of plant oils, juices from crushed fresh parts of the plants, or various prepared extracts applied on uncovered body parts. Overall, this review covers studies conducted only in a limited part of the African continent, highlighting the importance to undertake further research efforts to preserve the unique knowledge and traditions of the native tribes. [ABSTRACT FROM AUTHOR]

Introduction: The insect repellent compounds are used to protect humans, animals and plants against insect bites. Aromatic amides have insect repellent effects. N,N-diethyl-meta-toluamide (DEET) (C12H17NO) is one of the best insect repellents has been used for many years. DEET is a colorless, odorless liquid that is approximately insoluble in water and soluble in glycerin, ethanol, and isopropyl alcohol. Due to the solubility problem of DEET, its topical formulations usually have alcoholic bases, but these kind of formulations increase skin permeation and also systemic absorption of DEET, which leads to some toxic effects. The main goal of this study was to prepare the formulation of DEET niosomes in a topical dosage form with suitable stability properties. Materials and Methods: Three different methods were used to prepare niosome formulations: Dehydration rehydration vesicle method, direct mixing method, homogenizer method. Sorbitan surfactants, cholesterol, polyoxyethylenecetyl, phosphate buffer (pH 7.4), and charge inductive compounds like cetyltrimethylammonium bromide were used to provide a net negative charge to the final membrane structure. A high-performance liquid chromatography method was then used for the determination of the loaded DEET. Results: A large number of niosomes were multi-layered and have a spherical shape. In comparison, syringe method against direct mixing is more appropriate because of creation MLV and uniform niosomes but the best method is homogenizer method. Drug entrapment was between 14% and 21% in selected formulation. Conclusion: According to this study, homogenizing method can be used for formulation of DEET in niosome form in topical formulations. [ABSTRACT FROM AUTHOR]

The use of the latest advances in nanotechnology has revolutionized the way towards prevention and treatment of some skin affections. The use of nanoparticles and microparticles in dermatology with a cosmetic, preventive and therapeutic aim is becoming increasingly common. Less known but also thoroughly researched and used is the application of several active nano and microparticles in materials that are in contact with the skin, such as clothing, paper, various types of equipment used in everyday life, furniture, concrete, varnishes paints and so on. [ABSTRACT FROM AUTHOR]

The snow flea Ceratophysella sigillata, a winter-active species of springtail, produces unique polychlorinated octahydroisocoumarins to repel predators. The structure of the major compound, sigillin A, was elucidated through isolation, spectroscopic analysis, and X-ray crystallography. Sigillin A showed high repellent activity in a bioassay with predatory ants. A promising approach for the total synthesis of members of this new class of natural compounds was also developed. [ABSTRACT FROM AUTHOR]

Microencapsulation is a promising method for controlling and prolonging the release of safer, bio-based insect repellents, which can be used for protection against many vector-borne endemic diseases. Geraniol is an effective insect repellent; however, its encapsulation in gelatin/gum arabic, and its long-term retention have not been studied to date. In this study, complex coacervation was used to obtain novel geraniol-containing microcapsules using gelatin/gum arabic. The effect of processing conditions on the size and morphology of the microcapsules and the subsequent release properties was investigated. Optimal conditions included a coacervation pH of 4.45 and a crosslinking pH of 6.0. Lower mixing rates produced single core capsules with larger particle size (93 µm). Higher mixing rates resulted in multi-core capsules with smaller average particle sizes (34 µm). The geraniol contents of microcapsules were found to be 90%, 68%, and 73% for mixing rates of 700 RPM, 1000 RPM, and 1300 RPM, respectively. Microcapsule formulations showed excellent release profiles into humid air without any burst release, with retentions of 80%, 74%, and 76% at 26 days for mixing rates 700 RPM, 1000 RPM, and 1300 RPM, respectively. Encapsulation of geraniol results in longer-lasting retention compared to similar systems; hence it can be used as textile coatings for use in insect repellent clothing or incorporated into various carrier solutions for application as an area treatment. Our research highlights the possibility of tuning diffusion characteristics based on microcapsule morphology opening new applications for this technique. [Display omitted] [ABSTRACT FROM AUTHOR]

N,N-diethyl-m-toluamide (DEET) has been registered for commercial use as an insect repellent for over five decades, and is used widely across the world. Concerns over the safety of DEET first emerged during the 1980s after reports of encephalopathy following DEET exposure, particularly in children. However, the role of DEET in either the illness or deaths was and remains purely speculative. In response to these cases a number of reviews and investigations of DEET safety were carried out. Here we examine the methods used and information available to determine the safety of DEET in humans. Animal testing, observational studies and intervention trials have found no evidence of severe adverse events associated with recommended DEET use. Minor adverse effects noted in animal trials were associated with very large doses and were not replicated between different test species. The safety surveillance from extensive humans use reveals no association with severe adverse events. This review compares the toxicity assessment using three different models to define the risk assessment and safety threshold for DEET use in humans and discusses the clinical consequences of the thresholds derived from the models. The theoretical risks associated with wearing an insect repellent should be weighed against the reduction or prevention of the risk of fatal or debilitating diseases including malaria, dengue, yellow fever and filariasis. With over 48 million European residents travelling to regions where vector borne diseases are a threat in 2009, restricting the concentration of DEET containing repellents to 15% or less, as modelled in the 2010 EU directive, is likely to result in extensive sub-therapeutic activity where repellents are infrequently applied. Future European travellers, as a consequence of inadequate personal protection, could potentially be at increased risk of vector borne diseases. Risk assessments of repellents should take these factors into account when setting safe limits. [ABSTRACT FROM AUTHOR]

Highlights: [•] Interactions of 50 repellent chemicals with olfactory receptor neurons were performed. [•] Six different types of mosquito sensilla were studied. [•] Effects of chemical repellents on the mosquito olfactory system were approved. [•] Study is important for screening new mosquito repellents and mosquito control agents. [Copyright &y& Elsevier]

Simple Summary: The perception and processing of chemosensory stimuli are indispensable to the survival of living organisms. In insects, olfaction and gustation play a critical role in seeking food, finding mates and avoiding signs of danger. This review aims to present updated information about olfactory and gustatory signaling in the fruit fly Drosophila melanogaster. We have described the mechanisms involved in olfactory and gustatory perceptions at the molecular level, the receptors along with the allied molecules involved, and their signaling pathways in the fruit fly. Due to the magnifying problems of disease-causing insect vectors and crop pests, the applications of chemosensory signaling in controlling pests and insect vectors are also discussed. From a unicellular bacterium to a more complex human, smell and taste form an integral part of the basic sensory system. In fruit flies Drosophila melanogaster, the behavioral responses to odorants and tastants are simple, though quite sensitive, and robust. They explain the organization and elementary functioning of the chemosensory system. Molecular and functional analyses of the receptors and other critical molecules involved in olfaction and gustation are not yet completely understood. Hence, a better understanding of chemosensory cue-dependent fruit flies, playing a major role in deciphering the host-seeking behavior of pathogen transmitting insect vectors (mosquitoes, sandflies, ticks) and crop pests (Drosophila suzukii, Queensland fruit fly), is needed. Using D. melanogaster as a model organism, the knowledge gained may be implemented to design new means of controlling insects as well as in analyzing current batches of insect and pest repellents. In this review, the complete mechanisms of olfactory and gustatory perception, along with their implementation in controlling the global threat of disease-transmitting insect vectors and crop-damaging pests, are explained in fruit flies. [ABSTRACT FROM AUTHOR]

Coping strategies including smoke screens are used against nuisance bites of Simulium damnosum Theobald (Diptera:Simuliidae) in onchocerciasis endemic communities. To find more effective alternatives, the efficacy of commercially available N,N-diethyl-3-methylbenzamide (DEET) products with active concentrations of 9.5, 13, 25, 50 and 98.1-100% and 'NO MAS,' (active component: para-menthane-3,8-diol and lemon grass oil) were tested at Bui-Agblekame, Ghana. A Latin square study design was implemented using eight groups of two vector collectors each, who used repellents (treatment), mineral oil or nothing each day until the end of the study. Flies were caught and their numbers each hour recorded using the standard methods for onchocerciasis transmission studies. T-tests were used to compare the mean duration of protection and a one-way analysis of variance controlling for catchers and repellents was performed. Tukey's test was used to compare protection by repellents and mineral oil. The highest percentage protection was 80.8% by NO MAS and the least 42.5% by the 13% DEET product. The period of absolute protection was 5 h by NO MAS and 1 h by 50% DEET product. No significant increase in protection was offered beyond 25% active DEET products and no significance was observed in terms of catcher × repellent effect ( F = 1.731, d.f. = 48, P = 0.209). [ABSTRACT FROM AUTHOR]

Many insects such as mosquitoes cause life-threatening diseases such as malaria, yellow fever and West Nile virus. Malaria alone infects 500 million people annually and causes 1-3 million death per year. Volatile insect repellents, which are detected through the sense of smell, have long been used to protect humans against insect pests. Antifeedants are non-volatile aversive compounds that are detected through the sense of taste and prevent insects from feeding on plants. The molecular targets and signaling pathways required for sensing insect repellents and antifeedants are poorly understood. Transient Receptor Potential (TRP) Ca2+-permeable cation channels exist in organisms ranging from C. elegans to D. melanogaster and Homo sapiens. Drosophila has 13 family members, which mainly function in sensory physiology such as vision, thermotaxis and chemotaxis. G protein-coupled receptors (GPCRs) initiate olfactory signaling cascades in mammals and in nematodes C.elegans. However, the mechanisms of G protein signaling cascades in insect chemosensation are controversial. In this review, I will discuss the putative roles of G protein-coupled receptors (GPCRs) and Transient Receptor Potential (TRP) channels as targets for insect repellents. [ABSTRACT FROM AUTHOR]

The question of whether the insect repellent N,N-Diethyl-meta-toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers ( p < 0.01 for all variables), with subsequently reduced decomposition ( p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death. [ABSTRACT FROM AUTHOR]

Abstract: A monitoring programme was carried out on wastewater, surface and drinking water on the NW area of Spain during the four seasons of a year period (November 2007–September 2008). This study covered a series of emerging pollutants of different classes, including pharmaceuticals, neutral and acidic organophosphorus flame retardant/plasticizers (OPs), triclosan, phenoxy-herbicides, insect repellents and UV filters. From the total set of 53 compounds, 19 were found in raw wastewater with median concentrations higher than 0.1μgL−1. Among them, salicylic acid, ibuprofen and the UV filter benzophenone-4 (BP-4) were the most concentrated, exceeding the 1μgL−1 median value. Subsequently, 11 of these contaminants are not efficiently enough removed in the small WWTPs tested and their median concentrations in effluents still surpassed the 0.1μgL−1, so that they can spread through surface water. These chemicals are the pharmaceuticals naproxen, diclofenac and atenolol; the OPs tri(2-chloroethyl) phosphate (TCEP), tri(chloropropyl) phosphate (TCPP), tri-n-butyl phosphate (TnBP), diphenyl phosphate (DPhP) and diethylhexyl phosphate (DEHP); and the sulphonate UV filters BP-4 and 2-phenylbenzimidazole-5-sulphonic acid (PBSA). These OPs were then the dominant emerging pollutants occurring in surface and drinking water, where they are detected in the 20–200ngL−1 range. Pharmaceuticals and UV filters are typically below the 10ngL−1 level. Finally, herbicides were only detected in the last sampling campaign under the 100ngL−1 drinking water European Union limit. [Copyright &y& Elsevier]

Comparative inhalation toxicity studies of aerosols of insect repellents N,N-diethylbenzamide (DEB), N,N-diethylphenylacetamide (DEPA), and N,N-diethyl-3-methylbenzamide (DEET) were carried out in mice. The respiratory pattern was monitored using a computer program that recognizes the modifications of the breathing pattern. Exposure to the aerosols caused a dose-dependent decrease in normal breath, with an increase in airway obstruction. All the three insect “sensilla irritants” showed no significant mammalian sensory irritation. The acute LC50 value for a 4-h exposure of DEB, DEPA, and DEET aerosols in male mice was found to be >2.5 g/m3, 1714 mg/m3, and 1369 mg/m3, respectively. Irreversible depression in respiratory frequency was observed after exposure to DEB aerosol at a concentration of 277 mg/m3 and above, which did not revert back to normal level even after aerosol exposure was stopped. At a concentration of 156 mg/m3 of DEB, no respiratory depression was observed. DEPA and DEET caused no depression in respiratory frequency up to a concentration 1292 and 950 mg/m3, respectively. Hence the two insect repellents DEET and DEPA do not cause any harmful effect to the respiratory parameters in acute exposure, showing that they are more suitable chemicals to be used as insect repellents as compared to DEB. [ABSTRACT FROM AUTHOR]

Insect-borne diseases represent a worldwide threat. In addition to fight against vectors (insecticides) and disease prevention (vaccination against yellow fever, chemoprophylaxis against malaria), insect repellents applied on the skin could help reduce the heavy burden related to these diseases. In a field study performed in Senegal, we compared the efficacy of one skin application between 3 and 4 p.m. of four spray repellents [icaridine 20%, para-menthane-diol (PMD) 20% and 50% and DEET 50%] against placebo, among 100 healthy male and female volunteers experienced with mosquito capture. Double-blind randomized cross-over placebo-controlled study (Latin-square design) during five consecutive nights (7 p.m. to midnight) in two villages was conducted. To avoid residual effect, right or left leg was alternately exposed during consecutive nights and the exposed leg was washed before next night. The statistical model was random and mixed effectsanova. All four active repellents provided a significant and similar protection compared with placebo, lasting 8 h. However, there was a non-significant trend for a higher protection by DEET 50% than by PMD 20% ( P = 0.07). Duration of protection was similar for all repellents. Their effects were similar among men and women, and against Anopheles or other species. No serious adverse drug reaction was noticed. Using a rigorous methodology and a large number of volunteers, our well-controlled study demonstrated an important and similar protective effect of all four repellents compared with placebo. Such field studies should be required before approval of any newly developed repellent. [ABSTRACT FROM AUTHOR]

Alleviating the scourge of biting insects; Bioconjugates for new directions in pharmaceutical research; Sharing the benefits of research. [ABSTRACT FROM AUTHOR]

Abstract: Stir bar sorptive extraction (SBSE) in combination with thermodesorption–gas chromatography–mass spectrometry (TD–GC–MS) was applied for the determination of eight insect repellents and synergists in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20mL of water sample with 4g NaCl and stirred at 1000rpm for 180min. Then, the stir bar was subjected to TD–GC–MS. SBSE parameters (ionic strength, presence of organic solvent and time) were optimised. Blank contamination and carryover problems were also studied. The method affords detection limits between 0.5 and 30ng/L, except for dimethyl phthalate (DMP) (150ng/L) due to blank contamination problems. It shows good linearity with correlation coefficients over 0.997 and reproducibility (RSD) below 20%. The extraction efficiencies were between 29% for DMP and 80% for di-n-propyl isocinchomeronate (R-326). The feasibility of the method was tested by analysing real samples such as lake water, river water and wastewater. [Copyright &y& Elsevier]

Objectives. To assess the behavioural response of the F1 generation of Aedes aegyti (L) collected in the Metropolitan area of Monterrey (Nuevo Leon, Mexico) vs. three adulticides pyrethroids frequently used in public health. Materials and methods. We used a novel modular system called HITSS (High-Throughput Screening System) to evaluate two behavioral responses (contact irritation and spatial repellency), as well as the toxicity of three insecticides DDT, permeathrin and bifenthrin at different concentrations (0.025, 0.25, 25 and 250 nmol/cm2). Results. In the concentration 2.5 nmol/cm2, DDT (4.3 ± 2.4) and permethrin (8.0 ± 1.4) were the insecticides that are more irritating effect (p <0.05); the bifenthrin requires 20 times higher doses to achieve similar effects. In spatial repellency, the three insecticides tested have had a similar responses at all concentrations; DDT: 7 to 14%, permethrin: 9 to 15% and bifenthrin: 19% to 27%. Permethrin and bifenthrin in 0.025 nmol/cm2 concentrations, effects knockdown above 34%, with a mortality rate 19%, DDT requires 10 times higher concentrations to achieve similar effects. Conclusions. HITTS system can be used to assess the behavioural response to insecticides. [ABSTRACT FROM AUTHOR]

Abstract: DEET and oxybenzone are two essential active ingredients in repellent and sunscreen products. We performed a series of in vitro diffusion studies to evaluate the transmembrane permeation of DEET and oxybenzone across three artificial membranes, low-density polyethylene (LDPE), low fouling composite (LFC) and mixed cellulose esters (MCE), from concurrent use of commercial repellent and sunscreen preparations. Permeation of DEET and oxybenzone across the test membranes was synergistically increased when both the repellent and the sunscreen formulations were applied simultaneously. Different application sequences and formulation types also resulted in variable permeation profiles of DEET and oxybenzone. Compared to biological piglet epidermis under the identical experimental conditions, transmembrane permeation of DEET was suppressed in LDPE and LFC membranes, but enhanced in MCE membrane; transmembrane permeation of oxybenzone was reduced in LFC membrane, but increased in LDPE and MCE membranes. Permeability coefficients of DEET and oxybenzone in all three artificial membranes were significantly different from those in piglet skin. It was concluded that the permeation profiles of the compounds were dependent upon physicochemical characteristics of the membranes and the formulations. [Copyright &y& Elsevier]

Oil of neem, from the treeAzadirachta indicaA. Juss (Meliaceae), was evaluated for repellent and antifeedant activity againstCulicoidesbiting midges (Diptera: Ceratopogonidae), by three complementary methods with serial dilutions. Electroantennograms revealed the sensitivity ofCulicoides nubeculosus(Meigen) females to neem≥ 0.10%.Culicoides impunctatusGoetghebuer females were repelled by≥ 1% in a Y-tube olfactometer, Using a membrane feeder for wild-caught parous females ofC. impunctatus, the proportion blood-feeding was significantly reduced by topical applications of neem oil≥ 0.10% concentrations, with blood-feeding completely prevented by≥€1%. On the basis of these response data, we developed 2% neem-based formulations for personal protection against biting midges. [ABSTRACT FROM AUTHOR]

During summer months the insect repellent N,N-diethyl-m-toluamide (DEET) could always be detected in influents and effluents of wastewater treatment plants (WWTP) and anthropogenically influenced surface waters. In Germany the concentrations have decreased constantly since 1999, when DEET was substituted by Bayrepel. DEET can be degraded in WWTP, but only after an adaptation period and values in the influent above the threshold value. Since the year 2000 Bayrepel could also be detected during the summer months in the influents of WWTP, whereas in the effluents Bayrepel was not present. [ABSTRACT FROM AUTHOR]

Insect repellents such as N,N-diethyl-m-toluamide (DEET) which are used as protection against mosquitoes or ticks were detected in all wastewater and anthropogenically influenced surface waters analyzed. In Germany, the concentrations of DEET have constantly decreased since 1999, when DEET was substituted by Bayrepel (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl), 1-methylpropyl ester; KBR 3023) in commercial insect repellent formulations. A sensitive quantitative method was developed in order to study the occurrence and fate of Bayrepel in the aquatic environment. It was thus determined that Bayrepel undergoes rapid primary aerobic biodegradation, yielding a more stable metabolite, Bayrepel-acid (1-piperidinecarboxylic acid, 1-methylpropyl ester, 2-acetic acid). In order to study the biodegradation and investigate the fate of this metabolite, Bayrepel-acid was synthesized and characterized. Various chromatographic and mass spectrometric techniques, such as gas chromatography–mass spectrometry (MS) after derivatization, liquid chromatography (LC)–electrospray ionization (ESI) MS and LC–ESI time-of-flight MS were applied. [Copyright &y& Elsevier]

We conducted laboratory tests to assess the sensitivity to the insect repellent 1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-, 1-methylpropylester (known as KBR 3023 or Picaridin, trade name Bayrepel) of West African strains of the yellow fever mosquito Aedes aegypti and of malaria vectors of the Anopheles gambiae complex, in comparison with the standard repellent N,N-diethyl-3-methyl-benzamide (DEET). Test mosquitoes were exposed according to a 'separate arms' protocol to logarithmic dose increments applied on one arm of human subjects to evaluate the relative potency, and the median effective dosages (ED50 and ED90). According to a logistic regression model fitted to the experimental data, the dose-response relationship for the two repellents was the same within each species, thus pooled ED values were assessed for each mosquito separately. The median ED of KBR 3023 and DEET was estimated at 0.78 (95% confidence limits (CI): 0.57-1.04) and at 0.018 microg/cm2 (0.004-0.052) for mosquitoes of the An. gambiae complex and Ae. aegypti, respectively. ED90 values were 125.6 (81.4-201.3) and 24.0 microg/cm2 (5.7-208.5) for An. gambiae s.l. and Ae. aegypti, respectively. The relative potency of KBR 3023 was not significantly different from that of DEET for An. gambiae s.l. (95% confidence limits 0.7-1.0), whereas in the case of Ae. aegypti it was with 95% probability 1.1-2.0 times more potent than DEET. On the basis of available evidence, KBR 3023 represents a promising alternative to DEET for personal protection against bites of these important vectors of disease in the Afrotropical region. [ABSTRACT FROM AUTHOR]

This study analyzed 20,764 exposures involving insect repellants containing N,N-diethyl-m-toluamide (DEET) that were reported to poison control centers from 1993 to 1997. Nearly 70% of the cases reported no symptoms related to the exposure. The occurrence of symptoms was related to the route of exposure, with the highest rates associated with ocular exposures, followed by inhalation, multiple exposure routes, dermal, and ingestion. Two deaths were reported, one in a 26-year-old male and one in a 34-year-old female, both following a dermal exposure. Twenty-six subjects experienced major effects. The greatest number of reported exposures involved infants and children, but this group experienced lower rates of adverse effects than teens or adults. There was no clear relationship between DEET concentration and presence or severity of clinical effects. For the cases reported to poison control centers and included in this analysis, the risk of serious medical effects for labeled use of insect repellants containing N,N-diethyl-m-toluamide appears to be low. [ABSTRACT FROM AUTHOR]

A reversed-phase high-performance liquid chromatographic method with detection at 220 nm was developed and validated for the determination of ethyl-3-(N-n-butyl-N-acetyl)aminopropionate, IR 3535, in an insect repellent semi-solid product. A Hypersil ODS RP-C18 column (250×4.6 mm), 5 μm particle size, was equilibrated with a mobile phase consisted of water–acetonitrile (60:40, v/v). Its flow-rate was 1.0 ml/min. Excipients did not interfere with the determination of IR 3535 (Rs=8.663). Intra- and inter-day relative standard deviations for samples were not higher than 0.61 and 1.2%, respectively. Mean recovery was found not lower than 98.5% and not higher than 100.3%. The method of external standard was adopted. Calibration curves were linear in the concentration range between 1.0×10−6 and 5.0×10−4 M. Limits of detection and quantitation were 65 and 196 ng/ml, respectively. [Copyright &y& Elsevier]

Abstract. Acute toxicity and persistence of three insect repellents, deet and two piperidines (AI3-35765 and AI3-37220), were evaluated against mosquito larvae of Aedes albopictus (Skuse) and Anopheles albimanus Wiedemann (Diptera: Culicidae) in the laboratory, and against natural populations of Ae. albopictus in the field. In laboratory studies, the LC50 values of the repellents for first instars ranged between 0.005 and 0.021% (Ae. albopictus) and between 0.01 and 0.014% (An. albimanus) and, for fourth instars, between 0.019 and 0.034% (Ae. albopictus) and between 0.015 and 0.024% (An. albimanus). A 0.1% concentration of deet caused 90–100% mortality in first-instar Ae. albopictus for 4 weeks, whereas AI3-35765 and AI3-37220 at the same concentration killed 95–100% of larvae for 12 weeks and 98–100% of larvae for 33 weeks post-treatment, respectively. Deet and AI3-35765 at 0.1% concentration resulted in complete mortality of first-instar An. albimanus for 3 weeks post-treatment, whereas AI3-37220 resulted in 91–99% larval mortalities for 35 weeks post-treatment. A 0.1% concentration of AI3-37220 provided 77–98% larval mortality for 20 weeks and 63–97% larval mortality for 12 weeks post-treatment, respectively, against fourth-instar Ae. albopictus and An. albimanus. In the field, in artificial containers, the reduction of Ae. albopictus larvae caused by deet, AI3-35765 and AI3-37220 was 88–95% for 3–4 weeks, 98–100% for 7 weeks, and 82–100% for 13 weeks post-treatment, respectively. In used tyres, the same concentration of the repellents resulted in 100% reduction of Ae. albopictus larvae for 2 weeks (deet), 4 weeks (AI3-35765) and 5 weeks (AI3-37220) post-treatment. In cemetery flower vases, Aedes spp. larvae were eliminated for 4 weeks (deet) and 6 weeks post-treatment by both AI3-35765 and AI3-37220. These topical repellents (particularly AI3-37220) have good potential for development and use in the management of container-inhabiting mosquitoes because they deter oviposition and kill larvae. [ABSTRACT FROM AUTHOR]

Abstract. Three experimental approaches were used to evaluate the oviposition deterrency of three insect repellents, AI3-35765, AI3-37220 (piperidine compounds), and the standard N,N-diethyl-3-methylbenzamide (deet) to the mosquito Aedes albopictus Skuse (Diptera: Culicidae). Against laboratory-reared Ae. albopictus gravid females, the EC50 values of AI3-37220, AI3-35765 and deet were 0.004%, 0.008% and 0.011% in laboratory cages and 0.004%, 0.01% and 0.009% in an outdoor screened cage. For a natural population of Ae. albopictus tested in the field, the EC50 values were determined as 0.004%, 0.008% and 0.001%, respectively. Ageing concentrations of 0.1% of each repellent provided > 50% effective oviposition deterrency against the laboratory population of Ae. albopictus for 13 days in laboratory cages, for 15 days in the outdoor cage, and for 21 days against field population of Ae. albopictus in Florida. These topical skin repellents are effective oviposition deterrents for Ae. albopictus when employed at relatively low application rates. [ABSTRACT FROM AUTHOR]

(1) Respiratory distress and seizures developed in an 18-month-old boy following brief exposure to low-strength (17.6%) N,N-diethyl-m-toluamide (DEET). A review of the literature revealed 17 reports of DEET-induced encephalopathy in children. The objective of this study was to test the hypothesis that the potential toxicity of DEET is high and that available repellents containing DEET, irrespective of their strength, are not safe when applied to children's skin. (2) Although this is a case report, we used the features of published reports of DEET- induced encephalopathy in children to support the diagnosis, since the evidence that the child's illness was caused by DEET was circumstantial. In the following case analysis, clinical reports of children <16 years old have been reviewed and analyzed in an effort to relate direct DEET toxicity to various clinical, demographic, and toxic compound exposure factors (Fisher's exact test and logistic regression analysis). (3) DEET-induced encephalopathy in children (56% girls) followed not only ingestion or repeated and extensive application of repellents, but also a brief exposure to DEET (45%). Of those who reported a dermal exposure, 33% reported an exposure to a product containing DEET <20%. Seizures, the most prominent symptom (72%), were significantly more frequent when DEET solutions were applied to the skin (P<0.01). Mortality (16.6%) did not correlate significantly with the concentration of the DEET liquid used, duration of skin exposure, pattern of use, age, or sex. (4) Data of this case analysis suggest that repellents containing DEET are not safe when applied to children's skin and should be avoided in children. Additionally, since the potential toxicity of DEET is high, less toxic preparations should be probably substituted for DEET-containing repellents, whenever possible. [ABSTRACT FROM AUTHOR]

Looks at the use of mosquito repellents in the prevention of West Nile Virus. Efforts of the U.S. Centers for Disease Control and Prevention (CDC) to publicize repellent use to prevent the spread of the disease; Benefits of picaridin and oil of lemon eucalyptus for repelling mosquitoes; Description of the pathology of West Nile virus; Safety of several insect repellent ingredients; Comparison of the efficacy of picaridin and oil of lemon eucalyptus with that of DEET.

Presents a case study of a patient presented for allergological evaluation of a past episode of widespread eczema after direct application of an insect repellent. Hospitalization of the patient for contact dermatitis and treated with systemic corticosteroids and antihistamines; Active ingredients of the insect repellent; Need for additional studies to evaluate whether the insect repellent has a sensitizing capacity and whether other co-formulants are responsible for the reaction.