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1.
Aquat Toxicol ; 222: 105474, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32259658

RESUMO

Larval toxicity of ethanolic extract of C. parvula (Ex-Cp) was prominent in the second and the third instars at the maximum lethal dosage of 100 ppm with 98 and 97 % mortality rate respectively. The LC50 and LC90 was displayed at 43 ppm and 88 ppm dosage respectively. Correspondingly, the sub-lethal dosage (65 ppm) of Ex-Cp significantly alters the carboxylesterase (α and ß), GST and CYP450 enzyme level in both III and IV instar larvae in dose-dependent manner. Similarly, the Ex-Cp displayed significant repellent activity (97 %) with a maximum level of protection time (210 min). Photomicrography assay of Ex-Cp (65 ppm) were toxic to dengue larvae as compared to control. The non-target toxicity of Ex-Cp against the beneficial mosquito predators displayed less toxicity at the maximum dosage of 600 ppm as compared to Temephos. Thus the present research delivers the target and non-target toxicity of red algae C. parvula against the dengue mosquito vector.


Assuntos
Aedes/efeitos dos fármacos , Dengue , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Extratos Vegetais/farmacologia , Rodófitas/química , Aedes/virologia , Animais , Organismos Aquáticos/efeitos dos fármacos , Carboxilesterase/metabolismo , Dengue/virologia , Relação Dose-Resposta a Droga , Repelentes de Insetos/isolamento & purificação , Repelentes de Insetos/toxicidade , Larva/efeitos dos fármacos , Larva/enzimologia , Dose Letal Mediana , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/toxicidade , Poluentes Químicos da Água/toxicidade
2.
Am J Trop Med Hyg ; 102(4): 758-767, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32043439

RESUMO

Kala azar occurs among seasonal and migrant agricultural workers in northwest Ethiopia and accounts for almost 60% of the disease burden in the country. We conducted a quantitative study on the level of knowledge and practice of this vulnerable group in relation to kala azar transmission and acceptability of its vector control tools. A total of 403 workers were randomly selected from eight farms using a purposive sampling technique. Knowledge and practice scores were calculated based on 12 and 9 core questions, respectively. Binary logistic regression was used to identify factors associated with knowledge and practice. A large gap in knowledge of the disease and the vector was evident with 61.8%, 24.6%, and 13.6% of the workers having poor, moderate, and good levels of knowledge scores, respectively. Similarly, 95% of the seasonal workers reported poor level of use of protective measures against the bite of the sand fly vector. Good level of knowledge about kala azar and its sand fly vector was statistically associated with formal education (adjusted odds ratio [AOR] = 2.11; 95% CI = 1.17, 3.80; P < 0.05) and previous exposure to health education (AOR = 4.72; 95% CI = 1.99, 11.16; P < 0.001). Despite poor current knowledge and practice, a large proportion of the study participants showed interest in using vector control tools if made available, with 78% of the seasonal and migrant workers expressing some willingness to pay for different measures that can protect against sand fly bites. Therefore, we strongly recommend that comprehensive health education and vector control programs should be provided to these workers.


Assuntos
Agricultura , Leishmaniose Visceral/prevenção & controle , Estações do Ano , Migrantes , Adulto , Animais , Etiópia/epidemiologia , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Mordeduras e Picadas de Insetos/prevenção & controle , Repelentes de Insetos/economia , Repelentes de Insetos/farmacologia , Mosquiteiros Tratados com Inseticida , Masculino , Pessoa de Meia-Idade , Roupa de Proteção/economia , Psychodidae , Adulto Jovem
3.
Vet Parasitol ; 278: 109036, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32004852

RESUMO

Amblyomma sculptum is a tick of medical-veterinary importance. Areas with high infestations need to be monitored, and parasitized hosts treated accordingly. Carbon dioxide (CO2) traps and acaricides are commonly deployed as control measures, although with some disadvantages such as high costs, challenging logistics and vertebrate intoxication. Semiochemicals have the potential to improve tick attraction to traps and monitoring devices and alleviate the burden of A. sculptum infestations. Four concentrations (10, 5, 2.5 and 1.25 %) of 13 semiochemical candidates (CO2 only at 5 % as the standard, benzaldehyde, benzoic acid, salicylic acid, 2,6 diclorophenol, R-limonene, S-limonene, methyl salicylate, 1-octen-3-ol, acetone, ammonium hydroxide, isobutyric acid and lactic acid) were tested on unfed A. sculptum nymphs and adults using a Y-tube olfactometer to evaluated repellence and attraction behaviors. All stages tested were attracted to CO2, whereas nymphs were repelled by benzaldehyde and R-limonene, both at 10 %, and isobutyric acid at 5 and 10 %. Nymphs were attracted by methyl salicylate, benzoic acid and salicylic acid, all at 1.25 %, and by ammonium hydroxide at 2.5 %. Males were attracted by benzoic acid at 2.5 %, while females were repelled by benzaldehyde at 5 %. Mixtures with the attractive compounds achieved no attraction response. The compounds that caused attractiveness in the olfactometer assay (CO2, methyl salicylate, benzoic acid, salicylic acid and ammonium hydroxide) were placed randomly in traps in a grassland plot naturally infested with A. sculptum in triplicate. Notably, dry ice (CO2) remained the best at luring ticks in the field (P < 0.001). Benzoic acid should be further investigated since attractant activity was strongly confirmed in both laboratory and field tests. On the other hand, isobutyric acid and R-limonene could be better exploited due to their repellent role revealed by the lab assay, which makes them worthwhile molecules as natural repellents for the management of this tick.


Assuntos
Repelentes de Insetos/farmacologia , Ixodidae/efeitos dos fármacos , Feromônios/farmacologia , Infestações por Carrapato/prevenção & controle , Animais
4.
PLoS Negl Trop Dis ; 14(1): e0007970, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31961867

RESUMO

BACKGROUND: Arboviruses transmitted by day-biting Aedes mosquitoes are a major public health concern. With the challenges inherent in arbovirus vaccine and therapeutics development, vector control and bite prevention strategies are among the limited options available for immediate intervention. Bite prevention through personal protective technologies (PPT), such as topical mosquito repellents or repellent-impregnated clothing, may help to decrease biting rates and, therefore, the risk of disease in groups most susceptible to adverse outcomes from Zika virus. However, achieving high uptake and compliance with PPT can be challenging. METHODOLOGY/PRINCIPAL FINDINGS: To gain an insight into the knowledge and concerns of pregnant women surrounding Zika and their opinions regarding PPT, particularly repellent clothing, a focus group study was carried out with pregnant women, women of reproductive age, and semi-structured interviews with their male partners in two cities in Colombia. The discussions revealed shortfalls in basic knowledge of Zika virus, with several pregnant participants reporting being unaware of the potential for Zika-related congenital malformations. Although participants generally considered Zika to be a significant personal threat, most rated it as less of a concern than dengue or diarrheal diseases. Overall, repellent clothing and other forms of PPT were viewed as effective, although some participants expressed concerns over the high costs of repellents, and safety fears of regular contact with repellent chemicals, which they perceived as potentially harmful. Plant-derived repellents were considered to be safer than synthetic chemical repellents. Discussions also highlighted that health centers were the preferred source of information on bite-reduction. CONCLUSIONS/SIGNIFICANCE: Achieving high uptake and compliance with PPT in populations most at risk of adverse outcomes from Zika infection requires engaging key users in open dialogue to identify and address any practical issues regarding PPT use, and concerns over safety. The findings presented here suggest that educational campaigns should strongly emphasize the risks associated with Zika during pregnancy, and discuss safety profiles of approved synthetic repellents and the availability of EPA-approved plant-based repellents. In addition, the economic and political context should be a major consideration when evaluating personal mosquito-repellent strategies.


Assuntos
Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/psicologia , Zika virus/fisiologia , Adolescente , Adulto , Aedes/efeitos dos fármacos , Aedes/virologia , Animais , Colômbia , Estudos de Avaliação como Assunto , Feminino , Humanos , Repelentes de Insetos/farmacologia , Conhecimento , Masculino , Pessoa de Meia-Idade , Percepção , Equipamento de Proteção Individual/economia , Gravidez , Adulto Jovem , Infecção por Zika virus/economia , Infecção por Zika virus/virologia
5.
Chem Biodivers ; 17(2): e1900580, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31913571

RESUMO

Developing effective and eco-friendly antimicrobials and pesticides has become a highly important issue. The repellent, insecticidal and antimicrobial activity of essential oils (EOs) isolated by hydrodistillation from dried leaves of the three Eucalyptus species (E. cloeziana, E. umbellata and E. benthamii) were investigated. During GC/MS analysis, α-pinene (47.36 %), 1,8-cineol (38.53 %) and α-pinene (35.31 %) were identified as major components of E. cloeziana, E. umbellata and E. benthamii, respectively. The EOs from E. cloeziana exhibited the longest effective protection time (465 min, at 50.0 % w/w) for humans among the EOs studied. The effective protection time was 30 min and 300 min at concentrations of 12.5 % (w/w) and 25.0 % (w/w), respectively. Fumigating insecticidal activity of EOs from three Eucalyptus species was tested by airtight fumigation in conical flask, which indicated that essential oils had a highly and rapidly insecticidal activity on Culex pipiens quinquefasciatus. The antimicrobial activity of EOs was evaluated by using disc diffusion and agar dilution methods. There was no significant difference in the antibacterial activity of EOs from E. cloeziana and E. umbellate and they had the same MICs (20 mL/L) on Staphylococcus aureus, Salmonella typhi, Bacillus subtilis and Escherichia coli. E. benthamii had the worst microbial inhibitory effect among the three Eucalyptus essential oils and the MIC value for the test species is 40 mL/L except for Rhodotorula Harrison (10 mL/L).


Assuntos
Anti-Infecciosos/química , Eucalyptus/química , Repelentes de Insetos/química , Inseticidas/química , Óleos Voláteis/química , Folhas de Planta/metabolismo , Animais , Anti-Infecciosos/farmacologia , Aspergillus/efeitos dos fármacos , Candida/efeitos dos fármacos , Culex/efeitos dos fármacos , Eucalyptus/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Testes de Sensibilidade Microbiana , Óleos Voláteis/análise , Óleos Voláteis/farmacologia , Folhas de Planta/química
6.
Ecotoxicol Environ Saf ; 189: 109988, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31767459

RESUMO

Tribolium casteneum is a major stored grains pest causing huge loss by secreting toxic quinones' which make the grains unfit for human consumption. Increasing concern about the fast-growing resistance in T. casteneum against fumigants has evoked more intense research worldwide. Therefore, finding an eco-friendly alternative for the management of the pest is of great importance. In this study, the insecticidal activity of the essential oils (EOs) of Artemisia annua is evaluated. Chemical composition of the EOs eluted with methanol and petroleum ether was analysed through Gas chromatography-mass spectrometry (GC-MS). The result has reported a total of 13 & 16 compounds in the methanol and petroleum ether EOs respectively. In contact toxicity studies, adults were found more susceptible to the petroleum ether EOs (LD50 = 0.43 mg adult-1) than the methanolic EOs (LD50 = 1.87 mg adult-1). Petroleum ether EOs was also superior in fumigant assays against both the adults (0.81 mg L air-1) and larvae (0.65 mg L air-1). Moreover, the same was also recorded as a strong repellent. The bio-molecular studies conducted to gain an insight into the extent of metabolic disturbances inflicted in the treatment sets has shown a significant increase in Lipid peroxidase and decrease (p˂0.01) in protein, Acetylcholinesterase, Glutathione S Transferees, Reduced Glutathione level. This indicates the major signs of oxidative stress in the treatment sets. The Results ascertain the knowledge to develop natural insecticides from Artemisia annua using a potential solvent to be used in the future as an efficient management tool against T. casteneum.


Assuntos
Artemisia annua/química , Controle de Insetos/métodos , Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Tribolium/fisiologia , Animais , Repelentes de Insetos/química , Repelentes de Insetos/isolamento & purificação , Repelentes de Insetos/farmacologia , Inseticidas/química , Inseticidas/isolamento & purificação , Larva/metabolismo , Larva/fisiologia , Dose Letal Mediana , Óleos Voláteis/química , Óleos Voláteis/isolamento & purificação , Estresse Oxidativo/efeitos dos fármacos , Tribolium/metabolismo
7.
J Sci Food Agric ; 100(4): 1541-1546, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31769025

RESUMO

BACKGROUND: Citrus sinensis, Allium sativum, Ocimum basilicum, Mentha spicata, Curcuma longa, Carica papaya, Andrographis paniculata, Azadirachta indica, Cymbopogon citratus and Acorus calamus were compared in the form of extracts of chloroform, hexane and aqueous media for their effectiveness in repelling Tribolium castaneum. Filter paper of 9 cm in diameter was cut into halves. Using a micro-pipette, each extract was applied to one half of the filter paper. The volume applied was kept constant at 0.6 mL per 30 cm2 . The filter paper was dried and reattached leaving a 0.5 cm gap between, in a Petri-plate. Ten adults of T. castaneum were introduced and the repellency was observed after 30, 60 and 180 min. RESULTS: The aqueous extract of C. papaya exhibited the highest repellency (82-97%) followed by that of garlic bulbs (aqueous extract) with 86.67% repellency. Further, gunny bags were sprayed separately using bottle sprayers with the two most effective extracts at a constant volume of 42 mL per 575 cm2 . These treated gunny bags were compared with malathion-treated gunny bags in the insect management unit. The observations were taken after 2, 8 and 24 h. Papaya leaf extract-treated gunny bags showed relative repellent activity similar to that of malathion-treated gunny bags after 24 h of treatment. Thus, gas chromatography-mass spectrometry analysis of aqueous extract of papaya leaves was performed. CONCLUSIONS: It can be concluded that extract of papaya leaves containing 2-methoxy-4-vinylphenol (8.47% peak area) can be used as a repellent biopesticide. © 2019 Society of Chemical Industry.


Assuntos
Repelentes de Insetos/farmacologia , Extratos Vegetais/farmacologia , Tribolium/efeitos dos fármacos , Andrographis/química , Animais , Azadirachta/química , Carica/química , Curcuma/química , Cymbopogon/química , Alho/química , Repelentes de Insetos/química , Repelentes de Insetos/isolamento & purificação , Mentha spicata/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Tribolium/fisiologia
8.
J Ethnopharmacol ; 248: 112333, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31654797

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The use of Hazomalania voyronii, popularly known as hazomalana, to repel mosquitoes and resist against insect attacks is handed down from generation to generation in Madagascar. In the present study, we investigated the ability of the essential oils (EOs) obtained from the stem wood, fresh and dry bark of H. voyronii to keep important mosquito vectors (Aedes aegypti and Culex quinquefasciatus) away, as well as their toxicity on three insect species of agricultural and public health importance (Cx. quinquefasciatus, Musca domestica and Spodoptera littoralis). MATERIALS AND METHODS: Hydrodistillation was used to obtain EOs from stem wood, fresh and dry bark. The chemical compositions were achieved by gas chromatography-mass spectrometry (GC-MS). Toxicity assays using stem wood and bark EOs were performed on larvae of Cx. quinquefasciatus and S. littoralis, and adults of M. domestica by WHO and topical application methods, respectively. Mosquito repellent activity of the most effective EO, i.e. the bark one, was determined on human volunteers by arm-in-cage tests, and results were compared with that of the commercial repellent N,N-ddiethyl-m-toluamide (DEET). RESULTS: The H. voyronii EOs were characterized by oxygenated monoterpenes with perilla aldehyde (30.9-47.9%) and 1,8-cineole (19.7-33.2%) as the main constituents. The fresh and dry bark EOs were the most active on Cx. quinquefasciatus and S. littoralis larvae, respectively, with LC50/LD50 of 65.5  mg L-1, and 50.5  µg larva-1; the EOs from wood and fresh bark displayed the highest toxicity on M. domestica (LD50 values 60.8 and 65.8 µg adult-1, respectively). Repellence assay revealed an almost complete protection (>80%) from both mosquito species for 30 min when pure fresh bark EO was applied on the volunteers' arm, while DEET 10% repelled >80% of the mosquitoes up to 120 min from application. CONCLUSION: The traditional use of the bark EO to repel insects has been demonstrated although an extended-release formulation based on H. voyronii EOs is needed to increase the repellent effect over time. A wide spectrum of insecticidal activity has been provided as well, suggesting a possible use of H. voyronii EOs in the fabrication of green repellents and insecticides useful to control mosquito vectors and agricultural pests.


Assuntos
Aedes/efeitos dos fármacos , Culex/efeitos dos fármacos , Hernandiaceae , Moscas Domésticas/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Controle de Mosquitos , Óleos Voláteis/farmacologia , Casca de Planta , Óleos Vegetais/farmacologia , Spodoptera/efeitos dos fármacos , Madeira , Aedes/crescimento & desenvolvimento , Animais , Culex/embriologia , DEET/farmacologia , Hernandiaceae/química , Moscas Domésticas/crescimento & desenvolvimento , Humanos , Repelentes de Insetos/isolamento & purificação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Óleos Voláteis/isolamento & purificação , Casca de Planta/química , Óleos Vegetais/isolamento & purificação , Spodoptera/embriologia , Fatores de Tempo , Madeira/química
9.
Proc Natl Acad Sci U S A ; 117(1): 708-716, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31871198

RESUMO

Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.


Assuntos
Aedes/fisiologia , Comportamento Apetitivo/fisiologia , Percepção Olfatória/fisiologia , Orchidaceae/fisiologia , Polinização/fisiologia , Animais , Comportamento Apetitivo/efeitos dos fármacos , Antenas de Artrópodes/citologia , Antenas de Artrópodes/fisiologia , Encéfalo/fisiologia , DEET/farmacologia , Feminino , Repelentes de Insetos/farmacologia , Masculino , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/fisiologia , Odorantes , Percepção Olfatória/efeitos dos fármacos , Neurônios Receptores Olfatórios/fisiologia , Polinização/efeitos dos fármacos
10.
Pestic Biochem Physiol ; 161: 5-11, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31685196

RESUMO

The adulticidal, larvicidal, and repellent activity of 18 trifluoromethylphenyl amides (TFMPAs) was determined against Aedes aegypti mosquitoes. The compounds studied are the third generation designed from active structures of the previous two generations. N-(3,5-Bis(trifluoromethyl)phenyl)-2-chloroacetamide (8f) and N-(3,5-bis(trifluoromethyl)phenyl)-2,2,3,3,3-pentafluoropropanamide (8h) were most active against 1st stage Ae. aegypti larvae with LC50 values of 125 and 2.53 µM; for comparative purposes, the published LC50 for fipronil is 0.014 µM. Compound 8h was the most toxic against adult female Ae. aegypti with an LD50 = 2.12 nmol/mg, followed by 8f, and N-(3,5-bis(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (8g) with LD50 values of 4.27 and 4.73 nmol/mg, respectively, although these compounds were significantly less toxic than fipronil against adult female Ae. aegypti. Compounds N-(2-(trifluoromethyl)phenyl)butyramide (9c), N-(2-(trifluoromethyl)phenyl)pentanamide (9d) and N-(2-(trifluoromethyl)phenyl)hex-5-enamide (9e) were the best repellents for female Ae. aegypti, with minimum effective dosages (MEDs) of 0.026, 0.052, and 0.091 µmol/cm2, respectively, compared to DEET at 0.052 µmol/cm2. Out of 52 TFMPAs (total number of compounds from three generations of this research) compound 9c was the most active repellent along with two synthesized in our previous studies, 2-chloro-N-(3-(trifluoromethyl)phenyl)acetamide (6a) and 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c).


Assuntos
Aedes/efeitos dos fármacos , Amidas/farmacologia , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Aedes/embriologia , Animais , Bioensaio , Relação Dose-Resposta a Droga , Repelentes de Insetos/administração & dosagem , Repelentes de Insetos/química , Inseticidas/administração & dosagem , Inseticidas/química , Larva/efeitos dos fármacos , Relação Estrutura-Atividade
11.
J Food Sci ; 84(11): 3194-3203, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31589346

RESUMO

A multilayer film containing star anise essential oil and thymol coating layers (SAEO and TH, respectively), with insect repellent and antimicrobial properties, has been developed using bar coating and adhesive lamination processes. Our previous study reported the in vitro activities of this polypropylene film (PP)/SAEO/polyethylene terephthalate film (PET)/TH/low-density polyethylene film (LDPE) multilayer film. The current study focused on demonstrating the morphological, optical, and mechanical properties of the film, and evaluating its in vivo activities when used as a bread packaging material. The developed film was 15.03% thicker and 1.86% less transparent than the control film (without active agent coating layers: PP/PET/LDPE). While the color values of the developed film were slightly different from the control film, both films appeared similar to the naked eye. The tensile strength in the developed film was somewhat lower than that of the control film, while both films had statistically comparable values for elongation at break. During storage of sliced bread packaged in the developed film, the film both deterred insects from approaching toward and impeded the growth of microorganisms in the bread. These results suggest the potential applicability of the developed film as an active food packaging material with insect repellent and antimicrobial activities. PRACTICAL APPLICATION: A multilayer film incorporated with insect repellent and antimicrobial coating layers was applied in sliced wheat bread packaging. The developed film effectively inhibited approaches of stored-product insects to packaged bread and growth of microorganisms on the bread surface. It can be used as an active food packaging material that improves the safety and shelf-life of foods.


Assuntos
Antibacterianos/química , Pão/análise , Conservação de Alimentos/métodos , Illicium/química , Repelentes de Insetos/química , Óleos Voláteis/química , Timol/química , Animais , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Pão/microbiologia , Embalagem de Alimentos/instrumentação , Conservação de Alimentos/instrumentação , Repelentes de Insetos/farmacologia , Insetos/efeitos dos fármacos , Insetos/crescimento & desenvolvimento , Óleos Voláteis/farmacologia , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Polietileno/química , Polipropilenos/química , Timol/farmacologia , Triticum/química , Triticum/microbiologia
12.
Parasit Vectors ; 12(1): 421, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31477155

RESUMO

BACKGROUND: Knowledge of mosquito movement would aid the design of effective intervention strategies against malaria. However, data on mosquito movement through mark-recapture or genetics studies are challenging to collect, and so are not available for many sites. An additional source of information may come from secondary analyses of data from trials of repellents where household mosquito densities are collected. Using the study design of published trials, we developed a statistical model which can be used to estimate the movement between houses for mosquitoes displaced by a spatial repellent. The method uses information on the different distributions of mosquitoes between houses when no households are using spatial repellents compared to when there is incomplete coverage. The parameters to be estimated are the proportion of mosquitoes repelled, the proportion of those repelled that go to another house and the mean distance of movement between houses. Estimation is by maximum likelihood. RESULTS: We evaluated the method using simulation and found that data on the seasonal pattern of mosquito densities were required, which could be additionally collected during a trial. The method was able to provide accurate estimates from simulated data, except when the setting has few mosquitoes overall, few repelled, or the coverage with spatial repellent is low. The trial that motivated our analysis was found to have too few mosquitoes caught and repelled for our method to provide accurate results. CONCLUSIONS: We propose that the method could be used as a secondary analysis of trial data to gain estimates of mosquito movement in the presence of repellents for trials with sufficient numbers of mosquitoes caught and repelled and with coverage levels which allow sufficient numbers of houses with and without repellent. Estimates from this method may supplement those from mark-release-recapture studies, and be used in designing effective malaria intervention strategies, parameterizing mathematical models and in designing trials of vector control interventions.


Assuntos
Culicidae/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Mosquitos Vetores/efeitos dos fármacos , Distribuição Animal , Animais , Culicidae/fisiologia , Habitação , Funções Verossimilhança , Modelos Estatísticos , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia
13.
Environ Pollut ; 255(Pt 1): 113153, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31520906

RESUMO

Plant essential oils are regarded as interesting alternative tools to be integrated into the management of pest insects. However, as they generally consist of mixtures of numerous molecules, the physiological basis for their action is unresolved. Here, we evaluated the effects of essential oil of the Neotropical plant Siparuna guianensis Aubl., commonly known as Negramina, against an important pest insect: the green peach aphid Myzus persicae (Sulzer), and also in two non-target natural enemies: the ladybeetle predators Coleomegilla maculata (DeGeer) and Eriopis connexa (Germar). In addition, we conducted a computational docking analysis for predicting the physical interactions between the two Negramina essential oil major constituents: ß-myrcene and 2-undocanone, and the transient receptor potential (TRP) channels as potential binding receptors in the aphid and ladybeetles. As the most important results, Negramina essential oil caused mortality in M. persicae aphids with an LC95 = 1.08 mg/cm2, and also significantly repelled the aphids at concentrations as low as 0.14 mg/cm2. Our computational docking analysis reinforced such selectivity actions as the Negramina essential oil major compounds (i.e., ß-myrcene and 2-undocanone) bound to the TRP channels of M. persicae but not to ladybeetle-related TRP channels. Interestingly, the exposure to the Negramina essential oil did not affect the predatory abilities of C. maculata but increased the abilities of E. connexa to prey upon M. persicae. Collectively, our findings provided a physiological basis for the insecticidal and selectivity potential of Negramina essential oil, reinforcing its potential as a tool to be used in integrated pest control programs.


Assuntos
Afídeos/efeitos dos fármacos , Besouros/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Laurales/química , Óleos Voláteis/farmacologia , Óleos Vegetais/farmacologia , Monoterpenos Acíclicos/análise , Animais , Óleos Voláteis/química , Óleos Vegetais/química
14.
Acta Trop ; 200: 105171, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521623

RESUMO

The ability of Aedes albopictus Skuse to transmit several pathogens to humans makes it a very important mosquito with public health significance. Ecofriendly products as alternatives to synthetic chemicals for the control of mosquito vectors are needed. Therefore, the larvicidal and repellent effects of two nontoxic chemicals, butyl anthranilate (BA) and ethyl anthranilate (EA), at different concentrations were compared in A. albopictus. The repellency persistence of BA and three commercial mosquito repellent products (Liushen repellent spray, DKB Korean, Raid repellent spray) against A. albopictus was compared. The results showed that 0.1% concentrations of BA and EA solutions were highly toxic to A. albopictus larvae, and the mortality rate was >90% after 4 h of treatment. We found that BA was more repellent than EA, and at 0.1% BA and 1% EA, and the repellency rates were 53.62% and 38.47%, respectively. Overall, 5% BA presented a significantly longer repellency time than the three commercial repellent products against female A. albopictus. These results indicate that BA has significant larvicidal and repellent effects and can be exploited further for the development of ecofriendly alternatives to existing toxic chemicals currently used for mosquito control.


Assuntos
Aedes/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Larva/efeitos dos fármacos , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , ortoaminobenzoatos/farmacologia , Animais , Feminino , Humanos
15.
PLoS One ; 14(8): e0221659, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31442282

RESUMO

Ticks are second only to mosquitoes as vectors of disease to humans and animals. Tick host detection is mainly ascribed to Haller's organ, a complex sensory structure on the tick foreleg that detects odors, carbon dioxide and heat, but these host detection mechanisms are not well understood. There is anecdotal evidence that ticks and other ectoparasites are attracted to heat, but it has never been demonstrated that they use radiant heat to detect hosts at a distance. In fact, previous attempts to do this have concluded that radiant heat was not used by ticks. Here we use a novel thermotaxis assay to investigate the detection range, temperature dependence and repellent sensitivity of heat perception in ticks and to identify the sensory organ responsible for this sense. We show that Amblyomma americanum and Dermacentor variabilis ticks can locate a human from several meters away by radiant heat sensed by the part of Haller's organ known as the capsule, a covered spherical pit organ. An aperture in the capsule cover confers directionality and highly reflective interior surfaces of the capsule concentrate radiation on the sensilla to sharpen directionality and increase sensitivity. Commercial insect repellents provide an effective means of personal protection against potentially infectious tick bites by hindering host-seeking behavior. Low concentrations of the insect repellents DEET, picaridin, 2-undecanone, citronellal and nootkatone eliminate thermotaxis without affecting olfaction-stimulated host-seeking behavior. Our results demonstrate that the tick Haller's organ capsule is a radiant heat sensor used in host-finding and that repellents disrupt this sense at concentrations that do not disrupt olfaction. We anticipate that this discovery will significantly aid insect repellent research and provide novel targets for the development of innovative integrated pest management programs and personal protection strategies for ectoparasites and vector-borne disease.


Assuntos
Estruturas Animais/fisiologia , Temperatura Alta , Repelentes de Insetos/farmacologia , Ixodidae/fisiologia , Estruturas Animais/efeitos dos fármacos , Animais , Bioensaio , Feminino , Ixodidae/efeitos dos fármacos , Masculino , Movimento
16.
J Food Sci ; 84(9): 2520-2527, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31408214

RESUMO

Previous study reported the development of insect-proof halloysite nanotubes (HNTs) and food packaging; however, the duration of their insecticidal properties remains unclear. Here, we aimed to (1) demonstrate the duration of repellency of clove bud oil (CO) encapsulated by HNTs for more than 30 days, and (2) manufacture insect-proof film containing HNTs for commercial use. Also, the release behavior of CO from insect-resistant HNTs was evaluated and HNTs were applied to food packaging composed of polypropylene and low-density polyethylene films to prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larva infestation. CO, a natural insecticide, was embedded with HNTs and polyethyleneimine (PEI) via vacuum pulling process to cause a slow and gradual release of CO. The sustained release profile of CO from CO-containing HNTs with a PEI coating [(HNTs/CO/layer-by-layer (LBL)] was verified by gas chromatography analysis. The repellent activity of HNTs/CO/LBL was observed for up to 46 days, whereas CO film and HNTs/CO film exhibited no insecticidal activities during the test period. After 30-day exposure, the HNTs/CO/LBL film exhibited a 7-day extension in the penetration test. To evaluate the insecticidal properties of the insect-proof film (HNTs/CO/LBL scale-up film) manufactured in an industrial facility, the inhibitory effects of HNTs/CO/LBL scale-up film on insect infestation was elucidated in both the segregation and combination tests. As a result, HNTs/CO/LBL alone or gravure-printed film treated with HNTs/CO/LBL were capable of protecting food from insect infestation. PRACTICAL APPLICATION: Halloysite nanotubes containing natural insect repellent were applied to industrial production of food packaging. Commercial cornflake cereal packaging using insect-resistant film successfully inhibited pest infestation. Insect-proof film produced at an industrial facility can be utilized to protect processed food from insect infestation.


Assuntos
Óleo de Cravo/farmacologia , Embalagem de Alimentos/instrumentação , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Lepidópteros/efeitos dos fármacos , Nanotubos/química , Animais , Argila/química , Óleo de Cravo/química , Repelentes de Insetos/química , Inseticidas/química , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Lepidópteros/crescimento & desenvolvimento , Polietileno/química , Polipropilenos/química
17.
J Oleo Sci ; 68(9): 931-937, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31413242

RESUMO

The essential oil extracted from roots and rhizomes of Ligusticum jeholense Nakai et Kitagawa was investigated for its chemical composition by GC-MS analysis, and evaluated for its contact toxicity and repellency against Tribolium castaneum and Lasioderma serricorne, along with some of its individual components. The essential oil was rich in aromatics (65.34%) with low molecular weight. Major components included sedanolide (33.95%), 3-butylidenephthalide (18.76%), spathulenol (8.90%) and myristicin (6.76%). The results of bioassays indicated that the essential oil of L. jeholense and 3-butylidenephthalide possessed significant repellent activities against T. castaneum at 2 and 4 h post-exposure. Meanwhile, 3-butylidenephthalide had potent contact toxicity against L. serricorne (LD50 = 13.64 µg/adult). The minor component n-butylbenzene in the oil was highly toxic to T. castaneum (LD50 = 23.99 µg/adult) and L. serricorne (LD50 = 7.86 µg/adult) in contact assays, but failed to repel these beetles at all testing concentrations. Spathulenol and myristicin exerted good insecticidal and repellent effects on the two target insects. This work suggests that the essential oil of L. jeholense has promising potential for development as natural insecticide or repellent to control pest damage in warehouses.


Assuntos
Derivados de Benzeno/farmacologia , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Anidridos Ftálicos/farmacologia , Tribolium/efeitos dos fármacos , Animais , Ligusticum/química , Óleos Voláteis/análise , Óleos Voláteis/toxicidade
18.
J Cosmet Sci ; 70(4): 197-207, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31441773

RESUMO

Studies on topical repellent efficacy conducted with caged mosquitoes in the laboratory are important to both the development and regulation of insect repellents. Guidelines for laboratory studies stipulate specific densities, sex ratios, and biting rates, whereas those for field studies are governmentally required before a promising repellent can be registered for human use. These protocols stipulate minimum biting rates alone. Relatively little is known, however, about the influence of mosquito density and sex ratio on their biting propensity, either in the field or laboratory. Using Environmental Protection Agency guidelines for cage testing, we studied the influence of mosquito density and sex ratio in laboratory repellency tests of the biopesticide Ethyl butylacetylaminopropionate (IR3535™) (20%) against three mosquito species (Aedes aegypti, Anopheles aquasalis, and Culex quinquefasciatus). DEET [3-(N-acetyl-N-butyl) aminopropionic acid ethyl ester] (20%) in a laboratory prepared formulation was used as a comparison article. Studies were conducted by trained investigators at the BioAgri Laboratories in Brazil. We found that higher mosquito density generally decreased protection time, but that the influence of sex ratio was more complex. The presence of male mosquitoes increased protection times against Aedes and Anopheles perhaps because mate-seeking males interfered with female feeding. Interestingly, by contrast, protection times decreased against Culex in the presence of males. Such considerations may potentially assist in improving the match between cage and field testing under a broader range of conditions that permit more accurate labeling of repellents for safe and effective use by consumers.


Assuntos
Aedes , Anopheles , Culex , Repelentes de Insetos/farmacologia , Animais , Feminino , Repelentes de Insetos/química , Masculino , Propionatos , Razão de Masculinidade , Estados Unidos
19.
Insect Biochem Mol Biol ; 113: 103224, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31446031

RESUMO

In addition to its primary function as an insect repellent, DEET has many "off-label" properties, including a deterrent effect on the attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generated outward (inhibitory) currents on ORs sensitive to oviposition attractants. Here, we systematically investigated these inhibitory currents. We recorded dose-dependent outward currents elicited by DEET and other repellents on ORs from Culex quinquefasciatus, Aedes aegypti, and Anopheles gambiae. Similar responses were observed with other plant-derived and plant-inspired compounds, including methyl jasmonate and methyl dihydrojasmolate. Inward (regular) currents elicited by skatole upon activation of CquiOR21 were modulated when this oviposition attractant was coapplied with a repellent. Compounds that generate outward currents in ORs sensitive to oviposition attractants elicited inward currents in a DEET-sensitive receptor, CquiOR136. The best ligand for this receptor, methyl dihydrojasmolate, showed repellency activity but was not as strong as DEET in our test protocol.


Assuntos
Aedes/efeitos dos fármacos , Anopheles/efeitos dos fármacos , Culex/efeitos dos fármacos , Proteínas de Insetos/antagonistas & inibidores , Repelentes de Insetos/farmacologia , Oviposição/efeitos dos fármacos , Receptores Odorantes/antagonistas & inibidores , Aedes/fisiologia , Animais , Anopheles/fisiologia , Quimiotaxia/efeitos dos fármacos , Culex/fisiologia , Monoterpenos Cicloexânicos/farmacologia , DEET/farmacologia , Mentol/análogos & derivados , Mentol/farmacologia , Piperidinas/farmacologia , Propionatos/farmacologia
20.
Insect Biochem Mol Biol ; 113: 103213, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31442487

RESUMO

Mosquitoes rely heavily on the olfactory system to find a host for a bloodmeal, plants for a source of energy and suitable sites for oviposition. Here, we examined a cluster of eight odorant receptors (ORs), which includes one OR, CquiOR1, previously identified to be sensitive to plant-derived compounds. We cloned 5 ORs from Culex quinquefasciatus and two ORs from Aedes aegypti, ie, CquiOR2, CquiOR4, CquiOR5, CquiOR84, CquiOR85, AaegOR14, and AaegOR15 and then deorphanized these receptors using the Xenopus oocyte recording system and a large panel of odorants. 2-Phenylethanol, phenethyl formate, and phenethyl propionate were the best ligands for CquiOR4 somewhat resembling the profile of AaegOR15, which gave the strongest responses to phenethyl propionate, phenethyl formate, and acetophenone. In contrast, the best ligands for CquiOR5 were linalool, PMD, and linalool oxide. CquiOR4 was predominantly expressed in antennae of nonblood fed female mosquitoes, with transcript levels significantly reduced after a blood meal. 2-Phenylethanol showed repellency activity comparable to that of DEET at 1%. RNAi experiments suggest that at least in part 2-phenylethanol-elicited repellency is mediated by CquiOR4 activation.


Assuntos
Aedes/fisiologia , Culex/fisiologia , Flores/química , Proteínas de Insetos/genética , Odorantes/análise , Receptores Odorantes/genética , Aedes/genética , Animais , Quimiotaxia , Culex/genética , Feminino , Proteínas de Insetos/metabolismo , Repelentes de Insetos/farmacologia , Receptores Odorantes/metabolismo , Especificidade da Espécie
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