Survival of Conidiobolus spp. and Basidiobolus ranarum in relation to relative humidity and temperature

Survival of saprotrophs and opportunistic pathogens of arthropods was studied in 8 Conidiobolus spp. and in Basidiobolus ranarum. Response to brief adverse relative humidity (RH < 98 %) during conidium discharge ranged from large immediate loss of conidium viability (C. adiaeretus) to little effect (B. ranarum). Primary conidia stored under different combinations of RH (90–98.5 %) and temperature (2–35 °C) varied in median survival time (ST50 and ST10) from <1 d to >90 d. Conidia of C. osmodes and B. ranarum survived best at 2 °C; for other species 10 °C was optimal. For samples buried in a Larix plantation, primary conidia survived 28 d for C. adiaeretus (>81 d for its secondary conidia and microconidia) and 338 d for (B. ranarum). Retrieved mycelium (including resting spores) for all species, renewed growth after at least 81 d. Implications for niche differentiation and trophic modes are discussed.