Due to their ecological importance, fungi are suitable indicator organisms for anthropogenic stress. To estimate fungal biomass, the fungal membrane molecule ergosterol is often quantified as a proxy. Estimates based on ergosterol may, however, be distorted by exposure to demethylase inhibiting (DMI) fungicides, interfering with sterol synthesis. To test this hypothesis, we exposed ten fungal species to the DMI fungicide tebuconazole and measured concentrations of ergosterol and DNA per unit dry mass of the fungal hyphae. The latter served as alternative biomass proxy that is not specifically targeted by tebuconazole. Effects of tebuconazole on ergosterol concentrations were species-specific, while concentrations were on average reduced by 13%. In contrast, DNA concentrations were on average increased by 13%. We demonstrate that DMI fungicides – at close to field relevant levels – can distort fungal biomass estimation, complicating the use of this endpoint for environmental management.

由于其生态重要性，真菌是人为胁迫的合适指示生物。为了估计真菌生物量，通常将真菌膜分子麦角固醇量化为代理。但是，由于暴露于去甲基化酶抑制（DMI）杀菌剂会干扰基于甾醇的估计，从而干扰甾醇的合成。为了验证这一假设，我们将十种真菌暴露于DMI杀真菌剂tebuconazole中，并测量每单位干菌丝质量的麦角固醇和DNA浓度。后者用作替丁康唑未专门针对的替代生物质代理。戊唑醇对麦角固醇浓度的影响是物种特异性的，而浓度平均降低了13％。相反，DNA浓度平均增加了13％。