38th Annual Meeting of the Society for Invertebrate Pathology

The effect of tannic acid, which is one of the chemicals involved in the immune response of woody plants caused by defoliation, on the performance of gypsy moth (Lymantria dispar L.) and its susceptibility to nuclear polyhedrosis virus (LdNPV) was studied. The following parameters were estimated: larvae weight, mortality rate, activities of detoxification (glutathione-S-transferase and esterase) and antioxidant enzymes (superoxide-dismutase, catalase), and thiol content in the tissue of insect midgut. Tannic acid was found to increase susceptibility of gypsy moth larvae to LdNPV by feeding on artificial diet. Larval mass was increased too under tannic acid and virus treatment in comparison with control. But sensitivity of larvae fed on natural diet with tannic acid to LdNPV was decreased. It was also found that the concentration of oxidized thiols in midgut of larvae fed on as natural as artificial diet was increased under effect of tannic acid and virus. This result testifies to increase of oxidizing process in insect midgut. It was shown that the increased concentration of tannic acid benefited insects in the “host plant-herbivore-virus” interaction, though most likely the defoliation-induced tannic acid in vivo may act otherwise.