Determination of insecticides' lethal concentrations and metabolic enzyme levels in Triatoma dimidiata / Determinación de concentraciones letales y niveles de enzimas metabólicas de insecticidas en Triatoma dimidiata

Abstract: Objective: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. Materials and methods: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. Results: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and β-eterase levels. Conclusion: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.

Resumen: Objetivo: La factibilidad de usar los papeles impregnados y ensayos bioquímicos según la OMS para determinar concentraciones letales (CL50 y CL99) y niveles enzimáticos en la resistencia a insecticidas en Triatoma dimidiata. Material y métodos: Se calcularon la CL50 y CL99 con papeles impregnados según la OMS a diferentes concentraciones de malatión, propoxur y deltametrina; el porcentaje de acetilcolinesterasa insensible (iAChE); y los niveles de esterasas, glutatión S-transferasas, y monooxigenasas en ninfas de laboratorio del estadio I (5-7 días) se determinaron usando los ensayos bioquímicos según la OMS. Resultados: Se obtuvieron las CL50 y CL99 µg / cm2 respectivamente para malatión 43.83 y 114.38, propoxur 4.71 y 19.29, y deltametrina 5.80 y 40.46. Un 30% de las chinches tuvo iAChE, y sólo pocos individuos tuvieron niveles superiores de P450 y β-eterasas. Conclusión: Los papeles impregnados y ensayos bioquímicos que describe la OMS para otros insectos demostraron ser métodos factibles para monitorear la resistencia a insecticidas y las enzimas metabólicas involucradas en T. dimidiata.

Assessment of nephrotoxicity and histopathological lesions of albino rats exposure to DD-force and baygon insecticides / Evaluación de la nefrotoxicidad y lesiones histopatológicas tras la exposición de ratas Albino a los insecticidas DD-Force y Baygon

Although studies suggest adverse effects of pesticides, human exposure to insecticides in homes is increasing and reports on their health effects are limited. The study investigated nephrotoxic effects of organo phosphate and carbamate insecticides, DD-Force and Baygon, in albino rats. Forty-five albino rats divided into groups were exposed to DD-Force (dichlorvos) or Baygon (propoxur) indoor insecticidein wooden boxes in separate exposure duration of 1, 2, 3 and 4 hours/day for 14 consecutive days. Serum and kidney tissue obtained after sacrifice were used to determine markers of renal damage and histopathological analysis, respectively. Exposure of rats to the insecticides showed duration-dependent significant increases (p<0.05) in serum levels of urea, uric acid and creatinine compared to control. However, rats exposed to DD-Force insecticide induced significantly higher levels of urea, uric acid and creatinine compared to Baygon (p<0.05). Histopathological lesions were observed in rats exposed to the insecticides, particularly in the exposure duration of 3 or 4 hours/day. These findings suggest that acute exposure to DD-Force and Baygonis nephrotoxic and may induce renal damage in rats.

Aunque los estudios sugieren efectos adversos de los pesticidas, la exposición humana a los insecticidas en los hogares está aumentando y los informes sobre sus efectos sobre la salud son limitados. Este estudio investigó los efectos nefrotóxicos de los insecticidas órgano fosfato y carbamato, DD-Force y Baygon, en ratas albinas. Cuarenta y cinco ratas albinas divididas en grupos fueron expuestas a DD-Force (diclorvos) o Baygon (propoxur) insecticidas de interior en cajas de madera en una duración de exposición separada de 1, 2, 3 y 4 horas / día durante 14 días consecutivos. Muestras séricas y de tejido renal obtenidas después del sacrificio se utilizaron para determinar los marcadores de daño renal y el análisis histopatológico, respectivamente. La exposición de las ratas a los insecticidas mostró aumentos significativos dependientes de la duración (p<0.05) en los niveles séricos de urea, ácido úrico y creatinina en comparación con el control. Sin embargo, las ratas expuestas al insecticida DD-Force indujeron niveles significativamente más altos de urea, ácido úrico y creatinina en comparación con Baygon (p<0.05). Se observaron lesiones histopatológicas en ratas expuestas a los insecticidas, particularmente en la duración de exposición de 3 o 4 horas/día. Estos hallazgos sugieren que la exposición aguda a DD-Force y Baygonis nephrotóxico y puede inducir daño renal en ratas.

Propoxur-induced acetylcholine esterase inhibition and impairment of cognitive function: Attenuation by Withania somnifera.

Propoxur (2-isopropoxyphenyl N-methylcarbamate) is widely used as an acaricide in agriculture and public health programs. Studies have shown that sub-chronic exposure to propoxur can cause oxidative stress and immuno-suppression in rats. Carbamates are also known to exhibit inhibitory effect on cholinesterase activity, which is directly related to their cholinergic effects. In the present study, the effect of Withania somnifera (Ashwagandha), a widely used herbal drug possessing anti-stress and immuno-modulatory properties was studied on propoxur-induced acetylcholine esterase inhibition and impairment of cognitive function in rats. Male Wistar rats were divided into four groups. Group I was treated with olive oil and served as control. Group II was administered orally with propoxur (10 mg/kg b.wt.) in olive oil, group III received a combination of propoxur (10 mg/kg b.wt.) and W. somnifera (100 mg/kg b.wt.) suspension and group IV W. somnifera (100 mg/kg b.wt.) only. All animals were treated for 30 days. Cognitive behaviour was assessed by transfer latency using elevated plus maze. Blood and brain acetylcholine esterase (AChE) activity was also assessed. Oral administration of propoxur (10 mg/kg b.wt.) resulted in a significant reduction of brain and blood AChE activity. A significant prolongation of the acquisition as well as retention transfer latency was observed in propoxur-treated rats. Oral treatment of W. somnifera exerts protective effect and attenuates AChE inhibition and cognitive impairment caused by sub-chronic exposure to propoxur.

Deviation of negatively charged protein fractions in the trochophore and veliger larvae by the larvicidal action of baygon in freshwater pulmonate Gyraulus convexiusculus (Planorbidae).

In the present investigation egg capsules of Gyraulus convexiusculus were treated with different concentrations of baygon. A dose and duration dependent deviations in the number of negatively charged protein fractions in the trochophore and veliger larval stages were observed. It resulted into anomalies in the morphogenesis and organogenesis of corresponding larval stages. Most of the protein bands showed the decrease in the protein positive intensities in comparison to control. This suggested that baygon causes larval toxicity in Gyraulus convexiusculus.