Meeting Abstract
It is well-established that some parasitic microorganisms manipulate the behavior of their host, but the mechanisms by which they accomplish this remain a mystery, especially given the parasites’ small size in relation to their hosts. One possible means for overcoming this size discrepancy is for individuals to coordinate their behavior. Fungi from the species complex Ophiocordyceps unilateralis infect ants of the tribe Camponotini, inducing aberrant host behaviors that precisely place host cadavers in areas suited for parasite dispersal. Fungi are thought to enter the host as individual cells, which proliferate in the hemocoel for two to three weeks. This implies that the timing of host manipulation depends on the parasite reaching an optimal stage of development and distribution within the host. In this study, we examine the distribution of the fungus and its interaction with ant tissues at the time of manipulation. O. unilateralis fungi were visualized inside manipulated Camponotus castaneus ants using Serial Block-Face Scanning Electron Microscopy (SBF-SEM) and Confocal Laser Scanning Microscopy (CLSM). SBF-SEM images and 3D reconstructions of head and leg muscle tissue reveal that this parasite exhibits coordinated behavior by forming fungal networks through cell-cell fusions. CLSM images of the brain suggest that the fungus surrounds the brain but does not enter it while the host is still alive.
