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Food utilization and growth of cutworm Spodoptera litura Fabricius larvae exposed to nickel, and its effect on reproductive potential

Sun, Hong Xia, Tang, Wen Cheng, Chen, Hai, Chen, Wei, Zhang, Min, Liu, Xin, Zhang, Gu Ren
Chemosphere 2013 v.93 pp. 2319-2326
Spodoptera litura, cutworms, diet, exposure duration, fecundity, hatching, instars, larvae, nickel
Food utilization and growth of the 5th and 6th instar Spodoptera litura Fabricius larvae, and its effect on reproduction potential was evaluated by feeding larvae diets with different doses of Ni for 3 generations. Dose-dependent relationships between Ni levels and food consumption and growth were variable with different larval developmental period and Ni exposure duration. RCR, AD and RGR of the 6th instar larvae were much more affected by Ni exposure than those of 5th instar larvae, and the effects were strongest in the 3rd generation. It was found that RCR was significantly stimulated after 1 and 20mgkg−1 Ni exposure, while AD was significantly inhibited after 1, 5, 10 and 40mgkg−1 Ni exposure. However, lower levels of Ni (⩽5mgkg−1) significantly increased and higher levels of Ni (⩾10mgkg−1) significantly decreased RGR. In 3 successive generations, 10mgkg−1 Ni significantly increased the ECI and ECD of the 5th instar larvae, and 5mgkg−1 Ni significantly increased the ECD of the 6th instar larvae. However, ECD were all significantly inhibited with 20mgkg−1 Ni exposure. Results also revealed that durations of larvae were shortened at low levels of Ni, but extended at high levels of Ni. Fecundity was inhibited by the highest Ni doses in each generation, while improved by low Ni doses in the 3rd generation. Hatching rates in all treatments were significantly decreased in a Ni dose-dependent manner. Study indicated that effects of Ni on these parameters were predominant with the increasing Ni exposure period.