Impact of differential feeding on the growth and development of Helicoverpa armigera (Hubner).

The growth and development of Helicoverpa armigera was observed in the laboratory by feeding them on different foods viz; leaf, flower and fruit of lady finger, cotton, pigeon pea and chick pea. Based on the food ingested, food digested and food excreted as well as on weight and size of the larvae and the duration of larval period, the fruit of chick pea was found to be the most suitable food for H. armigera development, as the food ingesta and food digesta of the larvae on pigeon pea were more than on the other plants. On the pigeon pea pod the larval growth and development was fast and larval duration was short. Next to the fruit, the larvae preferred the leaf of lady finger and cotton and flower of pigeon pea. The results suggested that the larval growth and development was dependent on the feed i.e. both on the part and the type of the plant.

Impact of copper on the oxidative metabolism of the fry of common carp, Cyprinus carpio (Linn.) at different pH.

In order to evaluate the impact of copper on the energetics of a fish, the levels of glucose, glycogen, pyruvate and lactate, the rate of tissue oxygen consumption and the activities of glycogen phosphorylase, isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) were estimated in the whole body of the fry of Cyprinus carpio immediately after 1, 7, 15 and 30 days on exposure to a sublethal concentration of copper 0.08 mgl(-1) at pH 7.5 (normal), 6.0 (weak acidic) and 9.0 (weak alkaline). Aprogressive increase in glucose level and glycogen phosphorylase activity with the corresponding decrease in glycogen level over the time of exposure at pH 7.5 indicated glycogenolysis. Increase in the rate of oxygen consumption, pyruvate level and ICDH and SDH activities at days 1 and 7 (day 1 > 7) followed by their decrease at days 15 and 30 (day 15 < 30) at pH 7.5 indicated an initial elevation in the energetics of the fish fry with a gradual suppression of it on prolonged exposure. During this period the animal might have relied more on energetically less efficient glycolysis as evident by the progressive increase in the level of lactate and LDH activity. The degree of glycogenolysis was relatively more at pH 6.5 than at pH 7.5. At that pH, a progressive decrease in glucose level with an increase in the pyruvate and lactate levels and in LDH activity and a decrease in the rate of oxygen consumption and ICDH and SDH activities revealed greater reliance of the fish on anaerobic glycolysis than on oxidative metabolism. At pH 9.0 also the fish fry initially exhibited glycogenolysis, but gradually it came to normal on day 30 (day 1 > 7 > 15 > 30). Decrease in the glucose level, increase in pyruvate level, rate of oxygen consumption, and ICDH and SDH activities at all the days of exposure suggested an elevation in oxidative metabolism, but it also came to normal on prolonged exposure. Even the lactate level and LDH activity initially increased but gradually reached to normal on day 30. These results indicated that copper suppresses the energetics of the fish fry at pH 6.0, elevates at pH 9.0 relative to the changes at pH 7.5 suggesting that the toxicity of copper is dependent on pH of the water.