Bark beetle – fungal symbiosis. III. Ultrastructure of conidiogenesis in a Sporothrix ectosymbiont of the southern pine beetle

Abstract

SJB 133 is an isolate of a variety of Ceratocystis minor that is found in a Sporothrix imperfect state as an ectosymbiont of Dendroctonus frontalis Zimm. Within the mycangium (fungal transport pocket of the beetle), SJB 133 grows in yeast-like fashion. Cells contain prominent vacuoles which appear to bridge between dividing cells. Hypha-like transition cells are also present. In continuous culture on potato carrot agar, SJB 133 produces sympodial conidiophores. The resulting conidia are quite similar to the yeast-like cells in the mycangium and the conidiophores resemble some of the transition cells.