The effects of carbamate pesticide on fish in freshwater ecosystems: A review
There are potential hazards o non-target organisms associated with uncontrolled use of pesticides in agriculture and other purposes. Carbaryl is a methyl-carbamate 1- naphtholenol marketed in Nigeria as Vetox 85R and used in controlling soil insects and many insect pests of cash crops. It is also employed in controlling mites, lice, fleas, and ticks on poultry, cattle and domestic pets. Indiscriminate application on crop farms by aerial and ground spray, accidental spillages, dumping of empty pesticide containers into freshwaters and open fields, and leakages from containers are important means through which Vetox 85R gains entry into the environment. Vetox 85R is also applied on ponds and stagnant water purposely to control aquatic insects. Research reports reveal chronic and acute toxic effects of this chemical on fish and fish food. The deleterious effects of sublethal concentrations of carbaryl on fish during spawning period include rupture of blood vessels supplying the ovary with blood, rupture of ovigerous lamellae and enlargement of oocysts. Behavioral impact on fish includes restlessness. Chronically sub-lethal concentrations also resulted in hypoglycemia and depletion of liver glycogen. Other effects include rupture of the columnar epithelium of fish stomach. Carbamate insecticides are generally neurotoxic, inhibiting activity of cholinesterase. High concentration of carbaryl in water leads to fish and fish-food mortality.
Keywords: Carbaryl; fish; freshwater ecosystems; pesticide
International Journal of Natural and Applied Sciences Vol. 2 (3) 2006: pp. 235-240