Actividad repelente de aceites esenciales contra las picaduras de Lutzomyia migonei (Diptera: Psychodidae)

Repellent activity of plant essential oils against bites of Lutzomyia migonei (Diptera: Psychodidae). Natural repellents from plant extracts have demonstrated good efficacy against bites of some insect species. The present study evaluated the repellent effect of essential oils extracted from 8 plants species against bites of Lutzomyia migonei, the Leishmania vector. The essential oils were extracted by steam destillation in Clevenger chamber, from the following plants: Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plecthranthus amboinicus and Cinnamomun zeylanicum. Repellency tests were performed under laboratory conditions by the human hand method in cage assays, using female colonies of L. migonei. The more effective oils were tested at variable concentrations on different volunteers. The protection percentage and time were calculated. The results showed what oils of P. caeruleocanum and C. zeylanicum were the most effective. Although P. amboinicus oil also had repellent effect showed an irritant effect. The oils P. marginatum, H. suaveolens and P. racemosa showed no repellent effect, while the rest of oil extracts showed significant repellency in variable degrees. P. caeruleocanum and C. zeylanicum oils provided the 95% protection against bites of L. migonei for 3h. The P. caeruleocanum oil showed the greatest protection time, with a mean over 4h and 3h at concentrations of 50% and 10% respectively. The results suggest that the P. caeruleocanum oil could represent a potential natural repellent against Leishmania vectors. Rev. Biol. Trop. 58 (4): 1549-1560. Epub 2010 December 01.

Los repelentes naturales de extractos de plantas han mostrado eficacia contra diferentes especies de insectos. El presente estudio evaluó la acción repelente de aceites esenciales extraídos de ocho especies de plantas contra las picaduras de Lutzomyia migonei, vector de Leishmania. Los aceites esenciales se obtuvieron por hidrodestilación, utilizando una trampa de Clevenger, a partir de Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plectranthus amboinicus y Cinnamomun zeylanicum. Los ensayos de repelencia se realizaron sobre humanos en condiciones de laboratorio, frente a hembras de L. migonei provenientes de colonia, utilizando el método de la mano en la jaula. Los aceites con efecto repelente también se ensayaron con distintos voluntarios y concentraciones. Se determinó el porcentaje de protección y el tiempo de protección. Los resultados revelaron que el aceite de P. caeruleocanum y C. zeylanicum fueron los más efectivos. El aceite de P. amboinicus presentó efecto de repelencia satisfactorio, sin embargo, ocasionó picazón y toxicidad en la piel. Los aceites de P. marginatum, H. suaveolens y P. racemosa no evidenciaron efecto repelente; el resto de los aceites presentaron repelencia significativa en grado variable. Los aceites de P. caeruleocanum y C. zeylanicum mostraron un 95% de protección de 3h contra las picaduras de L. migonei. El aceite de P. caeruleocanum presentó el mayor tiempo de protección, de más de 4h y de 2h en concentraciones de 50% y 10%, respectivamente. Los resultados sugieren que el aceite P. caeruleocanum podría ser un potencial candidato como repelente natural contra la picadura de dípteros posibles transmisores de Leishmania.

Atividade inseticida in vitro do óleo de sementes de nim sobre Lutzomyia longipalpis (Diptera: Psychodidae) / In vitro insecticidal activity of seed neem oil on Lutzomyia longipalpis (Diptera: Psychodidae)

Lutzomyia longipalpis é o principal vetor da Leishmaniose visceral no Brasil. O objetivo deste trabalho foi avaliar o efeito do óleo de sementes de nim (Azadirachta indica) sobre ovos, larvas e adultos do vetor. Os insetos foram capturados no campo e mantidos no laboratório a ± 27 °C e 80 por cento de umidade relativa. Cinco tratamentos com diferentes concentrações foram realizados, usando-se dois controles negativos, um com água destilada e outro com Tween 80 (3 por cento) e um controle positivo com cipermetrina. Os ovos foram borrifados com o óleo em diferentes concentrações e avaliou-se o número de larvas eclodidas por 10 dias consecutivos. A mortalidade das larvas foi observada até a pupação, e a mortalidade dos adultos foi observada após 24, 48, e 72 horas. A análise estatística foi feita pelo teste de Tukey a 5 por cento de probabilidade. No teste com ovos, a maior concentração obteve 65,16 ± 3,24 por cento de eficácia. O teste com larvas apresentou 67,75 ± 2,21 por cento de eficácia na concentração de 100 mg.mL-1. Com adultos, a eficácia na concentração de 100 mg.mL-1 foi de 96,64 ± 4,11 por cento, após 24 horas. A análise fitoquímica revelou a presença de triterpenos. Esses resultados demonstram o potencial uso desse óleo no controle deste vetor.

Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Brazil. The objective was to evaluate the effect of oil from (Azadirachta indica) neem seeds on eggs, larvae and adults of the vector. The insects were captured in the field and kept in the laboratory at ± 27 °C and 80 percent relative humidity. Five treatments with different concentrations were performed using two negative controls (distilled water and Tween 80) and a positive control. The eggs were sprayed with the oil at different concentrations and the number of hatched larvae evaluated for 10 days. Mortality of larvae was observed to pupation and adult mortality was observed after 24, 48, and 72 hours. Statistical analysis was performed by Tukey test at 5 percent probability. The highest oil concentration of eggs obtained 65.16 ± 3.24 percent efficacy for reducing egg hatching. The test with larvae showed 67.75 ± 2.21 percent efficacy at a concentration of 100 mg.mL-1. In adults, the efficacy of the 100 mg.mL-1 concentration was 96.64 ± 4.11 percent after 24 hours. The phytochemical analysis revealed the presence of triterpenes. These results demonstrate the potential use of this oil in the control of this vector.

[Efficacy of deltamethrin-impregnated dog collars against sandflies at endemic focus of Bojnord district, North Khorasan province]

Domestic dogs are the most important reservoir of visceral leishmaniasis [VL] at the endemic foci of Iran. The disease are transmission to others dogs and human by sandflies, the logic of VL prevention in world is: dogs vaccination, chemical treatment dogs, diagnosis and eliminating of infected dogs, impregnated dogs with soaps that have been reported different degrees of success. Now using deltamethrin-impregnated dog collars have been pointed, because of its impacts good in prevents of infected dogs to VL. In this study, the Efficacy of indexs of dog collars [Scalibor Registered] was evaluated in North-Khorasan province.For this aim,6 dogs selected as well as had similar age, weight, race and not have VL. and randomly classified in two groups as treated and untreated In the beginning of the transmission season, three DMC was separately fitted to 3 dogs and the other ones were considered as control [collarless] group. Two weeks after collar fited and any 15 days from June 2006 to September 2007 in evening one of collar and collarless dogs with their regard replacement in any shift in. separate were exposed to wild-caught sandflies during night time [2 h after sunset] using two separate bed nets. At the end of exposure time, the sand flies were re-captured and transferred to inside netted caps and maintained at optimal condition for 24 hours in order to assess the mortality. Data analysis revealed that the blood-feeding index was 13.4% - 27.6% for DMS fitted dogs, and 54.2% - 59.3% for control [collarless] dogs which the difference is statistically significant [p<0.005]. Also the index of blood-feeding inhibition were 51.3% - 66.2% and 37% - 44.8% for collared and collarless dogs respectively and showed a significant difference [p<0.01]. The mortality was 20.42%- 21.88% for sand flies fed on collared dogs, and 1.04% - 6.17% for those fed on control dogs [p<0.004]. The range of combined effects [inhibition of blood-feeding and mortality] was found 72.37% - 86.62% for collared dogs, and 40.74% - 45.83% for control dogs. The findings of this study indicate the considerable effects of DMC on inhibition of blood-feeding as well as mortality of wild-caught sandflies

Dissociation between vasodilation and Leishmania infection-enhancing effects of sand fly saliva and maxadilan

In this study, the ability of maxadilan and Lutzomyia longipalpis salivary gland lysate to enhance the infection of CBA mice by Leishmania major and of BALB/c mice by L. braziliensis was tested. No difference was observed between sizes of lesion in CBA mice infected with L. major and treated or not with salivary gland lysate or maxadilan, although they were injected in concentrations that induced cutaneous vasodilation. Although parasites were more frequently observed in foot pads and spleens of animals treated with maxadilan than in the animals treated with salivary gland lysate or saline, the differences were small and not statistically significant. The lesions in BALB/c mice infected with L. braziliensis and treated with maxadilan were slightly larger than in animals that received Leishmania alone. Such differences disappeared 14 weeks after infection, and were statistically significant only in one of two experiments

Deltamethrin-impregnated dog collars have a potent anti-feeding and insecticidal effect on Lutzomyia longipalpis and Lutzomyia migonei

Deltamethrin-impregnated PVC dog collars were tested to assess if they were effective in protecting dogs from sand fly bites of Lutzomyia longipalpis and Lu. migonei. A protective effect against Old World species Phlebotomus perniciosus was demonstrated before. Four dogs wearing deltamethrin collars and three dogs wearing untreated collars (not impregnated with deltamethrin) were kept in separate kennels for over eight months in a village on the outskirts of Fortaleza in Cearß, Brazil. Periodically, a dog from each group was sedated, placed in a net cage for 2 h in which 150 female sand flies had been released 10-15 min before. Lu. longipalpis were used 4, 8, 12, 16, 22, 27, and 35 weeks after the attachment of the collars. Lu. migonei were used 3, 7, 11, 15, 22, 26, and 36 weeks after attachment. During 35 weeks, only 4.1 percent (81 of 2,022) Lu. longipalpis recovered from the nets with the deltamethrin collared dogs were engorged, an anti-feeding effect of 96 percent. Mortality initially was over 90 percent and at 35 weeks was 35 percent with half of the sand flies dying in the first 2 h. In contrast, 83 percent of the 2,094 Lu. longipalpis recovered from the nets containing the untreated collared dogs were engorged and the mortality ranged from zero to 18.8 percent on one occasion with 1.1 percent dying in the first 2 h. Similar findings were found with Lu. migonei: of 2,034 sand flies recovered over this period, only 70 were engorged, an anti-feeding effect of 96.5 percent, and mortality ranged from 91 percent initially to 46 percent at 36 weeks. In contrast, engorgement of controls ranged from 91 to71 percent and a mortality ranged from 3.5 to 29.8 percent. These studies show that deltamethrin impregnated collars can protect dogs against Brazilian sand flies for up to eight months. Thus, they should be useful in a program to control human and canine visceral leishmaniasis

Field monitoring of Cypermethrin residual effect on the mortality rates of the phlebotomine sand fly Lutzomyia longipalpis in the State of Paraíba, Brazil

In a visceral leishmaniasis endemic locality of northeast of Brazil where all settlements were treated with cypermethrin, a follow-up of Lutzomyia longipalpis populations was carried out by regular collections. The residual effect of the inseticide was studied using biological assays on three different types of walls. The results showed that the inseticides had an effect on intradomiciliar Lu. longipalpis populations limited to two months, and had no significant effect on peridomiciliar vector populations. The mortality rates of the tested sandflies were variable according to the type of wall. The decreasing of the inseticide effect was marked since the 3rd month, and mortality rates were identical whatever the type of wall since the 4th month. Unsufficient residual effect was detected after the 4th month.

La melatonina en el sistema inmunoneuroendocrino / Melatonin in the immuno-neuro-endocrine system

El conocimiento actual de las relaciones neuroendocrinas e inmunológicas confiere un rol importante a la melatonina (MT) en la regulación de los ritmos circadianos de los mamíferos. La función de la glándulapinela en todas las especies es traducir información del ciclo luz/oscuridad a los ritmos fisiológicos del organismo. La MT es producida casi exclusivamente en la oscuridad. En los humanos la secreción ocurre en correspondencia a la edad, disminuyendo en la vejez; guarda relación inversa con la temperatura del cuerpo; evidencia un efecto anti-estrés, posiblemente a través del sistema opioide; favorece la respuesta inmunológica y protege frente al daño tisular que provocan los radicales libres, por su fuerte acción antioxidante. La MT ha sido usada con éxito en la inducción del sueño en personas que ven perturbado su ritmo habitual de sueño por trabajos nocturnos, el síndrome de jet-lag u otras causas. No se ha logrado beneficio en el tratamiento de trastornos mayores del sueño, ni en la depresión ni en otros trastornos psiquiátricos. La presencia de receptores para la MT en múltiples órganos y sistemas estimula actualmente la investigación clínica sobre estas funciones posibles de la melatonina