Immune reactions of the lesser mulberry pyralid, Glyphodes pyloalis Walker (Lepidoptera: Pyralidae) to the entomopathogenic fungus, Beauveria bassiana (Bals.- Criv.) Vuill and two developmental hormones
Keywords:hemocyte, nodulation, juvenile hormone (JH), ecdysone, cellular immunity
Effects of Beauveria bassiana (Bals.-Criv.) spores on immune functions of Glyphodes pyloalis
Walker larvae were studied. Total and differential hemocyte counts revealed that infection by B. bassiana caused a dramatic change in hemocyte number. In vivo and in vitro studies demonstrated that increase in time exposure to fungal pathogen resulted in elevated phagocytic activity. Nodules were formed in response to spore injection and their numbers were maximal 6 h post injection. The phenoloxidase (PO) activity in treated larvae changed significantly 3 and 6 h after spore injection compared with the control larvae. The reduction in PO activity was observed 12 and 24 h post injection. Effect of two developmental hormones, juvenile hormone (JH) and ecdysone on cellular immune response of G. pyloalis were also evaluated. Larval treatment with JH prior to B. bassiana spore injection reduced nodulation while ecdysone enhanced it. These results demonstrated that ecdysone and JH play an important regulatory role in the immune response in the studied insect.