Effects of nickel exposure on testicular function, oxidative stress, and male reproductive dysfunction in Spodoptera litura Fabricius.

Nickel is an environmental pollutant that adversely affects the male reproductive system. In the present study, the effects of nickel exposure on Spodoptera litura Fabricius were investigated by feeding larvae artificial diets containing different doses of nickel for three generations. Damage to testes and effects on male reproduction were examined. The amount of nickel that accumulated in the testes of newly emerged males increased as the nickel dose in the diet increased during a single generation. Nickel exposure increased the amount of thiobarbituric acid reactive substances and decreased the amount of glutathione in treatment groups compared with the control. The activity levels of the antioxidant response indices superoxide dismutases, catalase, and glutathione peroxidase in the testes showed variable dose-dependent relationships with nickel doses and duration of exposure. Nickel doses also disrupted the development of the testes by decreasing the weight and volume of testes and the number of eupyrene and apyrene sperm bundles in treatment groups compared with the control. When the nickel-treated males mated with normal females, fecundity was inhibited by the higher nickel doses in all three generations, but fecundity significantly increased during the second generation, which received 5 mg kg(-1) nickel. Hatching rates in all treatments significantly decreased in a dose-dependent manner in the three successive generations. The effects of nickel on these parameters correlated with the duration of nickel exposure. Results indicate assays of testes may be a novel and efficient means of evaluating the effects of heavy metals on phytophagous insects in an agricultural environment.