Repellent Agent Research Articles

Deep renovation of an old single-family house including application of an water repellent agent – a case story

The 145 year old rural case building presented in this paper has undergone a deep renovation including internal insulation of the external walls to reduce the heat loss and improve the indoor thermal comfort. The internal insulation was a PUR-based insulation with channels of calcium silicate, experiencing to some extent capillary active behaviour. Sensors were installed between the existing wall and the internal insulation to monitor the development of hygrothermal conditions. The external façade was later hydrophobized with a water repellent agent to minimize the wind driven rain load. Measurements show that it takes time to get rid of the built-in moisture due to the application of internal insulation, however the moisture content expressed in relative humidity is slowly decreasing, although still high about two years after hydrophobizing the wall. Simulations show that the order of hydrophobizing the wall and applying internal insulation is important to promote drying of the wall.

Approaches to inhibit biofilm formation applying natural and artificial silk-based materials

The discovery of penicillin started a new era of health care since it allowed the effective treatment of formerly deadly infections. As a drawback, its overuse led to a growing number of multi-drug resistant pathogens. Challenging this arising threat, material research focuses on the development of microbe-killing or microbe repellent agents implementing such functions directly into materials. Due to their biocompatibility, non-immunogenicity and mechanical strength, silk-based materials are attractive candidates for applications in the biomedical field. Furthermore, it has been observed that silks display high persistency in their natural environment giving reason to suspect that they might be attractive candidates to prevent microbial infestation. The current review describes the process of biofilm formation on medical devices and the most common strategies to prevent it, divided into effects of surface topography, material modification and integrated additives. In this context, recent state of the art developments in the field of natural and artificial silk-based materials with microbe-repellant or antimicrobial properties are addressed. These silk properties are controversially discussed and conclusions are drawn as to which parameters will be decisive for the successful design of new bio-functional materials based on the blueprint of silk proteins.

Manufacture of Mikania micrantha vinegar and investigation of its repellent activity for Forcipomyia taiwana

Crude vinegar was prepared from Mikania micrantha plants using a steel kiln. The ether-extracted vinegar and acidic, phenolic, and neutral fractions were obtained by the partition method. The fundamental properties of crude vinegar, including its fractions applied to repel biting midges (Forcipomyia taiwana), were investigated. Results indicated that the crude vinegar had a moisture content of 91%, Gardner color value of 11.2, a reddish-brown color, specific gravity of 1.0164, pH of 5.36, organic acid content of 2.50%, and soluble tar content of 0.78%. In ether-extracted vinegar of M. micrantha, the acidic component was the major ingredient, followed by the neutral, phenolic, and nitrogenous components. The main organic compounds of the acidic, phenolic, nitrogenous, and neutral components were acetic acid, phenol, 3-pyridinol, and 2-furanmethanol, respectively. The results also demonstrated that the crude vinegar, ether-extracted vinegar, and the phenolic and neutral fractions effectively repelled biting midges, with absolute repellent times of 49, 87, 83, and 99 min, respectively. The repellent activity of ether-extracted vinegar and the phenolic and neutral fractions of M. micrantha vinegar on biting midges was higher than that of a commercial repellent agent (named Dinling) with absolute repellent time of 61 min.

Repellent Efficacy of Eucalyptus globulus and Syzygium aromaticum Essential Oils against Malaria Vector, Anopheles stephensi (Diptera: Culicidae).

Background:Mosquito species are highly considering as disease transmission as well as nuisance insects. One of the principal strategy to protect human from the mosquito bites is repellent agents. This study aimed to assess repellency of two organic essential oils, Eucalyptus globulus and Syzygium aromaticum from bites of malaria vector, Anopheles stephensi.Methods:The study was conducted in 2019–2020. The components of essential oils of E. globulus and S. aromaticum was determined using gas chromatography/mass spectrometry. The unfed female mosquitoes aged 2–5 d old were used in all experiments. In vivo Klun and Debboun module bioassays were utilized on human-volunteer skin. The essential oils at serial concentrations were used to find repellent efficacy against Anopheles landings and bites. To find the synergistic effect, four combinations of the essential oils were tested.Results:The main composition of E. globulus essential oil was 1,8-Cineol (78.20%), whereas that of S. aromaticum essential oil was 2-methoxy-3-(2-propenyl) (77.04%). Based on minimum effective dose (≤1% biting), 10% (v/v) of E. globulus showed high landing repellency (77.78%), whereas minimum effective dose of S. aromaticum at concentration of 1% had high landing repellency (88.89%). Among four combinations, the ratio of 1:1 of E. globulus (10%):S. aromaticum (1%) showed the most landing repellency (94.44%).Conclusion:The combinations of two essential oils had the most potential repellency effect against landing of mosquitoes. As essential oils are eco-friendly with less irritation for human skin, E. globulus and S. aromaticum essential oils are recommended as effective and safe mosquito repellents.

Biotreatment of ceramic bricks: The impact of the application method of an innovative bioproduct on biomineralization

The effect of biological treatments on protection of exposed construction materials in the built heritage may have great potential. This work reports the efficacy of several techniques (dropping, spraying, brushing, poulticing and absorption by capillarity) to apply a new bioproduct, produced by Escherichia coli cultures supplemented with iron, aiming to treat the surface of ceramic bricks. The results showed that most biotreatments improved the ceramic bricks resistance to water absorption, depending on the method of application of the bioproduct. Nevertheless, within the error range, the most efficient biotreatments were observed when the bioproduct was applied by dropping, brushing and spraying. The bioproduct analyzed in the present study can be stored and easily transported to construction sites, where it can be readily prepared by resuspension of the dried bioproduct in tap water. The water resistance effect of the bioproduct was attributed to the presence of a gelatinous biofilm and to the formation of amorphous biosilica aggregates (biomineralization by biosilicification) that filled the pores and voids of bricks samples. Acting as a mild water repellent agent, it may be a promising solution for protection of ceramic bricks, reducing the degradation rate, namely for compatible and ecological architectural heritage conservation practices.

Methodological approaches to the assessment of health risks associated with the use of repellent and insecticide agents

Introduction. The study’s relevance is due to the demand for repellent and insecticidal agents in the consumer market and their widespread use as protection against mosquitoes. At the same time, the problem of the impact on the human health of these funds has not been sufficiently studied. In this regard, analyzing the safety of repellents and insecticides for human health is of scientific interest. The aim of the study is to substantiate methodological approaches to assessing the risk to human health associated with the use of insecticides and repellents. Materials and methods. Authors used methods of analysis of scientific literature, toxicological methods for the study of health safety, methods of quantitative chemical analysis, biochemical methods for the study of blood serum, methods of mathematical modeling, health risk assessment methodology. Results. The assessment of the risk of negative responses from organs and systems of the body when exposed to repellents and insecticides has been carried out. Methodological approaches to assessing health risks under various scenarios for repellents and insecticides have been developed and tested. Conclusion. A feature of the proposed methodological approaches is the ability to take into account dose loads for various routes of entry of active substances into the body, the duration of exposure to a repellent or insecticide during regular use, and possible use in regimes exceeding normal use. As a result of the experiment, it was found that with the inhalation of an insecticide with 1% transfluthrin, the level of acceptable risk is observed at a level of exposure of transfluthrin in the air up to 0.0272 mg/m3. Under a percutaneous intake of the 50% DEET repellent, the acceptable risk level was noted at exposure less than 1200 mg/kg/day. In case of percutaneous arrival of the DETA repellent 7.5%, the level of acceptable risk is established under exposure up to 250 mg/kg/day.

Использование модельных объектов при оценке эффективности репеллентных средств на основе ДЭТА для индивидуальной защиты от кровососущих членистоногих

With the aim of unifying and simplifying the assessment of categories of the effectiveness of the repellents funds audited 473 studies 245 samples of repellent remedies on the basis of DEET in various formulations, made in 1995–2019 employees of the Scientific Research Disinfесtology Institute in laboratory and in field conditions. The experiments were conducted in parallel with the standards of the corresponding or expected categories of effectiveness of repellent remedies. The concordance of the results of standard laboratory experiments on a model object Ae. aegypti mosquitoes and the results obtained from testing repellent agents against natural populations of flying blood-sucking insects and taiga ticks is proved. The effectiveness of repellent remedies based on other repellent substances, as well as the effectiveness against other species, should continue to be investigated in full-scale conditions for individuals of natural populations. These remedies should be included in the system of categories of effectiveness of repellent products.

Durability of the hydrophobic treatment on brick and mortar

Hydrophobization lessens the water absorption by facade materials and is thus presumed to reduce moisture problems in internally insulated facades. However, to do this it should retain the water repellency performance throughout aging. The aim of this study is to evaluate the impact of aging on the durability of the hydrophobic treatment on bricks and mortars. The resulting absorption coefficient, after 635 repeating artificial aging cycles of alternating UV radiation (102 min) and water exposure (18 min) reveals that the hydrophobic layer maintains its water repellency performance both in brick and mortar. The samples were treated with two different water repellent agents in different concentrations and tested for capillary water uptake. Additionally, the findings show that cycles of weathering could contribute positively to further reduction of the absorption coefficient of hydrophobized brick and mortar samples. Subsequently, Karsten tube tests on samples from artificial aging illustrate the same water repellency performance as mock-up walls exposed to ambient conditions, six years after being hydrophobized. Contact angle measurements before and after artificial aging reveal that the beading effect declines through aging. However, the beading effect seems to be just a surface effect affected by UV-light. Moreover, after aging, hydrophobized brick and mortar samples, tested by visual inspection, maintain their appearance while untreated samples show signs of efflorescence. In total, these findings indicate that the water uptake of hydrophobized brick or mortar remains very low after aging including water spraying and UV light.

Repellency of Veratraldehyde (3,4-Dimethoxy Benzaldehyde) against Mosquito Females and Tick Nymphs

Arthropod-borne infectious diseases cause many deaths and a major economic burden worldwide. Repellents play an important role in protecting people from infectious biting arthropods. The repellency of veratraldehyde, a known food additive, and the WJ-1041 formulation containing 10% veratraldehyde was tested against Aedes albopictus and Culex pipiens pallens females and Haemaphysalis longicornis nymphs using arm-in-cage, indoor or filter paper tests. Veratraldehyde exhibited repellency similar to or lower than that of n,n-diethyl-meta-toluamide (DEET) against A. albopictus, but in H. longicornis, the activity of veratraldehyde was better than that of DEET. The repellency of the 10% veratraldehyde solution was comparable to that of 20% DEET against the two mosquitoes. When comparing repellency between the WJ-1041 formulation (10% veratraldehyde) and 10% DEET against C. pipiens pallens, A. Albopictus and H. longicornis, the two showed similar repellency and complete protection time (CPT) values. However, there was a small difference depending on the tested insects. The absorption of veratraldehyde via skin was minimal, if at all. The pharmacokinetic parameters (Cmax and Tmax) of veratraldehyde in blood samples of rats were not different from those of the control group. Based on these results, veratraldehyde has high potential to be commercialized as a repellent agent against infectious disease-borne pests in the near future.

Thermo-physiological comfort properties of various shirt fabrics treated with conventional and nano sized water-oil repellent and wrinkle resistant agents

The extreme temperatures and humidity are quite disturbing climatic conditions and clothing is the only protective material in these cases. During the interactions of the human body, clothing, and the environment, to maintain thermal equilibrium, thermo physiological comfort is crucially important. In general, the thermo physiological comfort features of a fabric include thermal conductivity, thermal flow, thermal absorbtivity, thermal resistance, thickness, water vapor permeability and air permeability. In this study, 21 different kinds of woven shirt fabrics produced from fibers in various blends have been treated with both classical and nano chemicals in four different concentrations to produce fabrics having different water-oil repellent and wrinkle resistant characteristics. The effects of the fiber type, treatment method, chemical type, and chemical concentration on the thermal, water vapor and air permeability properties of the fabrics treated with various finishing processes were investigated by statistical analysis. The results of thermal related properties, air permeability and water vapor permeability of the fabrics confirmed that using cotton, lyocell, and viscose shirt fabrics treated with transfer method could be advantageous, especially in hot climatic regions.

Impact of water repellent agent concentration on the effect of hydrophobization on building materials

It is desirable to avoid or lessen moisture-related problems in building components exposed to wind-driven rain via correct material design and/or choice. In some cases however – e.g. for historic building facades – the only possibility is to modify the hygric properties of existing materials. Hydrophobization treatment is suggested as a possible protocol, but the proper concentration of the water repellent agent to achieve the expected effect is still open to discussion. This study proposes the novel concept of a material-dependent critical agent concentration: the lowest concentration that ensures hydrophobic effectiveness on a specific material. For validation, the hygric impact of hydrophobization treatment at different agent concentrations is studied. Specifically, a balanced mixture of silanes and siloxanes is used as the agent, and eight experiments are performed on ceramic brick, lime mortar and sintered glass. Results demonstrate the existence of a material-dependent agent concentration. Only when treated above it will the hygric properties be significantly modified. Moreover, hydrophobization impacts the capillarity of a material much more than its hygroscopicity, due to the difficulty for the large molecules of water repellent agents to penetrate into fine pores. The bulk density, open porosity and pore size distribution are typically only minimally influenced.

Improvement of the depolluting and self-cleaning abilities of air lime mortars with dispersing admixtures

The aim of this study is to develop new air lime mortars with enhanced photocatalytic depolluting and self-cleaning abilities. Nanosilica, as pozzolanic mineral admixture, was used to improve the strength of mortars, whereas nanotitania (TiO2) was added to impart photocatalytic properties. At the same time, five different dispersing admixtures –superplasticizers– were added in bulk to the mortars to enhance the photocatalytic activity by reducing the rate of charge carrier recombination. Four polycarboxylate-based derivatives and a polynaphthalene sulfonate were tested aiming to achieve an efficient charge separation. In order to increase the lasting of the mortars subjected to water movements, sodium oleate was also added as a water repellent agent. Since the photoinduced hydrophilicity, responsible for the self-cleaning effect, might be affected by the water repellent, the compatibility between this admixture and the photocatalytic performance of the nanotitania was also investigated. Results showed that photocatalytic activity was improved due to the action of the superplasticizers as indicated by an average 33% increase of NO degradation, which is significant to the depolluting activity of these mortars. Furthermore, these mortars also showed a greatly reduced release of intermediate toxic compounds, mainly NO2: the selectivity factor (NOx/NO) reached values up to 87%. The self-cleaning ability, studied through dye degradation, of the mortars with SPs was also enhanced around 1.2 times. Three of the polycarboxylate-based superplasticizers enhanced the photosensitization of the dye under visible light irradiation, resulting in faster decolouring kinetics. In connection with the self-cleaning performance, these same SPs preserved the photoinduced hydrophilicity of the lime mortars, reaching good wettability of the surface of the mortars (water contact angles of ca. 10°), even in the presence of the sodium oleate, proving the compatible characteristics of the admixtures and allowing obtaining a new range of actively depolluting lime mortars.

Chemical composition and biological activities of essential oils of different plants of Ligusticum genus against three stored insects

ABSTRACT Apiaceae L. contains many potential plants as repellent and insecticidal resources. However, Ligusticum applied in the stored insect control is still under-evaluated. Hence, the chemical composition and bioactivities of five Ligusticum plants with abundant resources were investigated in this study against Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae), and Liposcelis bostrychophila (Psocoptera: Liposcelididae). The contact toxicity was found 24 h after treatment with Ligusticum pteridophyllum, Ligusticum ajanense, Ligusticum chuanxiong, Ligusticum thomsonii, and Ligusticum jeholense essential oils (LD50 = 87.99, 44.01, 21.53, 125.37, and >50% μg/adult; 89.82, 93.51, 28.42, 105.55, and 50.16 μg/adult; 7.87, 308.62, 67.82, and 195.06 μg/cm2, respectively). The five plants’ essential oils possessed poor fumigant toxicity against three target insects at the highest concentration. Moreover, all analyzed oils have good repellent activity in a dose-dependent manner. In conclusion, the tested oils have the potential to be developed as contact and repellent agents in protecting the stored products.

Essential oils of a few aromatic plants and their potential as knockdown, repellent and adulticidal agent to the filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae)

Use of synthetic products for the control of mosquito vectors raises serious concern about their negative impact on the environment, non-target organisms and human safety. Alternatively, the use of several natural products, particularly plant based essential oils have gained attention due to their good efficacy and ecofriendly nature. The adult knockdown effect and repellent activities of essential oils derived from three selected plants on Culex quinquefasciatus were evaluated. Data processing was performed using probit analysis. The results showed that essential oils from all the selected plants exhibited considerable knockdown effect on Cx. quinquefasciatus. In addition to this, all plant derived essential oils showed repellent activity which was significant in all concentrations. It is suggested that essential oils derived from Citrus limon were found to be very active as mosquito repellent.

Improving lime-based rendering mortars with admixtures

The present work presents focuses on the use of different admixtures for the development of rendering lime-based mortars with improved adhesion and durability, as well as reduction of cracking. To this aim, combinations of an adhesion improver (ethylene–vinyl acetate copolymer, EVA), a water repellent agent (sodium oleate), a viscosity enhancer (a starch derivative) and a mineral admixture (pozzolanic addition of nanosilica or metakaolin) were tested. The renders were applied on four different substrates (sandstone, limestone, granite and brick) to assess their performance.The influence of the admixtures’ combination on fluidity, stiffening time, adhesion, cracking, compressive strength, pore structure, frost resistance and durability against magnesium sulfate attack was evaluated. The EVA admixture was seen to enhance the adhesion when used in combination with oleate, metakaolin and starch. This combination also led to a minimized cracking. Opposite trends between adhesion and cracking were observed as a function of the porosity of the substrates and of the presence of small-sized capillary pores.The interferences with the carbonation accounted for the drops observed in compressive strength for the nanosilica-free tested renders; nanosilica-containing renders showed good compressive performance, due to the filling effect of the admixture and to the C-S-H formation. The use of most of the admixtures’ combinations was seen to clearly enhance the durability of the renders, in the face of freezing-thawing cycles as well as sulfate attack, proving the applicability of these lime-based renders for repair works of the Cultural Heritage and for new Civil Engineering applications.

Activity of Otostegia fruticosa (Lamiaceae) Leaves Extracts Against Lymphatic Filariasis Vector, Culex pipiens L. (Diptera: Culicidae)

The present study was carried out to evaluate the activity of methanol, ethyl acetate, chlorobenzene, and hexane extract from leaves of Otostegia fruticosaas larvicidal and repellent agents against Culex pipiens. The effect of tested extracts on the female reproductive potential treated as larvae was also investigated. The obtained results showed that hexane extract have potent larvicidal activitywithLC50 and LC90 values equal to (126.27 and 236.84 ppm), respectively followed by chlorobenzene (242.14 and 501.17 ppm), ethyl acetate (578.07 and 856.29 ppm) and methanol (653.00 and 1127.10 ppm). All tested extracts of O. fruticosa induced significant (P<0.01) reduction in fecundity and increased the infertility percentages of C. pipiens females developed from treated larvae as compared with control and these effects were solvent- and concentration-dependent. In addition, the repellency effect of tested extracts was found to be varied among tested extracts. Four hours post-treatment, the dose of 3.33 mg/cm2 recorded repellency percentages of 64.13 and 75.09 by methanol and ethyl acetate extracts, respectively. Meanwhile, chlorobenzene extract induced repellency percentages of 80.15, 75.94, and 65.84 for the doses of 3.33, 1.67 and 0.83 mg/cm2, respectively. Moreover, repellent activity of hexane extract at doses of 3.33, 1.67 and 0.83 mg/cm2 recorded 88.08, 79.01 and 75.50%, respectively.

Effect of Hydrophobic Treatments on Improving the Salt Frost Resistance of Concrete.

Hydrophobic treatment is an important method to improve the waterproof properties of concrete. To evaluate the effectiveness of hydrophobic treatments on improving the salt frost resistance of concrete, two representative commercial ordinary water repellent agents of silane and organosilicone emulsion were selected, and concrete specimens with three water/cement ratios were fabricated. After the application of repellent agents on concrete surfaces, accelerated saline (5% MgCl2) freeze-thaw cycles were conducted on the specimens. The mass losses and relative dynamic modulus of elasticity (RDME) of concrete were tested periodically. The contact angles and water absorption ratios of concrete with and without hydrophobic treatments were also tested. Results showed that the repellent agents could substantially enhance the hydrophobicity of concrete and greatly reduce its water absorption. Different repellent agents exerted diverse improvements on concrete hydrophobicity. Meanwhile, the repellent agents could improve concrete resistance against salt scaling and RDME losses to a certain degree, and concrete with strong hydrophobicity showed relatively high salt frost resistance. However, the ordinary water repellent agents cannot achieve the same enhancement on salt frost resistance of concrete as that on the water hydrophobicity of concrete. With saline freezing and thawing cycles, the hydrophobic layer formed by the repellent agents on superficial concrete was destroyed gradually. As a result, the salt frost resistance of concrete from the hydrophobic treatments was ultimately lost.

Influence of exposure environments and moisture content on water repellency of surface impregnation of cement-based materials

Water repellent treatment is one of the effective means to improve the durability of concrete. This paper aims to investigate the water repellency of cement-based materials treated with silane-based water repellent agent under different exposure environments. Five different exposure conditions were applied in this experiment, namely, standard moist curing room, in-door laboratory atmosphere, pre-oven-dried condition, and out-door natural environment with or without shelter. Three different types of mortars with water-to-cement ratios of 0.4, 0.5 and 0.6 were prepared. And three different dosages (200, 400, 600 g/m2) of silane gel were utilized on the surface of specimens. The impregnation depth and water absorption after hydrophobic treatment have been measured. Results indicate that the initial moisture condition of mortar has a significant influence on the efficiency of surface silane impregnation. The depth of silane impregnation gradually decreases with the increase of initial moisture condition. The water repellency of surface impregnation of cement-based materials was well exhibited under the condition of about 50% relative humidity. It illustrated that the moisture within the cement-based materials affects the hydrolysis reaction process and the formation of hydrophobic membrane. Thus, the water repellency of cement-based materials greatly depends on the initial moisture content and the thickness of hydrophobic layer.

Optimizing a fabricating program for wearable super-hydrophobic cotton by clean production technology of plasma and reducing chemical consumption

The atmospheric-pressure cold plasma jet was used as a clean production technology together with fluorine-free water repellent agent (FfWRA) to optimize the fabricating program for wearable super-hydrophobic cotton. By the contrasting test of sample surfaces treated via FfWRA and by plasma in advance with fluorine-free agent (P-FfWRA), it was concluded that the plasma can evidently strengthen the hydrophobic finishing effect. Hydrophobicity study indicates the contact angle on sample treated by P-FfWRA reached 153°. Even more important, meantime a 44.4% reduction in the chemical consumption can be achieved with the optimization method. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations verified that large amounts of nano-scaled roughness uniformly presented on the modified fiber surface. X-ray photoelectron spectroscopy (XPS) measurements reveals that there was a reduction of up to 40% in oxygenous groups on the cotton fabric processed by P-FfWRA. The washing test show that the P-FfWRA treated sample still have a strong hydrophobic surface with a contact angle of 147°even after washing 25 times. The breathability of the modified sample even has a small increase due to the variation in fiber diameter after the modification. The optimized fabricating program has been proved to be an environmentally friendly, high efficiency production technology. This paper provides theoretical support and practical significance for further research on the saving of the chemical consumption.

Screening of the Repellent Activity of 12 Essential Oils Against Adult German Cockroach (Dictyoptera: Blattellidae): Preparation of a Sustained Release Repellent Agent of Binary Oil-γ-CD and its Repellency in a Small Container.

Cockroaches are important sanitary pests and very difficult to control worldwide. With public concern about traditional insecticides, cockroach control agents should be environmentally friendly, highly efficient, and economical. In this article, 12 essential oils were screened to test their repellent effect against Blattella germanica. To develop essential oils as repellent agents, the oils were further examined in binary synergistic combinations. Ilex chinensis Sims (Sapindales: Aquifoliaceae) oil, Lavandula spp (Tubiflorae: Labiatae) oil, and Elsholtzia ciliata (Thunb.) Hyland (Tubiflorae: Labiatae) oil showed excellent repellent activities with lower RD50 (repellency dose for 50% of treated adults) values of 218.634, 154.590, and 223.989 µg/cm2, respectively, compared to those of other oils and the positive control. The I. chinensis oil and E. ciliata oil (weight ratio of 1:1.41) combination also displayed a remarkable synergistic effect against B. germanica. Their cotoxicity coefficient was 214.4. The major chemical constituents in E. ciliata and I. chinensis oils were respectively 3,7-dimethyl-1, 6-octadien-3-ol and methyl salicylate. The binary oil mixtures were formulated as a sustained release agent with γ-CD. The optimal preparation should be an 8:1 ratio of γ-CD to oils, with a 1 h stirring time, 50°C stirring temperature, and 1:12 ratio of γ-CD to ddH2O. The results of this study suggest that sustained release of binary oil-γ-CD exhibited a prolonged repellent activity (10 h) against B. germanica. This sustained-release agent could be further investigated and developed as a novel repellent preparation.