EFFECT OF COLD-ACCLIMATION ON THE ANTIOXIDANT DEFENSE SYSTEM OF 2 LARVAL LEPIDOPTERA (NOCTUIDAE)

Activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (CR), glutathione-S-transfe rase (CST), as well as total glutathione (tGSH) concentration were ana lyzed in the hemolymph and fat body of the European corn borer Ostrini a nubilalis Hubn. and the Mediterranean borer Sesamia cretica Led. (Le pidoptera, Noctuidae). Controls were maintained at 8 degrees C while e xperimental groups of larvae were exposed to -3 degrees C for ten days and then to -12 degrees C for 23 days (only for Ostrinia). Cold expos ure significantly increased fat body SOD, CR, and GST activities of Os trinia larvae. Only CST activity and tGSH levels increased significant ly in Ostrinia larval hemolymph on cold exposure. In Sesamia larvae af ter cold exposure, hemolymph CAT activity was significantly lower, whi le fat body tGSH increased. The antioxidant defense systems of these t wo species show differences, probably influenced by their respective c old-hardiness metabolism. According to its antioxidant profile, the re sponse of Ostrinia suggests a significant physiological alteration in its metabolism during cold exposure, indicating a compensatory mechani sm. By contrast this is not evident in Sesamia. (C) 1997 Wiley-Liss, I nc.