Volume 10, Issue 2 (2008)                   JAST 2008, 10(2): 135-146 | Back to browse issues page

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Bandani A R. The Effects of Entomopathogenic Fungus, Tolypocladium cylindrosporum on Cellular Defence System of Galleria mellonella. JAST 2008; 10 (2) :135-146
URL: http://jast.modares.ac.ir/article-23-10221-en.html
Department of Plant Protection, Faculty of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran.
Abstract:   (5580 Views)
The entomopathogenic-fungus-life cycle is associated with the synthesis and secretion of a number of toxic metabolites, including extracellular enzymes and the low-molecular weight compound (toxin). The potential for a successful pathogen relies on the ability to overcome the various host-defence systems. Interaction between the fungus, Tolypocla-dium (Deuteromycetes), its secondary metabolite, and its host cellular defence were inves-tigated using in vivo and in vitro studies. In vitro studies showed that toxins (efrapeptins) inhibit phagocytic activity of Galleria mellonella (Lep: Pyralidae) haemocytes. The effect of efrapeptins on phagocytosis was in a dose-dependent manner i.e. the amount of phago-cytosis in a treated cell-culture with 0, 3, and 30 g efrapeptins per well was about 12, 7.5, and 4.5 %, respectively (P<0.05). In vivo studies showed that injection of insects with 0, 0.25, and 0.025 g toxin rendered percentages of phagocytosis of 13, 11.5, and 7.2, respec-tively (P<0.05). There was no significant reduction in the total haemocyte count (THC) when larvae were injected with Tolypocladium cylindrosporum spores until 24 hours fol-lowing injection. However, THC was suppressed at 48 hours post-treatment of larvae with spores. Considering that toxin suppresses phagocytosis, nodule formation, but not THC, this study suggests that efrapeptins may interfere with the ligand-receptor interactions that are likely to occur in the plasma membrane of specific haemocytes.
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Received: 2010/01/27 | Accepted: 2010/01/27 | Published: 2010/01/27

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