Insights into the growth and biochemical defense responses associated with fenitrothion toxicity and uptake by freshwater cyanobacteria.

The extensive use of fenitrothion (FNT) in agricultural practices induces its persistence in soil and waterways. Therefore, it is essential to implement effective management practices such as using cyanobacteria for FNT removal and accumulation, particularly under accidental contamination. To this end, we evaluated the responses of two freshwater cyanobacteria taxa, Nostoc muscorum and Anabaena laxa to mild (7.5 mg L-1) and high (15 mg L-1) levels of FNT over a period of 7 d. Compared to N. muscorum, A. laxa was more tolerant to FNT, exhibiting higher FNT uptake and removal efficiencies at mild (16.3%) and high (17.5%) levels. FNT induced a dose-dependent decrease in cell growth, Chl a, phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase/oxygenase activities, which were more pronounced in N. muscorum. Moreover, FNT significantly increased oxidative damage markers i.e., increased lipid peroxidation (MDA), protein oxidation, H2O2 levels and NADPH oxidase enzyme activity, to more extent in N. muscorum. Compared to N. muscorum, A. laxa had high antioxidant capacity (FRAP), glutathione and increased activities of glutathione-S-transferase, glutathione reductase, glutathione peroxidase and superoxide dismutase, suggesting a robust antioxidant defense mechanism to mitigate FNT toxicity. However, N. muscorum devoted the induction of ascorbate content and the activity of catalase, peroxidase, monodehydroascorbate reductase, ascorbate peroxidase, and dehydroascorbate reductase enzymes. Although A. laxa had greater intracellular FNT, it experienced less FNT-induced oxidative stress, likely due to over production of antioxidants. Consequently, A. laxa is considered as a promising candidate for FNT phycoremediation. Our findings provide fundamental information on species-specific toxicity of FNT among cyanobacteria and the environmental risk of FNT toxicity in aquatic environments.

Pesticides in surface water of the Ondas river watershed, western Bahia, Brazil: Spatial-seasonal distribution and risk assessment.

This study investigated the occurrence and seasonal distribution of different classes of pesticides in surface waters of the Ondas River Watershed, as well as potential risks to the aquatic health and human water consumption in the western region of Bahia state, Brazil. Two gas chromatography-mass spectrometry analytical methods were applied to monitor 34 pesticides in water samples collected during both the dry and rainy seasons at 17 sites. Upon individual analysis, only γ-HCH, methoxychlor, demeton-S, methyl parathion, fenitrothion, chlorpyrifos, and azoxystrobin exhibited statistically significant differences between seasons. During rainy season, concentration medians of residues were higher for γ-HCH (74.7 ng L-1), methoxychlor (25.1 ng L-1), and azoxystrobin (47.2 ng L-1), potentially linked to historical contamination or illegal use. Conversely, pesticides like methyl parathion, fenitrothion, and chlorpyrifos, belonging to the organophosphate class, showed higher concentration medians in the dry period, measuring 75.1, 5.50, and 10.8 ng L-1, respectively, probably due to region crop activities. The risk quotient (RQ) assessment for aquatic life indicated that 59.0% of the samples in the dry season and 76.0% in the rainy season had RQ values greater than one, signifying a critical scenario for species conservation. Regarding human consumption, elevated risks were observed for heptachlor in both sampling periods and for azoxystrobin during the rainy season, surpassing RQ levels above 1, indicating danger in untreated water ingestion. Additionally, 24.0% and 53.0% of the samples in the dry and rainy seasons, respectively, contained at least one pesticide exceeding the EU resolution limit (100 ng L-1). Therefore, considering this information, implementing mitigation measures to avoid the river's contamination becomes imperative.

Determinación de la sensibilidad a insecticidas organofosforados, carbamato y piretroides en poblaciones de Aedes aegypti Linneaus, 1762 ( Díptera: Culicidae ) de Panamá / Determining the status of susceptibility to organophosphate, carbamate and pyrethroids insecticides in populations of Aedes aegypti Linneaus, 1762 ( Diptera: Culicidae ) in Panamá

Introducción. Se llevó a cabo un estudio para determinar la sensibilidad de Aedes aegypti provenientes de regiones de alto riesgo de transmisión de dengue en Panamá, a insecticidas organofosforados, carbamatos y piretroides. Objetivo. Evaluar la sensibilidad a insecticidas piretroides, organofosforados y carbamatos en poblaciones de Ae. aegypti provenientes de ocho sitios pertenecientes a siete municipios de Panamá. Materiales y métodos. Se recolectaron poblaciones de Ae. aegypti en diferentes tipos de criaderos localizados en áreas urbanas y se criaron en condiciones controladas de laboratorio. Con la generación F 1 de cada una de las cepas se hicieron bioensayos de sensibilidad siguiendo la metodología estandarizada por la Organización Mundial de la Salud para larvas y adultos. Resultados. Las ocho cepas de Ae. aegypti resultaron sensibles a los insecticidas piretroides deltametrina, lambdacihalotrina y ciflutrina, el organofosforado fenitrotión y los carbamato propoxur y bendiocarb. Solo la cepa CHITRE resultó con resistencia moderada al insecticida deltametrina en larvas (FR 50 =5x). Sin embargo, en adultos resultó sensible. Conclusiones. Es necesaria la vigilancia periódica de la sensibilidad de las poblaciones de Ae. aegypti de los municipios evaluados, con el propósito de conservar en las poblaciones el carácter sensible a estos insecticidas. Los insecticidas aplicados para el control de Ae. aegypti pueden seguir siendo utilizados en los municipios evaluados, pero depende de la sensibilidad de los mosquitos en el área específica.

Introduction: We studied the susceptibility to organophosphate, carbamate and pyrethroid insecticides of Aedes aegypti from different regions of high transmission risk for dengue in Panama. Objective: To evaluate the susceptibility to organophosphate, carbamate and pyrethroid insecticides in Ae. aegypti from eight sites belonging to seven municipalities in Panamá. Materials and methods: We collected Ae. aegypti larval populations in different types of breeding sites located in urban areas. Insects were reared in laboratory control conditions. With the F 1 generation of each strain we performed susceptibility bioassays using WHO standardized methodology for larvae and adults. Results: The eight Ae. Aegypti strains were susceptible to the pyrethroid insecticides: deltamethrin, lambdacyhalothrin and cifluthrin, to the organophosphate fenitrothrion, and to the carbamates propoxur and bendiocarb. Only the CHITRE strain exhibited a moderate resistance to the insecticide deltamethrin in larvae (FR 50 =5x). However, adults were susceptible. Conclusions: It is necessary to perform periodic surveillance to evaluate the susceptibility of Ae. aegypti populations in the studied municipalities with the purpose of preserving their susceptible. The insecticides applied for Ae. aegypti control can still be used in the evaluated municipalities; however it will depend on the susceptibility of the mosquitoes in the specific area.

Toxicological and biochemical analysis of the susceptibility of sylvatic Triatoma infestans from the Andean Valley of Bolivia to organophosphate insecticide

To increase our knowledge of the natural susceptibility of Triatoma infestans to an organophosphate insecticide, we performed toxicological and biochemical studies on three sylvatic populations from Bolivia and two populations from domestic dwellings from Bolivia and Argentina. Fifty-per-cent lethal doses (LD50) were determined based on the topical application of fenitrothion on first instar nymphs and mortality was assessed at 24 h. Both type of populations exhibited LD50ratios significantly higher than 1 with a range of the values (1.42-2.47); the maximum value were found in a sylvatic (-S) population, Veinte de Octubre-S. Samples were biochemically analysed using a glutathione S-transferase activity assay. The highest significant activity was obtained for Veinte de Octubre-S and the lowest activity was obtained for the reference population (102.69 and 54.23 pmol per minute per mg of protein respectively). Two out of the three sylvatic populations (Veinte de Octubre-S and Kirus Mayu-S) exhibited significantly higher glutathione S-transferase activity than that of the reference population. Based on this analysis of the natural susceptibility of this organism to organophosphate insecticides, continental and focal surveys of organophosphate susceptibility should be conducted to evaluate the evolution and distribution of this phenomenon.

Fenitrothion induced oxidative stress and morphological alterations of sperm and testes in male sprague-dawley rats

OBJECTIVE: Fenitrothion residue is found primarily in soil, water and food products and can lead to a variety of toxic effects on the immune, hepatobiliary and hematological systems. However, the effects of fenitrothion on the male reproductive system remain unclear. This study aimed to evaluate the effects of fenitrothion on the sperm and testes of male Sprague-Dawley rats. METHODS: A 20 mg/kg dose of fenitrothion was administered orally by gavages for 28 consecutive days. Blood sample was obtained by cardiac puncture and dissection of the testes and cauda epididymis was performed to obtain sperm. The effects of fenitrothion on the body and organ weight, biochemical and oxidative stress, sperm characteristics, histology and ultrastructural changes in the testes were evaluated. RESULTS: Fenitrothion significantly decreased the body weight gain and weight of the epididymis compared with the control group. Fenitrothion also decreased plasma cholinesterase activity compared with the control group. Fenitrothion altered the sperm characteristics, such as sperm concentration, sperm viability and normal sperm morphology, compared with the control group. Oxidative stress markers, such as malondialdehyde, protein carbonyl, total glutathione and glutathione S-transferase, were significantly increased and superoxide dismutase activity was significantly decreased in the fenitrothion-treated group compared with the control group. The histopathological and ultrastructural examination of the testes of the fenitrothion-treated group revealed alterations corresponding with the biochemical changes compared with the control group. CONCLUSION: A 20 mg/kg dose of fenitrothion caused deleterious effects on the sperm and testes of Sprague-Dawley rats.

Toxicidad de insecticidas organofosforados en Musca domestica Linnaeus, 1758, (Diptera: Muscidae), cepa "El Limón" estado Aragua Venezuela / Toxicity of organophosphorous insecticides in Musca domestica Linnaeus, 1758 (Diptera: Muscidae) El Limón, Aragua state Venezuela

Fue determinada la línea base de susceptibilidad a los insecticidas organofosforados, fenitrotion y malation en adultos de Musca domestica L.(Diptera: Muscidae) de la cepa “El Limón” mantenida en condiciones de laboratorio a 28 ºC,70 +10% de humedad relativa y fotoperíodo de 12 horas. En los bioensayos se usaron adultos provenientes de la generación filial 33, machos y hembras de tres días de edad. Los valores de la DL50 y la DL95 expresados en mg/mL para ambos insecticidas fueron determinados, a través de bioensayos, por aplicación tópica de insecticidas (0,6µL), inmovilizando previamente a los insectos a bajas temperaturas (-15 °C durante 1 ’10 ”) observando valores para el insecticida fenitrotion de DL50 y DL95 en adultos machos de 0,8880 y 4,3318 mg/mL respectivamente y valores de DL50 y DL95 en hembras de 1,2248 y 4,8112 mg/mL respectivamente. Los valores de DL50 y DL95 para el insecticida malation en adultos machos fueron de 60,6269 yde 160,8213 mg/mL respectivamente y valores de DL50 y DL95 en hembras fueron de 56,9426 y 171,1323 mg/mL respectivamente. Las respuestas de las moscas adultas cepa “El Limón” fueron homogéneas para ambos insecticidas.

Resistance of Aedes aegypti from the state of Säo Paulo, Brazil, to organophosphates insecticides

Since the reintroduction of Aedes aegypti in the state of Säo Paulo, in the middle of the 1980-decade, organophosphate insecticides are being used to control the dengue vector. In 1996, an annual program for monitoring the susceptibility of Ae. aegypti to the insecticides was implemented. Some of the results of this monitoring program are presented. Ae. aegypti populations from ten localities have been submitted to bioassays with the diagnostic dose of temephos and fenitrothion. Only two (Marília and Presidente Prudente) remain susceptible to both insecticides and one (Santos) exhibits true resistance. Ae. aegypti from the remaining localities showed an incipient altered susceptibility. Resistance ratios varied from 1.2 to 2.9 for temephos and from 1.5 to 3.2 to fenitrothion, indicating moderate levels of resistance. Biochemical assays did not detect alterations in the enzyme acetilcholinesterase, but indicated that resistance is associated with esterases

Controle da cigarrinha-verde (Empoasca kraemeri (Ross & Moore, 1957) (Hemiptera - Homoptera: cicadellidae)) no feijoeiro (Phaseolus vulgaris) / Control of cigarrinha-verde (Empoasca kraemeri (Ross & Moore, 1957) (Hemiptera - Homoptera: cicadellidae)) in the beans (Phaseolus vulgaris)

Estudou-se os efeitos tóxicos dos inseticidas esfenvalerato, fenitrotion, fenpropatrin e monocrotofos sobre as ninfas de E. kraemeri em cultura de feijoeiro. A pesquisa doi conduzida no município de Nepomuceno - MG, utilizando uma lavoura comerical de cultivar "Carioca". Os compostos foram diluídos em água nas doses recomendadas pelos fabricantes para o controle de pragas, sendo a aplicaçäo realizada através de um pulverizador costal, propiciando volume de aplicaçäo de 400 L/ha. Os resultados mostraram que todos os compostos controlaram a praga em questäo, porém o fenitrotion na dose de 750 g i.a./ha apresentou o maior nível médio de controle.

Metabolitos nitrofenólicos urinarios de insecticidas organofosforados / Nitrophenols urinary metabolite od organophosphorus insecticides

El nivel urinario de nitrofenoles puede constituir un indicador adecuado de esposición a insecticidas organofosforados, que contienen dichos grupos en su molécula. Se detalla la metodología para la evaluación de p-nitrofenol y p-nitrocresol en orina. Se hidrolizan 3 ml de orina con HCI (c), en un baño de agua a ebullición y luego se extraen los nitrofenoles con n-hexano-éter etílico 70:30. Tratando, posteriormente, una alicuota del extracto orgánico con hexametildisilazano en hexano, se forman los derivados sililados, que se cuantifican por CGL, empleando una columna de 3% SE-30 y detector de captura electrónica de 63Ni. El método descripto constituye una simplificación del recomendado por la Agencia para la Protección Ambiental (EPA), de los Estados Unidos, para la determinación de p-nitrofenol. Es sensible, preciso y se detectan 50 ng/ml de p-nitrofenol y 100 ng/ml de p-nitrocresol en la orina. La recuperación es superior al 85%. La aplicación del método a orina de ratas tratadas con paratión o fenitrotión, permitió encontrar picos coincidentes con los tiempos de retención del p-nitrofenol y p-nitrocresol, respectivamente. Será de utilidad en Toxicología Ocupacional para evaluar el grado de contaminación de trabajadores que emplean paratión, metil paratión y/o fenitrotión.

La campaña de emergencia mediante rociamientos en volumenes ultrarreducidos contra ejemplares adultos de Aedes aegypti realizada en 1982 en Paramaribo, Suriname / Emergency campaign by ultralow volume sprayers against adult. Aedes aegypti samples carried out during 1982 in Paramaribo, Suriname

En un intento de detener una epidemia de dengue en la ciudad de Paramaribo, se efectuaron en mayo y junio de 1982 rociamientos con malatión al 95%, aplicado con pulverizadores de volumen ultrarreducido (ULV) montados en camiones. Toda la ciudad, con una superficie de 70 Km**2 y 552 km de calles, fue rociada dos veces en 37 noches de un período de siete semanas y media, utilizando dos pulverizadores durante cuatro horas cada noche (18.00 a 22.00 horas), con un intervalo de una semana entre los dos rociamientos de cada zona. Durante las tres primeras semanas de la campaña, una dosis de 456 ml de ingrediente activo por Km de calle (50 ml/ha si la amplitud de barrido era de 91 m) produjo una gran mortalidad de Aedes aegypti adultos colocados en jaulas en el interior y en el exterior de los edificios de una manzana rociada; sin embargo, los resultados de las pruebas con trampas de ovipostura indicaron únicamente una pequeña reducción del número de huevos y solo durante unos tres días después de la aplicación de aerosol. Por consiguiente, se incrementó la dosis a 901 ml/Km (99 ml/ha) en las semanas 4-7, pero en una segunda zona de prueba se encontró que el número de trampas con huevos se reducía muy poco y durante un período breve. Por lo tanto, parece que ninguna de las dosis fue adecuada para eliminar la población adulta de A. aegypti y, además, que el método de aplicación fue demasiado lento para detener la epidemia de dengue, objetivo de la campaña

Normas técnicas y de procedimientos para la lucha química contra el vector de la enfermedad de Chagas / Technical standards and procedures for chemical campaigr against the vector of the Chagas' disease

Se describen las normas técnicas y de procedimientos a seguir en las distintas etapas de la lucha química contra los triatomíneoas vectores de la enfermedad de Chagas: para la etapa de ataque, se indican la metodología operativa, el relevamiento entomológico, el reconocimiento geográfico, tipos y dosificación de insecticidas, evaluación entomológica post-tratamiento y relevamiento cartográfico que deben seguirse. También se describe la metodología a emplear en las etapas de consolidación y de vigilancia entomológica; así como la que deben seguir los servicios jurisdiccionales coordinados por el Servicio Nacional de Chagas. Concluye con un glosario de términos utilizados

Modo de acción de insecticidas en Triatoma infestans / Mode of action of insecticides in Triatoma infestans

Se analizan la acción ovicida de compuestos sintéticos (clorados, fosforados, carbamatos y piretroideos) en insectos -especialmente en Triatoma infestans-; la metodología de evaluación toxicológica de insecticida y ovicidas en el laboratorio (inmovilización del insecto, aplicación del tóxico y tratamiento estadístico de los resultados, técnicas de medición de la acción ovicida) y factores intervinientes en ella. También se describen los pasos básicos del proceso de intoxicación de insectos (Triatoma infestans): penetración por cutícula (modo de entrada de insecticidas de contacto, cinética de la penetración de insecticidas, factores intervinientes en la velocidad de penetración y penetración por tráquea); mecanismos metabólicos de insecticidas (metabolismo activante y detoxificante); y, sitio de acción de los insecticidas (ataque a un centro vital) o lesión bioquímica. Se concluye destacando la necesidad de profundizar los conocimientos sobre los temas expuestos