Effects of metribuzin on rainbow trout (Oncorhynchus mykiss)

Abstract

AbstrAct:The aim of this study was to assess the effect of metribuzin on rainbow trout (Oncorhynchus mykiss). An experimental group of fish was exposed to Sencor 70 WG pesticide product (active substance 70% of metribuzin). The acute semistatical toxicity test lasting 96 h was performed on rainbow trout juveniles. The 96hLC50 value of Sencor 70 WG was 89.3 mg/l. An examination of the haematological and biochemical profile and histopathological tissue examinations were performed on one-to two-year-old rainbow trout after 96 h of exposure to Sencor WG 70 in a concentration of 89.3 mg/l. The experimental group showed significantly lower values (P < 0.01) of plasma total proteins, triacylglycerols, aspartate aminotransferase, ammonia, calcium, lactate, alkaline phosphatase, erythrocyte count, haematocrit and significantly higher (P < 0.01) values of erythrocyte haemoglobin compared to the control group. A significant decrease (P < 0.01) in both the relative and absolute lymphocyte count and a significant increase (P < 0.01) in both the relative and absolute count of neutrophile granulocytes were also recorded in the experimental group. The histopathological examination revealed mild proliferation of goblet cells of the respiratory epithelium of secondary gill lamellae and hyaline degeneration of epithelial cells of the renal tubules of the caudal kidney. This alteration of kidney resulted in hypoproteinaemia, followed by the formation of transudate in the body cavity. The metribuzin-based Sencor WG 70 pesticide product was classified among substances harmful to fish.

The Effects of Pyrethroid and Triazine Pesticides on Fish Physiology

“…In rodents, the dominant phase I metabolic reaction for triazine pesticides is cytochrome P450-mediated N-dealkylation (Hanioka et al, 1999 a,b). Triazine pesticides have a direct effect on kidney structure and function in freshwater fish (Velisek et al, 2008(Velisek et al, , 2009b. In our experiment, the caudal kidney of carp with chronic exposure to simazine showed destruction of the tubules, although chronic exposure to terbutryn had no effect on caudal kidney.…”

“…The source of ALP includes synthesis in the intestinal epithelium, kidney, and liver and is often increased in response to a biliary obstruction. Velisek et al (2008) also reported decreased ALP in rainbow trout after acute exposure to metribuzin. Chronic exposure to terbutryn at 0.2 and 2 µg/L resulted in significant increase in plasma AST and LDH activity.…”

“…In addition, this is a target organ of certain toxicants, since it is a major route for the excretion of foreign chemicals. It has been reported that acute and subchronic exposures to triazine result in lesions in kidneys and liver in fish (Velisek et al, 2008(Velisek et al, , 2009b. Simazine showed no effect on liver of common carp.…”

Recovery ability of common carp (Cyprinus carpio) after a short-term exposure to terbuthylazine

“…Velisek et al (2008) described a significant (P < 0.01) decrease in total protein, triacylglycerids, AST, calcium and lactate in blood plasma of O. mykiss after a 96-h treatment with a metribuzin-based pesticide Sencor 70 WG at a concentration of 96-h LC50. In that study, glucose, ALT and LDH were not affected when compared to the control group.…”

“…Histopathological changes in gills of O. mykiss exposed to metribuzin (Sencor 70 WG) for 96 h were described as mild proliferation of goblet cells of the respiratory epithelium of the secondary gill lamellae. Other alterations were revealed in the caudal kidney and liver (Velisek et al 2008). …”